Hi Matias,
> I am starting to evaluate zeromq, and I found interesting to test the
> 2.0 version
> (even if it is still in alpha state ?). From the web page, it seems the
> 2.0 version
> is much better than the actual stable release.
It solves couple of problems and inconveniences we've encountered with
version 1.0; also the interface is more familiar as it is based on POSIX
sockets, however, the code is still alpha, i.e. it haven't been
massively tested etc.
> I wanted to write a dummy client and a dummy server, just peer-to-peer. I am
> programing on a Linux box. I would like to get your inputs on how to
> improve the
> following code and I would like to know why I manage to get seg faults :
>
> /* server code */
> #include <zmq.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
>
> void no_deallocation(void* ignored) {};
>
> int main(char** argv) {
> void *ctx;
> void *s;
> zmq_msg_t *msg;
> ctx = zmq_init(1,1,0);
> s = zmq_socket(ctx, ZMQ_PUB);
> zmq_bind(s, "tcp://127.0.0.1:5555");
> zmq_msg_init_size(msg, 512);
>
> char string[512];
> while (1) {
> printf("Please type message to send (empty=exit) : ");
> gets(string);
> if (string[0]=='\0') {
> zmq_term(ctx);
> return(0);
> }
> int msg_len = strlen(string);
> printf(" ... sending %d bytes message\n", msg_len);
> zmq_msg_init_data(msg, string, msg_len, no_deallocation);
> printf(" - %d\n", zmq_send(s, msg, 0));
> }
> }
>
> /* client code */
> #include <zmq.h>
> #include <stdio.h>
> #include <signal.h>
>
> static int should_exit;
>
> void no_deallocation(void* ignored) {};
>
> void signal_handler(int signum) {
> switch (signum) {
> case SIGINT:
> should_exit=1;
> break;
> default:
> break;
> }
> }
>
> int main(char** argv) {
> should_exit = 0;
>
> struct sigaction a;
> a.sa_handler = signal_handler;
> sigemptyset(&a.sa_mask);
> sigaction(SIGINT, &a, NULL);
>
> void *ctx;
> void *s;
> zmq_msg_t msg;
>
> ctx = zmq_init(1,1,0);
> s = zmq_socket(ctx, ZMQ_SUB);
>
> printf("Connecting to 127.0.0.1:5555\n");
> zmq_connect(s, "tcp://127.0.0.1:5555");
>
> printf("Subscribing to receive any kind of message\n");
> zmq_setsockopt(s, ZMQ_SUBSCRIBE, "*", 1);
>
> while (! should_exit) {
> zmq_msg_init(&msg);
> if (zmq_recv(s, &msg, ZMQ_NOBLOCK) < 0) continue;
> printf("Received: %s\n", zmq_msg_data(&msg));
> }
> printf("Goodbye.\n");
> zmq_term(ctx);
> }
>
> The seg fault occur when : 1) I start the server program, 2) I start
> the client program, 3) I send some messages from server to client,
> 4) I close the client, 5) I restart the client, 6) I send another message =>
> crash.
Ok, reproduced. It's a bug. I'll have a look at it tomorrow.
>
> What am I missing ? I thought that reconnections etc. should
> all be handled by the library.
>
> Another thing : currently the receiver program is killing my CPU because
> of the while loop. I wanted to use polling instead (with the right context
> initialization with the ZMQ_POLL flag and the appropriate call to zmq_poll),
> but I couldn't because "zmq_pollitem_t" is undefined in zmq.h...
Hm, looking at zmq.h:
typedef struct
{
void *socket;
int fd;
short events;
short revents;
} zmq_pollitem_t;
Any idea why it's undefined on your box? What's the actual error message?
Martin