ec9d0d146b
Fixes race conditions in limit enforcement by putting worker processes in a DynamicSupervisor
92 lines
2.4 KiB
Elixir
92 lines
2.4 KiB
Elixir
defmodule Pleroma.Gun.ConnectionPool.WorkerSupervisor do
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@doc "Supervisor for pool workers. Does not do anything except enforce max connection limit"
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use DynamicSupervisor
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def start_link(opts) do
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DynamicSupervisor.start_link(__MODULE__, opts, name: __MODULE__)
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end
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def init(_opts) do
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DynamicSupervisor.init(
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strategy: :one_for_one,
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max_children: Pleroma.Config.get([:connections_pool, :max_connections])
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)
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end
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def start_worker(opts) do
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case DynamicSupervisor.start_child(__MODULE__, {Pleroma.Gun.ConnectionPool.Worker, opts}) do
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{:error, :max_children} ->
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case free_pool() do
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:ok -> start_worker(opts)
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:error -> {:error, :pool_full}
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end
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res ->
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res
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end
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end
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@registry Pleroma.Gun.ConnectionPool
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@enforcer_key "enforcer"
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defp free_pool 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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max_connections = Pleroma.Config.get([:connections_pool, :max_connections])
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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(:no_unused_conns)
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unused_conns ->
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unused_conns
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|> Enum.sort(fn {_pid1, crf1, last_reference1}, {_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, _, _} ->
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DynamicSupervisor.terminate_child(__MODULE__, pid)
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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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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, :no_unused_conns} ->
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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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end
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