forked from mirrors/akkoma
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
95 lines
2.8 KiB
Elixir
95 lines
2.8 KiB
Elixir
defmodule Pleroma.Gun.ConnectionPool.Worker do
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alias Pleroma.Gun
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use GenServer
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@registry Pleroma.Gun.ConnectionPool
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@impl true
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def init([uri, key, opts, client_pid]) do
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time = :os.system_time(:second)
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# Register before opening connection to prevent race conditions
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with {:ok, _owner} <- Registry.register(@registry, key, {nil, [client_pid], 1, time}),
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{:ok, conn_pid} <- Gun.Conn.open(uri, opts),
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Process.link(conn_pid) do
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{_, _} =
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Registry.update_value(@registry, key, fn {_, used_by, crf, last_reference} ->
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{conn_pid, used_by, crf, last_reference}
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end)
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send(client_pid, {:conn_pid, conn_pid})
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{:ok, %{key: key, timer: nil}, :hibernate}
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else
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err -> {:stop, err}
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end
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end
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@impl true
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def handle_cast({:add_client, client_pid, send_pid_back}, %{key: key} = state) do
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time = :os.system_time(:second)
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{{conn_pid, _, _, _}, _} =
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Registry.update_value(@registry, key, fn {conn_pid, used_by, crf, last_reference} ->
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{conn_pid, [client_pid | used_by], crf(time - last_reference, crf), time}
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end)
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if send_pid_back, do: send(client_pid, {:conn_pid, conn_pid})
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state =
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if state.timer != nil do
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Process.cancel_timer(state[:timer])
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%{state | timer: nil}
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else
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state
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end
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{:noreply, state, :hibernate}
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end
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@impl true
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def handle_cast({:remove_client, client_pid}, %{key: key} = state) do
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{{_conn_pid, used_by, _crf, _last_reference}, _} =
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Registry.update_value(@registry, key, fn {conn_pid, used_by, crf, last_reference} ->
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{conn_pid, List.delete(used_by, client_pid), crf, last_reference}
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end)
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timer =
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if used_by == [] do
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max_idle = Pleroma.Config.get([:connections_pool, :max_idle_time], 30_000)
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Process.send_after(self(), :idle_close, max_idle)
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else
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nil
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end
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{:noreply, %{state | timer: timer}, :hibernate}
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end
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@impl true
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def handle_info(:idle_close, state) do
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# Gun monitors the owner process, and will close the connection automatically
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# when it's terminated
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{:stop, :normal, state}
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end
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# Gracefully shutdown if the connection got closed without any streams left
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@impl true
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def handle_info({:gun_down, _pid, _protocol, _reason, []}, state) do
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{:stop, :normal, state}
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end
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# Otherwise, shutdown with an error
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@impl true
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def handle_info({:gun_down, _pid, _protocol, _reason, _killed_streams} = down_message, state) do
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{:stop, {:error, down_message}, state}
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end
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@impl true
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def handle_call(:idle_close, _, %{key: key} = state) do
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Registry.unregister(@registry, key)
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{:stop, :normal, state}
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end
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# LRFU policy: https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.55.1478
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defp crf(time_delta, prev_crf) do
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1 + :math.pow(0.5, time_delta / 100) * prev_crf
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end
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end
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