Blog post: Untangling Evented Code with Ruby Fibers

Collection of convenience classes and patches to common EventMachine clients to make them Fiber aware and friendly. Word of warning: even though fibers have been backported to Ruby 1.8.x, these classes assume Ruby 1.9 (if you're using fibers in production, you should be on 1.9 anyway)

Features:

• Fiber aware connection pool with sync/async query support
• Multi request interface which accepts any callback enabled client
• Fibered iterator to allow concurrency control & mixing of sync / async
• em-http-request: .get, etc are synchronous, while .aget, etc are async
• em-mysqlplus: .query is synchronous, while .aquery is async
• remcached: .get, etc, and .multi_* methods are synchronous
• em-mongo: .find, .first are synchronous
• bitly v2 and v3: synchronous api calls with EM::HttpRequest.

require "em-synchrony/em-http"
EventMachine.synchrony do
    res = EventMachine::HttpRequest.new("http://www.postrank.com").get
    p "Look ma, no callbacks!"
    p res

    EventMachine.stop
end

require "em-synchrony/em-http"
EM.synchrony do
    concurrency = 2
    urls = ['http://url.1.com', 'http://url2.com']

    # iterator will execute async blocks until completion, .each, .inject also work!
    results = EM::Synchrony::Iterator.new(urls, concurrency).map do |url, iter|

        # fire async requests, on completion advance the iterator
        http = EventMachine::HttpRequest.new(url).aget
        http.callback { iter.return(http) }
    end

    p results # all completed requests
    EventMachine.stop
end

require "em-synchrony/em-mysqlplus"
EventMachine.synchrony do
    db = EventMachine::Synchrony::ConnectionPool.new(size: 2) do
        EventMachine::MySQL.new(host: "localhost")
    end

    multi = EventMachine::Synchrony::Multi.new
    multi.add :a, db.aquery("select sleep(1)")
    multi.add :b, db.aquery("select sleep(1)")
    res = multi.perform

    p "Look ma, no callbacks, and parallel MySQL requests!"
    p res

    EventMachine.stop
end

require "em-synchrony/em-http"
EventMachine.synchrony do
    multi = EventMachine::Synchrony::Multi.new
    multi.add :a, EventMachine::HttpRequest.new("http://www.postrank.com").aget
    multi.add :b, EventMachine::HttpRequest.new("http://www.postrank.com").apost
    res = multi.perform

    p "Look ma, no callbacks, and parallel HTTP requests!"
    p res

    EventMachine.stop
end

(The MIT License)

Copyright (c) 2010 Ilya Grigorik

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.