akkoma/lib/pleroma/gun/connection_pool/worker.ex
rinpatch a705637dcf Connection Pool: fix LRFU implementation to not actually be LRU
The numbers of the native time unit were so small the CRF was always 1,
making it an LRU. This commit switches the time to miliseconds and changes
the time delta multiplier to the one yielding mostly highest hit rates according
to the paper
2020-07-15 15:26:35 +03:00

121 lines
3.4 KiB
Elixir

defmodule Pleroma.Gun.ConnectionPool.Worker do
alias Pleroma.Gun
use GenServer, restart: :temporary
@registry Pleroma.Gun.ConnectionPool
def start_link([key | _] = opts) do
GenServer.start_link(__MODULE__, opts, name: {:via, Registry, {@registry, key}})
end
@impl true
def init([key, uri, opts, client_pid]) do
with {:ok, conn_pid} <- Gun.Conn.open(uri, opts),
Process.link(conn_pid) do
time = :erlang.monotonic_time(:millisecond)
{_, _} =
Registry.update_value(@registry, key, fn _ ->
{conn_pid, [client_pid], 1, time}
end)
send(client_pid, {:conn_pid, conn_pid})
{:ok,
%{key: key, timer: nil, client_monitors: %{client_pid => Process.monitor(client_pid)}},
:hibernate}
else
err -> {:stop, err}
end
end
@impl true
def handle_cast({:add_client, client_pid, send_pid_back}, %{key: key} = state) do
time = :erlang.monotonic_time(:millisecond)
{{conn_pid, _, _, _}, _} =
Registry.update_value(@registry, key, fn {conn_pid, used_by, crf, last_reference} ->
{conn_pid, [client_pid | used_by], crf(time - last_reference, crf), time}
end)
if send_pid_back, do: send(client_pid, {:conn_pid, conn_pid})
state =
if state.timer != nil do
Process.cancel_timer(state[:timer])
%{state | timer: nil}
else
state
end
ref = Process.monitor(client_pid)
state = put_in(state.client_monitors[client_pid], ref)
{:noreply, state, :hibernate}
end
@impl true
def handle_cast({:remove_client, client_pid}, %{key: key} = state) do
{{_conn_pid, used_by, _crf, _last_reference}, _} =
Registry.update_value(@registry, key, fn {conn_pid, used_by, crf, last_reference} ->
{conn_pid, List.delete(used_by, client_pid), crf, last_reference}
end)
{ref, state} = pop_in(state.client_monitors[client_pid])
Process.demonitor(ref)
timer =
if used_by == [] do
max_idle = Pleroma.Config.get([:connections_pool, :max_idle_time], 30_000)
Process.send_after(self(), :idle_close, max_idle)
else
nil
end
{:noreply, %{state | timer: timer}, :hibernate}
end
@impl true
def handle_info(:idle_close, state) do
# Gun monitors the owner process, and will close the connection automatically
# when it's terminated
{:stop, :normal, state}
end
# Gracefully shutdown if the connection got closed without any streams left
@impl true
def handle_info({:gun_down, _pid, _protocol, _reason, []}, state) do
{:stop, :normal, state}
end
# Otherwise, shutdown with an error
@impl true
def handle_info({:gun_down, _pid, _protocol, _reason, _killed_streams} = down_message, state) do
{:stop, {:error, down_message}, state}
end
@impl true
def handle_info({:DOWN, _ref, :process, pid, reason}, state) do
# Sometimes the client is dead before we demonitor it in :remove_client, so the message
# arrives anyway
case state.client_monitors[pid] do
nil ->
{:noreply, state, :hibernate}
_ref ->
:telemetry.execute(
[:pleroma, :connection_pool, :client_death],
%{client_pid: pid, reason: reason},
%{key: state.key}
)
handle_cast({:remove_client, pid}, state)
end
end
# LRFU policy: https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.55.1478
defp crf(time_delta, prev_crf) do
1 + :math.pow(0.5, 0.0001 * time_delta) * prev_crf
end
end