Synchronized publisher in PHP

Table of Contents

<?php
/*
* Synchronized publisher
*
* @author Ian Barber <ian(dot)barber(at)gmail(dot)com>
*/

// We wait for 10 subscribers
define("SUBSCRIBERS_EXPECTED", 10);

$context = new ZMQContext();

// Socket to talk to clients
$publisher = new ZMQSocket($context, ZMQ::SOCKET_PUB);
$publisher->bind("tcp://*:5561");

// Socket to receive signals
$syncservice = new ZMQSocket($context, ZMQ::SOCKET_REP);
$syncservice->bind("tcp://*:5562");

// Get synchronization from subscribers
$subscribers = 0;
while ($subscribers < SUBSCRIBERS_EXPECTED) {
// - wait for synchronization request
$string = $syncservice->recv();
// - send synchronization reply
$syncservice->send("");
$subscribers++;
}

// Now broadcast exactly 1M updates followed by END
for ($update_nbr = 0; $update_nbr < 1000000; $update_nbr++) {
$publisher->send("Rhubarb");
}

$publisher->send("END");

sleep (1); // Give 0MQ/2.0.x time to flush output