IPC and counters

[Simon Wistow]

On Wed, Oct 15, 2008 at 12:08:43AM +0100, me said:
Tell a lie, what I want is

     Parent:
 
     my $id  = $message->id;
     my $n   = scalar(@children);
     my $sem = IPC::Semaphore->new(IPC_PRIVATE, 2, IPC_CREAT);
     $sem->setall(1, $n-1);
     foreach my $child (@children) {
         $child->send($message, $sem->id);
     }
 
     Child:
 
     my ($msg, $sem_id)  = get_message();
     my $sem = IPC::Semaphore->new($sem_id);
     if (0 == $sem->op(0, -1, IPC_NOWAIT)) {
         do_something($message);
     }
 
     # If we're the last then clean up
     if (EAGAIN == $sem->op(1,-1, IPC_NOWAIT)) {
         $sem->remove;
     }