Clone server, Model Four in C

//
// Clone server Model Four
//

// Lets us build this source without creating a library
#include "kvsimple.c"

static int s_send_single (char *key, void *data, void *args);

// Routing information for a key-value snapshot
typedef struct {
void *socket; // ROUTER socket to send to
zframe_t *identity; // Identity of peer who requested state
char *subtree; // Client subtree specification
} kvroute_t;

int main (void)
{
// Prepare our context and sockets
zctx_t *ctx = zctx_new ();
void *snapshot = zsocket_new (ctx, ZMQ_ROUTER);
zsocket_bind (snapshot, "tcp://*:5556");
void *publisher = zsocket_new (ctx, ZMQ_PUB);
zsocket_bind (publisher, "tcp://*:5557");
void *collector = zsocket_new (ctx, ZMQ_PULL);
zsocket_bind (collector, "tcp://*:5558");

int64_t sequence = 0;
zhash_t *kvmap = zhash_new ();

zmq_pollitem_t items [] = {
{ collector, 0, ZMQ_POLLIN, 0 },
{ snapshot, 0, ZMQ_POLLIN, 0 }
};
while (!zctx_interrupted) {
int rc = zmq_poll (items, 2, 1000 * ZMQ_POLL_MSEC);

// Apply state update sent from client
if (items [0].revents & ZMQ_POLLIN) {
kvmsg_t *kvmsg = kvmsg_recv (collector);
if (!kvmsg)
break; // Interrupted
kvmsg_set_sequence (kvmsg, ++sequence);
kvmsg_send (kvmsg, publisher);
kvmsg_store (&kvmsg, kvmap);
printf ("I: publishing update %5d\n", (int) sequence);
}
// Execute state snapshot request
if (items [1].revents & ZMQ_POLLIN) {
zframe_t *identity = zframe_recv (snapshot);
if (!identity)
break; // Interrupted

// Request is in second frame of message
char *request = zstr_recv (snapshot);
char *subtree = NULL;
if (streq (request, "ICANHAZ?")) {
free (request);
subtree = zstr_recv (snapshot);
}
else {
printf ("E: bad request, aborting\n");
break;
}
// Send state snapshot to client
kvroute_t routing = { snapshot, identity, subtree };

// For each entry in kvmap, send kvmsg to client
zhash_foreach (kvmap, s_send_single, &routing);

// Now send END message with sequence number
printf ("I: sending shapshot=%d\n", (int) sequence);
zframe_send (&identity, snapshot, ZFRAME_MORE);
kvmsg_t *kvmsg = kvmsg_new (sequence);
kvmsg_set_key (kvmsg, "KTHXBAI");
kvmsg_set_body (kvmsg, (byte *) subtree, 0);
kvmsg_send (kvmsg, snapshot);
kvmsg_destroy (&kvmsg);
free (subtree);
}
}
printf (" Interrupted\n%d messages handled\n", (int) sequence);
zhash_destroy (&kvmap);
zctx_destroy (&ctx);

return 0;
}

// Send one state snapshot key-value pair to a socket
// Hash item data is our kvmsg object, ready to send

static int
s_send_single (char *key, void *data, void *args)
{
kvroute_t *kvroute = (kvroute_t *) args;
kvmsg_t *kvmsg = (kvmsg_t *) data;
if (strlen (kvroute->subtree) <= strlen (kvmsg_key (kvmsg))
&& memcmp (kvroute->subtree,
kvmsg_key (kvmsg), strlen (kvroute->subtree)) == 0) {
// Send identity of recipient first
zframe_send (&kvroute->identity,
kvroute->socket, ZFRAME_MORE + ZFRAME_REUSE);
kvmsg_send (kvmsg, kvroute->socket);
}
return 0;
}