Getting Started

Installation

Add the gem to your project:

$ bundle add async-await

Usage

"async" Keyword

This gem provides module Async::Await which introduces the async keyword. This keyword is used to define asynchronous methods. The method will return an Async::Task object, which can be waited on to get the result.

require 'async/await'

class Coop
	include Async::Await
	
	async def count_chickens(area_name)
		3.times do |i|
			sleep rand
			
			puts "Found a chicken in the #{area_name}!"
		end
	end

	async def count_all_chickens
		# These methods all run at the same time.
		count_chickens("garden")
		count_chickens("house")
		
		# We wait for the result
		count_chickens("tree").wait
	end
end

coop = Coop.new
coop.count_all_chickens

This interface was originally designed as a joke, but may be useful in some limited contexts. It is not recommended for general use.

Enumerable

This gem provides module Async::Await::Enumerable which adds async support to the Enumerable module. This allows you to use concurrency in a more functional style.

require "async/await/enumerable"

[1, 2, 3].async_each do |i|
	sleep rand
	puts i
end

This will run the block for each element in the array concurrently.

Using a Semaphore

In order to prevent unlimited concurrency, you can use a semaphore to limit the number of concurrent tasks. This is useful when you want to limit the number of concurrent tasks to a specific number.

require "async/await/enumerable"
require "async/semaphore"

semaphore = Async::Semaphore.new(2)

[1, 2, 3].async_each(parent: semaphore) do |i|
	sleep rand
	puts i
end