[ANN] celluloid 0.5.0: easy-to-use concurrent objects for Ruby

ruby-talk
1

Celluloid provides a simple and natural way to build fault-tolerant
concurrent programs in Ruby. With Celluloid, you can build systems out
of concurrent objects just as easily as you build sequential programs
out of regular objects. Recommended for any developer, including
novices, Celluloid should help ease your worries about building
multithreaded Ruby programs.

- RDoc: http://celluloid.github.com/
- Github: http://github.com/tarcieri/celluloid

Celluloid wraps objects in threads, allowing them to run concurrently,
while still letting you talk to them using standard Ruby method call
conventions. It also enables asynchronous method calls which tell a
method to do something in the background, and futures, which let you
request a method be executed then check back later for the result.

My blog has more information on Celluloid:


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Version 0.5.0 includes some awesome new features as well some
performance improvements refactoring of the internals. Celluloid now
uses a simple thread pool to improve the performance of short-lived
actors.

This release introduces a backwards incompatible change in Celluloid's
API. Previous releases of Celluloid let you define actors by including
Celluloid::Actor directly. This is no longer supported. Please define
actors using "include Celluloid":

    class MyActor
      include Celluloid
      ...
    end

Please define actors as bove. Using "include Celluloid::Actor" will
now cause errors.

Version 0.5.0 also introduces Celluloid::IO, which allows you to
define actors which make blocking I/O operations but still process
messages in the meantime. Celluloid::IO is an alternative
implementation of actors designed to allow them to multiplex both
incoming messages an IO objects.

To wait on an IO object to become readable or writeable, use the
Celluloid::IO#wait_readable and #wait_writeable methods respectively.
These methods will still allow the actor to respond to messages in the
meantime.

The following class shows the usage of wait_readable and now ships
with Celluloid as Celluloid::TCPServer:

    class TCPServer
      include Celluloid::IO

      # Bind a TCP server to the given host and port
      def initialize(host, port)
        @server = ::TCPServer.new host, port
        run!
      end

      # Run the TCP server event loop
      def run
        while true
          wait_readable(@server) { on_connect @server.accept }
        end
      end

      # Terminate this server
      def terminate
        @server.close
        super
      end

      # Called whenever a new connection is opened
      def on_connect(connection)
        connection.close
      end
    end

--

Full changelog follows:

* "include Celluloid::Actor" no longer supported. Use "include Celluloid"
* New Celluloid::IO module for actors that multiplex IO operations
* Major overhaul of Celluloid::Actor internals (see 25e22cc1)
* Actor threads are pooled in Celluloid::Actor::Pool, improving the
speed of creating short-lived actors by over 2X
* Classes that include Celluloid now have a #current_actor instance method
* Celluloid#async allows actors to make indefinitely blocking calls
while still responding to messages
* Fix a potential thread safety bug in Thread#mailbox
* Experimental Celluloid::TCPServer for people wanting to write
servers in Celluloid. This may wind up in another gem, so use at your
own risk!
* Magically skip ahead a few version numbers to impart the magnitude
of this release. It's my versioning scheme and I can do what I wanna.

--
Tony Arcieri