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https://git.pleroma.social/pleroma/pleroma.git
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58a4f350a8
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
130 lines
3.8 KiB
Elixir
130 lines
3.8 KiB
Elixir
defmodule Pleroma.Gun.ConnectionPool do
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@registry __MODULE__
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def get_conn(uri, opts) do
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case enforce_pool_limits() do
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:ok ->
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key = "#{uri.scheme}:#{uri.host}:#{uri.port}"
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case Registry.lookup(@registry, key) do
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# The key has already been registered, but connection is not up yet
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[{worker_pid, {nil, _used_by, _crf, _last_reference}}] ->
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get_gun_pid_from_worker(worker_pid)
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[{worker_pid, {gun_pid, _used_by, _crf, _last_reference}}] ->
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GenServer.cast(worker_pid, {:add_client, self(), false})
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{:ok, gun_pid}
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[] ->
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# :gun.set_owner fails in :connected state for whatevever reason,
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# so we open the connection in the process directly and send it's pid back
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# We trust gun to handle timeouts by itself
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case GenServer.start(Pleroma.Gun.ConnectionPool.Worker, [uri, key, opts, self()],
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timeout: :infinity
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) do
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{:ok, _worker_pid} ->
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receive do
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{:conn_pid, pid} -> {:ok, pid}
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end
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{:error, {:error, {:already_registered, worker_pid}}} ->
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get_gun_pid_from_worker(worker_pid)
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err ->
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err
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end
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end
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:error ->
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{:error, :pool_full}
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end
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end
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@enforcer_key "enforcer"
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defp enforce_pool_limits() do
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max_connections = Pleroma.Config.get([:connections_pool, :max_connections])
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if Registry.count(@registry) >= max_connections do
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case Registry.lookup(@registry, @enforcer_key) do
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[] ->
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pid =
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spawn(fn ->
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{:ok, _pid} = Registry.register(@registry, @enforcer_key, nil)
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reclaim_max =
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[:connections_pool, :reclaim_multiplier]
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|> Pleroma.Config.get()
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|> Kernel.*(max_connections)
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|> round
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|> max(1)
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unused_conns =
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Registry.select(
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@registry,
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[
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{{:_, :"$1", {:_, :"$2", :"$3", :"$4"}}, [{:==, :"$2", []}],
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[{{:"$1", :"$3", :"$4"}}]}
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]
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)
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case unused_conns do
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[] ->
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exit(:pool_full)
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unused_conns ->
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unused_conns
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|> Enum.sort(fn {_pid1, crf1, last_reference1},
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{_pid2, crf2, last_reference2} ->
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crf1 <= crf2 and last_reference1 <= last_reference2
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end)
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|> Enum.take(reclaim_max)
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|> Enum.each(fn {pid, _, _} -> GenServer.call(pid, :idle_close) end)
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end
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end)
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wait_for_enforcer_finish(pid)
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[{pid, _}] ->
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wait_for_enforcer_finish(pid)
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end
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else
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:ok
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end
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end
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defp wait_for_enforcer_finish(pid) do
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ref = Process.monitor(pid)
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receive do
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{:DOWN, ^ref, :process, ^pid, :pool_full} ->
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:error
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{:DOWN, ^ref, :process, ^pid, :normal} ->
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:ok
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end
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end
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defp get_gun_pid_from_worker(worker_pid) do
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# GenServer.call will block the process for timeout length if
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# the server crashes on startup (which will happen if gun fails to connect)
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# so instead we use cast + monitor
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ref = Process.monitor(worker_pid)
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GenServer.cast(worker_pid, {:add_client, self(), true})
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receive do
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{:conn_pid, pid} -> {:ok, pid}
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{:DOWN, ^ref, :process, ^worker_pid, reason} -> reason
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end
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end
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def release_conn(conn_pid) do
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[worker_pid] =
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Registry.select(@registry, [
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{{:_, :"$1", {:"$2", :_, :_, :_}}, [{:==, :"$2", conn_pid}], [:"$1"]}
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])
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GenServer.cast(worker_pid, {:remove_client, self()})
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end
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end
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