Module: RemoteSignaller

^Module RemoteSignaller

In:	util/remotesignaller.rb

RemoteSignaller mixin

Signal process(es) when some event happens.

Advantages:

Simple concept.
Simple implementation.
Like an observer except no data is passed, just the occurrence of the event itself.

Disadvantages:

Signaller process has to define the event and set up the signal. (You could use XMLRPC to set up the signal.)
Terminology reversed from Observer/Observable. In this case, the "Observable" is the "RemoteSignaller".

Example use:

Let one process know another (non-child process) has terminated.

Methods

add_signalled count_signalled del_all_signalled del_signalled signal_waiting

Public Instance methods

add_signalled(sig, pid)

Add a process to be signalled.

sig: signal to be sent
pid: pid of process to be signalled

# File util/remotesignaller.rb, line 61
def add_signalled(sig, pid)
  @observers = Hash.new unless defined? @observers
  @observers[pid] = sig
end

signal_waiting(signum = "ALL")

Send signal to all waiting processes.

signum: Signal processes waiting on this signal, or all waiting processes if signum is "ALL". signum is a string naming the signal desired, or the string "ALL".
Returns:: Array of processes which could not be signalled.

# File util/remotesignaller.rb, line 74
def signal_waiting(signum = "ALL")
  dead = []
  if defined? @observers
    @observers.each_pair {
      |pid, sig|
      if signum == "ALL" || signum == sig
	begin
	  Process.kill(sig, pid)
	rescue
	  dead << pid
	end
      end
    }
  end
  dead
end

del_signalled(pid)

Delete a waiting process.

pid: Delete process with pid == pid.

# File util/remotesignaller.rb, line 94
def del_signalled(pid)
  @observers.delete(pid) if defined? @observers
end

del_all_signalled(signum = "ALL")

Delete all waiting processes.

signum: Delete processes waiting on this signal, or all waiting processes if signum is "ALL". signum is a string naming the signal desired, or the string "ALL".

# File util/remotesignaller.rb, line 104
def del_all_signalled(signum = "ALL")
  if defined? @observers
    @observers.delete_if { 
      |pid, sig|
      signum == "ALL" || signum == sig
    }
  end
end

count_signalled(signum = "ALL")

Count processes waiting on signals.

signum: Count processes waiting on this signal, or all waiting processes if signum is "ALL". signum is a string naming the signal desired, or the string "ALL".

# File util/remotesignaller.rb, line 119
def count_signalled(signum = "ALL")
  if defined? @observers
    @observers.find_all { 
      |pid, sig|
      signum == "ALL" || signum == sig
    }.size
  else
    0
  end
end