int main (void)
{
zctx_t *ctx = zctx_new ();
void *frontend = zsocket_new (ctx, ZMQ_ROUTER);
void *backend = zsocket_new (ctx, ZMQ_ROUTER);
zsocket_bind (frontend, "tcp://*:5555"); // For clients
zsocket_bind (backend, "tcp://*:5556"); // For workers
// List of available workers
zlist_t *workers = zlist_new ();
// Send out heartbeats at regular intervals
uint64_t heartbeat_at = zclock_time () + HEARTBEAT_INTERVAL;
while (1) {
zmq_pollitem_t items [] = {
{ backend, 0, ZMQ_POLLIN, 0 },
{ frontend, 0, ZMQ_POLLIN, 0 }
};
// Poll frontend only if we have available workers
int rc = zmq_poll (items, zlist_size (workers)? 2: 1,
HEARTBEAT_INTERVAL * ZMQ_POLL_MSEC);
if (rc == -1)
break; // Interrupted
// Handle worker activity on backend
if (items [0].revents & ZMQ_POLLIN) {
// Use worker address for LRU routing
zmsg_t *msg = zmsg_recv (backend);
if (!msg)
break; // Interrupted
// Any sign of life from worker means it's ready
zframe_t *address = zmsg_unwrap (msg);
worker_t *worker = s_worker_new (address);
s_worker_ready (worker, workers);
// Validate control message, or return reply to client
if (zmsg_size (msg) == 1) {
zframe_t *frame = zmsg_first (msg);
if (memcmp (zframe_data (frame), PPP_READY, 1)
&& memcmp (zframe_data (frame), PPP_HEARTBEAT, 1)) {
printf ("E: invalid message from worker");
zmsg_dump (msg);
}
zmsg_destroy (&msg);
}
else
zmsg_send (&msg, frontend);
}
if (items [1].revents & ZMQ_POLLIN) {
// Now get next client request, route to next worker
zmsg_t *msg = zmsg_recv (frontend);
if (!msg)
break; // Interrupted
zmsg_push (msg, s_workers_next (workers));
zmsg_send (&msg, backend);
}
// .split handle heartbeating
// We handle heartbeating after any socket activity. First we send
// heartbeats to any idle workers if it's time. Then we purge any
// dead workers:
if (zclock_time () >= heartbeat_at) {
worker_t *worker = (worker_t *) zlist_first (workers);
while (worker) {
zframe_send (&worker->address, backend,
ZFRAME_REUSE + ZFRAME_MORE);
zframe_t *frame = zframe_new (PPP_HEARTBEAT, 1);
zframe_send (&frame, backend, 0);
worker = (worker_t *) zlist_next (workers);
}
heartbeat_at = zclock_time () + HEARTBEAT_INTERVAL;
}
s_workers_purge (workers);
}
// When we're done, clean up properly
while (zlist_size (workers)) {
worker_t *worker = (worker_t *) zlist_pop (workers);
s_worker_destroy (&worker);
}
zlist_destroy (&workers);
zctx_destroy (&ctx);
return 0;
}
int main(void)
{
zctx_t *ctx = zctx_new();
void *frontend = zsocket_new(ctx, ZMQ_ROUTER);
void *backend = zsocket_new(ctx, ZMQ_ROUTER);
zsocket_bind(frontend, "tcp://127.0.0.1:5555");
zsocket_bind(backend, "tcp://127.0.0.1:5556");
zlist_t *workers = zlist_new();
uint64_t heartbeat_at = zclock_time() + HEARTBEAT_INTERVAL;
while (true){
zmq_pollitem_t items [] ={
{backend, 0, ZMQ_POLLIN, 0},
{frontend, 0, ZMQ_POLLIN, 0}
};
int rc = zmq_poll(items, zlist_size(worker)?2:1);
if (rc == -1)
break;
if (items[0].revents & ZMQ_POLLIN){
zmsg_t *msg = zmsg_recv(backend);
if (!msg)
break;
zframe_t *identity = zmsg_unwrap(msg);
worker_t *worker = s_worker_new(identity);
s_worker_ready(worker, workers);
if (zmsg_size(msg) == 1){
zframe_t *frame = zmsg_first(msg);
if (memcmp(zframe_data(frame), PPP_READY, 1) && memcmp(zframe_data(frame), PPP_HEARTBEAT, 1)){
printf("E: invalid message from worker");
zmsg_dump(msg);
}
zmsg_destroy(&msg);
}
else
zmsg_send(&msg, frontend);
}
if (items[1].revents & ZMQ_POLLIN){
zmsg_t *msg = zmsg_recv(frontend);
if (!msg)
break;
zframe_t *identity = s_workers_next(workers);
zmsg_prepend(msg, &identity);
zmsg_send(&msg, backend);
}
if (zclock_time() >= heartbeat_at){
worker_t *worker = (worker_t *)zlist_first(workers);
while (worker){
zframe_send(&worker->identity, backend, ZFRAME_REUSE + ZFRAME_MORE);
zframe_t *frame = zframe_new(PPP_HEARTBEAT, 1);
zframe_send(&frame, backend, 0);
worker = (worker_t *)zlist_next(workers);
}
heartbeat_at = zclock_time() + HEARTBEAT_INTERVAL;
}
s_workers_purge(workers);
}
while (zlist_size(workers)){
worker_t *worker = (worker_t *)zlist_pop(workers);
s_worker_destroy(&worker);
}
zlist_destroy(&workers);
zctx_destroy(&ctx);
return 0;
}
