Merge branch 'docs/ap_c2s' into 'develop'
[akkoma] / lib / pleroma / gun / connection_pool.ex
1 # Pleroma: A lightweight social networking server
2 # Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
3 # SPDX-License-Identifier: AGPL-3.0-only
4
5 defmodule Pleroma.Gun.ConnectionPool do
6 @registry __MODULE__
7
8 alias Pleroma.Gun.ConnectionPool.WorkerSupervisor
9
10 def children do
11 [
12 {Registry, keys: :unique, name: @registry},
13 Pleroma.Gun.ConnectionPool.WorkerSupervisor
14 ]
15 end
16
17 @spec get_conn(URI.t(), keyword()) :: {:ok, pid()} | {:error, term()}
18 def get_conn(uri, opts) do
19 key = "#{uri.scheme}:#{uri.host}:#{uri.port}"
20
21 case Registry.lookup(@registry, key) do
22 # The key has already been registered, but connection is not up yet
23 [{worker_pid, nil}] ->
24 get_gun_pid_from_worker(worker_pid, true)
25
26 [{worker_pid, {gun_pid, _used_by, _crf, _last_reference}}] ->
27 GenServer.call(worker_pid, :add_client)
28 {:ok, gun_pid}
29
30 [] ->
31 # :gun.set_owner fails in :connected state for whatevever reason,
32 # so we open the connection in the process directly and send it's pid back
33 # We trust gun to handle timeouts by itself
34 case WorkerSupervisor.start_worker([key, uri, opts, self()]) do
35 {:ok, worker_pid} ->
36 get_gun_pid_from_worker(worker_pid, false)
37
38 {:error, {:already_started, worker_pid}} ->
39 get_gun_pid_from_worker(worker_pid, true)
40
41 err ->
42 err
43 end
44 end
45 end
46
47 defp get_gun_pid_from_worker(worker_pid, register) do
48 # GenServer.call will block the process for timeout length if
49 # the server crashes on startup (which will happen if gun fails to connect)
50 # so instead we use cast + monitor
51
52 ref = Process.monitor(worker_pid)
53 if register, do: GenServer.cast(worker_pid, {:add_client, self()})
54
55 receive do
56 {:conn_pid, pid} ->
57 Process.demonitor(ref)
58 {:ok, pid}
59
60 {:DOWN, ^ref, :process, ^worker_pid, reason} ->
61 case reason do
62 {:shutdown, {:error, _} = error} -> error
63 {:shutdown, error} -> {:error, error}
64 _ -> {:error, reason}
65 end
66 end
67 end
68
69 @spec release_conn(pid()) :: :ok
70 def release_conn(conn_pid) do
71 # :ets.fun2ms(fn {_, {worker_pid, {gun_pid, _, _, _}}} when gun_pid == conn_pid ->
72 # worker_pid end)
73 query_result =
74 Registry.select(@registry, [
75 {{:_, :"$1", {:"$2", :_, :_, :_}}, [{:==, :"$2", conn_pid}], [:"$1"]}
76 ])
77
78 case query_result do
79 [worker_pid] ->
80 GenServer.call(worker_pid, :remove_client)
81
82 [] ->
83 :ok
84 end
85 end
86 end