SYNOPSIS

  the Slave class forks a process and starts a drb server in the child using
  any object as the server.  the process is detached so it is not required
  (nor possible) to wait on the child pid.  a Heartbeat is set up between the
  parent and child processes so that the child will exit of the parent exits
  for any reason - preventing orphaned slaves from running indefinitely.  the
  purpose of Slaves is to be able to easily set up a collection of objects
  communicating via drb protocols instead of having to use IPC. 

  typical usage:

    slave = Slave::new{ AnyObject.new }

    slave.object                  #=> handle on drb object
    slave.uri                     #=> uri of the drb object
    slave.socket                  #=> unix domain socket path for drb object
    slave.psname                  #=> title shown in ps/top

    object = slave.object

    value = object.any_method     #=> use the object normally 

  slaves may be configured via the environment, the Slave class, or via the
  ctor for object itself.  attributes which may be configured include

    * object : specify the slave object.  otherwise block value is used.
    * socket_creation_attempts : specify how many attempts to create a unix domain socket will be made 
    * debug : turn on some logging to STDERR
    * psname : specify the name that will appear in 'top' ($0)
    * at_exit : specify a lambda to be called in the *parent* when the child dies
    * dumped : specify that the slave object should *not* be DRbUndumped (default is DRbUndumped) 
    * threadsafe : wrap the slave object with ThreadSafe to implement gross thread safety 

URIS

  http://rubyforge.org/projects/codeforpeople/
  http://codeforpeople.com/lib/ruby/slave

HISTORY

  1.2.0:
    - cleaned up a bunch of warnings.  thanks eric kolve <ekolve@gmail.com>
      for reporting them.

  1.1.0:
    - replaced HeartBeat class with LifeLine.

    - __HUGE__ cleanup of file descriptor/fork management with tons of help
      from skaar and ezra.  thanks guys!

    - introduced Slave.object method used to return any object directory from
      a child process.  see samples/g.rb.

    - indroduced keyword to automatically make slave objects threadsafe.
      remember that your slave object must be threadsafe because they are
      being server via DRb!!!


  1.0.0:
    - THIS RELEASE IS !! NOT !! BACKWARD COMPATIBLE.  NOTE NEW CTOR SYNTAX.

    - detach method also sets up at_exit handler.  extra protection from
      zombies.

    - ezra zygmuntowicz asked for a feature whereby a parent could be notified
      when a child exited.  obviously such a mechanism should be both async
      and sync.  to accomplish this the wait method was extended to support a
      callback with is either sync or async

        slave = Server.new{ Server.new }

        slave.wait and puts 'this is sync!'

        slave.wait(:non_block=>true){ 'this is async!' }
   
    - patch to getval from skaar<skaar@waste.org>.  the impl dropped opts
      delgating to the class method from the instance one.

  0.2.0:
    incorporated joel vanderWerf's patch such that, if no object is passed the
    block is used to create one ONLY in the child.  this avoids having a copy
    in both parent and child is that needs to be avoided due to, for instance,
    resource consumption.


  0.0.1:
    - patch from Logan Capaldo adds block form to slave new, block is run in the
      child

    - added a few more samples/*

    - added Slave#wait

    - added status information to slaves

    - added close-on-exec flag to pipes in parent process

  0.0.0:
    - initial version

SAMPLES

@samples