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:

    obj = AnyClass::new

    slave = Slave::new obj 

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

  other usage: 

  set the pulse_rate used for the Heartbeat

    slave = Slave::new MyClass::new, 'pulse_rate' => 10

  same

    Slave::pulse_rate = 10
    slave = Slave::new MyClass::new

  same

    ENV['SLAVE_PULSE_RATE'] = 10
    slave = Slave::new MyClass::new

  to avoid having a copy of the object in both the parent and child use the
  block form

    slave = Slave::new{ Server::new }  # copy only in child!
    server = slave.object

  if both an object AND a block are passed the object is passed to the block
  in the child process

    slave = Slave::new(Server::new){|server| p 'in child!' }

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

    * socket_creation_attempts
    * pulse_rate 
    * psname
    * debug 

HISTORY

  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