From 58a4f350a8bc361d793cb96442f856362c18f195 Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Wed, 6 May 2020 01:51:10 +0300
Subject: [PATCH 01/33] Refactor gun pooling and simplify adapter option
 insertion

This patch refactors gun pooling to use Elixir process registry and
simplifies adapter option insertion.

Having the pool use process registry instead of a GenServer has a number of advantages:
- Simpler code: the initial implementation adds about half the lines of code it deletes
- Concurrency: unlike a GenServer, ETS-based registry can handle multiple checkout/checkin
requests at the same time
- Precise and easy idle connection clousure: current proposal for closing idle connections in
the GenServer-based pool needs to filter through all connections once a minute and compare their
last active time with closing time. With Elixir process registry this can be done
by just using `Process.send_after`/`Process.cancel_timer` in the worker process.
- Lower memory footprint: In my tests `gun-memory-leak` branch uses about 290mb on peak load (250 connections)
and 235mb on idle (5-10 connections). Registry-based pool uses 210mb on idle and 240mb on peak load
---
 config/config.exs                          |   2 +
 lib/pleroma/application.ex                 |   8 +-
 lib/pleroma/gun/conn.ex                    |  78 +-----
 lib/pleroma/gun/connection_pool.ex         | 129 ++++++++++
 lib/pleroma/gun/connection_pool/worker.ex  |  95 +++++++
 lib/pleroma/http/adapter_helper.ex         | 133 +++++++++-
 lib/pleroma/http/adapter_helper/default.ex |  17 ++
 lib/pleroma/http/adapter_helper/gun.ex     |  32 +--
 lib/pleroma/http/adapter_helper/hackney.ex |   3 +
 lib/pleroma/http/connection.ex             | 124 ---------
 lib/pleroma/http/http.ex                   |  53 ++--
 lib/pleroma/pool/connections.ex            | 283 ---------------------
 lib/pleroma/pool/pool.ex                   |  22 --
 lib/pleroma/pool/request.ex                |  65 -----
 lib/pleroma/pool/supervisor.ex             |  42 ---
 lib/pleroma/reverse_proxy/client/tesla.ex  |   2 +-
 16 files changed, 402 insertions(+), 686 deletions(-)
 create mode 100644 lib/pleroma/gun/connection_pool.ex
 create mode 100644 lib/pleroma/gun/connection_pool/worker.ex
 create mode 100644 lib/pleroma/http/adapter_helper/default.ex
 delete mode 100644 lib/pleroma/http/connection.ex
 delete mode 100644 lib/pleroma/pool/connections.ex
 delete mode 100644 lib/pleroma/pool/pool.ex
 delete mode 100644 lib/pleroma/pool/request.ex
 delete mode 100644 lib/pleroma/pool/supervisor.ex

diff --git a/config/config.exs b/config/config.exs
index 6fc84efc2..577ccc198 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -647,8 +647,10 @@
   prepare: :unnamed
 
 config :pleroma, :connections_pool,
+  reclaim_multiplier: 0.1,
   checkin_timeout: 250,
   max_connections: 250,
+  max_idle_time: 30_000,
   retry: 1,
   retry_timeout: 1000,
   await_up_timeout: 5_000
diff --git a/lib/pleroma/application.ex b/lib/pleroma/application.ex
index 3282c6882..be14c1f9f 100644
--- a/lib/pleroma/application.ex
+++ b/lib/pleroma/application.ex
@@ -223,9 +223,7 @@ defp task_children(_) do
 
   # start hackney and gun pools in tests
   defp http_children(_, :test) do
-    hackney_options = Config.get([:hackney_pools, :federation])
-    hackney_pool = :hackney_pool.child_spec(:federation, hackney_options)
-    [hackney_pool, Pleroma.Pool.Supervisor]
+    http_children(Tesla.Adapter.Hackney, nil) ++ http_children(Tesla.Adapter.Gun, nil)
   end
 
   defp http_children(Tesla.Adapter.Hackney, _) do
@@ -244,7 +242,9 @@ defp http_children(Tesla.Adapter.Hackney, _) do
     end
   end
 
-  defp http_children(Tesla.Adapter.Gun, _), do: [Pleroma.Pool.Supervisor]
+  defp http_children(Tesla.Adapter.Gun, _) do
+    [{Registry, keys: :unique, name: Pleroma.Gun.ConnectionPool}]
+  end
 
   defp http_children(_, _), do: []
 end
diff --git a/lib/pleroma/gun/conn.ex b/lib/pleroma/gun/conn.ex
index cd25a2e74..77f78c7ff 100644
--- a/lib/pleroma/gun/conn.ex
+++ b/lib/pleroma/gun/conn.ex
@@ -3,40 +3,11 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Gun.Conn do
-  @moduledoc """
-  Struct for gun connection data
-  """
   alias Pleroma.Gun
-  alias Pleroma.Pool.Connections
 
   require Logger
 
-  @type gun_state :: :up | :down
-  @type conn_state :: :active | :idle
-
-  @type t :: %__MODULE__{
-          conn: pid(),
-          gun_state: gun_state(),
-          conn_state: conn_state(),
-          used_by: [pid()],
-          last_reference: pos_integer(),
-          crf: float(),
-          retries: pos_integer()
-        }
-
-  defstruct conn: nil,
-            gun_state: :open,
-            conn_state: :init,
-            used_by: [],
-            last_reference: 0,
-            crf: 1,
-            retries: 0
-
-  @spec open(String.t() | URI.t(), atom(), keyword()) :: :ok | nil
-  def open(url, name, opts \\ [])
-  def open(url, name, opts) when is_binary(url), do: open(URI.parse(url), name, opts)
-
-  def open(%URI{} = uri, name, opts) do
+  def open(%URI{} = uri, opts) do
     pool_opts = Pleroma.Config.get([:connections_pool], [])
 
     opts =
@@ -45,30 +16,10 @@ def open(%URI{} = uri, name, opts) do
       |> Map.put_new(:retry, pool_opts[:retry] || 1)
       |> Map.put_new(:retry_timeout, pool_opts[:retry_timeout] || 1000)
       |> Map.put_new(:await_up_timeout, pool_opts[:await_up_timeout] || 5_000)
+      |> Map.put_new(:supervise, false)
       |> maybe_add_tls_opts(uri)
 
-    key = "#{uri.scheme}:#{uri.host}:#{uri.port}"
-
-    max_connections = pool_opts[:max_connections] || 250
-
-    conn_pid =
-      if Connections.count(name) < max_connections do
-        do_open(uri, opts)
-      else
-        close_least_used_and_do_open(name, uri, opts)
-      end
-
-    if is_pid(conn_pid) do
-      conn = %Pleroma.Gun.Conn{
-        conn: conn_pid,
-        gun_state: :up,
-        conn_state: :active,
-        last_reference: :os.system_time(:second)
-      }
-
-      :ok = Gun.set_owner(conn_pid, Process.whereis(name))
-      Connections.add_conn(name, key, conn)
-    end
+    do_open(uri, opts)
   end
 
   defp maybe_add_tls_opts(opts, %URI{scheme: "http"}), do: opts
@@ -81,7 +32,7 @@ defp maybe_add_tls_opts(opts, %URI{scheme: "https", host: host}) do
       reuse_sessions: false,
       verify_fun:
         {&:ssl_verify_hostname.verify_fun/3,
-         [check_hostname: Pleroma.HTTP.Connection.format_host(host)]}
+         [check_hostname: Pleroma.HTTP.AdapterHelper.format_host(host)]}
     ]
 
     tls_opts =
@@ -105,7 +56,7 @@ defp do_open(uri, %{proxy: {proxy_host, proxy_port}} = opts) do
          {:ok, _} <- Gun.await_up(conn, opts[:await_up_timeout]),
          stream <- Gun.connect(conn, connect_opts),
          {:response, :fin, 200, _} <- Gun.await(conn, stream) do
-      conn
+      {:ok, conn}
     else
       error ->
         Logger.warn(
@@ -141,7 +92,7 @@ defp do_open(uri, %{proxy: {proxy_type, proxy_host, proxy_port}} = opts) do
 
     with {:ok, conn} <- Gun.open(proxy_host, proxy_port, opts),
          {:ok, _} <- Gun.await_up(conn, opts[:await_up_timeout]) do
-      conn
+      {:ok, conn}
     else
       error ->
         Logger.warn(
@@ -155,11 +106,11 @@ defp do_open(uri, %{proxy: {proxy_type, proxy_host, proxy_port}} = opts) do
   end
 
   defp do_open(%URI{host: host, port: port} = uri, opts) do
-    host = Pleroma.HTTP.Connection.parse_host(host)
+    host = Pleroma.HTTP.AdapterHelper.parse_host(host)
 
     with {:ok, conn} <- Gun.open(host, port, opts),
          {:ok, _} <- Gun.await_up(conn, opts[:await_up_timeout]) do
-      conn
+      {:ok, conn}
     else
       error ->
         Logger.warn(
@@ -171,7 +122,7 @@ defp do_open(%URI{host: host, port: port} = uri, opts) do
   end
 
   defp destination_opts(%URI{host: host, port: port}) do
-    host = Pleroma.HTTP.Connection.parse_host(host)
+    host = Pleroma.HTTP.AdapterHelper.parse_host(host)
     %{host: host, port: port}
   end
 
@@ -181,17 +132,6 @@ defp add_http2_opts(opts, "https", tls_opts) do
 
   defp add_http2_opts(opts, _, _), do: opts
 
-  defp close_least_used_and_do_open(name, uri, opts) do
-    with [{key, conn} | _conns] <- Connections.get_unused_conns(name),
-         :ok <- Gun.close(conn.conn) do
-      Connections.remove_conn(name, key)
-
-      do_open(uri, opts)
-    else
-      [] -> {:error, :pool_overflowed}
-    end
-  end
-
   def compose_uri_log(%URI{scheme: scheme, host: host, path: path}) do
     "#{scheme}://#{host}#{path}"
   end
diff --git a/lib/pleroma/gun/connection_pool.ex b/lib/pleroma/gun/connection_pool.ex
new file mode 100644
index 000000000..e6abee69c
--- /dev/null
+++ b/lib/pleroma/gun/connection_pool.ex
@@ -0,0 +1,129 @@
+defmodule Pleroma.Gun.ConnectionPool do
+  @registry __MODULE__
+
+  def get_conn(uri, opts) do
+    case enforce_pool_limits() do
+      :ok ->
+        key = "#{uri.scheme}:#{uri.host}:#{uri.port}"
+
+        case Registry.lookup(@registry, key) do
+          # The key has already been registered, but connection is not up yet
+          [{worker_pid, {nil, _used_by, _crf, _last_reference}}] ->
+            get_gun_pid_from_worker(worker_pid)
+
+          [{worker_pid, {gun_pid, _used_by, _crf, _last_reference}}] ->
+            GenServer.cast(worker_pid, {:add_client, self(), false})
+            {:ok, gun_pid}
+
+          [] ->
+            # :gun.set_owner fails in :connected state for whatevever reason,
+            # so we open the connection in the process directly and send it's pid back
+            # We trust gun to handle timeouts by itself
+            case GenServer.start(Pleroma.Gun.ConnectionPool.Worker, [uri, key, opts, self()],
+                   timeout: :infinity
+                 ) do
+              {:ok, _worker_pid} ->
+                receive do
+                  {:conn_pid, pid} -> {:ok, pid}
+                end
+
+              {:error, {:error, {:already_registered, worker_pid}}} ->
+                get_gun_pid_from_worker(worker_pid)
+
+              err ->
+                err
+            end
+        end
+
+      :error ->
+        {:error, :pool_full}
+    end
+  end
+
+  @enforcer_key "enforcer"
+  defp enforce_pool_limits() do
+    max_connections = Pleroma.Config.get([:connections_pool, :max_connections])
+
+    if Registry.count(@registry) >= max_connections do
+      case Registry.lookup(@registry, @enforcer_key) do
+        [] ->
+          pid =
+            spawn(fn ->
+              {:ok, _pid} = Registry.register(@registry, @enforcer_key, nil)
+
+              reclaim_max =
+                [:connections_pool, :reclaim_multiplier]
+                |> Pleroma.Config.get()
+                |> Kernel.*(max_connections)
+                |> round
+                |> max(1)
+
+              unused_conns =
+                Registry.select(
+                  @registry,
+                  [
+                    {{:_, :"$1", {:_, :"$2", :"$3", :"$4"}}, [{:==, :"$2", []}],
+                     [{{:"$1", :"$3", :"$4"}}]}
+                  ]
+                )
+
+              case unused_conns do
+                [] ->
+                  exit(:pool_full)
+
+                unused_conns ->
+                  unused_conns
+                  |> Enum.sort(fn {_pid1, crf1, last_reference1},
+                                  {_pid2, crf2, last_reference2} ->
+                    crf1 <= crf2 and last_reference1 <= last_reference2
+                  end)
+                  |> Enum.take(reclaim_max)
+                  |> Enum.each(fn {pid, _, _} -> GenServer.call(pid, :idle_close) end)
+              end
+            end)
+
+          wait_for_enforcer_finish(pid)
+
+        [{pid, _}] ->
+          wait_for_enforcer_finish(pid)
+      end
+    else
+      :ok
+    end
+  end
+
+  defp wait_for_enforcer_finish(pid) do
+    ref = Process.monitor(pid)
+
+    receive do
+      {:DOWN, ^ref, :process, ^pid, :pool_full} ->
+        :error
+
+      {:DOWN, ^ref, :process, ^pid, :normal} ->
+        :ok
+    end
+  end
+
+  defp get_gun_pid_from_worker(worker_pid) do
+    # GenServer.call will block the process for timeout length if
+    # the server crashes on startup (which will happen if gun fails to connect)
+    # so instead we use cast + monitor
+
+    ref = Process.monitor(worker_pid)
+    GenServer.cast(worker_pid, {:add_client, self(), true})
+
+    receive do
+      {:conn_pid, pid} -> {:ok, pid}
+      {:DOWN, ^ref, :process, ^worker_pid, reason} -> reason
+    end
+  end
+
+  def release_conn(conn_pid) do
+    [worker_pid] =
+      Registry.select(@registry, [
+        {{:_, :"$1", {:"$2", :_, :_, :_}}, [{:==, :"$2", conn_pid}], [:"$1"]}
+      ])
+
+    GenServer.cast(worker_pid, {:remove_client, self()})
+  end
+end
diff --git a/lib/pleroma/gun/connection_pool/worker.ex b/lib/pleroma/gun/connection_pool/worker.ex
new file mode 100644
index 000000000..ebde4bbf6
--- /dev/null
+++ b/lib/pleroma/gun/connection_pool/worker.ex
@@ -0,0 +1,95 @@
+defmodule Pleroma.Gun.ConnectionPool.Worker do
+  alias Pleroma.Gun
+  use GenServer
+
+  @registry Pleroma.Gun.ConnectionPool
+
+  @impl true
+  def init([uri, key, opts, client_pid]) do
+    time = :os.system_time(:second)
+    # Register before opening connection to prevent race conditions
+    with {:ok, _owner} <- Registry.register(@registry, key, {nil, [client_pid], 1, time}),
+         {:ok, conn_pid} <- Gun.Conn.open(uri, opts),
+         Process.link(conn_pid) do
+      {_, _} =
+        Registry.update_value(@registry, key, fn {_, used_by, crf, last_reference} ->
+          {conn_pid, used_by, crf, last_reference}
+        end)
+
+      send(client_pid, {:conn_pid, conn_pid})
+      {:ok, %{key: key, timer: nil}, :hibernate}
+    else
+      err -> {:stop, err}
+    end
+  end
+
+  @impl true
+  def handle_cast({:add_client, client_pid, send_pid_back}, %{key: key} = state) do
+    time = :os.system_time(:second)
+
+    {{conn_pid, _, _, _}, _} =
+      Registry.update_value(@registry, key, fn {conn_pid, used_by, crf, last_reference} ->
+        {conn_pid, [client_pid | used_by], crf(time - last_reference, crf), time}
+      end)
+
+    if send_pid_back, do: send(client_pid, {:conn_pid, conn_pid})
+
+    state =
+      if state.timer != nil do
+        Process.cancel_timer(state[:timer])
+        %{state | timer: nil}
+      else
+        state
+      end
+
+    {:noreply, state, :hibernate}
+  end
+
+  @impl true
+  def handle_cast({:remove_client, client_pid}, %{key: key} = state) do
+    {{_conn_pid, used_by, _crf, _last_reference}, _} =
+      Registry.update_value(@registry, key, fn {conn_pid, used_by, crf, last_reference} ->
+        {conn_pid, List.delete(used_by, client_pid), crf, last_reference}
+      end)
+
+    timer =
+      if used_by == [] do
+        max_idle = Pleroma.Config.get([:connections_pool, :max_idle_time], 30_000)
+        Process.send_after(self(), :idle_close, max_idle)
+      else
+        nil
+      end
+
+    {:noreply, %{state | timer: timer}, :hibernate}
+  end
+
+  @impl true
+  def handle_info(:idle_close, state) do
+    # Gun monitors the owner process, and will close the connection automatically
+    # when it's terminated
+    {:stop, :normal, state}
+  end
+
+  # Gracefully shutdown if the connection got closed without any streams left
+  @impl true
+  def handle_info({:gun_down, _pid, _protocol, _reason, []}, state) do
+    {:stop, :normal, state}
+  end
+
+  # Otherwise, shutdown with an error
+  @impl true
+  def handle_info({:gun_down, _pid, _protocol, _reason, _killed_streams} = down_message, state) do
+    {:stop, {:error, down_message}, state}
+  end
+
+  @impl true
+  def handle_call(:idle_close, _, %{key: key} = state) do
+    Registry.unregister(@registry, key)
+    {:stop, :normal, state}
+  end
+
+  # LRFU policy: https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.55.1478
+  defp crf(time_delta, prev_crf) do
+    1 + :math.pow(0.5, time_delta / 100) * prev_crf
+  end
+end
diff --git a/lib/pleroma/http/adapter_helper.ex b/lib/pleroma/http/adapter_helper.ex
index 510722ff9..0532ea31d 100644
--- a/lib/pleroma/http/adapter_helper.ex
+++ b/lib/pleroma/http/adapter_helper.ex
@@ -3,7 +3,21 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.HTTP.AdapterHelper do
-  alias Pleroma.HTTP.Connection
+  @moduledoc """
+  Configure Tesla.Client with default and customized adapter options.
+  """
+  @defaults [pool: :federation]
+
+  @type ip_address :: ipv4_address() | ipv6_address()
+  @type ipv4_address :: {0..255, 0..255, 0..255, 0..255}
+  @type ipv6_address ::
+          {0..65_535, 0..65_535, 0..65_535, 0..65_535, 0..65_535, 0..65_535, 0..65_535, 0..65_535}
+  @type proxy_type() :: :socks4 | :socks5
+  @type host() :: charlist() | ip_address()
+
+  alias Pleroma.Config
+  alias Pleroma.HTTP.AdapterHelper
+  require Logger
 
   @type proxy ::
           {Connection.host(), pos_integer()}
@@ -11,24 +25,13 @@ defmodule Pleroma.HTTP.AdapterHelper do
 
   @callback options(keyword(), URI.t()) :: keyword()
   @callback after_request(keyword()) :: :ok
-
-  @spec options(keyword(), URI.t()) :: keyword()
-  def options(opts, _uri) do
-    proxy = Pleroma.Config.get([:http, :proxy_url], nil)
-    maybe_add_proxy(opts, format_proxy(proxy))
-  end
-
-  @spec maybe_get_conn(URI.t(), keyword()) :: keyword()
-  def maybe_get_conn(_uri, opts), do: opts
-
-  @spec after_request(keyword()) :: :ok
-  def after_request(_opts), do: :ok
+  @callback get_conn(URI.t(), keyword()) :: {:ok, term()} | {:error, term()}
 
   @spec format_proxy(String.t() | tuple() | nil) :: proxy() | nil
   def format_proxy(nil), do: nil
 
   def format_proxy(proxy_url) do
-    case Connection.parse_proxy(proxy_url) do
+    case parse_proxy(proxy_url) do
       {:ok, host, port} -> {host, port}
       {:ok, type, host, port} -> {type, host, port}
       _ -> nil
@@ -38,4 +41,106 @@ def format_proxy(proxy_url) do
   @spec maybe_add_proxy(keyword(), proxy() | nil) :: keyword()
   def maybe_add_proxy(opts, nil), do: opts
   def maybe_add_proxy(opts, proxy), do: Keyword.put_new(opts, :proxy, proxy)
+
+  @doc """
+  Merge default connection & adapter options with received ones.
+  """
+
+  @spec options(URI.t(), keyword()) :: keyword()
+  def options(%URI{} = uri, opts \\ []) do
+    @defaults
+    |> pool_timeout()
+    |> Keyword.merge(opts)
+    |> adapter_helper().options(uri)
+  end
+
+  defp pool_timeout(opts) do
+    {config_key, default} =
+      if adapter() == Tesla.Adapter.Gun do
+        {:pools, Config.get([:pools, :default, :timeout])}
+      else
+        {:hackney_pools, 10_000}
+      end
+
+    timeout = Config.get([config_key, opts[:pool], :timeout], default)
+
+    Keyword.merge(opts, timeout: timeout)
+  end
+
+  @spec after_request(keyword()) :: :ok
+  def after_request(opts), do: adapter_helper().after_request(opts)
+
+  def get_conn(uri, opts), do: adapter_helper().get_conn(uri, opts)
+  defp adapter, do: Application.get_env(:tesla, :adapter)
+
+  defp adapter_helper do
+    case adapter() do
+      Tesla.Adapter.Gun -> AdapterHelper.Gun
+      Tesla.Adapter.Hackney -> AdapterHelper.Hackney
+      _ -> AdapterHelper.Default
+    end
+  end
+
+  @spec parse_proxy(String.t() | tuple() | nil) ::
+          {:ok, host(), pos_integer()}
+          | {:ok, proxy_type(), host(), pos_integer()}
+          | {:error, atom()}
+          | nil
+
+  def parse_proxy(nil), do: nil
+
+  def parse_proxy(proxy) when is_binary(proxy) do
+    with [host, port] <- String.split(proxy, ":"),
+         {port, ""} <- Integer.parse(port) do
+      {:ok, parse_host(host), port}
+    else
+      {_, _} ->
+        Logger.warn("Parsing port failed #{inspect(proxy)}")
+        {:error, :invalid_proxy_port}
+
+      :error ->
+        Logger.warn("Parsing port failed #{inspect(proxy)}")
+        {:error, :invalid_proxy_port}
+
+      _ ->
+        Logger.warn("Parsing proxy failed #{inspect(proxy)}")
+        {:error, :invalid_proxy}
+    end
+  end
+
+  def parse_proxy(proxy) when is_tuple(proxy) do
+    with {type, host, port} <- proxy do
+      {:ok, type, parse_host(host), port}
+    else
+      _ ->
+        Logger.warn("Parsing proxy failed #{inspect(proxy)}")
+        {:error, :invalid_proxy}
+    end
+  end
+
+  @spec parse_host(String.t() | atom() | charlist()) :: charlist() | ip_address()
+  def parse_host(host) when is_list(host), do: host
+  def parse_host(host) when is_atom(host), do: to_charlist(host)
+
+  def parse_host(host) when is_binary(host) do
+    host = to_charlist(host)
+
+    case :inet.parse_address(host) do
+      {:error, :einval} -> host
+      {:ok, ip} -> ip
+    end
+  end
+
+  @spec format_host(String.t()) :: charlist()
+  def format_host(host) do
+    host_charlist = to_charlist(host)
+
+    case :inet.parse_address(host_charlist) do
+      {:error, :einval} ->
+        :idna.encode(host_charlist)
+
+      {:ok, _ip} ->
+        host_charlist
+    end
+  end
 end
diff --git a/lib/pleroma/http/adapter_helper/default.ex b/lib/pleroma/http/adapter_helper/default.ex
new file mode 100644
index 000000000..218cfacc0
--- /dev/null
+++ b/lib/pleroma/http/adapter_helper/default.ex
@@ -0,0 +1,17 @@
+defmodule Pleroma.HTTP.AdapterHelper.Default do
+  alias Pleroma.HTTP.AdapterHelper
+
+  @behaviour Pleroma.HTTP.AdapterHelper
+
+  @spec options(keyword(), URI.t()) :: keyword()
+  def options(opts, _uri) do
+    proxy = Pleroma.Config.get([:http, :proxy_url], nil)
+    AdapterHelper.maybe_add_proxy(opts, AdapterHelper.format_proxy(proxy))
+  end
+
+  @spec after_request(keyword()) :: :ok
+  def after_request(_opts), do: :ok
+
+  @spec get_conn(URI.t(), keyword()) :: {:ok, keyword()}
+  def get_conn(_uri, opts), do: {:ok, opts}
+end
diff --git a/lib/pleroma/http/adapter_helper/gun.ex b/lib/pleroma/http/adapter_helper/gun.ex
index ead7cdc6b..6f7cc9784 100644
--- a/lib/pleroma/http/adapter_helper/gun.ex
+++ b/lib/pleroma/http/adapter_helper/gun.ex
@@ -5,8 +5,8 @@
 defmodule Pleroma.HTTP.AdapterHelper.Gun do
   @behaviour Pleroma.HTTP.AdapterHelper
 
+  alias Pleroma.Gun.ConnectionPool
   alias Pleroma.HTTP.AdapterHelper
-  alias Pleroma.Pool.Connections
 
   require Logger
 
@@ -31,13 +31,13 @@ def options(incoming_opts \\ [], %URI{} = uri) do
     |> Keyword.merge(config_opts)
     |> add_scheme_opts(uri)
     |> AdapterHelper.maybe_add_proxy(proxy)
-    |> maybe_get_conn(uri, incoming_opts)
+    |> Keyword.merge(incoming_opts)
   end
 
   @spec after_request(keyword()) :: :ok
   def after_request(opts) do
     if opts[:conn] && opts[:body_as] != :chunks do
-      Connections.checkout(opts[:conn], self(), :gun_connections)
+      ConnectionPool.release_conn(opts[:conn])
     end
 
     :ok
@@ -51,27 +51,11 @@ defp add_scheme_opts(opts, %{scheme: "https"}) do
     |> Keyword.put(:tls_opts, log_level: :warning)
   end
 
-  defp maybe_get_conn(adapter_opts, uri, incoming_opts) do
-    {receive_conn?, opts} =
-      adapter_opts
-      |> Keyword.merge(incoming_opts)
-      |> Keyword.pop(:receive_conn, true)
-
-    if Connections.alive?(:gun_connections) and receive_conn? do
-      checkin_conn(uri, opts)
-    else
-      opts
-    end
-  end
-
-  defp checkin_conn(uri, opts) do
-    case Connections.checkin(uri, :gun_connections) do
-      nil ->
-        Task.start(Pleroma.Gun.Conn, :open, [uri, :gun_connections, opts])
-        opts
-
-      conn when is_pid(conn) ->
-        Keyword.merge(opts, conn: conn, close_conn: false)
+  @spec get_conn(URI.t(), keyword()) :: {:ok, keyword()} | {:error, atom()}
+  def get_conn(uri, opts) do
+    case ConnectionPool.get_conn(uri, opts) do
+      {:ok, conn_pid} -> {:ok, Keyword.merge(opts, conn: conn_pid, close_conn: false)}
+      err -> err
     end
   end
 end
diff --git a/lib/pleroma/http/adapter_helper/hackney.ex b/lib/pleroma/http/adapter_helper/hackney.ex
index 3972a03a9..42d552740 100644
--- a/lib/pleroma/http/adapter_helper/hackney.ex
+++ b/lib/pleroma/http/adapter_helper/hackney.ex
@@ -25,4 +25,7 @@ def options(connection_opts \\ [], %URI{} = uri) do
   defp add_scheme_opts(opts, _), do: opts
 
   def after_request(_), do: :ok
+
+  @spec get_conn(URI.t(), keyword()) :: {:ok, keyword()}
+  def get_conn(_uri, opts), do: {:ok, opts}
 end
diff --git a/lib/pleroma/http/connection.ex b/lib/pleroma/http/connection.ex
deleted file mode 100644
index ebacf7902..000000000
--- a/lib/pleroma/http/connection.ex
+++ /dev/null
@@ -1,124 +0,0 @@
-# Pleroma: A lightweight social networking server
-# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
-# SPDX-License-Identifier: AGPL-3.0-only
-
-defmodule Pleroma.HTTP.Connection do
-  @moduledoc """
-  Configure Tesla.Client with default and customized adapter options.
-  """
-
-  alias Pleroma.Config
-  alias Pleroma.HTTP.AdapterHelper
-
-  require Logger
-
-  @defaults [pool: :federation]
-
-  @type ip_address :: ipv4_address() | ipv6_address()
-  @type ipv4_address :: {0..255, 0..255, 0..255, 0..255}
-  @type ipv6_address ::
-          {0..65_535, 0..65_535, 0..65_535, 0..65_535, 0..65_535, 0..65_535, 0..65_535, 0..65_535}
-  @type proxy_type() :: :socks4 | :socks5
-  @type host() :: charlist() | ip_address()
-
-  @doc """
-  Merge default connection & adapter options with received ones.
-  """
-
-  @spec options(URI.t(), keyword()) :: keyword()
-  def options(%URI{} = uri, opts \\ []) do
-    @defaults
-    |> pool_timeout()
-    |> Keyword.merge(opts)
-    |> adapter_helper().options(uri)
-  end
-
-  defp pool_timeout(opts) do
-    {config_key, default} =
-      if adapter() == Tesla.Adapter.Gun do
-        {:pools, Config.get([:pools, :default, :timeout])}
-      else
-        {:hackney_pools, 10_000}
-      end
-
-    timeout = Config.get([config_key, opts[:pool], :timeout], default)
-
-    Keyword.merge(opts, timeout: timeout)
-  end
-
-  @spec after_request(keyword()) :: :ok
-  def after_request(opts), do: adapter_helper().after_request(opts)
-
-  defp adapter, do: Application.get_env(:tesla, :adapter)
-
-  defp adapter_helper do
-    case adapter() do
-      Tesla.Adapter.Gun -> AdapterHelper.Gun
-      Tesla.Adapter.Hackney -> AdapterHelper.Hackney
-      _ -> AdapterHelper
-    end
-  end
-
-  @spec parse_proxy(String.t() | tuple() | nil) ::
-          {:ok, host(), pos_integer()}
-          | {:ok, proxy_type(), host(), pos_integer()}
-          | {:error, atom()}
-          | nil
-
-  def parse_proxy(nil), do: nil
-
-  def parse_proxy(proxy) when is_binary(proxy) do
-    with [host, port] <- String.split(proxy, ":"),
-         {port, ""} <- Integer.parse(port) do
-      {:ok, parse_host(host), port}
-    else
-      {_, _} ->
-        Logger.warn("Parsing port failed #{inspect(proxy)}")
-        {:error, :invalid_proxy_port}
-
-      :error ->
-        Logger.warn("Parsing port failed #{inspect(proxy)}")
-        {:error, :invalid_proxy_port}
-
-      _ ->
-        Logger.warn("Parsing proxy failed #{inspect(proxy)}")
-        {:error, :invalid_proxy}
-    end
-  end
-
-  def parse_proxy(proxy) when is_tuple(proxy) do
-    with {type, host, port} <- proxy do
-      {:ok, type, parse_host(host), port}
-    else
-      _ ->
-        Logger.warn("Parsing proxy failed #{inspect(proxy)}")
-        {:error, :invalid_proxy}
-    end
-  end
-
-  @spec parse_host(String.t() | atom() | charlist()) :: charlist() | ip_address()
-  def parse_host(host) when is_list(host), do: host
-  def parse_host(host) when is_atom(host), do: to_charlist(host)
-
-  def parse_host(host) when is_binary(host) do
-    host = to_charlist(host)
-
-    case :inet.parse_address(host) do
-      {:error, :einval} -> host
-      {:ok, ip} -> ip
-    end
-  end
-
-  @spec format_host(String.t()) :: charlist()
-  def format_host(host) do
-    host_charlist = to_charlist(host)
-
-    case :inet.parse_address(host_charlist) do
-      {:error, :einval} ->
-        :idna.encode(host_charlist)
-
-      {:ok, _ip} ->
-        host_charlist
-    end
-  end
-end
diff --git a/lib/pleroma/http/http.ex b/lib/pleroma/http/http.ex
index 66ca75367..8ded76601 100644
--- a/lib/pleroma/http/http.ex
+++ b/lib/pleroma/http/http.ex
@@ -7,7 +7,7 @@ defmodule Pleroma.HTTP do
     Wrapper for `Tesla.request/2`.
   """
 
-  alias Pleroma.HTTP.Connection
+  alias Pleroma.HTTP.AdapterHelper
   alias Pleroma.HTTP.Request
   alias Pleroma.HTTP.RequestBuilder, as: Builder
   alias Tesla.Client
@@ -60,49 +60,26 @@ def post(url, body, headers \\ [], options \\ []),
           {:ok, Env.t()} | {:error, any()}
   def request(method, url, body, headers, options) when is_binary(url) do
     uri = URI.parse(url)
-    adapter_opts = Connection.options(uri, options[:adapter] || [])
-    options = put_in(options[:adapter], adapter_opts)
-    params = options[:params] || []
-    request = build_request(method, headers, options, url, body, params)
+    adapter_opts = AdapterHelper.options(uri, options[:adapter] || [])
 
-    adapter = Application.get_env(:tesla, :adapter)
-    client = Tesla.client([Tesla.Middleware.FollowRedirects], adapter)
+    case AdapterHelper.get_conn(uri, adapter_opts) do
+      {:ok, adapter_opts} ->
+        options = put_in(options[:adapter], adapter_opts)
+        params = options[:params] || []
+        request = build_request(method, headers, options, url, body, params)
 
-    pid = Process.whereis(adapter_opts[:pool])
+        adapter = Application.get_env(:tesla, :adapter)
+        client = Tesla.client([Tesla.Middleware.FollowRedirects], adapter)
 
-    pool_alive? =
-      if adapter == Tesla.Adapter.Gun && pid do
-        Process.alive?(pid)
-      else
-        false
-      end
+        response = request(client, request)
 
-    request_opts =
-      adapter_opts
-      |> Enum.into(%{})
-      |> Map.put(:env, Pleroma.Config.get([:env]))
-      |> Map.put(:pool_alive?, pool_alive?)
+        AdapterHelper.after_request(adapter_opts)
 
-    response = request(client, request, request_opts)
+        response
 
-    Connection.after_request(adapter_opts)
-
-    response
-  end
-
-  @spec request(Client.t(), keyword(), map()) :: {:ok, Env.t()} | {:error, any()}
-  def request(%Client{} = client, request, %{env: :test}), do: request(client, request)
-
-  def request(%Client{} = client, request, %{body_as: :chunks}), do: request(client, request)
-
-  def request(%Client{} = client, request, %{pool_alive?: false}), do: request(client, request)
-
-  def request(%Client{} = client, request, %{pool: pool, timeout: timeout}) do
-    :poolboy.transaction(
-      pool,
-      &Pleroma.Pool.Request.execute(&1, client, request, timeout),
-      timeout
-    )
+      err ->
+        err
+    end
   end
 
   @spec request(Client.t(), keyword()) :: {:ok, Env.t()} | {:error, any()}
diff --git a/lib/pleroma/pool/connections.ex b/lib/pleroma/pool/connections.ex
deleted file mode 100644
index acafe1bea..000000000
--- a/lib/pleroma/pool/connections.ex
+++ /dev/null
@@ -1,283 +0,0 @@
-# Pleroma: A lightweight social networking server
-# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
-# SPDX-License-Identifier: AGPL-3.0-only
-
-defmodule Pleroma.Pool.Connections do
-  use GenServer
-
-  alias Pleroma.Config
-  alias Pleroma.Gun
-
-  require Logger
-
-  @type domain :: String.t()
-  @type conn :: Pleroma.Gun.Conn.t()
-
-  @type t :: %__MODULE__{
-          conns: %{domain() => conn()},
-          opts: keyword()
-        }
-
-  defstruct conns: %{}, opts: []
-
-  @spec start_link({atom(), keyword()}) :: {:ok, pid()}
-  def start_link({name, opts}) do
-    GenServer.start_link(__MODULE__, opts, name: name)
-  end
-
-  @impl true
-  def init(opts), do: {:ok, %__MODULE__{conns: %{}, opts: opts}}
-
-  @spec checkin(String.t() | URI.t(), atom()) :: pid() | nil
-  def checkin(url, name)
-  def checkin(url, name) when is_binary(url), do: checkin(URI.parse(url), name)
-
-  def checkin(%URI{} = uri, name) do
-    timeout = Config.get([:connections_pool, :checkin_timeout], 250)
-
-    GenServer.call(name, {:checkin, uri}, timeout)
-  end
-
-  @spec alive?(atom()) :: boolean()
-  def alive?(name) do
-    if pid = Process.whereis(name) do
-      Process.alive?(pid)
-    else
-      false
-    end
-  end
-
-  @spec get_state(atom()) :: t()
-  def get_state(name) do
-    GenServer.call(name, :state)
-  end
-
-  @spec count(atom()) :: pos_integer()
-  def count(name) do
-    GenServer.call(name, :count)
-  end
-
-  @spec get_unused_conns(atom()) :: [{domain(), conn()}]
-  def get_unused_conns(name) do
-    GenServer.call(name, :unused_conns)
-  end
-
-  @spec checkout(pid(), pid(), atom()) :: :ok
-  def checkout(conn, pid, name) do
-    GenServer.cast(name, {:checkout, conn, pid})
-  end
-
-  @spec add_conn(atom(), String.t(), Pleroma.Gun.Conn.t()) :: :ok
-  def add_conn(name, key, conn) do
-    GenServer.cast(name, {:add_conn, key, conn})
-  end
-
-  @spec remove_conn(atom(), String.t()) :: :ok
-  def remove_conn(name, key) do
-    GenServer.cast(name, {:remove_conn, key})
-  end
-
-  @impl true
-  def handle_cast({:add_conn, key, conn}, state) do
-    state = put_in(state.conns[key], conn)
-
-    Process.monitor(conn.conn)
-    {:noreply, state}
-  end
-
-  @impl true
-  def handle_cast({:checkout, conn_pid, pid}, state) do
-    state =
-      with true <- Process.alive?(conn_pid),
-           {key, conn} <- find_conn(state.conns, conn_pid),
-           used_by <- List.keydelete(conn.used_by, pid, 0) do
-        conn_state = if used_by == [], do: :idle, else: conn.conn_state
-
-        put_in(state.conns[key], %{conn | conn_state: conn_state, used_by: used_by})
-      else
-        false ->
-          Logger.debug("checkout for closed conn #{inspect(conn_pid)}")
-          state
-
-        nil ->
-          Logger.debug("checkout for alive conn #{inspect(conn_pid)}, but is not in state")
-          state
-      end
-
-    {:noreply, state}
-  end
-
-  @impl true
-  def handle_cast({:remove_conn, key}, state) do
-    state = put_in(state.conns, Map.delete(state.conns, key))
-    {:noreply, state}
-  end
-
-  @impl true
-  def handle_call({:checkin, uri}, from, state) do
-    key = "#{uri.scheme}:#{uri.host}:#{uri.port}"
-
-    case state.conns[key] do
-      %{conn: pid, gun_state: :up} = conn ->
-        time = :os.system_time(:second)
-        last_reference = time - conn.last_reference
-        crf = crf(last_reference, 100, conn.crf)
-
-        state =
-          put_in(state.conns[key], %{
-            conn
-            | last_reference: time,
-              crf: crf,
-              conn_state: :active,
-              used_by: [from | conn.used_by]
-          })
-
-        {:reply, pid, state}
-
-      %{gun_state: :down} ->
-        {:reply, nil, state}
-
-      nil ->
-        {:reply, nil, state}
-    end
-  end
-
-  @impl true
-  def handle_call(:state, _from, state), do: {:reply, state, state}
-
-  @impl true
-  def handle_call(:count, _from, state) do
-    {:reply, Enum.count(state.conns), state}
-  end
-
-  @impl true
-  def handle_call(:unused_conns, _from, state) do
-    unused_conns =
-      state.conns
-      |> Enum.filter(&filter_conns/1)
-      |> Enum.sort(&sort_conns/2)
-
-    {:reply, unused_conns, state}
-  end
-
-  defp filter_conns({_, %{conn_state: :idle, used_by: []}}), do: true
-  defp filter_conns(_), do: false
-
-  defp sort_conns({_, c1}, {_, c2}) do
-    c1.crf <= c2.crf and c1.last_reference <= c2.last_reference
-  end
-
-  @impl true
-  def handle_info({:gun_up, conn_pid, _protocol}, state) do
-    %{origin_host: host, origin_scheme: scheme, origin_port: port} = Gun.info(conn_pid)
-
-    host =
-      case :inet.ntoa(host) do
-        {:error, :einval} -> host
-        ip -> ip
-      end
-
-    key = "#{scheme}:#{host}:#{port}"
-
-    state =
-      with {key, conn} <- find_conn(state.conns, conn_pid, key),
-           {true, key} <- {Process.alive?(conn_pid), key} do
-        put_in(state.conns[key], %{
-          conn
-          | gun_state: :up,
-            conn_state: :active,
-            retries: 0
-        })
-      else
-        {false, key} ->
-          put_in(
-            state.conns,
-            Map.delete(state.conns, key)
-          )
-
-        nil ->
-          :ok = Gun.close(conn_pid)
-
-          state
-      end
-
-    {:noreply, state}
-  end
-
-  @impl true
-  def handle_info({:gun_down, conn_pid, _protocol, _reason, _killed}, state) do
-    retries = Config.get([:connections_pool, :retry], 1)
-    # we can't get info on this pid, because pid is dead
-    state =
-      with {key, conn} <- find_conn(state.conns, conn_pid),
-           {true, key} <- {Process.alive?(conn_pid), key} do
-        if conn.retries == retries do
-          :ok = Gun.close(conn.conn)
-
-          put_in(
-            state.conns,
-            Map.delete(state.conns, key)
-          )
-        else
-          put_in(state.conns[key], %{
-            conn
-            | gun_state: :down,
-              retries: conn.retries + 1
-          })
-        end
-      else
-        {false, key} ->
-          put_in(
-            state.conns,
-            Map.delete(state.conns, key)
-          )
-
-        nil ->
-          Logger.debug(":gun_down for conn which isn't found in state")
-
-          state
-      end
-
-    {:noreply, state}
-  end
-
-  @impl true
-  def handle_info({:DOWN, _ref, :process, conn_pid, reason}, state) do
-    Logger.debug("received DOWN message for #{inspect(conn_pid)} reason -> #{inspect(reason)}")
-
-    state =
-      with {key, conn} <- find_conn(state.conns, conn_pid) do
-        Enum.each(conn.used_by, fn {pid, _ref} ->
-          Process.exit(pid, reason)
-        end)
-
-        put_in(
-          state.conns,
-          Map.delete(state.conns, key)
-        )
-      else
-        nil ->
-          Logger.debug(":DOWN for conn which isn't found in state")
-
-          state
-      end
-
-    {:noreply, state}
-  end
-
-  defp find_conn(conns, conn_pid) do
-    Enum.find(conns, fn {_key, conn} ->
-      conn.conn == conn_pid
-    end)
-  end
-
-  defp find_conn(conns, conn_pid, conn_key) do
-    Enum.find(conns, fn {key, conn} ->
-      key == conn_key and conn.conn == conn_pid
-    end)
-  end
-
-  def crf(current, steps, crf) do
-    1 + :math.pow(0.5, current / steps) * crf
-  end
-end
diff --git a/lib/pleroma/pool/pool.ex b/lib/pleroma/pool/pool.ex
deleted file mode 100644
index 21a6fbbc5..000000000
--- a/lib/pleroma/pool/pool.ex
+++ /dev/null
@@ -1,22 +0,0 @@
-# Pleroma: A lightweight social networking server
-# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
-# SPDX-License-Identifier: AGPL-3.0-only
-
-defmodule Pleroma.Pool do
-  def child_spec(opts) do
-    poolboy_opts =
-      opts
-      |> Keyword.put(:worker_module, Pleroma.Pool.Request)
-      |> Keyword.put(:name, {:local, opts[:name]})
-      |> Keyword.put(:size, opts[:size])
-      |> Keyword.put(:max_overflow, opts[:max_overflow])
-
-    %{
-      id: opts[:id] || {__MODULE__, make_ref()},
-      start: {:poolboy, :start_link, [poolboy_opts, [name: opts[:name]]]},
-      restart: :permanent,
-      shutdown: 5000,
-      type: :worker
-    }
-  end
-end
diff --git a/lib/pleroma/pool/request.ex b/lib/pleroma/pool/request.ex
deleted file mode 100644
index 3fb930db7..000000000
--- a/lib/pleroma/pool/request.ex
+++ /dev/null
@@ -1,65 +0,0 @@
-# Pleroma: A lightweight social networking server
-# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
-# SPDX-License-Identifier: AGPL-3.0-only
-
-defmodule Pleroma.Pool.Request do
-  use GenServer
-
-  require Logger
-
-  def start_link(args) do
-    GenServer.start_link(__MODULE__, args)
-  end
-
-  @impl true
-  def init(_), do: {:ok, []}
-
-  @spec execute(pid() | atom(), Tesla.Client.t(), keyword(), pos_integer()) ::
-          {:ok, Tesla.Env.t()} | {:error, any()}
-  def execute(pid, client, request, timeout) do
-    GenServer.call(pid, {:execute, client, request}, timeout)
-  end
-
-  @impl true
-  def handle_call({:execute, client, request}, _from, state) do
-    response = Pleroma.HTTP.request(client, request)
-
-    {:reply, response, state}
-  end
-
-  @impl true
-  def handle_info({:gun_data, _conn, _stream, _, _}, state) do
-    {:noreply, state}
-  end
-
-  @impl true
-  def handle_info({:gun_up, _conn, _protocol}, state) do
-    {:noreply, state}
-  end
-
-  @impl true
-  def handle_info({:gun_down, _conn, _protocol, _reason, _killed}, state) do
-    {:noreply, state}
-  end
-
-  @impl true
-  def handle_info({:gun_error, _conn, _stream, _error}, state) do
-    {:noreply, state}
-  end
-
-  @impl true
-  def handle_info({:gun_push, _conn, _stream, _new_stream, _method, _uri, _headers}, state) do
-    {:noreply, state}
-  end
-
-  @impl true
-  def handle_info({:gun_response, _conn, _stream, _, _status, _headers}, state) do
-    {:noreply, state}
-  end
-
-  @impl true
-  def handle_info(msg, state) do
-    Logger.warn("Received unexpected message #{inspect(__MODULE__)} #{inspect(msg)}")
-    {:noreply, state}
-  end
-end
diff --git a/lib/pleroma/pool/supervisor.ex b/lib/pleroma/pool/supervisor.ex
deleted file mode 100644
index faf646cb2..000000000
--- a/lib/pleroma/pool/supervisor.ex
+++ /dev/null
@@ -1,42 +0,0 @@
-# Pleroma: A lightweight social networking server
-# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
-# SPDX-License-Identifier: AGPL-3.0-only
-
-defmodule Pleroma.Pool.Supervisor do
-  use Supervisor
-
-  alias Pleroma.Config
-  alias Pleroma.Pool
-
-  def start_link(args) do
-    Supervisor.start_link(__MODULE__, args, name: __MODULE__)
-  end
-
-  def init(_) do
-    conns_child = %{
-      id: Pool.Connections,
-      start:
-        {Pool.Connections, :start_link, [{:gun_connections, Config.get([:connections_pool])}]}
-    }
-
-    Supervisor.init([conns_child | pools()], strategy: :one_for_one)
-  end
-
-  defp pools do
-    pools = Config.get(:pools)
-
-    pools =
-      if Config.get([Pleroma.Upload, :proxy_remote]) == false do
-        Keyword.delete(pools, :upload)
-      else
-        pools
-      end
-
-    for {pool_name, pool_opts} <- pools do
-      pool_opts
-      |> Keyword.put(:id, {Pool, pool_name})
-      |> Keyword.put(:name, pool_name)
-      |> Pool.child_spec()
-    end
-  end
-end
diff --git a/lib/pleroma/reverse_proxy/client/tesla.ex b/lib/pleroma/reverse_proxy/client/tesla.ex
index e81ea8bde..65785445d 100644
--- a/lib/pleroma/reverse_proxy/client/tesla.ex
+++ b/lib/pleroma/reverse_proxy/client/tesla.ex
@@ -48,7 +48,7 @@ def stream_body(%{pid: pid, opts: opts, fin: true}) do
     # if there were redirects we need to checkout old conn
     conn = opts[:old_conn] || opts[:conn]
 
-    if conn, do: :ok = Pleroma.Pool.Connections.checkout(conn, self(), :gun_connections)
+    if conn, do: :ok = Pleroma.Gun.ConnectionPool.release_conn(conn)
 
     :done
   end

From fffbcffb8c9ce1e96de5d1a5e15005e271deacd4 Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Wed, 6 May 2020 21:41:34 +0300
Subject: [PATCH 02/33] Connection Pool: don't enforce pool limits if no new
 connection needs to be opened

---
 lib/pleroma/gun/connection_pool.ex | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/lib/pleroma/gun/connection_pool.ex b/lib/pleroma/gun/connection_pool.ex
index e6abee69c..ed7ddff81 100644
--- a/lib/pleroma/gun/connection_pool.ex
+++ b/lib/pleroma/gun/connection_pool.ex
@@ -2,20 +2,20 @@ defmodule Pleroma.Gun.ConnectionPool do
   @registry __MODULE__
 
   def get_conn(uri, opts) do
-    case enforce_pool_limits() do
-      :ok ->
-        key = "#{uri.scheme}:#{uri.host}:#{uri.port}"
+    key = "#{uri.scheme}:#{uri.host}:#{uri.port}"
 
-        case Registry.lookup(@registry, key) do
-          # The key has already been registered, but connection is not up yet
-          [{worker_pid, {nil, _used_by, _crf, _last_reference}}] ->
-            get_gun_pid_from_worker(worker_pid)
+    case Registry.lookup(@registry, key) do
+      # The key has already been registered, but connection is not up yet
+      [{worker_pid, {nil, _used_by, _crf, _last_reference}}] ->
+        get_gun_pid_from_worker(worker_pid)
 
-          [{worker_pid, {gun_pid, _used_by, _crf, _last_reference}}] ->
-            GenServer.cast(worker_pid, {:add_client, self(), false})
-            {:ok, gun_pid}
+      [{worker_pid, {gun_pid, _used_by, _crf, _last_reference}}] ->
+        GenServer.cast(worker_pid, {:add_client, self(), false})
+        {:ok, gun_pid}
 
-          [] ->
+      [] ->
+        case enforce_pool_limits() do
+          :ok ->
             # :gun.set_owner fails in :connected state for whatevever reason,
             # so we open the connection in the process directly and send it's pid back
             # We trust gun to handle timeouts by itself
@@ -33,10 +33,10 @@ def get_conn(uri, opts) do
               err ->
                 err
             end
-        end
 
-      :error ->
-        {:error, :pool_full}
+          :error ->
+            {:error, :pool_full}
+        end
     end
   end
 

From d08b1576990ca33ac4178fb757ec03a777c55b5b Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Wed, 6 May 2020 21:51:10 +0300
Subject: [PATCH 03/33] Connection pool: check that there actually is a result

Sometimes connections died before being released to the pool, resulting
in MatchErrors
---
 lib/pleroma/gun/connection_pool.ex | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/lib/pleroma/gun/connection_pool.ex b/lib/pleroma/gun/connection_pool.ex
index ed7ddff81..0daf1da44 100644
--- a/lib/pleroma/gun/connection_pool.ex
+++ b/lib/pleroma/gun/connection_pool.ex
@@ -119,11 +119,17 @@ defp get_gun_pid_from_worker(worker_pid) do
   end
 
   def release_conn(conn_pid) do
-    [worker_pid] =
+    query_result =
       Registry.select(@registry, [
         {{:_, :"$1", {:"$2", :_, :_, :_}}, [{:==, :"$2", conn_pid}], [:"$1"]}
       ])
 
-    GenServer.cast(worker_pid, {:remove_client, self()})
+    case query_result do
+      [worker_pid] ->
+        GenServer.cast(worker_pid, {:remove_client, self()})
+
+      [] ->
+        :ok
+    end
   end
 end

From ec9d0d146b4ec6752f8f2896ace9bb5585469773 Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Wed, 6 May 2020 23:14:24 +0300
Subject: [PATCH 04/33] Connection pool: Fix race conditions in limit
 enforcement

Fixes race conditions in limit enforcement by putting worker processes
in a DynamicSupervisor
---
 lib/pleroma/application.ex                    |   2 +-
 lib/pleroma/gun/connection_pool.ex            | 105 ++++--------------
 lib/pleroma/gun/connection_pool/worker.ex     |  12 +-
 .../gun/connection_pool/worker_supervisor.ex  |  91 +++++++++++++++
 4 files changed, 118 insertions(+), 92 deletions(-)
 create mode 100644 lib/pleroma/gun/connection_pool/worker_supervisor.ex

diff --git a/lib/pleroma/application.ex b/lib/pleroma/application.ex
index be14c1f9f..cfdaf1770 100644
--- a/lib/pleroma/application.ex
+++ b/lib/pleroma/application.ex
@@ -243,7 +243,7 @@ defp http_children(Tesla.Adapter.Hackney, _) do
   end
 
   defp http_children(Tesla.Adapter.Gun, _) do
-    [{Registry, keys: :unique, name: Pleroma.Gun.ConnectionPool}]
+    Pleroma.Gun.ConnectionPool.children()
   end
 
   defp http_children(_, _), do: []
diff --git a/lib/pleroma/gun/connection_pool.ex b/lib/pleroma/gun/connection_pool.ex
index 0daf1da44..545bfaf7f 100644
--- a/lib/pleroma/gun/connection_pool.ex
+++ b/lib/pleroma/gun/connection_pool.ex
@@ -1,6 +1,15 @@
 defmodule Pleroma.Gun.ConnectionPool do
   @registry __MODULE__
 
+  alias Pleroma.Gun.ConnectionPool.WorkerSupervisor
+
+  def children do
+    [
+      {Registry, keys: :unique, name: @registry},
+      Pleroma.Gun.ConnectionPool.WorkerSupervisor
+    ]
+  end
+
   def get_conn(uri, opts) do
     key = "#{uri.scheme}:#{uri.host}:#{uri.port}"
 
@@ -14,96 +23,24 @@ def get_conn(uri, opts) do
         {:ok, gun_pid}
 
       [] ->
-        case enforce_pool_limits() do
-          :ok ->
-            # :gun.set_owner fails in :connected state for whatevever reason,
-            # so we open the connection in the process directly and send it's pid back
-            # We trust gun to handle timeouts by itself
-            case GenServer.start(Pleroma.Gun.ConnectionPool.Worker, [uri, key, opts, self()],
-                   timeout: :infinity
-                 ) do
-              {:ok, _worker_pid} ->
-                receive do
-                  {:conn_pid, pid} -> {:ok, pid}
-                end
-
-              {:error, {:error, {:already_registered, worker_pid}}} ->
-                get_gun_pid_from_worker(worker_pid)
-
-              err ->
-                err
+        # :gun.set_owner fails in :connected state for whatevever reason,
+        # so we open the connection in the process directly and send it's pid back
+        # We trust gun to handle timeouts by itself
+        case WorkerSupervisor.start_worker([uri, key, opts, self()]) do
+          {:ok, _worker_pid} ->
+            receive do
+              {:conn_pid, pid} -> {:ok, pid}
             end
 
-          :error ->
-            {:error, :pool_full}
+          {:error, {:error, {:already_registered, worker_pid}}} ->
+            get_gun_pid_from_worker(worker_pid)
+
+          err ->
+            err
         end
     end
   end
 
-  @enforcer_key "enforcer"
-  defp enforce_pool_limits() do
-    max_connections = Pleroma.Config.get([:connections_pool, :max_connections])
-
-    if Registry.count(@registry) >= max_connections do
-      case Registry.lookup(@registry, @enforcer_key) do
-        [] ->
-          pid =
-            spawn(fn ->
-              {:ok, _pid} = Registry.register(@registry, @enforcer_key, nil)
-
-              reclaim_max =
-                [:connections_pool, :reclaim_multiplier]
-                |> Pleroma.Config.get()
-                |> Kernel.*(max_connections)
-                |> round
-                |> max(1)
-
-              unused_conns =
-                Registry.select(
-                  @registry,
-                  [
-                    {{:_, :"$1", {:_, :"$2", :"$3", :"$4"}}, [{:==, :"$2", []}],
-                     [{{:"$1", :"$3", :"$4"}}]}
-                  ]
-                )
-
-              case unused_conns do
-                [] ->
-                  exit(:pool_full)
-
-                unused_conns ->
-                  unused_conns
-                  |> Enum.sort(fn {_pid1, crf1, last_reference1},
-                                  {_pid2, crf2, last_reference2} ->
-                    crf1 <= crf2 and last_reference1 <= last_reference2
-                  end)
-                  |> Enum.take(reclaim_max)
-                  |> Enum.each(fn {pid, _, _} -> GenServer.call(pid, :idle_close) end)
-              end
-            end)
-
-          wait_for_enforcer_finish(pid)
-
-        [{pid, _}] ->
-          wait_for_enforcer_finish(pid)
-      end
-    else
-      :ok
-    end
-  end
-
-  defp wait_for_enforcer_finish(pid) do
-    ref = Process.monitor(pid)
-
-    receive do
-      {:DOWN, ^ref, :process, ^pid, :pool_full} ->
-        :error
-
-      {:DOWN, ^ref, :process, ^pid, :normal} ->
-        :ok
-    end
-  end
-
   defp get_gun_pid_from_worker(worker_pid) do
     # GenServer.call will block the process for timeout length if
     # the server crashes on startup (which will happen if gun fails to connect)
diff --git a/lib/pleroma/gun/connection_pool/worker.ex b/lib/pleroma/gun/connection_pool/worker.ex
index ebde4bbf6..25fafc64c 100644
--- a/lib/pleroma/gun/connection_pool/worker.ex
+++ b/lib/pleroma/gun/connection_pool/worker.ex
@@ -1,9 +1,13 @@
 defmodule Pleroma.Gun.ConnectionPool.Worker do
   alias Pleroma.Gun
-  use GenServer
+  use GenServer, restart: :temporary
 
   @registry Pleroma.Gun.ConnectionPool
 
+  def start_link(opts) do
+    GenServer.start_link(__MODULE__, opts)
+  end
+
   @impl true
   def init([uri, key, opts, client_pid]) do
     time = :os.system_time(:second)
@@ -82,12 +86,6 @@ def handle_info({:gun_down, _pid, _protocol, _reason, _killed_streams} = down_me
     {:stop, {:error, down_message}, state}
   end
 
-  @impl true
-  def handle_call(:idle_close, _, %{key: key} = state) do
-    Registry.unregister(@registry, key)
-    {:stop, :normal, state}
-  end
-
   # LRFU policy: https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.55.1478
   defp crf(time_delta, prev_crf) do
     1 + :math.pow(0.5, time_delta / 100) * prev_crf
diff --git a/lib/pleroma/gun/connection_pool/worker_supervisor.ex b/lib/pleroma/gun/connection_pool/worker_supervisor.ex
new file mode 100644
index 000000000..5b546bd87
--- /dev/null
+++ b/lib/pleroma/gun/connection_pool/worker_supervisor.ex
@@ -0,0 +1,91 @@
+defmodule Pleroma.Gun.ConnectionPool.WorkerSupervisor do
+  @doc "Supervisor for pool workers. Does not do anything except enforce max connection limit"
+
+  use DynamicSupervisor
+
+  def start_link(opts) do
+    DynamicSupervisor.start_link(__MODULE__, opts, name: __MODULE__)
+  end
+
+  def init(_opts) do
+    DynamicSupervisor.init(
+      strategy: :one_for_one,
+      max_children: Pleroma.Config.get([:connections_pool, :max_connections])
+    )
+  end
+
+  def start_worker(opts) do
+    case DynamicSupervisor.start_child(__MODULE__, {Pleroma.Gun.ConnectionPool.Worker, opts}) do
+      {:error, :max_children} ->
+        case free_pool() do
+          :ok -> start_worker(opts)
+          :error -> {:error, :pool_full}
+        end
+
+      res ->
+        res
+    end
+  end
+
+  @registry Pleroma.Gun.ConnectionPool
+  @enforcer_key "enforcer"
+  defp free_pool do
+    case Registry.lookup(@registry, @enforcer_key) do
+      [] ->
+        pid =
+          spawn(fn ->
+            {:ok, _pid} = Registry.register(@registry, @enforcer_key, nil)
+
+            max_connections = Pleroma.Config.get([:connections_pool, :max_connections])
+
+            reclaim_max =
+              [:connections_pool, :reclaim_multiplier]
+              |> Pleroma.Config.get()
+              |> Kernel.*(max_connections)
+              |> round
+              |> max(1)
+
+            unused_conns =
+              Registry.select(
+                @registry,
+                [
+                  {{:_, :"$1", {:_, :"$2", :"$3", :"$4"}}, [{:==, :"$2", []}],
+                   [{{:"$1", :"$3", :"$4"}}]}
+                ]
+              )
+
+            case unused_conns do
+              [] ->
+                exit(:no_unused_conns)
+
+              unused_conns ->
+                unused_conns
+                |> Enum.sort(fn {_pid1, crf1, last_reference1}, {_pid2, crf2, last_reference2} ->
+                  crf1 <= crf2 and last_reference1 <= last_reference2
+                end)
+                |> Enum.take(reclaim_max)
+                |> Enum.each(fn {pid, _, _} ->
+                  DynamicSupervisor.terminate_child(__MODULE__, pid)
+                end)
+            end
+          end)
+
+        wait_for_enforcer_finish(pid)
+
+      [{pid, _}] ->
+        wait_for_enforcer_finish(pid)
+    end
+  end
+
+  defp wait_for_enforcer_finish(pid) do
+    ref = Process.monitor(pid)
+
+    receive do
+      {:DOWN, ^ref, :process, ^pid, :no_unused_conns} ->
+        :error
+
+      {:DOWN, ^ref, :process, ^pid, :normal} ->
+        :ok
+    end
+  end
+end

From 0ffde499b8a8f31c82183253bdd692c75733ca2f Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Wed, 15 Jul 2020 15:24:47 +0300
Subject: [PATCH 05/33] Connection Pool: register workers using :via

---
 lib/pleroma/gun/connection_pool.ex              |  8 +++++---
 lib/pleroma/gun/connection_pool/worker.ex       | 17 ++++++++---------
 .../gun/connection_pool/worker_supervisor.ex    |  3 +--
 3 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/lib/pleroma/gun/connection_pool.ex b/lib/pleroma/gun/connection_pool.ex
index 545bfaf7f..e951872fe 100644
--- a/lib/pleroma/gun/connection_pool.ex
+++ b/lib/pleroma/gun/connection_pool.ex
@@ -15,7 +15,7 @@ def get_conn(uri, opts) do
 
     case Registry.lookup(@registry, key) do
       # The key has already been registered, but connection is not up yet
-      [{worker_pid, {nil, _used_by, _crf, _last_reference}}] ->
+      [{worker_pid, nil}] ->
         get_gun_pid_from_worker(worker_pid)
 
       [{worker_pid, {gun_pid, _used_by, _crf, _last_reference}}] ->
@@ -26,13 +26,13 @@ def get_conn(uri, opts) do
         # :gun.set_owner fails in :connected state for whatevever reason,
         # so we open the connection in the process directly and send it's pid back
         # We trust gun to handle timeouts by itself
-        case WorkerSupervisor.start_worker([uri, key, opts, self()]) do
+        case WorkerSupervisor.start_worker([key, uri, opts, self()]) do
           {:ok, _worker_pid} ->
             receive do
               {:conn_pid, pid} -> {:ok, pid}
             end
 
-          {:error, {:error, {:already_registered, worker_pid}}} ->
+          {:error, {:already_started, worker_pid}} ->
             get_gun_pid_from_worker(worker_pid)
 
           err ->
@@ -56,6 +56,8 @@ defp get_gun_pid_from_worker(worker_pid) do
   end
 
   def release_conn(conn_pid) do
+    # :ets.fun2ms(fn {_, {worker_pid, {gun_pid, _, _, _}}} when gun_pid == conn_pid ->
+    #    worker_pid end)
     query_result =
       Registry.select(@registry, [
         {{:_, :"$1", {:"$2", :_, :_, :_}}, [{:==, :"$2", conn_pid}], [:"$1"]}
diff --git a/lib/pleroma/gun/connection_pool/worker.ex b/lib/pleroma/gun/connection_pool/worker.ex
index 25fafc64c..0a94f16a2 100644
--- a/lib/pleroma/gun/connection_pool/worker.ex
+++ b/lib/pleroma/gun/connection_pool/worker.ex
@@ -4,20 +4,19 @@ defmodule Pleroma.Gun.ConnectionPool.Worker do
 
   @registry Pleroma.Gun.ConnectionPool
 
-  def start_link(opts) do
-    GenServer.start_link(__MODULE__, opts)
+  def start_link([key | _] = opts) do
+    GenServer.start_link(__MODULE__, opts, name: {:via, Registry, {@registry, key}})
   end
 
   @impl true
-  def init([uri, key, opts, client_pid]) do
-    time = :os.system_time(:second)
-    # Register before opening connection to prevent race conditions
-    with {:ok, _owner} <- Registry.register(@registry, key, {nil, [client_pid], 1, time}),
-         {:ok, conn_pid} <- Gun.Conn.open(uri, opts),
+  def init([key, uri, opts, client_pid]) do
+    with {:ok, conn_pid} <- Gun.Conn.open(uri, opts),
          Process.link(conn_pid) do
+      time = :os.system_time(:second)
+
       {_, _} =
-        Registry.update_value(@registry, key, fn {_, used_by, crf, last_reference} ->
-          {conn_pid, used_by, crf, last_reference}
+        Registry.update_value(@registry, key, fn _ ->
+          {conn_pid, [client_pid], 1, time}
         end)
 
       send(client_pid, {:conn_pid, conn_pid})
diff --git a/lib/pleroma/gun/connection_pool/worker_supervisor.ex b/lib/pleroma/gun/connection_pool/worker_supervisor.ex
index 5b546bd87..d090c034e 100644
--- a/lib/pleroma/gun/connection_pool/worker_supervisor.ex
+++ b/lib/pleroma/gun/connection_pool/worker_supervisor.ex
@@ -1,5 +1,5 @@
 defmodule Pleroma.Gun.ConnectionPool.WorkerSupervisor do
-  @doc "Supervisor for pool workers. Does not do anything except enforce max connection limit"
+  @moduledoc "Supervisor for pool workers. Does not do anything except enforce max connection limit"
 
   use DynamicSupervisor
 
@@ -35,7 +35,6 @@ defp free_pool do
         pid =
           spawn(fn ->
             {:ok, _pid} = Registry.register(@registry, @enforcer_key, nil)
-
             max_connections = Pleroma.Config.get([:connections_pool, :max_connections])
 
             reclaim_max =

From 7738fbbaf5a6fcd6a10b4ef0a2dcea731a3d4192 Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Wed, 15 Jul 2020 15:26:25 +0300
Subject: [PATCH 06/33] Connection pool: implement logging and telemetry events

---
 lib/pleroma/application.ex                    |  1 +
 .../gun/connection_pool/worker_supervisor.ex  | 44 ++++++++++---
 lib/pleroma/telemetry/logger.ex               | 62 +++++++++++++++++++
 3 files changed, 100 insertions(+), 7 deletions(-)
 create mode 100644 lib/pleroma/telemetry/logger.ex

diff --git a/lib/pleroma/application.ex b/lib/pleroma/application.ex
index cfdaf1770..37fcdf293 100644
--- a/lib/pleroma/application.ex
+++ b/lib/pleroma/application.ex
@@ -39,6 +39,7 @@ def start(_type, _args) do
     # every time the application is restarted, so we disable module
     # conflicts at runtime
     Code.compiler_options(ignore_module_conflict: true)
+    Pleroma.Telemetry.Logger.attach()
     Config.Holder.save_default()
     Pleroma.HTML.compile_scrubbers()
     Config.DeprecationWarnings.warn()
diff --git a/lib/pleroma/gun/connection_pool/worker_supervisor.ex b/lib/pleroma/gun/connection_pool/worker_supervisor.ex
index d090c034e..4b5d10d2a 100644
--- a/lib/pleroma/gun/connection_pool/worker_supervisor.ex
+++ b/lib/pleroma/gun/connection_pool/worker_supervisor.ex
@@ -18,8 +18,12 @@ def start_worker(opts) do
     case DynamicSupervisor.start_child(__MODULE__, {Pleroma.Gun.ConnectionPool.Worker, opts}) do
       {:error, :max_children} ->
         case free_pool() do
-          :ok -> start_worker(opts)
-          :error -> {:error, :pool_full}
+          :ok ->
+            start_worker(opts)
+
+          :error ->
+            :telemetry.execute([:pleroma, :connection_pool, :provision_failure], %{opts: opts})
+            {:error, :pool_full}
         end
 
       res ->
@@ -44,6 +48,14 @@ defp free_pool do
               |> round
               |> max(1)
 
+            :telemetry.execute([:pleroma, :connection_pool, :reclaim, :start], %{}, %{
+              max_connections: max_connections,
+              reclaim_max: reclaim_max
+            })
+
+            # :ets.fun2ms(
+            # fn {_, {worker_pid, {_, used_by, crf, last_reference}}} when used_by == [] ->
+            #   {worker_pid, crf, last_reference} end)
             unused_conns =
               Registry.select(
                 @registry,
@@ -55,17 +67,35 @@ defp free_pool do
 
             case unused_conns do
               [] ->
+                :telemetry.execute(
+                  [:pleroma, :connection_pool, :reclaim, :stop],
+                  %{reclaimed_count: 0},
+                  %{
+                    max_connections: max_connections
+                  }
+                )
+
                 exit(:no_unused_conns)
 
               unused_conns ->
-                unused_conns
-                |> Enum.sort(fn {_pid1, crf1, last_reference1}, {_pid2, crf2, last_reference2} ->
-                  crf1 <= crf2 and last_reference1 <= last_reference2
-                end)
-                |> Enum.take(reclaim_max)
+                reclaimed =
+                  unused_conns
+                  |> Enum.sort(fn {_pid1, crf1, last_reference1},
+                                  {_pid2, crf2, last_reference2} ->
+                    crf1 <= crf2 and last_reference1 <= last_reference2
+                  end)
+                  |> Enum.take(reclaim_max)
+
+                reclaimed
                 |> Enum.each(fn {pid, _, _} ->
                   DynamicSupervisor.terminate_child(__MODULE__, pid)
                 end)
+
+                :telemetry.execute(
+                  [:pleroma, :connection_pool, :reclaim, :stop],
+                  %{reclaimed_count: Enum.count(reclaimed)},
+                  %{max_connections: max_connections}
+                )
             end
           end)
 
diff --git a/lib/pleroma/telemetry/logger.ex b/lib/pleroma/telemetry/logger.ex
new file mode 100644
index 000000000..d76dd37b5
--- /dev/null
+++ b/lib/pleroma/telemetry/logger.ex
@@ -0,0 +1,62 @@
+defmodule Pleroma.Telemetry.Logger do
+  @moduledoc "Transforms Pleroma telemetry events to logs"
+
+  require Logger
+
+  @events [
+    [:pleroma, :connection_pool, :reclaim, :start],
+    [:pleroma, :connection_pool, :reclaim, :stop],
+    [:pleroma, :connection_pool, :provision_failure]
+  ]
+  def attach do
+    :telemetry.attach_many("pleroma-logger", @events, &handle_event/4, [])
+  end
+
+  # Passing anonymous functions instead of strings to logger is intentional,
+  # that way strings won't be concatenated if the message is going to be thrown
+  # out anyway due to higher log level configured
+
+  def handle_event(
+        [:pleroma, :connection_pool, :reclaim, :start],
+        _,
+        %{max_connections: max_connections, reclaim_max: reclaim_max},
+        _
+      ) do
+    Logger.debug(fn ->
+      "Connection pool is exhausted (reached #{max_connections} connections). Starting idle connection cleanup to reclaim as much as #{
+        reclaim_max
+      } connections"
+    end)
+  end
+
+  def handle_event(
+        [:pleroma, :connection_pool, :reclaim, :stop],
+        %{reclaimed_count: 0},
+        _,
+        _
+      ) do
+    Logger.error(fn ->
+      "Connection pool failed to reclaim any connections due to all of them being in use. It will have to drop requests for opening connections to new hosts"
+    end)
+  end
+
+  def handle_event(
+        [:pleroma, :connection_pool, :reclaim, :stop],
+        %{reclaimed_count: reclaimed_count},
+        _,
+        _
+      ) do
+    Logger.debug(fn -> "Connection pool cleaned up #{reclaimed_count} idle connections" end)
+  end
+
+  def handle_event(
+        [:pleroma, :connection_pool, :provision_failure],
+        %{opts: [key | _]},
+        _,
+        _
+      ) do
+    Logger.error(fn ->
+      "Connection pool had to refuse opening a connection to #{key} due to connection limit exhaustion"
+    end)
+  end
+end

From e94ba05e523d735cd7a357a3aa30e433f60ef9a3 Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Thu, 7 May 2020 16:11:48 +0300
Subject: [PATCH 07/33] Connection pool: Fix a possible infinite recursion if
 the pool is exhausted

---
 .../gun/connection_pool/worker_supervisor.ex       | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/lib/pleroma/gun/connection_pool/worker_supervisor.ex b/lib/pleroma/gun/connection_pool/worker_supervisor.ex
index 4b5d10d2a..5cb8d488a 100644
--- a/lib/pleroma/gun/connection_pool/worker_supervisor.ex
+++ b/lib/pleroma/gun/connection_pool/worker_supervisor.ex
@@ -14,16 +14,14 @@ def init(_opts) do
     )
   end
 
-  def start_worker(opts) do
+  def start_worker(opts, retry \\ false) do
     case DynamicSupervisor.start_child(__MODULE__, {Pleroma.Gun.ConnectionPool.Worker, opts}) do
       {:error, :max_children} ->
-        case free_pool() do
-          :ok ->
-            start_worker(opts)
-
-          :error ->
-            :telemetry.execute([:pleroma, :connection_pool, :provision_failure], %{opts: opts})
-            {:error, :pool_full}
+        if retry or free_pool() == :error do
+          :telemetry.execute([:pleroma, :connection_pool, :provision_failure], %{opts: opts})
+          {:error, :pool_full}
+        else
+          start_worker(opts, true)
         end
 
       res ->

From 1b15cb066c612c72d106e7e7026819ea14e0ceab Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Fri, 8 May 2020 18:18:59 +0300
Subject: [PATCH 08/33] Connection pool: Add client death tracking

While running this in production I noticed a number of ghost
processes with all their clients dead before they released the connection,
so let's track them to log it and remove them from clients
---
 lib/pleroma/gun/connection_pool/worker.ex | 31 ++++++++++++++++++++++-
 lib/pleroma/telemetry/logger.ex           | 16 +++++++++++-
 2 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/lib/pleroma/gun/connection_pool/worker.ex b/lib/pleroma/gun/connection_pool/worker.ex
index 0a94f16a2..8467325f3 100644
--- a/lib/pleroma/gun/connection_pool/worker.ex
+++ b/lib/pleroma/gun/connection_pool/worker.ex
@@ -20,7 +20,10 @@ def init([key, uri, opts, client_pid]) do
         end)
 
       send(client_pid, {:conn_pid, conn_pid})
-      {:ok, %{key: key, timer: nil}, :hibernate}
+
+      {:ok,
+       %{key: key, timer: nil, client_monitors: %{client_pid => Process.monitor(client_pid)}},
+       :hibernate}
     else
       err -> {:stop, err}
     end
@@ -45,6 +48,9 @@ def handle_cast({:add_client, client_pid, send_pid_back}, %{key: key} = state) d
         state
       end
 
+    ref = Process.monitor(client_pid)
+
+    state = put_in(state.client_monitors[client_pid], ref)
     {:noreply, state, :hibernate}
   end
 
@@ -55,6 +61,9 @@ def handle_cast({:remove_client, client_pid}, %{key: key} = state) do
         {conn_pid, List.delete(used_by, client_pid), crf, last_reference}
       end)
 
+    {ref, state} = pop_in(state.client_monitors[client_pid])
+    Process.demonitor(ref)
+
     timer =
       if used_by == [] do
         max_idle = Pleroma.Config.get([:connections_pool, :max_idle_time], 30_000)
@@ -85,6 +94,26 @@ def handle_info({:gun_down, _pid, _protocol, _reason, _killed_streams} = down_me
     {:stop, {:error, down_message}, state}
   end
 
+  @impl true
+  def handle_info({:DOWN, _ref, :process, pid, reason}, state) do
+    # Sometimes the client is dead before we demonitor it in :remove_client, so the message
+    # arrives anyway
+
+    case state.client_monitors[pid] do
+      nil ->
+        {:noreply, state, :hibernate}
+
+      _ref ->
+        :telemetry.execute(
+          [:pleroma, :connection_pool, :client_death],
+          %{client_pid: pid, reason: reason},
+          %{key: state.key}
+        )
+
+        handle_cast({:remove_client, pid}, state)
+    end
+  end
+
   # LRFU policy: https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.55.1478
   defp crf(time_delta, prev_crf) do
     1 + :math.pow(0.5, time_delta / 100) * prev_crf
diff --git a/lib/pleroma/telemetry/logger.ex b/lib/pleroma/telemetry/logger.ex
index d76dd37b5..4cacae02f 100644
--- a/lib/pleroma/telemetry/logger.ex
+++ b/lib/pleroma/telemetry/logger.ex
@@ -6,7 +6,8 @@ defmodule Pleroma.Telemetry.Logger do
   @events [
     [:pleroma, :connection_pool, :reclaim, :start],
     [:pleroma, :connection_pool, :reclaim, :stop],
-    [:pleroma, :connection_pool, :provision_failure]
+    [:pleroma, :connection_pool, :provision_failure],
+    [:pleroma, :connection_pool, :client_death]
   ]
   def attach do
     :telemetry.attach_many("pleroma-logger", @events, &handle_event/4, [])
@@ -59,4 +60,17 @@ def handle_event(
       "Connection pool had to refuse opening a connection to #{key} due to connection limit exhaustion"
     end)
   end
+
+  def handle_event(
+        [:pleroma, :connection_pool, :client_death],
+        %{client_pid: client_pid, reason: reason},
+        %{key: key},
+        _
+      ) do
+    Logger.warn(fn ->
+      "Pool worker for #{key}: Client #{inspect(client_pid)} died before releasing the connection with #{
+        inspect(reason)
+      }"
+    end)
+  end
 end

From 281ddd5e371c5698489774e703106bd7c3ccb56b Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Fri, 8 May 2020 19:57:11 +0300
Subject: [PATCH 09/33] Connection pool: fix connections being supervised by
 gun_sup

---
 lib/pleroma/gun/api.ex | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/pleroma/gun/api.ex b/lib/pleroma/gun/api.ex
index f51cd7db8..09be74392 100644
--- a/lib/pleroma/gun/api.ex
+++ b/lib/pleroma/gun/api.ex
@@ -19,7 +19,8 @@ defmodule Pleroma.Gun.API do
     :tls_opts,
     :tcp_opts,
     :socks_opts,
-    :ws_opts
+    :ws_opts,
+    :supervise
   ]
 
   @impl Gun

From 94c8f3cfafb92c6d092549b24bb69f3870e1c0d8 Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Sat, 16 May 2020 11:49:19 +0300
Subject: [PATCH 10/33] Use a custom pool-aware FollowRedirects middleware

---
 lib/pleroma/http/adapter_helper.ex            |   4 -
 lib/pleroma/http/adapter_helper/default.ex    |   3 -
 lib/pleroma/http/adapter_helper/gun.ex        |   9 --
 lib/pleroma/http/adapter_helper/hackney.ex    |   2 -
 lib/pleroma/http/http.ex                      |   9 +-
 .../tesla/middleware/follow_redirects.ex      | 106 ++++++++++++++++++
 6 files changed, 109 insertions(+), 24 deletions(-)
 create mode 100644 lib/pleroma/tesla/middleware/follow_redirects.ex

diff --git a/lib/pleroma/http/adapter_helper.ex b/lib/pleroma/http/adapter_helper.ex
index 0532ea31d..bcb9b2b1e 100644
--- a/lib/pleroma/http/adapter_helper.ex
+++ b/lib/pleroma/http/adapter_helper.ex
@@ -24,7 +24,6 @@ defmodule Pleroma.HTTP.AdapterHelper do
           | {Connection.proxy_type(), Connection.host(), pos_integer()}
 
   @callback options(keyword(), URI.t()) :: keyword()
-  @callback after_request(keyword()) :: :ok
   @callback get_conn(URI.t(), keyword()) :: {:ok, term()} | {:error, term()}
 
   @spec format_proxy(String.t() | tuple() | nil) :: proxy() | nil
@@ -67,9 +66,6 @@ defp pool_timeout(opts) do
     Keyword.merge(opts, timeout: timeout)
   end
 
-  @spec after_request(keyword()) :: :ok
-  def after_request(opts), do: adapter_helper().after_request(opts)
-
   def get_conn(uri, opts), do: adapter_helper().get_conn(uri, opts)
   defp adapter, do: Application.get_env(:tesla, :adapter)
 
diff --git a/lib/pleroma/http/adapter_helper/default.ex b/lib/pleroma/http/adapter_helper/default.ex
index 218cfacc0..e13441316 100644
--- a/lib/pleroma/http/adapter_helper/default.ex
+++ b/lib/pleroma/http/adapter_helper/default.ex
@@ -9,9 +9,6 @@ def options(opts, _uri) do
     AdapterHelper.maybe_add_proxy(opts, AdapterHelper.format_proxy(proxy))
   end
 
-  @spec after_request(keyword()) :: :ok
-  def after_request(_opts), do: :ok
-
   @spec get_conn(URI.t(), keyword()) :: {:ok, keyword()}
   def get_conn(_uri, opts), do: {:ok, opts}
 end
diff --git a/lib/pleroma/http/adapter_helper/gun.ex b/lib/pleroma/http/adapter_helper/gun.ex
index 6f7cc9784..5b4629978 100644
--- a/lib/pleroma/http/adapter_helper/gun.ex
+++ b/lib/pleroma/http/adapter_helper/gun.ex
@@ -34,15 +34,6 @@ def options(incoming_opts \\ [], %URI{} = uri) do
     |> Keyword.merge(incoming_opts)
   end
 
-  @spec after_request(keyword()) :: :ok
-  def after_request(opts) do
-    if opts[:conn] && opts[:body_as] != :chunks do
-      ConnectionPool.release_conn(opts[:conn])
-    end
-
-    :ok
-  end
-
   defp add_scheme_opts(opts, %{scheme: "http"}), do: opts
 
   defp add_scheme_opts(opts, %{scheme: "https"}) do
diff --git a/lib/pleroma/http/adapter_helper/hackney.ex b/lib/pleroma/http/adapter_helper/hackney.ex
index 42d552740..cd569422b 100644
--- a/lib/pleroma/http/adapter_helper/hackney.ex
+++ b/lib/pleroma/http/adapter_helper/hackney.ex
@@ -24,8 +24,6 @@ def options(connection_opts \\ [], %URI{} = uri) do
 
   defp add_scheme_opts(opts, _), do: opts
 
-  def after_request(_), do: :ok
-
   @spec get_conn(URI.t(), keyword()) :: {:ok, keyword()}
   def get_conn(_uri, opts), do: {:ok, opts}
 end
diff --git a/lib/pleroma/http/http.ex b/lib/pleroma/http/http.ex
index 8ded76601..afcb4d738 100644
--- a/lib/pleroma/http/http.ex
+++ b/lib/pleroma/http/http.ex
@@ -69,14 +69,11 @@ def request(method, url, body, headers, options) when is_binary(url) do
         request = build_request(method, headers, options, url, body, params)
 
         adapter = Application.get_env(:tesla, :adapter)
-        client = Tesla.client([Tesla.Middleware.FollowRedirects], adapter)
+        client = Tesla.client([Pleroma.HTTP.Middleware.FollowRedirects], adapter)
 
-        response = request(client, request)
-
-        AdapterHelper.after_request(adapter_opts)
-
-        response
+        request(client, request)
 
+      # Connection release is handled in a custom FollowRedirects middleware
       err ->
         err
     end
diff --git a/lib/pleroma/tesla/middleware/follow_redirects.ex b/lib/pleroma/tesla/middleware/follow_redirects.ex
new file mode 100644
index 000000000..f2c502c69
--- /dev/null
+++ b/lib/pleroma/tesla/middleware/follow_redirects.ex
@@ -0,0 +1,106 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2015-2020 Tymon Tobolski <https://github.com/teamon/tesla/blob/master/lib/tesla/middleware/follow_redirects.ex>
+# Copyright © 2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.HTTP.Middleware.FollowRedirects do
+  @moduledoc """
+  Pool-aware version of https://github.com/teamon/tesla/blob/master/lib/tesla/middleware/follow_redirects.ex
+
+  Follow 3xx redirects
+  ## Options
+  - `:max_redirects` - limit number of redirects (default: `5`)
+  """
+
+  alias Pleroma.Gun.ConnectionPool
+
+  @behaviour Tesla.Middleware
+
+  @max_redirects 5
+  @redirect_statuses [301, 302, 303, 307, 308]
+
+  @impl Tesla.Middleware
+  def call(env, next, opts \\ []) do
+    max = Keyword.get(opts, :max_redirects, @max_redirects)
+
+    redirect(env, next, max)
+  end
+
+  defp redirect(env, next, left) do
+    opts = env.opts[:adapter]
+
+    case Tesla.run(env, next) do
+      {:ok, %{status: status} = res} when status in @redirect_statuses and left > 0 ->
+        release_conn(opts)
+
+        case Tesla.get_header(res, "location") do
+          nil ->
+            {:ok, res}
+
+          location ->
+            location = parse_location(location, res)
+
+            case get_conn(location, opts) do
+              {:ok, opts} ->
+                %{env | opts: Keyword.put(env.opts, :adapter, opts)}
+                |> new_request(res.status, location)
+                |> redirect(next, left - 1)
+
+              e ->
+                e
+            end
+        end
+
+      {:ok, %{status: status}} when status in @redirect_statuses ->
+        release_conn(opts)
+        {:error, {__MODULE__, :too_many_redirects}}
+
+      other ->
+        unless opts[:body_as] == :chunks do
+          release_conn(opts)
+        end
+
+        other
+    end
+  end
+
+  defp get_conn(location, opts) do
+    uri = URI.parse(location)
+
+    case ConnectionPool.get_conn(uri, opts) do
+      {:ok, conn} ->
+        {:ok, Keyword.merge(opts, conn: conn)}
+
+      e ->
+        e
+    end
+  end
+
+  defp release_conn(opts) do
+    ConnectionPool.release_conn(opts[:conn])
+  end
+
+  # The 303 (See Other) redirect was added in HTTP/1.1 to indicate that the originally
+  # requested resource is not available, however a related resource (or another redirect)
+  # available via GET is available at the specified location.
+  # https://tools.ietf.org/html/rfc7231#section-6.4.4
+  defp new_request(env, 303, location), do: %{env | url: location, method: :get, query: []}
+
+  # The 307 (Temporary Redirect) status code indicates that the target
+  # resource resides temporarily under a different URI and the user agent
+  # MUST NOT change the request method (...)
+  # https://tools.ietf.org/html/rfc7231#section-6.4.7
+  defp new_request(env, 307, location), do: %{env | url: location}
+
+  defp new_request(env, _, location), do: %{env | url: location, query: []}
+
+  defp parse_location("https://" <> _rest = location, _env), do: location
+  defp parse_location("http://" <> _rest = location, _env), do: location
+
+  defp parse_location(location, env) do
+    env.url
+    |> URI.parse()
+    |> URI.merge(location)
+    |> URI.to_string()
+  end
+end

From 4128e3a84a2b6d75a8f92759e65ee673b47cec01 Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Sun, 17 May 2020 22:16:02 +0300
Subject: [PATCH 11/33] HTTP: Implement max request limits

---
 config/config.exs                      | 15 ++++++---------
 lib/pleroma/application.ex             |  3 ++-
 lib/pleroma/http/adapter_helper/gun.ex | 21 +++++++++++++++++++++
 lib/pleroma/http/http.ex               | 17 ++++++++++++++++-
 mix.exs                                |  3 +++
 mix.lock                               |  1 +
 6 files changed, 49 insertions(+), 11 deletions(-)

diff --git a/config/config.exs b/config/config.exs
index 577ccc198..dfc7a99d1 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -648,7 +648,8 @@
 
 config :pleroma, :connections_pool,
   reclaim_multiplier: 0.1,
-  checkin_timeout: 250,
+  connection_acquisition_wait: 250,
+  connection_acquisition_retries: 5,
   max_connections: 250,
   max_idle_time: 30_000,
   retry: 1,
@@ -658,23 +659,19 @@
 config :pleroma, :pools,
   federation: [
     size: 50,
-    max_overflow: 10,
-    timeout: 150_000
+    max_waiting: 10
   ],
   media: [
     size: 50,
-    max_overflow: 10,
-    timeout: 150_000
+    max_waiting: 10
   ],
   upload: [
     size: 25,
-    max_overflow: 5,
-    timeout: 300_000
+    max_waiting: 5
   ],
   default: [
     size: 10,
-    max_overflow: 2,
-    timeout: 10_000
+    max_waiting: 2
   ]
 
 config :pleroma, :hackney_pools,
diff --git a/lib/pleroma/application.ex b/lib/pleroma/application.ex
index 37fcdf293..0ffb55358 100644
--- a/lib/pleroma/application.ex
+++ b/lib/pleroma/application.ex
@@ -244,7 +244,8 @@ defp http_children(Tesla.Adapter.Hackney, _) do
   end
 
   defp http_children(Tesla.Adapter.Gun, _) do
-    Pleroma.Gun.ConnectionPool.children()
+    Pleroma.Gun.ConnectionPool.children() ++
+      [{Task, &Pleroma.HTTP.AdapterHelper.Gun.limiter_setup/0}]
   end
 
   defp http_children(_, _), do: []
diff --git a/lib/pleroma/http/adapter_helper/gun.ex b/lib/pleroma/http/adapter_helper/gun.ex
index 5b4629978..883f7f6f7 100644
--- a/lib/pleroma/http/adapter_helper/gun.ex
+++ b/lib/pleroma/http/adapter_helper/gun.ex
@@ -49,4 +49,25 @@ def get_conn(uri, opts) do
       err -> err
     end
   end
+
+  @prefix Pleroma.Gun.ConnectionPool
+  def limiter_setup do
+    wait = Pleroma.Config.get([:connections_pool, :connection_acquisition_wait])
+    retries = Pleroma.Config.get([:connections_pool, :connection_acquisition_retries])
+
+    :pools
+    |> Pleroma.Config.get([])
+    |> Enum.each(fn {name, opts} ->
+      max_running = Keyword.get(opts, :size, 50)
+      max_waiting = Keyword.get(opts, :max_waiting, 10)
+
+      :ok =
+        ConcurrentLimiter.new(:"#{@prefix}.#{name}", max_running, max_waiting,
+          wait: wait,
+          max_retries: retries
+        )
+    end)
+
+    :ok
+  end
 end
diff --git a/lib/pleroma/http/http.ex b/lib/pleroma/http/http.ex
index afcb4d738..6128bc4cf 100644
--- a/lib/pleroma/http/http.ex
+++ b/lib/pleroma/http/http.ex
@@ -71,7 +71,13 @@ def request(method, url, body, headers, options) when is_binary(url) do
         adapter = Application.get_env(:tesla, :adapter)
         client = Tesla.client([Pleroma.HTTP.Middleware.FollowRedirects], adapter)
 
-        request(client, request)
+        maybe_limit(
+          fn ->
+            request(client, request)
+          end,
+          adapter,
+          adapter_opts
+        )
 
       # Connection release is handled in a custom FollowRedirects middleware
       err ->
@@ -92,4 +98,13 @@ defp build_request(method, headers, options, url, body, params) do
     |> Builder.add_param(:query, :query, params)
     |> Builder.convert_to_keyword()
   end
+
+  @prefix Pleroma.Gun.ConnectionPool
+  defp maybe_limit(fun, Tesla.Adapter.Gun, opts) do
+    ConcurrentLimiter.limit(:"#{@prefix}.#{opts[:pool] || :default}", fun)
+  end
+
+  defp maybe_limit(fun, _, _) do
+    fun.()
+  end
 end
diff --git a/mix.exs b/mix.exs
index 741f917e6..4dfce58e7 100644
--- a/mix.exs
+++ b/mix.exs
@@ -191,6 +191,9 @@ defp deps do
       {:plug_static_index_html, "~> 1.0.0"},
       {:excoveralls, "~> 0.12.1", only: :test},
       {:flake_id, "~> 0.1.0"},
+      {:concurrent_limiter,
+       git: "https://git.pleroma.social/pleroma/elixir-libraries/concurrent_limiter",
+       ref: "8eee96c6ba39b9286ec44c51c52d9f2758951365"},
       {:remote_ip,
        git: "https://git.pleroma.social/pleroma/remote_ip.git",
        ref: "b647d0deecaa3acb140854fe4bda5b7e1dc6d1c8"},
diff --git a/mix.lock b/mix.lock
index f801f9e0c..89c97decf 100644
--- a/mix.lock
+++ b/mix.lock
@@ -15,6 +15,7 @@
   "certifi": {:hex, :certifi, "2.5.2", "b7cfeae9d2ed395695dd8201c57a2d019c0c43ecaf8b8bcb9320b40d6662f340", [:rebar3], [{:parse_trans, "~>3.3", [hex: :parse_trans, repo: "hexpm", optional: false]}], "hexpm", "3b3b5f36493004ac3455966991eaf6e768ce9884693d9968055aeeeb1e575040"},
   "combine": {:hex, :combine, "0.10.0", "eff8224eeb56498a2af13011d142c5e7997a80c8f5b97c499f84c841032e429f", [:mix], [], "hexpm", "1b1dbc1790073076580d0d1d64e42eae2366583e7aecd455d1215b0d16f2451b"},
   "comeonin": {:hex, :comeonin, "5.3.1", "7fe612b739c78c9c1a75186ef2d322ce4d25032d119823269d0aa1e2f1e20025", [:mix], [], "hexpm", "d6222483060c17f0977fad1b7401ef0c5863c985a64352755f366aee3799c245"},
+  "concurrent_limiter": {:git, "https://git.pleroma.social/pleroma/elixir-libraries/concurrent_limiter", "8eee96c6ba39b9286ec44c51c52d9f2758951365", [ref: "8eee96c6ba39b9286ec44c51c52d9f2758951365"]},
   "connection": {:hex, :connection, "1.0.4", "a1cae72211f0eef17705aaededacac3eb30e6625b04a6117c1b2db6ace7d5976", [:mix], [], "hexpm", "4a0850c9be22a43af9920a71ab17c051f5f7d45c209e40269a1938832510e4d9"},
   "cors_plug": {:hex, :cors_plug, "1.5.2", "72df63c87e4f94112f458ce9d25800900cc88608c1078f0e4faddf20933eda6e", [:mix], [{:plug, "~> 1.3 or ~> 1.4 or ~> 1.5", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm", "9af027d20dc12dd0c4345a6b87247e0c62965871feea0bfecf9764648b02cc69"},
   "cowboy": {:hex, :cowboy, "2.7.0", "91ed100138a764355f43316b1d23d7ff6bdb0de4ea618cb5d8677c93a7a2f115", [:rebar3], [{:cowlib, "~> 2.8.0", [hex: :cowlib, repo: "hexpm", optional: false]}, {:ranch, "~> 1.7.1", [hex: :ranch, repo: "hexpm", optional: false]}], "hexpm", "04fd8c6a39edc6aaa9c26123009200fc61f92a3a94f3178c527b70b767c6e605"},

From 721e89e88bafbf0db15b590604e886e37f3291c7 Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Thu, 28 May 2020 14:06:18 +0300
Subject: [PATCH 12/33] Remove tests for old pool

---
 test/http/adapter_helper/gun_test.exs | 171 ------
 test/http/connection_test.exs         | 135 -----
 test/pool/connections_test.exs        | 760 --------------------------
 3 files changed, 1066 deletions(-)
 delete mode 100644 test/http/connection_test.exs
 delete mode 100644 test/pool/connections_test.exs

diff --git a/test/http/adapter_helper/gun_test.exs b/test/http/adapter_helper/gun_test.exs
index 2e961826e..49eebf355 100644
--- a/test/http/adapter_helper/gun_test.exs
+++ b/test/http/adapter_helper/gun_test.exs
@@ -9,24 +9,10 @@ defmodule Pleroma.HTTP.AdapterHelper.GunTest do
   import Mox
 
   alias Pleroma.Config
-  alias Pleroma.Gun.Conn
   alias Pleroma.HTTP.AdapterHelper.Gun
-  alias Pleroma.Pool.Connections
 
   setup :verify_on_exit!
 
-  defp gun_mock(_) do
-    gun_mock()
-    :ok
-  end
-
-  defp gun_mock do
-    Pleroma.GunMock
-    |> stub(:open, fn _, _, _ -> Task.start_link(fn -> Process.sleep(1000) end) end)
-    |> stub(:await_up, fn _, _ -> {:ok, :http} end)
-    |> stub(:set_owner, fn _, _ -> :ok end)
-  end
-
   describe "options/1" do
     setup do: clear_config([:http, :adapter], a: 1, b: 2)
 
@@ -62,46 +48,12 @@ test "https url with non standart port" do
       assert opts[:certificates_verification]
     end
 
-    test "get conn on next request" do
-      gun_mock()
-      level = Application.get_env(:logger, :level)
-      Logger.configure(level: :debug)
-      on_exit(fn -> Logger.configure(level: level) end)
-      uri = URI.parse("http://some-domain2.com")
-
-      opts = Gun.options(uri)
-
-      assert opts[:conn] == nil
-      assert opts[:close_conn] == nil
-
-      Process.sleep(50)
-      opts = Gun.options(uri)
-
-      assert is_pid(opts[:conn])
-      assert opts[:close_conn] == false
-    end
-
     test "merges with defaul http adapter config" do
       defaults = Gun.options([receive_conn: false], URI.parse("https://example.com"))
       assert Keyword.has_key?(defaults, :a)
       assert Keyword.has_key?(defaults, :b)
     end
 
-    test "default ssl adapter opts with connection" do
-      gun_mock()
-      uri = URI.parse("https://some-domain.com")
-
-      :ok = Conn.open(uri, :gun_connections)
-
-      opts = Gun.options(uri)
-
-      assert opts[:certificates_verification]
-      refute opts[:tls_opts] == []
-
-      assert opts[:close_conn] == false
-      assert is_pid(opts[:conn])
-    end
-
     test "parses string proxy host & port" do
       proxy = Config.get([:http, :proxy_url])
       Config.put([:http, :proxy_url], "localhost:8123")
@@ -132,127 +84,4 @@ test "passed opts have more weight than defaults" do
       assert opts[:proxy] == {'example.com', 4321}
     end
   end
-
-  describe "options/1 with receive_conn parameter" do
-    setup :gun_mock
-
-    test "receive conn by default" do
-      uri = URI.parse("http://another-domain.com")
-      :ok = Conn.open(uri, :gun_connections)
-
-      received_opts = Gun.options(uri)
-      assert received_opts[:close_conn] == false
-      assert is_pid(received_opts[:conn])
-    end
-
-    test "don't receive conn if receive_conn is false" do
-      uri = URI.parse("http://another-domain.com")
-      :ok = Conn.open(uri, :gun_connections)
-
-      opts = [receive_conn: false]
-      received_opts = Gun.options(opts, uri)
-      assert received_opts[:close_conn] == nil
-      assert received_opts[:conn] == nil
-    end
-  end
-
-  describe "after_request/1" do
-    setup :gun_mock
-
-    test "body_as not chunks" do
-      uri = URI.parse("http://some-domain.com")
-      :ok = Conn.open(uri, :gun_connections)
-      opts = Gun.options(uri)
-      :ok = Gun.after_request(opts)
-      conn = opts[:conn]
-
-      assert %Connections{
-               conns: %{
-                 "http:some-domain.com:80" => %Pleroma.Gun.Conn{
-                   conn: ^conn,
-                   conn_state: :idle,
-                   used_by: []
-                 }
-               }
-             } = Connections.get_state(:gun_connections)
-    end
-
-    test "body_as chunks" do
-      uri = URI.parse("http://some-domain.com")
-      :ok = Conn.open(uri, :gun_connections)
-      opts = Gun.options([body_as: :chunks], uri)
-      :ok = Gun.after_request(opts)
-      conn = opts[:conn]
-      self = self()
-
-      assert %Connections{
-               conns: %{
-                 "http:some-domain.com:80" => %Pleroma.Gun.Conn{
-                   conn: ^conn,
-                   conn_state: :active,
-                   used_by: [{^self, _}]
-                 }
-               }
-             } = Connections.get_state(:gun_connections)
-    end
-
-    test "with no connection" do
-      uri = URI.parse("http://uniq-domain.com")
-
-      :ok = Conn.open(uri, :gun_connections)
-
-      opts = Gun.options([body_as: :chunks], uri)
-      conn = opts[:conn]
-      opts = Keyword.delete(opts, :conn)
-      self = self()
-
-      :ok = Gun.after_request(opts)
-
-      assert %Connections{
-               conns: %{
-                 "http:uniq-domain.com:80" => %Pleroma.Gun.Conn{
-                   conn: ^conn,
-                   conn_state: :active,
-                   used_by: [{^self, _}]
-                 }
-               }
-             } = Connections.get_state(:gun_connections)
-    end
-
-    test "with ipv4" do
-      uri = URI.parse("http://127.0.0.1")
-      :ok = Conn.open(uri, :gun_connections)
-      opts = Gun.options(uri)
-      :ok = Gun.after_request(opts)
-      conn = opts[:conn]
-
-      assert %Connections{
-               conns: %{
-                 "http:127.0.0.1:80" => %Pleroma.Gun.Conn{
-                   conn: ^conn,
-                   conn_state: :idle,
-                   used_by: []
-                 }
-               }
-             } = Connections.get_state(:gun_connections)
-    end
-
-    test "with ipv6" do
-      uri = URI.parse("http://[2a03:2880:f10c:83:face:b00c:0:25de]")
-      :ok = Conn.open(uri, :gun_connections)
-      opts = Gun.options(uri)
-      :ok = Gun.after_request(opts)
-      conn = opts[:conn]
-
-      assert %Connections{
-               conns: %{
-                 "http:2a03:2880:f10c:83:face:b00c:0:25de:80" => %Pleroma.Gun.Conn{
-                   conn: ^conn,
-                   conn_state: :idle,
-                   used_by: []
-                 }
-               }
-             } = Connections.get_state(:gun_connections)
-    end
-  end
 end
diff --git a/test/http/connection_test.exs b/test/http/connection_test.exs
deleted file mode 100644
index 7c94a50b2..000000000
--- a/test/http/connection_test.exs
+++ /dev/null
@@ -1,135 +0,0 @@
-# Pleroma: A lightweight social networking server
-# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
-# SPDX-License-Identifier: AGPL-3.0-only
-
-defmodule Pleroma.HTTP.ConnectionTest do
-  use ExUnit.Case
-  use Pleroma.Tests.Helpers
-
-  import ExUnit.CaptureLog
-
-  alias Pleroma.Config
-  alias Pleroma.HTTP.Connection
-
-  describe "parse_host/1" do
-    test "as atom to charlist" do
-      assert Connection.parse_host(:localhost) == 'localhost'
-    end
-
-    test "as string to charlist" do
-      assert Connection.parse_host("localhost.com") == 'localhost.com'
-    end
-
-    test "as string ip to tuple" do
-      assert Connection.parse_host("127.0.0.1") == {127, 0, 0, 1}
-    end
-  end
-
-  describe "parse_proxy/1" do
-    test "ip with port" do
-      assert Connection.parse_proxy("127.0.0.1:8123") == {:ok, {127, 0, 0, 1}, 8123}
-    end
-
-    test "host with port" do
-      assert Connection.parse_proxy("localhost:8123") == {:ok, 'localhost', 8123}
-    end
-
-    test "as tuple" do
-      assert Connection.parse_proxy({:socks4, :localhost, 9050}) ==
-               {:ok, :socks4, 'localhost', 9050}
-    end
-
-    test "as tuple with string host" do
-      assert Connection.parse_proxy({:socks5, "localhost", 9050}) ==
-               {:ok, :socks5, 'localhost', 9050}
-    end
-  end
-
-  describe "parse_proxy/1 errors" do
-    test "ip without port" do
-      capture_log(fn ->
-        assert Connection.parse_proxy("127.0.0.1") == {:error, :invalid_proxy}
-      end) =~ "parsing proxy fail \"127.0.0.1\""
-    end
-
-    test "host without port" do
-      capture_log(fn ->
-        assert Connection.parse_proxy("localhost") == {:error, :invalid_proxy}
-      end) =~ "parsing proxy fail \"localhost\""
-    end
-
-    test "host with bad port" do
-      capture_log(fn ->
-        assert Connection.parse_proxy("localhost:port") == {:error, :invalid_proxy_port}
-      end) =~ "parsing port in proxy fail \"localhost:port\""
-    end
-
-    test "ip with bad port" do
-      capture_log(fn ->
-        assert Connection.parse_proxy("127.0.0.1:15.9") == {:error, :invalid_proxy_port}
-      end) =~ "parsing port in proxy fail \"127.0.0.1:15.9\""
-    end
-
-    test "as tuple without port" do
-      capture_log(fn ->
-        assert Connection.parse_proxy({:socks5, :localhost}) == {:error, :invalid_proxy}
-      end) =~ "parsing proxy fail {:socks5, :localhost}"
-    end
-
-    test "with nil" do
-      assert Connection.parse_proxy(nil) == nil
-    end
-  end
-
-  describe "options/3" do
-    setup do: clear_config([:http, :proxy_url])
-
-    test "without proxy_url in config" do
-      Config.delete([:http, :proxy_url])
-
-      opts = Connection.options(%URI{})
-      refute Keyword.has_key?(opts, :proxy)
-    end
-
-    test "parses string proxy host & port" do
-      Config.put([:http, :proxy_url], "localhost:8123")
-
-      opts = Connection.options(%URI{})
-      assert opts[:proxy] == {'localhost', 8123}
-    end
-
-    test "parses tuple proxy scheme host and port" do
-      Config.put([:http, :proxy_url], {:socks, 'localhost', 1234})
-
-      opts = Connection.options(%URI{})
-      assert opts[:proxy] == {:socks, 'localhost', 1234}
-    end
-
-    test "passed opts have more weight than defaults" do
-      Config.put([:http, :proxy_url], {:socks5, 'localhost', 1234})
-
-      opts = Connection.options(%URI{}, proxy: {'example.com', 4321})
-
-      assert opts[:proxy] == {'example.com', 4321}
-    end
-  end
-
-  describe "format_host/1" do
-    test "with domain" do
-      assert Connection.format_host("example.com") == 'example.com'
-    end
-
-    test "with idna domain" do
-      assert Connection.format_host("ですexample.com") == 'xn--example-183fne.com'
-    end
-
-    test "with ipv4" do
-      assert Connection.format_host("127.0.0.1") == '127.0.0.1'
-    end
-
-    test "with ipv6" do
-      assert Connection.format_host("2a03:2880:f10c:83:face:b00c:0:25de") ==
-               '2a03:2880:f10c:83:face:b00c:0:25de'
-    end
-  end
-end
diff --git a/test/pool/connections_test.exs b/test/pool/connections_test.exs
deleted file mode 100644
index aeda54875..000000000
--- a/test/pool/connections_test.exs
+++ /dev/null
@@ -1,760 +0,0 @@
-# Pleroma: A lightweight social networking server
-# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
-# SPDX-License-Identifier: AGPL-3.0-only
-
-defmodule Pleroma.Pool.ConnectionsTest do
-  use ExUnit.Case, async: true
-  use Pleroma.Tests.Helpers
-
-  import ExUnit.CaptureLog
-  import Mox
-
-  alias Pleroma.Gun.Conn
-  alias Pleroma.GunMock
-  alias Pleroma.Pool.Connections
-
-  setup :verify_on_exit!
-
-  setup_all do
-    name = :test_connections
-    {:ok, pid} = Connections.start_link({name, [checkin_timeout: 150]})
-    {:ok, _} = Registry.start_link(keys: :unique, name: Pleroma.GunMock)
-
-    on_exit(fn ->
-      if Process.alive?(pid), do: GenServer.stop(name)
-    end)
-
-    {:ok, name: name}
-  end
-
-  defp open_mock(num \\ 1) do
-    GunMock
-    |> expect(:open, num, &start_and_register(&1, &2, &3))
-    |> expect(:await_up, num, fn _, _ -> {:ok, :http} end)
-    |> expect(:set_owner, num, fn _, _ -> :ok end)
-  end
-
-  defp connect_mock(mock) do
-    mock
-    |> expect(:connect, &connect(&1, &2))
-    |> expect(:await, &await(&1, &2))
-  end
-
-  defp info_mock(mock), do: expect(mock, :info, &info(&1))
-
-  defp start_and_register('gun-not-up.com', _, _), do: {:error, :timeout}
-
-  defp start_and_register(host, port, _) do
-    {:ok, pid} = Task.start_link(fn -> Process.sleep(1000) end)
-
-    scheme =
-      case port do
-        443 -> "https"
-        _ -> "http"
-      end
-
-    Registry.register(GunMock, pid, %{
-      origin_scheme: scheme,
-      origin_host: host,
-      origin_port: port
-    })
-
-    {:ok, pid}
-  end
-
-  defp info(pid) do
-    [{_, info}] = Registry.lookup(GunMock, pid)
-    info
-  end
-
-  defp connect(pid, _) do
-    ref = make_ref()
-    Registry.register(GunMock, ref, pid)
-    ref
-  end
-
-  defp await(pid, ref) do
-    [{_, ^pid}] = Registry.lookup(GunMock, ref)
-    {:response, :fin, 200, []}
-  end
-
-  defp now, do: :os.system_time(:second)
-
-  describe "alive?/2" do
-    test "is alive", %{name: name} do
-      assert Connections.alive?(name)
-    end
-
-    test "returns false if not started" do
-      refute Connections.alive?(:some_random_name)
-    end
-  end
-
-  test "opens connection and reuse it on next request", %{name: name} do
-    open_mock()
-    url = "http://some-domain.com"
-    key = "http:some-domain.com:80"
-    refute Connections.checkin(url, name)
-    :ok = Conn.open(url, name)
-
-    conn = Connections.checkin(url, name)
-    assert is_pid(conn)
-    assert Process.alive?(conn)
-
-    self = self()
-
-    %Connections{
-      conns: %{
-        ^key => %Conn{
-          conn: ^conn,
-          gun_state: :up,
-          used_by: [{^self, _}],
-          conn_state: :active
-        }
-      }
-    } = Connections.get_state(name)
-
-    reused_conn = Connections.checkin(url, name)
-
-    assert conn == reused_conn
-
-    %Connections{
-      conns: %{
-        ^key => %Conn{
-          conn: ^conn,
-          gun_state: :up,
-          used_by: [{^self, _}, {^self, _}],
-          conn_state: :active
-        }
-      }
-    } = Connections.get_state(name)
-
-    :ok = Connections.checkout(conn, self, name)
-
-    %Connections{
-      conns: %{
-        ^key => %Conn{
-          conn: ^conn,
-          gun_state: :up,
-          used_by: [{^self, _}],
-          conn_state: :active
-        }
-      }
-    } = Connections.get_state(name)
-
-    :ok = Connections.checkout(conn, self, name)
-
-    %Connections{
-      conns: %{
-        ^key => %Conn{
-          conn: ^conn,
-          gun_state: :up,
-          used_by: [],
-          conn_state: :idle
-        }
-      }
-    } = Connections.get_state(name)
-  end
-
-  test "reuse connection for idna domains", %{name: name} do
-    open_mock()
-    url = "http://ですsome-domain.com"
-    refute Connections.checkin(url, name)
-
-    :ok = Conn.open(url, name)
-
-    conn = Connections.checkin(url, name)
-    assert is_pid(conn)
-    assert Process.alive?(conn)
-
-    self = self()
-
-    %Connections{
-      conns: %{
-        "http:ですsome-domain.com:80" => %Conn{
-          conn: ^conn,
-          gun_state: :up,
-          used_by: [{^self, _}],
-          conn_state: :active
-        }
-      }
-    } = Connections.get_state(name)
-
-    reused_conn = Connections.checkin(url, name)
-
-    assert conn == reused_conn
-  end
-
-  test "reuse for ipv4", %{name: name} do
-    open_mock()
-    url = "http://127.0.0.1"
-
-    refute Connections.checkin(url, name)
-
-    :ok = Conn.open(url, name)
-
-    conn = Connections.checkin(url, name)
-    assert is_pid(conn)
-    assert Process.alive?(conn)
-
-    self = self()
-
-    %Connections{
-      conns: %{
-        "http:127.0.0.1:80" => %Conn{
-          conn: ^conn,
-          gun_state: :up,
-          used_by: [{^self, _}],
-          conn_state: :active
-        }
-      }
-    } = Connections.get_state(name)
-
-    reused_conn = Connections.checkin(url, name)
-
-    assert conn == reused_conn
-
-    :ok = Connections.checkout(conn, self, name)
-    :ok = Connections.checkout(reused_conn, self, name)
-
-    %Connections{
-      conns: %{
-        "http:127.0.0.1:80" => %Conn{
-          conn: ^conn,
-          gun_state: :up,
-          used_by: [],
-          conn_state: :idle
-        }
-      }
-    } = Connections.get_state(name)
-  end
-
-  test "reuse for ipv6", %{name: name} do
-    open_mock()
-    url = "http://[2a03:2880:f10c:83:face:b00c:0:25de]"
-
-    refute Connections.checkin(url, name)
-
-    :ok = Conn.open(url, name)
-
-    conn = Connections.checkin(url, name)
-    assert is_pid(conn)
-    assert Process.alive?(conn)
-
-    self = self()
-
-    %Connections{
-      conns: %{
-        "http:2a03:2880:f10c:83:face:b00c:0:25de:80" => %Conn{
-          conn: ^conn,
-          gun_state: :up,
-          used_by: [{^self, _}],
-          conn_state: :active
-        }
-      }
-    } = Connections.get_state(name)
-
-    reused_conn = Connections.checkin(url, name)
-
-    assert conn == reused_conn
-  end
-
-  test "up and down ipv4", %{name: name} do
-    open_mock()
-    |> info_mock()
-    |> allow(self(), name)
-
-    self = self()
-    url = "http://127.0.0.1"
-    :ok = Conn.open(url, name)
-    conn = Connections.checkin(url, name)
-    send(name, {:gun_down, conn, nil, nil, nil})
-    send(name, {:gun_up, conn, nil})
-
-    %Connections{
-      conns: %{
-        "http:127.0.0.1:80" => %Conn{
-          conn: ^conn,
-          gun_state: :up,
-          used_by: [{^self, _}],
-          conn_state: :active
-        }
-      }
-    } = Connections.get_state(name)
-  end
-
-  test "up and down ipv6", %{name: name} do
-    self = self()
-
-    open_mock()
-    |> info_mock()
-    |> allow(self, name)
-
-    url = "http://[2a03:2880:f10c:83:face:b00c:0:25de]"
-    :ok = Conn.open(url, name)
-    conn = Connections.checkin(url, name)
-    send(name, {:gun_down, conn, nil, nil, nil})
-    send(name, {:gun_up, conn, nil})
-
-    %Connections{
-      conns: %{
-        "http:2a03:2880:f10c:83:face:b00c:0:25de:80" => %Conn{
-          conn: ^conn,
-          gun_state: :up,
-          used_by: [{^self, _}],
-          conn_state: :active
-        }
-      }
-    } = Connections.get_state(name)
-  end
-
-  test "reuses connection based on protocol", %{name: name} do
-    open_mock(2)
-    http_url = "http://some-domain.com"
-    http_key = "http:some-domain.com:80"
-    https_url = "https://some-domain.com"
-    https_key = "https:some-domain.com:443"
-
-    refute Connections.checkin(http_url, name)
-    :ok = Conn.open(http_url, name)
-    conn = Connections.checkin(http_url, name)
-    assert is_pid(conn)
-    assert Process.alive?(conn)
-
-    refute Connections.checkin(https_url, name)
-    :ok = Conn.open(https_url, name)
-    https_conn = Connections.checkin(https_url, name)
-
-    refute conn == https_conn
-
-    reused_https = Connections.checkin(https_url, name)
-
-    refute conn == reused_https
-
-    assert reused_https == https_conn
-
-    %Connections{
-      conns: %{
-        ^http_key => %Conn{
-          conn: ^conn,
-          gun_state: :up
-        },
-        ^https_key => %Conn{
-          conn: ^https_conn,
-          gun_state: :up
-        }
-      }
-    } = Connections.get_state(name)
-  end
-
-  test "connection can't get up", %{name: name} do
-    expect(GunMock, :open, &start_and_register(&1, &2, &3))
-    url = "http://gun-not-up.com"
-
-    assert capture_log(fn ->
-             refute Conn.open(url, name)
-             refute Connections.checkin(url, name)
-           end) =~
-             "Opening connection to http://gun-not-up.com failed with error {:error, :timeout}"
-  end
-
-  test "process gun_down message and then gun_up", %{name: name} do
-    self = self()
-
-    open_mock()
-    |> info_mock()
-    |> allow(self, name)
-
-    url = "http://gun-down-and-up.com"
-    key = "http:gun-down-and-up.com:80"
-    :ok = Conn.open(url, name)
-    conn = Connections.checkin(url, name)
-
-    assert is_pid(conn)
-    assert Process.alive?(conn)
-
-    %Connections{
-      conns: %{
-        ^key => %Conn{
-          conn: ^conn,
-          gun_state: :up,
-          used_by: [{^self, _}]
-        }
-      }
-    } = Connections.get_state(name)
-
-    send(name, {:gun_down, conn, :http, nil, nil})
-
-    %Connections{
-      conns: %{
-        ^key => %Conn{
-          conn: ^conn,
-          gun_state: :down,
-          used_by: [{^self, _}]
-        }
-      }
-    } = Connections.get_state(name)
-
-    send(name, {:gun_up, conn, :http})
-
-    conn2 = Connections.checkin(url, name)
-    assert conn == conn2
-
-    assert is_pid(conn2)
-    assert Process.alive?(conn2)
-
-    %Connections{
-      conns: %{
-        ^key => %Conn{
-          conn: _,
-          gun_state: :up,
-          used_by: [{^self, _}, {^self, _}]
-        }
-      }
-    } = Connections.get_state(name)
-  end
-
-  test "async processes get same conn for same domain", %{name: name} do
-    open_mock()
-    url = "http://some-domain.com"
-    :ok = Conn.open(url, name)
-
-    tasks =
-      for _ <- 1..5 do
-        Task.async(fn ->
-          Connections.checkin(url, name)
-        end)
-      end
-
-    tasks_with_results = Task.yield_many(tasks)
-
-    results =
-      Enum.map(tasks_with_results, fn {task, res} ->
-        res || Task.shutdown(task, :brutal_kill)
-      end)
-
-    conns = for {:ok, value} <- results, do: value
-
-    %Connections{
-      conns: %{
-        "http:some-domain.com:80" => %Conn{
-          conn: conn,
-          gun_state: :up
-        }
-      }
-    } = Connections.get_state(name)
-
-    assert Enum.all?(conns, fn res -> res == conn end)
-  end
-
-  test "remove frequently used and idle", %{name: name} do
-    open_mock(3)
-    self = self()
-    http_url = "http://some-domain.com"
-    https_url = "https://some-domain.com"
-    :ok = Conn.open(https_url, name)
-    :ok = Conn.open(http_url, name)
-
-    conn1 = Connections.checkin(https_url, name)
-
-    [conn2 | _conns] =
-      for _ <- 1..4 do
-        Connections.checkin(http_url, name)
-      end
-
-    http_key = "http:some-domain.com:80"
-
-    %Connections{
-      conns: %{
-        ^http_key => %Conn{
-          conn: ^conn2,
-          gun_state: :up,
-          conn_state: :active,
-          used_by: [{^self, _}, {^self, _}, {^self, _}, {^self, _}]
-        },
-        "https:some-domain.com:443" => %Conn{
-          conn: ^conn1,
-          gun_state: :up,
-          conn_state: :active,
-          used_by: [{^self, _}]
-        }
-      }
-    } = Connections.get_state(name)
-
-    :ok = Connections.checkout(conn1, self, name)
-
-    another_url = "http://another-domain.com"
-    :ok = Conn.open(another_url, name)
-    conn = Connections.checkin(another_url, name)
-
-    %Connections{
-      conns: %{
-        "http:another-domain.com:80" => %Conn{
-          conn: ^conn,
-          gun_state: :up
-        },
-        ^http_key => %Conn{
-          conn: _,
-          gun_state: :up
-        }
-      }
-    } = Connections.get_state(name)
-  end
-
-  describe "with proxy" do
-    test "as ip", %{name: name} do
-      open_mock()
-      |> connect_mock()
-
-      url = "http://proxy-string.com"
-      key = "http:proxy-string.com:80"
-      :ok = Conn.open(url, name, proxy: {{127, 0, 0, 1}, 8123})
-
-      conn = Connections.checkin(url, name)
-
-      %Connections{
-        conns: %{
-          ^key => %Conn{
-            conn: ^conn,
-            gun_state: :up
-          }
-        }
-      } = Connections.get_state(name)
-
-      reused_conn = Connections.checkin(url, name)
-
-      assert reused_conn == conn
-    end
-
-    test "as host", %{name: name} do
-      open_mock()
-      |> connect_mock()
-
-      url = "http://proxy-tuple-atom.com"
-      :ok = Conn.open(url, name, proxy: {'localhost', 9050})
-      conn = Connections.checkin(url, name)
-
-      %Connections{
-        conns: %{
-          "http:proxy-tuple-atom.com:80" => %Conn{
-            conn: ^conn,
-            gun_state: :up
-          }
-        }
-      } = Connections.get_state(name)
-
-      reused_conn = Connections.checkin(url, name)
-
-      assert reused_conn == conn
-    end
-
-    test "as ip and ssl", %{name: name} do
-      open_mock()
-      |> connect_mock()
-
-      url = "https://proxy-string.com"
-
-      :ok = Conn.open(url, name, proxy: {{127, 0, 0, 1}, 8123})
-      conn = Connections.checkin(url, name)
-
-      %Connections{
-        conns: %{
-          "https:proxy-string.com:443" => %Conn{
-            conn: ^conn,
-            gun_state: :up
-          }
-        }
-      } = Connections.get_state(name)
-
-      reused_conn = Connections.checkin(url, name)
-
-      assert reused_conn == conn
-    end
-
-    test "as host and ssl", %{name: name} do
-      open_mock()
-      |> connect_mock()
-
-      url = "https://proxy-tuple-atom.com"
-      :ok = Conn.open(url, name, proxy: {'localhost', 9050})
-      conn = Connections.checkin(url, name)
-
-      %Connections{
-        conns: %{
-          "https:proxy-tuple-atom.com:443" => %Conn{
-            conn: ^conn,
-            gun_state: :up
-          }
-        }
-      } = Connections.get_state(name)
-
-      reused_conn = Connections.checkin(url, name)
-
-      assert reused_conn == conn
-    end
-
-    test "with socks type", %{name: name} do
-      open_mock()
-
-      url = "http://proxy-socks.com"
-
-      :ok = Conn.open(url, name, proxy: {:socks5, 'localhost', 1234})
-
-      conn = Connections.checkin(url, name)
-
-      %Connections{
-        conns: %{
-          "http:proxy-socks.com:80" => %Conn{
-            conn: ^conn,
-            gun_state: :up
-          }
-        }
-      } = Connections.get_state(name)
-
-      reused_conn = Connections.checkin(url, name)
-
-      assert reused_conn == conn
-    end
-
-    test "with socks4 type and ssl", %{name: name} do
-      open_mock()
-      url = "https://proxy-socks.com"
-
-      :ok = Conn.open(url, name, proxy: {:socks4, 'localhost', 1234})
-
-      conn = Connections.checkin(url, name)
-
-      %Connections{
-        conns: %{
-          "https:proxy-socks.com:443" => %Conn{
-            conn: ^conn,
-            gun_state: :up
-          }
-        }
-      } = Connections.get_state(name)
-
-      reused_conn = Connections.checkin(url, name)
-
-      assert reused_conn == conn
-    end
-  end
-
-  describe "crf/3" do
-    setup do
-      crf = Connections.crf(1, 10, 1)
-      {:ok, crf: crf}
-    end
-
-    test "more used will have crf higher", %{crf: crf} do
-      # used 3 times
-      crf1 = Connections.crf(1, 10, crf)
-      crf1 = Connections.crf(1, 10, crf1)
-
-      # used 2 times
-      crf2 = Connections.crf(1, 10, crf)
-
-      assert crf1 > crf2
-    end
-
-    test "recently used will have crf higher on equal references", %{crf: crf} do
-      # used 3 sec ago
-      crf1 = Connections.crf(3, 10, crf)
-
-      # used 4 sec ago
-      crf2 = Connections.crf(4, 10, crf)
-
-      assert crf1 > crf2
-    end
-
-    test "equal crf on equal reference and time", %{crf: crf} do
-      # used 2 times
-      crf1 = Connections.crf(1, 10, crf)
-
-      # used 2 times
-      crf2 = Connections.crf(1, 10, crf)
-
-      assert crf1 == crf2
-    end
-
-    test "recently used will have higher crf", %{crf: crf} do
-      crf1 = Connections.crf(2, 10, crf)
-      crf1 = Connections.crf(1, 10, crf1)
-
-      crf2 = Connections.crf(3, 10, crf)
-      crf2 = Connections.crf(4, 10, crf2)
-      assert crf1 > crf2
-    end
-  end
-
-  describe "get_unused_conns/1" do
-    test "crf is equalent, sorting by reference", %{name: name} do
-      Connections.add_conn(name, "1", %Conn{
-        conn_state: :idle,
-        last_reference: now() - 1
-      })
-
-      Connections.add_conn(name, "2", %Conn{
-        conn_state: :idle,
-        last_reference: now()
-      })
-
-      assert [{"1", _unused_conn} | _others] = Connections.get_unused_conns(name)
-    end
-
-    test "reference is equalent, sorting by crf", %{name: name} do
-      Connections.add_conn(name, "1", %Conn{
-        conn_state: :idle,
-        crf: 1.999
-      })
-
-      Connections.add_conn(name, "2", %Conn{
-        conn_state: :idle,
-        crf: 2
-      })
-
-      assert [{"1", _unused_conn} | _others] = Connections.get_unused_conns(name)
-    end
-
-    test "higher crf and lower reference", %{name: name} do
-      Connections.add_conn(name, "1", %Conn{
-        conn_state: :idle,
-        crf: 3,
-        last_reference: now() - 1
-      })
-
-      Connections.add_conn(name, "2", %Conn{
-        conn_state: :idle,
-        crf: 2,
-        last_reference: now()
-      })
-
-      assert [{"2", _unused_conn} | _others] = Connections.get_unused_conns(name)
-    end
-
-    test "lower crf and lower reference", %{name: name} do
-      Connections.add_conn(name, "1", %Conn{
-        conn_state: :idle,
-        crf: 1.99,
-        last_reference: now() - 1
-      })
-
-      Connections.add_conn(name, "2", %Conn{
-        conn_state: :idle,
-        crf: 2,
-        last_reference: now()
-      })
-
-      assert [{"1", _unused_conn} | _others] = Connections.get_unused_conns(name)
-    end
-  end
-
-  test "count/1" do
-    name = :test_count
-    {:ok, _} = Connections.start_link({name, [checkin_timeout: 150]})
-    assert Connections.count(name) == 0
-    Connections.add_conn(name, "1", %Conn{conn: self()})
-    assert Connections.count(name) == 1
-    Connections.remove_conn(name, "1")
-    assert Connections.count(name) == 0
-  end
-end

From bf3492ceb31f6332a4c58feba271e3755fabe25a Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Sat, 6 Jun 2020 17:53:39 +0300
Subject: [PATCH 13/33] Connection Pool: add tests

---
 test/gun/conneciton_pool_test.exs | 101 ++++++++++++++++++++++++++++++
 1 file changed, 101 insertions(+)
 create mode 100644 test/gun/conneciton_pool_test.exs

diff --git a/test/gun/conneciton_pool_test.exs b/test/gun/conneciton_pool_test.exs
new file mode 100644
index 000000000..aea908fac
--- /dev/null
+++ b/test/gun/conneciton_pool_test.exs
@@ -0,0 +1,101 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Gun.ConnectionPoolTest do
+  use Pleroma.DataCase
+
+  import Mox
+  import ExUnit.CaptureLog
+  alias Pleroma.Config
+  alias Pleroma.Gun.ConnectionPool
+
+  defp gun_mock(_) do
+    Pleroma.GunMock
+    |> stub(:open, fn _, _, _ -> Task.start_link(fn -> Process.sleep(100) end) end)
+    |> stub(:await_up, fn _, _ -> {:ok, :http} end)
+    |> stub(:set_owner, fn _, _ -> :ok end)
+
+    :ok
+  end
+
+  setup :set_mox_from_context
+  setup :gun_mock
+
+  test "gives the same connection to 2 concurrent requests" do
+    Enum.map(
+      [
+        "http://www.korean-books.com.kp/KBMbooks/en/periodic/pictorial/20200530163914.pdf",
+        "http://www.korean-books.com.kp/KBMbooks/en/periodic/pictorial/20200528183427.pdf"
+      ],
+      fn uri ->
+        uri = URI.parse(uri)
+        task_parent = self()
+
+        Task.start_link(fn ->
+          {:ok, conn} = ConnectionPool.get_conn(uri, [])
+          ConnectionPool.release_conn(conn)
+          send(task_parent, conn)
+        end)
+      end
+    )
+
+    [pid, pid] =
+      for _ <- 1..2 do
+        receive do
+          pid -> pid
+        end
+      end
+  end
+
+  test "connection limit is respected with concurrent requests" do
+    clear_config([:connections_pool, :max_connections]) do
+      Config.put([:connections_pool, :max_connections], 1)
+      # The supervisor needs a reboot to apply the new config setting
+      Process.exit(Process.whereis(Pleroma.Gun.ConnectionPool.WorkerSupervisor), :kill)
+
+      on_exit(fn ->
+        Process.exit(Process.whereis(Pleroma.Gun.ConnectionPool.WorkerSupervisor), :kill)
+      end)
+    end
+
+    capture_log(fn ->
+      Enum.map(
+        [
+          "https://ninenines.eu/",
+          "https://youtu.be/PFGwMiDJKNY"
+        ],
+        fn uri ->
+          uri = URI.parse(uri)
+          task_parent = self()
+
+          Task.start_link(fn ->
+            result = ConnectionPool.get_conn(uri, [])
+            # Sleep so that we don't end up with a situation,
+            # where request from the second process gets processed
+            # only after the first process already released the connection
+            Process.sleep(50)
+
+            case result do
+              {:ok, pid} ->
+                ConnectionPool.release_conn(pid)
+
+              _ ->
+                nil
+            end
+
+            send(task_parent, result)
+          end)
+        end
+      )
+
+      [{:error, :pool_full}, {:ok, _pid}] =
+        for _ <- 1..2 do
+          receive do
+            result -> result
+          end
+        end
+        |> Enum.sort()
+    end)
+  end
+end

From 00926a63fb174a8bcb2f496921c5d17e04e44b1d Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Tue, 16 Jun 2020 16:20:28 +0300
Subject: [PATCH 14/33] Adapter Helper: Use built-in ip address type

---
 lib/pleroma/http/adapter_helper.ex | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/lib/pleroma/http/adapter_helper.ex b/lib/pleroma/http/adapter_helper.ex
index bcb9b2b1e..8ca433732 100644
--- a/lib/pleroma/http/adapter_helper.ex
+++ b/lib/pleroma/http/adapter_helper.ex
@@ -8,12 +8,8 @@ defmodule Pleroma.HTTP.AdapterHelper do
   """
   @defaults [pool: :federation]
 
-  @type ip_address :: ipv4_address() | ipv6_address()
-  @type ipv4_address :: {0..255, 0..255, 0..255, 0..255}
-  @type ipv6_address ::
-          {0..65_535, 0..65_535, 0..65_535, 0..65_535, 0..65_535, 0..65_535, 0..65_535, 0..65_535}
   @type proxy_type() :: :socks4 | :socks5
-  @type host() :: charlist() | ip_address()
+  @type host() :: charlist() | :inet.ip_address()
 
   alias Pleroma.Config
   alias Pleroma.HTTP.AdapterHelper
@@ -114,7 +110,7 @@ def parse_proxy(proxy) when is_tuple(proxy) do
     end
   end
 
-  @spec parse_host(String.t() | atom() | charlist()) :: charlist() | ip_address()
+  @spec parse_host(String.t() | atom() | charlist()) :: charlist() | :inet.ip_address()
   def parse_host(host) when is_list(host), do: host
   def parse_host(host) when is_atom(host), do: to_charlist(host)
 

From 7882f28569bfaee2996d059990eec279415f0785 Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Wed, 17 Jun 2020 12:54:13 +0300
Subject: [PATCH 15/33] Use erlang monotonic time for CRF calculation

---
 lib/pleroma/gun/connection_pool/worker.ex | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/pleroma/gun/connection_pool/worker.ex b/lib/pleroma/gun/connection_pool/worker.ex
index 8467325f3..418cb18c1 100644
--- a/lib/pleroma/gun/connection_pool/worker.ex
+++ b/lib/pleroma/gun/connection_pool/worker.ex
@@ -12,7 +12,7 @@ def start_link([key | _] = opts) do
   def init([key, uri, opts, client_pid]) do
     with {:ok, conn_pid} <- Gun.Conn.open(uri, opts),
          Process.link(conn_pid) do
-      time = :os.system_time(:second)
+      time = :erlang.monotonic_time()
 
       {_, _} =
         Registry.update_value(@registry, key, fn _ ->
@@ -31,7 +31,7 @@ def init([key, uri, opts, client_pid]) do
 
   @impl true
   def handle_cast({:add_client, client_pid, send_pid_back}, %{key: key} = state) do
-    time = :os.system_time(:second)
+    time = :erlang.monotonic_time()
 
     {{conn_pid, _, _, _}, _} =
       Registry.update_value(@registry, key, fn {conn_pid, used_by, crf, last_reference} ->

From 007843b75e0c7087dad1ef932224b21327d81793 Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Tue, 23 Jun 2020 15:38:45 +0300
Subject: [PATCH 16/33] Add documentation for new connection pool settings and
 remove some

`:retry_timeout` and `:retry` got removed because reconnecting on failure is
something the new pool intentionally doesn't do.

`:max_overflow` had to go in favor of `:max_waiting`, I didn't reuse the key because
the settings are very different in their behaviour.

`:checkin_timeout` got removed in favor of `:connection_acquisition_wait`,
I didn't reuse the key because the settings are somewhat different.

I didn't do any migrations/deprecation warnings/changelog entries because
these settings were never in stable.
---
 config/description.exs           | 158 ++++++++-----------------------
 docs/configuration/cheatsheet.md |  30 +++---
 lib/pleroma/gun/conn.ex          |   2 -
 3 files changed, 53 insertions(+), 137 deletions(-)

diff --git a/config/description.exs b/config/description.exs
index afc4dcd79..f1c6773f1 100644
--- a/config/description.exs
+++ b/config/description.exs
@@ -3161,36 +3161,37 @@
     description: "Advanced settings for `gun` connections pool",
     children: [
       %{
-        key: :checkin_timeout,
+        key: :connection_acquisition_wait,
         type: :integer,
-        description: "Timeout to checkin connection from pool. Default: 250ms.",
+        description:
+          "Timeout to acquire a connection from pool.The total max time is this value multiplied by the number of retries. Default: 250ms.",
         suggestions: [250]
       },
+      %{
+        key: :connection_acquisition_retries,
+        type: :integer,
+        description:
+          "Number of attempts to acquire the connection from the pool if it is overloaded. Default: 5",
+        suggestions: [5]
+      },
       %{
         key: :max_connections,
         type: :integer,
         description: "Maximum number of connections in the pool. Default: 250 connections.",
         suggestions: [250]
       },
-      %{
-        key: :retry,
-        type: :integer,
-        description:
-          "Number of retries, while `gun` will try to reconnect if connection goes down. Default: 1.",
-        suggestions: [1]
-      },
-      %{
-        key: :retry_timeout,
-        type: :integer,
-        description:
-          "Time between retries when `gun` will try to reconnect in milliseconds. Default: 1000ms.",
-        suggestions: [1000]
-      },
       %{
         key: :await_up_timeout,
         type: :integer,
         description: "Timeout while `gun` will wait until connection is up. Default: 5000ms.",
         suggestions: [5000]
+      },
+      %{
+        key: :reclaim_multiplier,
+        type: :integer,
+        description:
+          "Multiplier for the number of idle connection to be reclaimed if the pool is full. For example if the pool maxes out at 250 connections and this setting is set to 0.3, the pool will reclaim at most 75 idle connections if it's overloaded. Default: 0.1",
+        suggestions: [0.1]
       }
     ]
   },
@@ -3199,108 +3200,29 @@
     key: :pools,
     type: :group,
     description: "Advanced settings for `gun` workers pools",
-    children: [
-      %{
-        key: :federation,
-        type: :keyword,
-        description: "Settings for federation pool.",
-        children: [
-          %{
-            key: :size,
-            type: :integer,
-            description: "Number workers in the pool.",
-            suggestions: [50]
-          },
-          %{
-            key: :max_overflow,
-            type: :integer,
-            description: "Number of additional workers if pool is under load.",
-            suggestions: [10]
-          },
-          %{
-            key: :timeout,
-            type: :integer,
-            description: "Timeout while `gun` will wait for response.",
-            suggestions: [150_000]
-          }
-        ]
-      },
-      %{
-        key: :media,
-        type: :keyword,
-        description: "Settings for media pool.",
-        children: [
-          %{
-            key: :size,
-            type: :integer,
-            description: "Number workers in the pool.",
-            suggestions: [50]
-          },
-          %{
-            key: :max_overflow,
-            type: :integer,
-            description: "Number of additional workers if pool is under load.",
-            suggestions: [10]
-          },
-          %{
-            key: :timeout,
-            type: :integer,
-            description: "Timeout while `gun` will wait for response.",
-            suggestions: [150_000]
-          }
-        ]
-      },
-      %{
-        key: :upload,
-        type: :keyword,
-        description: "Settings for upload pool.",
-        children: [
-          %{
-            key: :size,
-            type: :integer,
-            description: "Number workers in the pool.",
-            suggestions: [25]
-          },
-          %{
-            key: :max_overflow,
-            type: :integer,
-            description: "Number of additional workers if pool is under load.",
-            suggestions: [5]
-          },
-          %{
-            key: :timeout,
-            type: :integer,
-            description: "Timeout while `gun` will wait for response.",
-            suggestions: [300_000]
-          }
-        ]
-      },
-      %{
-        key: :default,
-        type: :keyword,
-        description: "Settings for default pool.",
-        children: [
-          %{
-            key: :size,
-            type: :integer,
-            description: "Number workers in the pool.",
-            suggestions: [10]
-          },
-          %{
-            key: :max_overflow,
-            type: :integer,
-            description: "Number of additional workers if pool is under load.",
-            suggestions: [2]
-          },
-          %{
-            key: :timeout,
-            type: :integer,
-            description: "Timeout while `gun` will wait for response.",
-            suggestions: [10_000]
-          }
-        ]
-      }
-    ]
+    children:
+      Enum.map([:federation, :media, :upload, :default], fn pool_name ->
+        %{
+          key: pool_name,
+          type: :keyword,
+          description: "Settings for #{pool_name} pool.",
+          children: [
+            %{
+              key: :size,
+              type: :integer,
+              description: "Maximum number of concurrent requests in the pool.",
+              suggestions: [50]
+            },
+            %{
+              key: :max_waiting,
+              type: :integer,
+              description:
+                "Maximum number of requests waiting for other requests to finish. After this number is reached, the pool will start returning errrors when a new request is made",
+              suggestions: [10]
+            }
+          ]
+        }
+      end)
   },
   %{
     group: :pleroma,
diff --git a/docs/configuration/cheatsheet.md b/docs/configuration/cheatsheet.md
index ba62a721e..6c1babba3 100644
--- a/docs/configuration/cheatsheet.md
+++ b/docs/configuration/cheatsheet.md
@@ -448,36 +448,32 @@ For each pool, the options are:
 
 *For `gun` adapter*
 
-Advanced settings for connections pool. Pool with opened connections. These connections can be reused in worker pools.
+Settings for HTTP connection pool.
 
-For big instances it's recommended to increase `config :pleroma, :connections_pool, max_connections: 500` up to 500-1000.
-It will increase memory usage, but federation would work faster.
-
-* `:checkin_timeout` - timeout to checkin connection from pool. Default: 250ms.
-* `:max_connections` - maximum number of connections in the pool. Default: 250 connections.
-* `:retry` - number of retries, while `gun` will try to reconnect if connection goes down. Default: 1.
-* `:retry_timeout` - time between retries when `gun` will try to reconnect in milliseconds. Default: 1000ms.
-* `:await_up_timeout` - timeout while `gun` will wait until connection is up. Default: 5000ms.
+* `:connection_acquisition_wait` - Timeout to acquire a connection from pool.The total max time is this value multiplied by the number of retries.
+* `connection_acquisition_retries` - Number of attempts to acquire the connection from the pool if it is overloaded. Each attempt is timed `:connection_acquisition_wait` apart.
+* `:max_connections` - Maximum number of connections in the pool.
+* `:await_up_timeout` - Timeout to connect to the host.
+* `:reclaim_multiplier` - Multiplied by `:max_connections` this will be the maximum number of idle connections that will be reclaimed in case the pool is overloaded.
 
 ### :pools
 
 *For `gun` adapter*
 
-Advanced settings for workers pools.
+Settings for request pools. These pools are limited on top of `:connections_pool`.
 
 There are four pools used:
 
-* `:federation` for the federation jobs.
-  You may want this pool max_connections to be at least equal to the number of federator jobs + retry queue jobs.
-* `:media` for rich media, media proxy
-* `:upload` for uploaded media (if using a remote uploader and `proxy_remote: true`)
-* `:default` for other requests
+* `:federation` for the federation jobs. You may want this pool's max_connections to be at least equal to the number of federator jobs + retry queue jobs.
+* `:media` - for rich media, media proxy.
+* `:upload` - for proxying media when a remote uploader is used and `proxy_remote: true`.
+* `:default` - for other requests.
 
 For each pool, the options are:
 
-* `:size` - how much workers the pool can hold
+* `:size` - limit to how much requests can be concurrently executed.
 * `:timeout` - timeout while `gun` will wait for response
-* `:max_overflow` - additional workers if pool is under load
+* `:max_waiting` - limit to how much requests can be waiting for others to finish, after this is reached, subsequent requests will be dropped.
 
 ## Captcha
 
diff --git a/lib/pleroma/gun/conn.ex b/lib/pleroma/gun/conn.ex
index 77f78c7ff..9dc8880db 100644
--- a/lib/pleroma/gun/conn.ex
+++ b/lib/pleroma/gun/conn.ex
@@ -13,8 +13,6 @@ def open(%URI{} = uri, opts) do
     opts =
       opts
       |> Enum.into(%{})
-      |> Map.put_new(:retry, pool_opts[:retry] || 1)
-      |> Map.put_new(:retry_timeout, pool_opts[:retry_timeout] || 1000)
       |> Map.put_new(:await_up_timeout, pool_opts[:await_up_timeout] || 5_000)
       |> Map.put_new(:supervise, false)
       |> maybe_add_tls_opts(uri)

From 37f1e781cb19594a6534efbc4d28e793d5960915 Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Tue, 23 Jun 2020 20:36:21 +0300
Subject: [PATCH 17/33] Gun adapter helper: fix wildcard cert issues on OTP 23

See https://bugs.erlang.org/browse/ERL-1260 for more info.

The ssl match function is basically copied from mint, except
that `:string.lowercase/1` was replaced by `:string.casefold`.
It was a TODO in mint's code, so might as well do it since we don't need
to support OTP <20.

Closes #1834
---
 lib/pleroma/http/adapter_helper/gun.ex | 29 +++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/lib/pleroma/http/adapter_helper/gun.ex b/lib/pleroma/http/adapter_helper/gun.ex
index 883f7f6f7..07aaed7f6 100644
--- a/lib/pleroma/http/adapter_helper/gun.ex
+++ b/lib/pleroma/http/adapter_helper/gun.ex
@@ -39,9 +39,36 @@ defp add_scheme_opts(opts, %{scheme: "http"}), do: opts
   defp add_scheme_opts(opts, %{scheme: "https"}) do
     opts
     |> Keyword.put(:certificates_verification, true)
-    |> Keyword.put(:tls_opts, log_level: :warning)
+    |> Keyword.put(:tls_opts,
+      log_level: :warning,
+      customize_hostname_check: [match_fun: &ssl_match_fun/2]
+    )
   end
 
+  # ssl_match_fun is adapted from [Mint](https://github.com/elixir-mint/mint)
+  # Copyright 2018 Eric Meadows-Jönsson and Andrea Leopardi
+
+  # Wildcard domain handling for DNS ID entries in the subjectAltName X.509
+  # extension. Note that this is a subset of the wildcard patterns implemented
+  # by OTP when matching against the subject CN attribute, but this is the only
+  # wildcard usage defined by the CA/Browser Forum's Baseline Requirements, and
+  # therefore the only pattern used in commercially issued certificates.
+  defp ssl_match_fun({:dns_id, reference}, {:dNSName, [?*, ?. | presented]}) do
+    case domain_without_host(reference) do
+      '' ->
+        :default
+
+      domain ->
+        :string.casefold(domain) == :string.casefold(presented)
+    end
+  end
+
+  defp ssl_match_fun(_reference, _presented), do: :default
+
+  defp domain_without_host([]), do: []
+  defp domain_without_host([?. | domain]), do: domain
+  defp domain_without_host([_ | more]), do: domain_without_host(more)
+
   @spec get_conn(URI.t(), keyword()) :: {:ok, keyword()} | {:error, atom()}
   def get_conn(uri, opts) do
     case ConnectionPool.get_conn(uri, opts) do

From 9df59189747620c60173e6a67f8721971f123efd Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Tue, 23 Jun 2020 15:52:57 +0300
Subject: [PATCH 18/33] config.exs: make gun the default again

---
 config/config.exs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/config/config.exs b/config/config.exs
index dfc7a99d1..30b5e83bd 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -172,7 +172,7 @@
   "application/ld+json" => ["activity+json"]
 }
 
-config :tesla, adapter: Tesla.Adapter.Hackney
+config :tesla, adapter: Tesla.Adapter.Gun
 
 # Configures http settings, upstream proxy etc.
 config :pleroma, :http,

From 12fa5541f01ca5cfe082a62dac3317da78043e8f Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Tue, 30 Jun 2020 15:58:53 +0300
Subject: [PATCH 19/33] FollowRedirects: Unconditionally release the connection
 if there is an error

There is no need for streaming the body if there is no body
---
 lib/pleroma/tesla/middleware/follow_redirects.ex | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/pleroma/tesla/middleware/follow_redirects.ex b/lib/pleroma/tesla/middleware/follow_redirects.ex
index f2c502c69..5a7032215 100644
--- a/lib/pleroma/tesla/middleware/follow_redirects.ex
+++ b/lib/pleroma/tesla/middleware/follow_redirects.ex
@@ -55,6 +55,10 @@ defp redirect(env, next, left) do
         release_conn(opts)
         {:error, {__MODULE__, :too_many_redirects}}
 
+      {:error, _} = e ->
+        release_conn(opts)
+        e
+
       other ->
         unless opts[:body_as] == :chunks do
           release_conn(opts)

From 9b73c35ca8b051316815461247b802bc8567854f Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Tue, 30 Jun 2020 18:35:15 +0300
Subject: [PATCH 20/33] Request limiter setup: consider {:error, :existing} a
 success

When the application restarts (which happens after certain config
changes), the limiters are not destroyed, so `ConcurrentLimiter.new`
will produce {:error, :existing}
---
 lib/pleroma/http/adapter_helper/gun.ex | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/lib/pleroma/http/adapter_helper/gun.ex b/lib/pleroma/http/adapter_helper/gun.ex
index 07aaed7f6..b8c4cc59c 100644
--- a/lib/pleroma/http/adapter_helper/gun.ex
+++ b/lib/pleroma/http/adapter_helper/gun.ex
@@ -88,11 +88,17 @@ def limiter_setup do
       max_running = Keyword.get(opts, :size, 50)
       max_waiting = Keyword.get(opts, :max_waiting, 10)
 
-      :ok =
+      result =
         ConcurrentLimiter.new(:"#{@prefix}.#{name}", max_running, max_waiting,
           wait: wait,
           max_retries: retries
         )
+
+      case result do
+        :ok -> :ok
+        {:error, :existing} -> :ok
+        e -> raise e
+      end
     end)
 
     :ok

From a705637dcf7ffe063c9c0f3f190f57e44aaa63f2 Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Thu, 2 Jul 2020 01:53:27 +0300
Subject: [PATCH 21/33] Connection Pool: fix LRFU implementation to not
 actually be LRU

The numbers of the native time unit were so small the CRF was always 1,
making it an LRU. This commit switches the time to miliseconds and changes
the time delta multiplier to the one yielding mostly highest hit rates according
to the paper
---
 lib/pleroma/gun/connection_pool/worker.ex | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lib/pleroma/gun/connection_pool/worker.ex b/lib/pleroma/gun/connection_pool/worker.ex
index 418cb18c1..ec0502621 100644
--- a/lib/pleroma/gun/connection_pool/worker.ex
+++ b/lib/pleroma/gun/connection_pool/worker.ex
@@ -12,7 +12,7 @@ def start_link([key | _] = opts) do
   def init([key, uri, opts, client_pid]) do
     with {:ok, conn_pid} <- Gun.Conn.open(uri, opts),
          Process.link(conn_pid) do
-      time = :erlang.monotonic_time()
+      time = :erlang.monotonic_time(:millisecond)
 
       {_, _} =
         Registry.update_value(@registry, key, fn _ ->
@@ -31,7 +31,7 @@ def init([key, uri, opts, client_pid]) do
 
   @impl true
   def handle_cast({:add_client, client_pid, send_pid_back}, %{key: key} = state) do
-    time = :erlang.monotonic_time()
+    time = :erlang.monotonic_time(:millisecond)
 
     {{conn_pid, _, _, _}, _} =
       Registry.update_value(@registry, key, fn {conn_pid, used_by, crf, last_reference} ->
@@ -116,6 +116,6 @@ def handle_info({:DOWN, _ref, :process, pid, reason}, state) do
 
   # LRFU policy: https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.55.1478
   defp crf(time_delta, prev_crf) do
-    1 + :math.pow(0.5, time_delta / 100) * prev_crf
+    1 + :math.pow(0.5, 0.0001 * time_delta) * prev_crf
   end
 end

From 33747e9366ef7422c9b39ac360ad1d96405bc4fd Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Mon, 6 Jul 2020 12:13:02 +0300
Subject: [PATCH 22/33] config.exs: set gun retries to 0

The new pooling code just removes the connection when it's down,
there is no need to reconnect a connection that is just sitting idle,
better just open a new one next time it's needed
---
 config/config.exs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/config/config.exs b/config/config.exs
index 30b5e83bd..61406687a 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -652,8 +652,7 @@
   connection_acquisition_retries: 5,
   max_connections: 250,
   max_idle_time: 30_000,
-  retry: 1,
-  retry_timeout: 1000,
+  retry: 0,
   await_up_timeout: 5_000
 
 config :pleroma, :pools,

From 46dd276d686e49676101e2af743aad61393f4b70 Mon Sep 17 00:00:00 2001
From: href <href@random.sh>
Date: Tue, 7 Jul 2020 18:56:17 +0200
Subject: [PATCH 23/33] ConnectionPool.Worker: Open gun conn in continue
 instead of init

---
 lib/pleroma/gun/connection_pool/worker.ex | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/lib/pleroma/gun/connection_pool/worker.ex b/lib/pleroma/gun/connection_pool/worker.ex
index ec0502621..6ee622fb0 100644
--- a/lib/pleroma/gun/connection_pool/worker.ex
+++ b/lib/pleroma/gun/connection_pool/worker.ex
@@ -9,7 +9,12 @@ def start_link([key | _] = opts) do
   end
 
   @impl true
-  def init([key, uri, opts, client_pid]) do
+  def init([_key, _uri, _opts, _client_pid] = opts) do
+    {:ok, nil, {:continue, {:connect, opts}}}
+  end
+
+  @impl true
+  def handle_continue({:connect, [key, uri, opts, client_pid]}, _) do
     with {:ok, conn_pid} <- Gun.Conn.open(uri, opts),
          Process.link(conn_pid) do
       time = :erlang.monotonic_time(:millisecond)
@@ -21,7 +26,7 @@ def init([key, uri, opts, client_pid]) do
 
       send(client_pid, {:conn_pid, conn_pid})
 
-      {:ok,
+      {:noreply,
        %{key: key, timer: nil, client_monitors: %{client_pid => Process.monitor(client_pid)}},
        :hibernate}
     else

From 6a0f2bdf8ceb4127678cc55406a02d41c7fb0ed7 Mon Sep 17 00:00:00 2001
From: href <href@random.sh>
Date: Wed, 8 Jul 2020 13:01:02 +0200
Subject: [PATCH 24/33] Ensure connections error get known by the caller

---
 lib/pleroma/gun/connection_pool.ex        | 22 ++++++++++++----------
 lib/pleroma/gun/connection_pool/worker.ex |  3 ++-
 lib/pleroma/http/adapter_helper/gun.ex    |  2 +-
 3 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/lib/pleroma/gun/connection_pool.ex b/lib/pleroma/gun/connection_pool.ex
index e951872fe..d3eead7d8 100644
--- a/lib/pleroma/gun/connection_pool.ex
+++ b/lib/pleroma/gun/connection_pool.ex
@@ -16,7 +16,7 @@ def get_conn(uri, opts) do
     case Registry.lookup(@registry, key) do
       # The key has already been registered, but connection is not up yet
       [{worker_pid, nil}] ->
-        get_gun_pid_from_worker(worker_pid)
+        get_gun_pid_from_worker(worker_pid, true)
 
       [{worker_pid, {gun_pid, _used_by, _crf, _last_reference}}] ->
         GenServer.cast(worker_pid, {:add_client, self(), false})
@@ -27,13 +27,11 @@ def get_conn(uri, opts) do
         # so we open the connection in the process directly and send it's pid back
         # We trust gun to handle timeouts by itself
         case WorkerSupervisor.start_worker([key, uri, opts, self()]) do
-          {:ok, _worker_pid} ->
-            receive do
-              {:conn_pid, pid} -> {:ok, pid}
-            end
+          {:ok, worker_pid} ->
+            get_gun_pid_from_worker(worker_pid, false)
 
           {:error, {:already_started, worker_pid}} ->
-            get_gun_pid_from_worker(worker_pid)
+            get_gun_pid_from_worker(worker_pid, true)
 
           err ->
             err
@@ -41,17 +39,21 @@ def get_conn(uri, opts) do
     end
   end
 
-  defp get_gun_pid_from_worker(worker_pid) do
+  defp get_gun_pid_from_worker(worker_pid, register) do
     # GenServer.call will block the process for timeout length if
     # the server crashes on startup (which will happen if gun fails to connect)
     # so instead we use cast + monitor
 
     ref = Process.monitor(worker_pid)
-    GenServer.cast(worker_pid, {:add_client, self(), true})
+    if register, do: GenServer.cast(worker_pid, {:add_client, self(), true})
 
     receive do
-      {:conn_pid, pid} -> {:ok, pid}
-      {:DOWN, ^ref, :process, ^worker_pid, reason} -> reason
+      {:conn_pid, pid} ->
+        Process.demonitor(ref)
+        {:ok, pid}
+
+      {:DOWN, ^ref, :process, ^worker_pid, reason} ->
+        {:error, reason}
     end
   end
 
diff --git a/lib/pleroma/gun/connection_pool/worker.ex b/lib/pleroma/gun/connection_pool/worker.ex
index 6ee622fb0..16a508ad9 100644
--- a/lib/pleroma/gun/connection_pool/worker.ex
+++ b/lib/pleroma/gun/connection_pool/worker.ex
@@ -30,7 +30,8 @@ def handle_continue({:connect, [key, uri, opts, client_pid]}, _) do
        %{key: key, timer: nil, client_monitors: %{client_pid => Process.monitor(client_pid)}},
        :hibernate}
     else
-      err -> {:stop, err}
+      err ->
+        {:stop, err, nil}
     end
   end
 
diff --git a/lib/pleroma/http/adapter_helper/gun.ex b/lib/pleroma/http/adapter_helper/gun.ex
index b8c4cc59c..74677ddb5 100644
--- a/lib/pleroma/http/adapter_helper/gun.ex
+++ b/lib/pleroma/http/adapter_helper/gun.ex
@@ -14,7 +14,7 @@ defmodule Pleroma.HTTP.AdapterHelper.Gun do
     connect_timeout: 5_000,
     domain_lookup_timeout: 5_000,
     tls_handshake_timeout: 5_000,
-    retry: 1,
+    retry: 0,
     retry_timeout: 1000,
     await_up_timeout: 5_000
   ]

From 23d714ed3038a24eb78314d52807c46d8b8de2f3 Mon Sep 17 00:00:00 2001
From: href <href@random.sh>
Date: Wed, 8 Jul 2020 13:22:42 +0200
Subject: [PATCH 25/33] Fix race in enforcer/reclaimer start

---
 lib/pleroma/gun/connection_pool/reclaimer.ex  | 85 +++++++++++++++++++
 .../gun/connection_pool/worker_supervisor.ex  | 81 +-----------------
 2 files changed, 89 insertions(+), 77 deletions(-)
 create mode 100644 lib/pleroma/gun/connection_pool/reclaimer.ex

diff --git a/lib/pleroma/gun/connection_pool/reclaimer.ex b/lib/pleroma/gun/connection_pool/reclaimer.ex
new file mode 100644
index 000000000..1793ac3ee
--- /dev/null
+++ b/lib/pleroma/gun/connection_pool/reclaimer.ex
@@ -0,0 +1,85 @@
+defmodule Pleroma.Gun.ConnectionPool.Reclaimer do
+  use GenServer, restart: :temporary
+
+  @registry Pleroma.Gun.ConnectionPool
+
+  def start_monitor() do
+    pid =
+      case :gen_server.start(__MODULE__, [], name: {:via, Registry, {@registry, "reclaimer"}}) do
+        {:ok, pid} ->
+          pid
+
+        {:error, {:already_registered, pid}} ->
+          pid
+      end
+
+    {pid, Process.monitor(pid)}
+  end
+
+  @impl true
+  def init(_) do
+    {:ok, nil, {:continue, :reclaim}}
+  end
+
+  @impl true
+  def handle_continue(:reclaim, _) do
+    max_connections = Pleroma.Config.get([:connections_pool, :max_connections])
+
+    reclaim_max =
+      [:connections_pool, :reclaim_multiplier]
+      |> Pleroma.Config.get()
+      |> Kernel.*(max_connections)
+      |> round
+      |> max(1)
+
+    :telemetry.execute([:pleroma, :connection_pool, :reclaim, :start], %{}, %{
+      max_connections: max_connections,
+      reclaim_max: reclaim_max
+    })
+
+    # :ets.fun2ms(
+    # fn {_, {worker_pid, {_, used_by, crf, last_reference}}} when used_by == [] ->
+    #   {worker_pid, crf, last_reference} end)
+    unused_conns =
+      Registry.select(
+        @registry,
+        [
+          {{:_, :"$1", {:_, :"$2", :"$3", :"$4"}}, [{:==, :"$2", []}], [{{:"$1", :"$3", :"$4"}}]}
+        ]
+      )
+
+    case unused_conns do
+      [] ->
+        :telemetry.execute(
+          [:pleroma, :connection_pool, :reclaim, :stop],
+          %{reclaimed_count: 0},
+          %{
+            max_connections: max_connections
+          }
+        )
+
+        {:stop, :no_unused_conns, nil}
+
+      unused_conns ->
+        reclaimed =
+          unused_conns
+          |> Enum.sort(fn {_pid1, crf1, last_reference1}, {_pid2, crf2, last_reference2} ->
+            crf1 <= crf2 and last_reference1 <= last_reference2
+          end)
+          |> Enum.take(reclaim_max)
+
+        reclaimed
+        |> Enum.each(fn {pid, _, _} ->
+          DynamicSupervisor.terminate_child(Pleroma.Gun.ConnectionPool.WorkerSupervisor, pid)
+        end)
+
+        :telemetry.execute(
+          [:pleroma, :connection_pool, :reclaim, :stop],
+          %{reclaimed_count: Enum.count(reclaimed)},
+          %{max_connections: max_connections}
+        )
+
+        {:stop, :normal, nil}
+    end
+  end
+end
diff --git a/lib/pleroma/gun/connection_pool/worker_supervisor.ex b/lib/pleroma/gun/connection_pool/worker_supervisor.ex
index 5cb8d488a..39615c956 100644
--- a/lib/pleroma/gun/connection_pool/worker_supervisor.ex
+++ b/lib/pleroma/gun/connection_pool/worker_supervisor.ex
@@ -29,89 +29,16 @@ def start_worker(opts, retry \\ false) do
     end
   end
 
-  @registry Pleroma.Gun.ConnectionPool
-  @enforcer_key "enforcer"
   defp free_pool do
-    case Registry.lookup(@registry, @enforcer_key) do
-      [] ->
-        pid =
-          spawn(fn ->
-            {:ok, _pid} = Registry.register(@registry, @enforcer_key, nil)
-            max_connections = Pleroma.Config.get([:connections_pool, :max_connections])
-
-            reclaim_max =
-              [:connections_pool, :reclaim_multiplier]
-              |> Pleroma.Config.get()
-              |> Kernel.*(max_connections)
-              |> round
-              |> max(1)
-
-            :telemetry.execute([:pleroma, :connection_pool, :reclaim, :start], %{}, %{
-              max_connections: max_connections,
-              reclaim_max: reclaim_max
-            })
-
-            # :ets.fun2ms(
-            # fn {_, {worker_pid, {_, used_by, crf, last_reference}}} when used_by == [] ->
-            #   {worker_pid, crf, last_reference} end)
-            unused_conns =
-              Registry.select(
-                @registry,
-                [
-                  {{:_, :"$1", {:_, :"$2", :"$3", :"$4"}}, [{:==, :"$2", []}],
-                   [{{:"$1", :"$3", :"$4"}}]}
-                ]
-              )
-
-            case unused_conns do
-              [] ->
-                :telemetry.execute(
-                  [:pleroma, :connection_pool, :reclaim, :stop],
-                  %{reclaimed_count: 0},
-                  %{
-                    max_connections: max_connections
-                  }
-                )
-
-                exit(:no_unused_conns)
-
-              unused_conns ->
-                reclaimed =
-                  unused_conns
-                  |> Enum.sort(fn {_pid1, crf1, last_reference1},
-                                  {_pid2, crf2, last_reference2} ->
-                    crf1 <= crf2 and last_reference1 <= last_reference2
-                  end)
-                  |> Enum.take(reclaim_max)
-
-                reclaimed
-                |> Enum.each(fn {pid, _, _} ->
-                  DynamicSupervisor.terminate_child(__MODULE__, pid)
-                end)
-
-                :telemetry.execute(
-                  [:pleroma, :connection_pool, :reclaim, :stop],
-                  %{reclaimed_count: Enum.count(reclaimed)},
-                  %{max_connections: max_connections}
-                )
-            end
-          end)
-
-        wait_for_enforcer_finish(pid)
-
-      [{pid, _}] ->
-        wait_for_enforcer_finish(pid)
-    end
+    wait_for_reclaimer_finish(Pleroma.Gun.ConnectionPool.Reclaimer.start_monitor())
   end
 
-  defp wait_for_enforcer_finish(pid) do
-    ref = Process.monitor(pid)
-
+  defp wait_for_reclaimer_finish({pid, mon}) do
     receive do
-      {:DOWN, ^ref, :process, ^pid, :no_unused_conns} ->
+      {:DOWN, ^mon, :process, ^pid, :no_unused_conns} ->
         :error
 
-      {:DOWN, ^ref, :process, ^pid, :normal} ->
+      {:DOWN, ^mon, :process, ^pid, :normal} ->
         :ok
     end
   end

From 53ba6815b170d7d5c11282933b99730209f526ea Mon Sep 17 00:00:00 2001
From: href <href@random.sh>
Date: Wed, 8 Jul 2020 13:58:38 +0200
Subject: [PATCH 26/33] parentheses...

---
 lib/pleroma/gun/connection_pool/reclaimer.ex | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/pleroma/gun/connection_pool/reclaimer.ex b/lib/pleroma/gun/connection_pool/reclaimer.ex
index 1793ac3ee..cea800882 100644
--- a/lib/pleroma/gun/connection_pool/reclaimer.ex
+++ b/lib/pleroma/gun/connection_pool/reclaimer.ex
@@ -3,7 +3,7 @@ defmodule Pleroma.Gun.ConnectionPool.Reclaimer do
 
   @registry Pleroma.Gun.ConnectionPool
 
-  def start_monitor() do
+  def start_monitor do
     pid =
       case :gen_server.start(__MODULE__, [], name: {:via, Registry, {@registry, "reclaimer"}}) do
         {:ok, pid} ->

From 6b1f6a1cf7efc8bbaf099c7363a5aeadd256c781 Mon Sep 17 00:00:00 2001
From: href <href@random.sh>
Date: Wed, 8 Jul 2020 14:59:10 +0200
Subject: [PATCH 27/33] Bump gun

---
 mix.exs  | 2 +-
 mix.lock | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/mix.exs b/mix.exs
index 4dfce58e7..db2e9324e 100644
--- a/mix.exs
+++ b/mix.exs
@@ -141,7 +141,7 @@ defp deps do
       {:castore, "~> 0.1"},
       {:cowlib, "~> 2.8", override: true},
       {:gun,
-       github: "ninenines/gun", ref: "e1a69b36b180a574c0ac314ced9613fdd52312cc", override: true},
+       github: "ninenines/gun", ref: "921c47146b2d9567eac7e9a4d2ccc60fffd4f327", override: true},
       {:jason, "~> 1.0"},
       {:mogrify, "~> 0.6.1"},
       {:ex_aws, "~> 2.1"},
diff --git a/mix.lock b/mix.lock
index 89c97decf..06add0510 100644
--- a/mix.lock
+++ b/mix.lock
@@ -50,7 +50,7 @@
   "gen_stage": {:hex, :gen_stage, "0.14.3", "d0c66f1c87faa301c1a85a809a3ee9097a4264b2edf7644bf5c123237ef732bf", [:mix], [], "hexpm"},
   "gen_state_machine": {:hex, :gen_state_machine, "2.0.5", "9ac15ec6e66acac994cc442dcc2c6f9796cf380ec4b08267223014be1c728a95", [:mix], [], "hexpm"},
   "gettext": {:hex, :gettext, "0.17.4", "f13088e1ec10ce01665cf25f5ff779e7df3f2dc71b37084976cf89d1aa124d5c", [:mix], [], "hexpm", "3c75b5ea8288e2ee7ea503ff9e30dfe4d07ad3c054576a6e60040e79a801e14d"},
-  "gun": {:git, "https://github.com/ninenines/gun.git", "e1a69b36b180a574c0ac314ced9613fdd52312cc", [ref: "e1a69b36b180a574c0ac314ced9613fdd52312cc"]},
+  "gun": {:git, "https://github.com/ninenines/gun.git", "921c47146b2d9567eac7e9a4d2ccc60fffd4f327", [ref: "921c47146b2d9567eac7e9a4d2ccc60fffd4f327"]},
   "hackney": {:hex, :hackney, "1.16.0", "5096ac8e823e3a441477b2d187e30dd3fff1a82991a806b2003845ce72ce2d84", [:rebar3], [{:certifi, "2.5.2", [hex: :certifi, repo: "hexpm", optional: false]}, {:idna, "6.0.1", [hex: :idna, repo: "hexpm", optional: false]}, {:metrics, "1.0.1", [hex: :metrics, repo: "hexpm", optional: false]}, {:mimerl, "~>1.1", [hex: :mimerl, repo: "hexpm", optional: false]}, {:parse_trans, "3.3.0", [hex: :parse_trans, repo: "hexpm", optional: false]}, {:ssl_verify_fun, "1.1.6", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}], "hexpm", "3bf0bebbd5d3092a3543b783bf065165fa5d3ad4b899b836810e513064134e18"},
   "html_entities": {:hex, :html_entities, "0.5.1", "1c9715058b42c35a2ab65edc5b36d0ea66dd083767bef6e3edb57870ef556549", [:mix], [], "hexpm", "30efab070904eb897ff05cd52fa61c1025d7f8ef3a9ca250bc4e6513d16c32de"},
   "html_sanitize_ex": {:hex, :html_sanitize_ex, "1.3.0", "f005ad692b717691203f940c686208aa3d8ffd9dd4bb3699240096a51fa9564e", [:mix], [{:mochiweb, "~> 2.15", [hex: :mochiweb, repo: "hexpm", optional: false]}], "hexpm"},

From ebfa59168942df9f8df73972a407cd2beada41e1 Mon Sep 17 00:00:00 2001
From: href <href@random.sh>
Date: Wed, 8 Jul 2020 15:02:56 +0200
Subject: [PATCH 28/33] Go back to upstream Tesla

---
 mix.exs  | 4 +---
 mix.lock | 2 +-
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/mix.exs b/mix.exs
index db2e9324e..52b4cf268 100644
--- a/mix.exs
+++ b/mix.exs
@@ -135,9 +135,7 @@ defp deps do
       {:poison, "~> 3.0", override: true},
       # {:tesla, "~> 1.3", override: true},
       {:tesla,
-       git: "https://git.pleroma.social/pleroma/elixir-libraries/tesla.git",
-       ref: "61b7503cef33f00834f78ddfafe0d5d9dec2270b",
-       override: true},
+       github: "teamon/tesla", ref: "af3707078b10793f6a534938e56b963aff82fe3c", override: true},
       {:castore, "~> 0.1"},
       {:cowlib, "~> 2.8", override: true},
       {:gun,
diff --git a/mix.lock b/mix.lock
index 06add0510..8dd37a40f 100644
--- a/mix.lock
+++ b/mix.lock
@@ -108,7 +108,7 @@
   "swoosh": {:git, "https://github.com/swoosh/swoosh", "c96e0ca8a00d8f211ec1f042a4626b09f249caa5", [ref: "c96e0ca8a00d8f211ec1f042a4626b09f249caa5"]},
   "syslog": {:hex, :syslog, "1.1.0", "6419a232bea84f07b56dc575225007ffe34d9fdc91abe6f1b2f254fd71d8efc2", [:rebar3], [], "hexpm", "4c6a41373c7e20587be33ef841d3de6f3beba08519809329ecc4d27b15b659e1"},
   "telemetry": {:hex, :telemetry, "0.4.2", "2808c992455e08d6177322f14d3bdb6b625fbcfd233a73505870d8738a2f4599", [:rebar3], [], "hexpm", "2d1419bd9dda6a206d7b5852179511722e2b18812310d304620c7bd92a13fcef"},
-  "tesla": {:git, "https://git.pleroma.social/pleroma/elixir-libraries/tesla.git", "61b7503cef33f00834f78ddfafe0d5d9dec2270b", [ref: "61b7503cef33f00834f78ddfafe0d5d9dec2270b"]},
+  "tesla": {:git, "https://github.com/teamon/tesla.git", "af3707078b10793f6a534938e56b963aff82fe3c", [ref: "af3707078b10793f6a534938e56b963aff82fe3c"]},
   "timex": {:hex, :timex, "3.6.1", "efdf56d0e67a6b956cc57774353b0329c8ab7726766a11547e529357ffdc1d56", [:mix], [{:combine, "~> 0.10", [hex: :combine, repo: "hexpm", optional: false]}, {:gettext, "~> 0.10", [hex: :gettext, repo: "hexpm", optional: false]}, {:tzdata, "~> 0.1.8 or ~> 0.5 or ~> 1.0.0", [hex: :tzdata, repo: "hexpm", optional: false]}], "hexpm", "f354efb2400dd7a80fd9eb6c8419068c4f632da4ac47f3d8822d6e33f08bc852"},
   "trailing_format_plug": {:hex, :trailing_format_plug, "0.0.7", "64b877f912cf7273bed03379936df39894149e35137ac9509117e59866e10e45", [:mix], [{:plug, "> 0.12.0", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm", "bd4fde4c15f3e993a999e019d64347489b91b7a9096af68b2bdadd192afa693f"},
   "tzdata": {:hex, :tzdata, "1.0.3", "73470ad29dde46e350c60a66e6b360d3b99d2d18b74c4c349dbebbc27a09a3eb", [:mix], [{:hackney, "~> 1.0", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm", "a6e1ee7003c4d04ecbd21dd3ec690d4c6662db5d3bbdd7262d53cdf5e7c746c1"},

From ce1a42bd04bcf352ea1565b411444a98261b0a96 Mon Sep 17 00:00:00 2001
From: href <href@random.sh>
Date: Wed, 8 Jul 2020 15:12:09 +0200
Subject: [PATCH 29/33] Simplify TLS opts

- `verify_fun` is not useful now
- use `customize_check_hostname` (OTP 20+ so OK)
- `partial_chain` is useless as of OTP 21.1 (wasn't there, but hackney/..
uses it)
---
 lib/pleroma/gun/conn.ex                |  5 ++---
 lib/pleroma/http/adapter_helper/gun.ex | 28 --------------------------
 2 files changed, 2 insertions(+), 31 deletions(-)

diff --git a/lib/pleroma/gun/conn.ex b/lib/pleroma/gun/conn.ex
index 9dc8880db..5c12e8153 100644
--- a/lib/pleroma/gun/conn.ex
+++ b/lib/pleroma/gun/conn.ex
@@ -28,9 +28,8 @@ defp maybe_add_tls_opts(opts, %URI{scheme: "https", host: host}) do
       cacertfile: CAStore.file_path(),
       depth: 20,
       reuse_sessions: false,
-      verify_fun:
-        {&:ssl_verify_hostname.verify_fun/3,
-         [check_hostname: Pleroma.HTTP.AdapterHelper.format_host(host)]}
+      log_level: :warning,
+      customize_hostname_check: [match_fun: :public_key.pkix_verify_hostname_match_fun(:https)]
     ]
 
     tls_opts =
diff --git a/lib/pleroma/http/adapter_helper/gun.ex b/lib/pleroma/http/adapter_helper/gun.ex
index 74677ddb5..b4ff8306c 100644
--- a/lib/pleroma/http/adapter_helper/gun.ex
+++ b/lib/pleroma/http/adapter_helper/gun.ex
@@ -39,36 +39,8 @@ defp add_scheme_opts(opts, %{scheme: "http"}), do: opts
   defp add_scheme_opts(opts, %{scheme: "https"}) do
     opts
     |> Keyword.put(:certificates_verification, true)
-    |> Keyword.put(:tls_opts,
-      log_level: :warning,
-      customize_hostname_check: [match_fun: &ssl_match_fun/2]
-    )
   end
 
-  # ssl_match_fun is adapted from [Mint](https://github.com/elixir-mint/mint)
-  # Copyright 2018 Eric Meadows-Jönsson and Andrea Leopardi
-
-  # Wildcard domain handling for DNS ID entries in the subjectAltName X.509
-  # extension. Note that this is a subset of the wildcard patterns implemented
-  # by OTP when matching against the subject CN attribute, but this is the only
-  # wildcard usage defined by the CA/Browser Forum's Baseline Requirements, and
-  # therefore the only pattern used in commercially issued certificates.
-  defp ssl_match_fun({:dns_id, reference}, {:dNSName, [?*, ?. | presented]}) do
-    case domain_without_host(reference) do
-      '' ->
-        :default
-
-      domain ->
-        :string.casefold(domain) == :string.casefold(presented)
-    end
-  end
-
-  defp ssl_match_fun(_reference, _presented), do: :default
-
-  defp domain_without_host([]), do: []
-  defp domain_without_host([?. | domain]), do: domain
-  defp domain_without_host([_ | more]), do: domain_without_host(more)
-
   @spec get_conn(URI.t(), keyword()) :: {:ok, keyword()} | {:error, atom()}
   def get_conn(uri, opts) do
     case ConnectionPool.get_conn(uri, opts) do

From afd378f84c4c1b784eba11b35c21e0b6ae3d7915 Mon Sep 17 00:00:00 2001
From: href <href@random.sh>
Date: Wed, 8 Jul 2020 16:02:57 +0200
Subject: [PATCH 30/33] host is now useless

---
 lib/pleroma/gun/conn.ex | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/pleroma/gun/conn.ex b/lib/pleroma/gun/conn.ex
index 5c12e8153..a3f75a4bb 100644
--- a/lib/pleroma/gun/conn.ex
+++ b/lib/pleroma/gun/conn.ex
@@ -22,7 +22,7 @@ def open(%URI{} = uri, opts) do
 
   defp maybe_add_tls_opts(opts, %URI{scheme: "http"}), do: opts
 
-  defp maybe_add_tls_opts(opts, %URI{scheme: "https", host: host}) do
+  defp maybe_add_tls_opts(opts, %URI{scheme: "https"}) do
     tls_opts = [
       verify: :verify_peer,
       cacertfile: CAStore.file_path(),

From e499275076422631b31f1455ab720aae9d7786d2 Mon Sep 17 00:00:00 2001
From: href <href@random.sh>
Date: Wed, 8 Jul 2020 19:23:32 +0200
Subject: [PATCH 31/33] Don't test tls_options in adapter helper test.

---
 test/http/adapter_helper/gun_test.exs | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/test/http/adapter_helper/gun_test.exs b/test/http/adapter_helper/gun_test.exs
index 49eebf355..80589c73d 100644
--- a/test/http/adapter_helper/gun_test.exs
+++ b/test/http/adapter_helper/gun_test.exs
@@ -21,7 +21,6 @@ test "https url with default port" do
 
       opts = Gun.options([receive_conn: false], uri)
       assert opts[:certificates_verification]
-      assert opts[:tls_opts][:log_level] == :warning
     end
 
     test "https ipv4 with default port" do
@@ -29,7 +28,6 @@ test "https ipv4 with default port" do
 
       opts = Gun.options([receive_conn: false], uri)
       assert opts[:certificates_verification]
-      assert opts[:tls_opts][:log_level] == :warning
     end
 
     test "https ipv6 with default port" do
@@ -37,7 +35,6 @@ test "https ipv6 with default port" do
 
       opts = Gun.options([receive_conn: false], uri)
       assert opts[:certificates_verification]
-      assert opts[:tls_opts][:log_level] == :warning
     end
 
     test "https url with non standart port" do

From 6d583bcc3b23c0c16aefa3f34155e7e15b745b01 Mon Sep 17 00:00:00 2001
From: href <href@random.sh>
Date: Mon, 13 Jul 2020 10:44:36 +0200
Subject: [PATCH 32/33] Set a default timeout for Gun adapter timeout

---
 lib/pleroma/http/adapter_helper.ex | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/lib/pleroma/http/adapter_helper.ex b/lib/pleroma/http/adapter_helper.ex
index 8ca433732..9ec3836b0 100644
--- a/lib/pleroma/http/adapter_helper.ex
+++ b/lib/pleroma/http/adapter_helper.ex
@@ -44,15 +44,17 @@ def maybe_add_proxy(opts, proxy), do: Keyword.put_new(opts, :proxy, proxy)
   @spec options(URI.t(), keyword()) :: keyword()
   def options(%URI{} = uri, opts \\ []) do
     @defaults
-    |> pool_timeout()
+    |> put_timeout()
     |> Keyword.merge(opts)
     |> adapter_helper().options(uri)
   end
 
-  defp pool_timeout(opts) do
+  # For Hackney, this is the time a connection can stay idle in the pool.
+  # For Gun, this is the timeout to receive a message from Gun.
+  defp put_timeout(opts) do
     {config_key, default} =
       if adapter() == Tesla.Adapter.Gun do
-        {:pools, Config.get([:pools, :default, :timeout])}
+        {:pools, Config.get([:pools, :default, :timeout], 5_000)}
       else
         {:hackney_pools, 10_000}
       end

From 7115c5f82efe1ca1817da3152ba3cbc66e0da1a4 Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Wed, 15 Jul 2020 15:58:08 +0300
Subject: [PATCH 33/33] ConnectionPool.Worker: do not stop with an error when
 there is a timeout

This produced error log messages about GenServer termination
every time the connection was not open due to a timeout.

Instead we stop with `{:shutdown, <gun_error>}` since shutting down
when the connection can't be established is normal behavior.
---
 lib/pleroma/gun/connection_pool.ex        | 5 ++++-
 lib/pleroma/gun/connection_pool/worker.ex | 2 +-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/lib/pleroma/gun/connection_pool.ex b/lib/pleroma/gun/connection_pool.ex
index d3eead7d8..8b41a668c 100644
--- a/lib/pleroma/gun/connection_pool.ex
+++ b/lib/pleroma/gun/connection_pool.ex
@@ -53,7 +53,10 @@ defp get_gun_pid_from_worker(worker_pid, register) do
         {:ok, pid}
 
       {:DOWN, ^ref, :process, ^worker_pid, reason} ->
-        {:error, reason}
+        case reason do
+          {:shutdown, error} -> error
+          _ -> {:error, reason}
+        end
     end
   end
 
diff --git a/lib/pleroma/gun/connection_pool/worker.ex b/lib/pleroma/gun/connection_pool/worker.ex
index 16a508ad9..f33447cb6 100644
--- a/lib/pleroma/gun/connection_pool/worker.ex
+++ b/lib/pleroma/gun/connection_pool/worker.ex
@@ -31,7 +31,7 @@ def handle_continue({:connect, [key, uri, opts, client_pid]}, _) do
        :hibernate}
     else
       err ->
-        {:stop, err, nil}
+        {:stop, {:shutdown, err}, nil}
     end
   end