lpclient2.c

//  Lazy Pirate client
//  Use zmq_poll to do a safe request-reply
//  To run, start lpserver and then randomly kill/restart it
//  Modified by Laurent Alebarde 2013-06-06

#include "czmq.h"
#define REQUEST_TIMEOUT     2500    //  msecs, (> 1000!)
#define REQUEST_RETRIES     3       //  Before we abandon
#define SERVER_ENDPOINT     "tcp://localhost:5555"

int main (void)
{
    zctx_t *ctx = zctx_new ();
    printf ("I: connecting to server...\n");
    void *client = zsocket_new (ctx, ZMQ_REQ);
    assert (client);
    zsocket_connect (client, SERVER_ENDPOINT);

    int sequence = 0;
    int retries_left = REQUEST_RETRIES;
    bool is_interrupted = zctx_interrupted; // [email protected] 2013-06-06 R1
    while (retries_left && !is_interrupted) { // [email protected] 2013-06-06 R1
        //  We send a request, then we work to get a reply
        char request [10];
        sprintf (request, "%d", ++sequence);
        zstr_send (client, request);

        int expect_reply = 1;
        while (expect_reply) {
            //  Poll socket for a reply, with timeout
            zmq_pollitem_t items [] = { { client, 0, ZMQ_POLLIN, 0 } };
            int rc = zmq_poll (items, 1, REQUEST_TIMEOUT * ZMQ_POLL_MSEC);
            if (rc == -1) {
                is_interrupted = zctx_interrupted;  // [email protected] 2013-06-06 R1
        break;        //  Interrupted
        }

            //  .split process server reply
            //  Here we process a server reply and exit our loop if the
            //  reply is valid. If we didn't a reply we close the client
            //  socket and resend the request. We try a number of times
            //  before finally abandoning:

            if (items [0].revents & ZMQ_POLLIN) {
                //  We got a reply from the server, must match sequence
                char *reply = zstr_recv (client);
                if (!reply) {
            is_interrupted = zctx_interrupted; // [email protected] 2013-06-06 R1
                    break;      //  Interrupted
        }
                if (atoi (reply) == sequence) {
                    printf ("I: server replied OK (%s)\n", reply);
                    retries_left = REQUEST_RETRIES;
                    expect_reply = 0;
                }
               else
                    printf ("E: malformed reply from server: %s\n",
                        reply);

                free (reply);
        }
            else
        if (rc >= 1) {  // [email protected] 2013-06-06 R2
                printf ("E: malformed reply from server\n");
        break; // retry without destroying/rebuilding the socket  // [email protected] 2013-06-06 R3
            }
            else
            if (--retries_left == 0) {
                printf ("E: server seems to be offline, abandoning\n");
                break;
            }
            else {
                printf ("W: no response from server, retrying...\n");
                //  Old socket is confused; close it and open a new one
                zsocket_destroy (ctx, client);
                printf ("I: reconnecting to server...\n");
                client = zsocket_new (ctx, ZMQ_REQ);
                zsocket_connect (client, SERVER_ENDPOINT);
                //  Send request again, on new socket
                zstr_send (client, request);
            }
        }
    is_interrupted = zctx_interrupted;  // [email protected] 2013-06-06 R1
    }
    zsocket_destroy (ctx, client);  // [email protected] 2013-06-06 R1
    zctx_destroy (&ctx);
    return 0;
}