SlackThrottle

Slack Web API wrapper library that automatically throttles all requests according to API rate limits.

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Installation

Add slack_throttle to your list of dependencies in mix.exs:

def deps do
  [{:slack_throttle, "~> 0.2.0"}]
end

Ensure slack_throttle is started before your application:

def application do
  [applications: [:slack_throttle]]
end

Usage

Look up the API method you want to use in the Slack documentation. Function names are method names with dots replaced by underscores:

# method: channels.info
iex> SlackThrottle.API.channels_info("some token", %{channel: "C123456"})
%{"ok" => true, "channel" => %{"id" => "C123456", ...}}

If you don't care about the response, e.g. when broadcasting a message, use :cast as the third argument:

# method: chat.postMessage
iex> SlackThrottle.API.chat_postMessage("some token", params, :cast)
:ok

Broadcasts are executed asynchronously and return :ok immediately.

Rate Limits

The Slack Web API is subject to rate limiting. Requests are only allowed at a rate of one per second on a per-access-token basis.

To comply with these restrictions, the library queues all function calls (grouped by access token) and executes them at the given rate. These queues are priority queues: Regular blocking function calls have higher priority than asynchronous broadcasts (the :cast ones).

Configuration

The API throttle rate :api_throttle can be configured as well as the timeout for blocking function calls :enqueue_sync_timeout:

config :slack_throttle,
  api_throttle: 1000, # in milliseconds
  enqueue_sync_timeout: 20000 # in milliseconds

Built for and used by

lunchorder, a lunch order list making Slack app

License

MIT