forked from AkkomaGang/akkoma
Connection pool: Fix race conditions in limit enforcement
Fixes race conditions in limit enforcement by putting worker processes in a DynamicSupervisor
This commit is contained in:
rinpatch
parent
d08b157699
commit
ec9d0d146b
4 changed files with 118 additions and 92 deletions
|
|
@ -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: []
|
||||
|
|
|
|||
|
|
@ -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)
|
||||
|
|
|
|||
|
|
@ -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
|
||||
|
|
|
|||
91
lib/pleroma/gun/connection_pool/worker_supervisor.ex
Normal file
91
lib/pleroma/gun/connection_pool/worker_supervisor.ex
Normal file
|
|
@ -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
|
||||
Loading…
Reference in a new issue