akkoma/lib/pleroma/plugs/rate_limiter/limiter_supervisor.ex
rinpatch 4d416343fa rate limiter: Fix a race condition
When multiple requests are processed by rate limiter plug at the same
time and the bucket is not yet initialized, both would try to initialize
the bucket resulting in an internal server error.
2020-03-01 01:13:07 +03:00

50 lines
1.1 KiB
Elixir

defmodule Pleroma.Plugs.RateLimiter.LimiterSupervisor do
use DynamicSupervisor
import Cachex.Spec
def start_link(init_arg) do
DynamicSupervisor.start_link(__MODULE__, init_arg, name: __MODULE__)
end
def add_or_return_limiter(limiter_name, expiration) do
result =
DynamicSupervisor.start_child(
__MODULE__,
%{
id: String.to_atom("rl_#{limiter_name}"),
start:
{Cachex, :start_link,
[
limiter_name,
[
expiration:
expiration(
default: expiration,
interval: check_interval(expiration),
lazy: true
)
]
]}
}
)
case result do
{:ok, _pid} = result -> result
{:error, {:already_started, pid}} -> {:ok, pid}
_ -> result
end
end
@impl true
def init(_init_arg) do
DynamicSupervisor.init(strategy: :one_for_one)
end
defp check_interval(exp) do
(exp / 2)
|> Kernel.trunc()
|> Kernel.min(5000)
|> Kernel.max(1)
end
end