pleroma/lib/pleroma/gun/connection_pool.ex
2020-10-12 12:00:50 -05:00

87 lines
2.5 KiB
Elixir

# Pleroma: A lightweight social networking server
# Copyright © 2017-2020 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