# Pleroma: A lightweight social networking server # Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/> # SPDX-License-Identifier: AGPL-3.0-only 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 @spec get_conn(URI.t(), keyword()) :: {:ok, pid()} | {:error, term()} def get_conn(uri, opts) do 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}] -> get_gun_pid_from_worker(worker_pid, true) [{worker_pid, {gun_pid, _used_by, _crf, _last_reference}}] -> GenServer.call(worker_pid, :add_client) {: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 WorkerSupervisor.start_worker([key, uri, opts, self()]) do {:ok, worker_pid} -> get_gun_pid_from_worker(worker_pid, false) {:error, {:already_started, worker_pid}} -> get_gun_pid_from_worker(worker_pid, true) err -> err end end end 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) if register, do: GenServer.cast(worker_pid, {:add_client, self()}) receive do {:conn_pid, pid} -> Process.demonitor(ref) {:ok, pid} {:DOWN, ^ref, :process, ^worker_pid, reason} -> case reason do {:shutdown, {:error, _} = error} -> error {:shutdown, error} -> {:error, error} _ -> {:error, reason} end end end @spec release_conn(pid()) :: :ok 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"]} ]) case query_result do [worker_pid] -> GenServer.call(worker_pid, :remove_client) [] -> :ok end end end