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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] = opts) do
{:ok, nil, {:continue, {:connect, opts}}}
end
@impl true
def handle_continue({:connect, [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})
{:noreply,
%{key: key, timer: nil, client_monitors: %{client_pid => Process.monitor(client_pid)}},
:hibernate}
else
err ->
{:stop, {:shutdown, err}, nil}
end
end
@impl true
def handle_cast({:add_client, client_pid}, state) do
case handle_call(:add_client, {client_pid, nil}, state) do
{:reply, conn_pid, state, :hibernate} ->
send(client_pid, {:conn_pid, conn_pid})
{:noreply, state, :hibernate}
end
end
@impl true
def handle_cast({:remove_client, client_pid}, state) do
case handle_call(:remove_client, {client_pid, nil}, state) do
{:reply, _, state, :hibernate} ->
{:noreply, state, :hibernate}
end
end
@impl true
def handle_call(:add_client, {client_pid, _}, %{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)
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)
{:reply, conn_pid, state, :hibernate}
end
@impl true
def handle_call(: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
{:reply, :ok, %{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
:telemetry.execute(
[:pleroma, :connection_pool, :client_death],
%{client_pid: pid, reason: reason},
%{key: state.key}
)
handle_cast({:remove_client, pid}, state)
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
|
