From: Michael Granger <ged@...>
Date: 2003-07-23T22:24:42+09:00
Subject: [ANN] IO-Reactor 0.04

Hi fellow Rubyists,

I'd like to announce version 0.04 of the 'IO-Reactor' module, which 
used to be called 'Ruby-Poll', and used to wrap the poll(2) system 
call. It no longer does so, for two reasons:

   * poll() is not very portable
   * poll() doesn't work with Ruby's threads (ie., a blocking call to 
poll() blocks all threads).

Since I find that the API simplifies some IO tasks, and is (I think) a 
more Ruby-ish IO idiom, I've rewritten the backend using IO::select, 
while keeping (mostly) the same interface. The last version of the 
'Ruby-Poll' module will continue to be available for the foreseeable 
future, but will no longer be actively maintained.

So, what's IO-Reactor?

It's an implementation of an asynchronous multiplexed IO Reactor class 
which is based on the Reactor design pattern found in _Pattern-Oriented 
Software Architecture, Volume 2: Patterns for Concurrent and Networked 
Objects_. It allows a single thread to demultiplex and dispatch events 
from one or more IO objects to the appropriate handler. In other words, 
you can take a collection of IO objects, register them all with the 
reactor with handlers for read, write, and error events, and then drive 
IO in your application all with one call.

A simple example:

   require 'io/reactor'
   require 'socket'

   reactorobj = IO::Reactor::new

   # Open a listening socket on port 1138 and register it with the
   # reactor. When a :read event occurs on it, it means an incoming
   # connection has been established
   sock = TCPServer::new('localhost', 1138)
   reactorobj.register( sock, :read ) {|sock,event|
       case event

       # Accept the incoming connection, registering it also with
       # the reactor; events on client sockets are handled by the
       # #clientHandler method (not shown).
       when :read
           clsock = sock.accept
           reactorobj.register( clsock, :read, :write,
               &method(:clientHandler) )

       # Errors on the main listening socket cause the whole
       # reactor to be shut down
       when :error
           reactorobj.clear
           $stderr.puts "Server error: Shutting down"

       else
           $stderr.puts "Unhandled event: #{event}"
       end
   }

   # Drive the reactor until it's empty with a single thread
   Thread::new { reactorobj.poll until reactorobj.empty? }

The module can be downloaded from its project page at:

   http://www.deveiate.org/code/IO-Reactor.shtml

The API documentation can be viewed at:

   http://www.deveiate.org/code/IO-Reactor/

Comments, bug reports, and feedback are welcomed.

Thanks for your time,
--
Michael Granger <ged@FaerieMUD.org>
Rubymage, Believer, Architect
The FaerieMUD Consortium <http://www.FaerieMUD.org/>