function worker_thread()
{
$context = new ZMQContext();
$worker = $context->getSocket(ZMQ::SOCKET_REQ);
$worker->connect("ipc://backend.ipc");
// Tell broker we're ready for work
$worker->send("READY");
while (true) {
$zmsg = new Zmsg($worker);
$zmsg->recv();
// Additional logic to clean up workers.
if ($zmsg->address() == "END") {
exit;
}
printf("Worker: %s\n", $zmsg->body());
$zmsg->body_set("OK");
$zmsg->send();
}
}
$poll = new ZMQPoll();
$poll->add($backend, ZMQ::POLL_IN);
// Poll frontend only if we have available workers
if ($available_workers) {
$poll->add($frontend, ZMQ::POLL_IN);
}
$events = $poll->poll($read, $write);
foreach ($read as $socket) {
$zmsg = new Zmsg($socket);
$zmsg->recv();
// Handle worker activity on backend
if ($socket === $backend) {
// Use worker address for LRU routing
assert($available_workers < MAX_WORKERS);
array_push($worker_queue, $zmsg->unwrap());
$available_workers++;
// Return reply to client if it's not a READY
if ($zmsg->address() != "READY") {
$zmsg->set_socket($frontend)->send();
}
} elseif ($socket === $frontend) {
// Now get next client request, route to next worker
// REQ socket in worker needs an envelope delimiter
// Dequeue and drop the next worker address
$zmsg->wrap(array_shift($worker_queue), "");
$zmsg->set_socket($backend)->send();
$available_workers--;
}
}
// We never exit the main loop
}
// Poll frontend only if we have available workers
if ($queue->size()) {
$poll->add($frontend, ZMQ::POLL_IN);
}
$events = $poll->poll($read, $write, HEARTBEAT_INTERVAL * 1000 * 1000);
// microseconds
if ($events > 0) {
foreach ($read as $socket) {
$zmsg = new Zmsg($socket);
$zmsg->recv();
// Handle worker activity on backend
if ($socket === $backend) {
$identity = $zmsg->unwrap();
// Return reply to client if it's not a control message
if ($zmsg->parts() == 1) {
if ($zmsg->address() == "READY") {
$queue->s_worker_delete($identity);
$queue->s_worker_append($identity);
} else {
if ($zmsg->address() == 'HEARTBEAT') {
$queue->s_worker_refresh($identity);
} else {
printf("E: invalid message from %s%s%s", $identity, PHP_EOL, $zmsg->__toString());
}
}
} else {
$zmsg->set_socket($frontend)->send();
$queue->s_worker_append($identity);
}
} else {
// Now get next client request, route to next worker
// If we have no workers anyhow, wait indefinitely
try {
$events = $poll->poll($readable, $writeable, $capacity ? 1000000 : -1);
} catch (ZMQPollException $e) {
break;
}
if ($events > 0) {
foreach ($readable as $socket) {
$zmsg = new Zmsg($socket);
// Handle reply from local worker
if ($socket === $localbe) {
$zmsg->recv();
// Use worker address for LRU routing
$worker_queue[] = $zmsg->unwrap();
$capacity++;
if ($zmsg->address() == "READY") {
continue;
}
} else {
if ($socket === $cloudbe) {
// We don't use peer broker address for anything
$zmsg->recv()->unwrap();
}
}
// Route reply to cloud if it's addressed to a broker
for ($argn = 2; $argn < $_SERVER['argc']; $argn++) {
if ($zmsg->address() == $_SERVER['argv'][$argn]) {
$zmsg->set_socket($cloudfe)->send();
$zmsg = null;
}
}
