Untitled-1
defmodule Horionos.Services.RateLimiter do
@moduledoc """
Rate limiter service.
"""
use GenServer
@callback check_rate(String.t(), integer(), integer()) :: :ok | :error
@table_name :rate_limiter
@spec start_link(any()) :: :ignore | {:error, any()} | {:ok, pid()}
#
def start_link(_opts) do
GenServer.start_link(__MODULE__, [], name: __MODULE__)
end
@spec init(any()) :: {:ok, map()}
#
def init(_) do
:ets.new(@table_name, [:set, :named_table, :public, read_concurrency: true])
{:ok, %{}}
end
@doc """
Checks if the action is allowed based on the given key, limit, and time window.
## Parameters
- key: A unique identifier for the action (e.g., "confirmation_instructions:user@example.com")
- limit: The maximum number of actions allowed within the time window
- window: The time window in milliseconds
## Returns
- :ok if the action is allowed
- :error if the rate limit has been exceeded
"""
@spec check_rate(String.t(), integer(), integer()) :: :ok | :error
#
def check_rate(key, limit, window) do
now = System.system_time(:millisecond)
case :ets.lookup(@table_name, key) do
[{^key, _count, last_reset}] when now - last_reset > window ->
:ets.insert(@table_name, {key, 1, now})
:ok
[{^key, count, _last_reset}] when count >= limit ->
:error
[{^key, _count, _last_reset}] ->
:ets.update_counter(@table_name, key, {2, 1})
:ok
[] ->
:ets.insert(@table_name, {key, 1, now})
:ok
end
end
end