* prod.c - the program reads lines of text from the standard input
 * and sends them to the POSIX message queue, specified with
 * the first parameter. Optional second parameter can specify
 * the queue length (default: 1), and the third: sleep time before
 * each message was sent.
 * Example call:
 *  ./prod /mq 5
 */#include "mqcommon.h"

int main(int argc, char *argv[])
{
    char buf[25], *mq_name;
    int msgnr = 0, quelen = 0, timeout=0;
    mqd_t mqdes;
    struct mq_attr attr;

    if (argc < 2 || argc > 4)
        err_quit("usage: prod MQ_NAME [quelen [ timeout]]\n\n");
    mq_name = argv[1];
    if (argc > 2)
        quelen = atoi(argv[2]);
    if (quelen < 1)
        quelen = 1;
    if (argc > 3)
        timeout = atoi(argv[3]);
    //remove existing queue (we don't care if it succeeds)
    Mq_unlink(mq_name);
    attr.mq_maxmsg = quelen;    // queue length
    attr.mq_msgsize = sizeof(buf);  // message length
    // create the queue
    mqdes = Mq_open(mq_name, O_RDWR | O_CREAT, FILE_MODE, &attr);
    fprintf(stderr, "Message queue %s created, PID=%ld\n", mq_name,
        (long)getpid());
    Mq_getattr(mqdes, &attr);
    fprintf(stderr, "maxmsg=%ld, msgsize%ld, in queue: %ld\n",
        attr.mq_maxmsg, attr.mq_msgsize, attr.mq_curmsgs);
    while (fgets(buf, sizeof(buf), stdin)) {
        char *ptr;
        int pri = msgnr % 3;
        ptr = strchr(buf, '\n');
        if (ptr)
            *ptr = '\0';
        else
            buf[sizeof(buf) - 1] = '\0';
        if (timeout>0) sleep(timeout);
        if (Mq_send(mqdes, buf, strlen(buf) + 1, pri))
            break;
        msgnr++;
        printf("Prod: sent msg nr  %d, pri=%d\n", msgnr, pri);
    }
    // close the producer access to the queue
    Mq_close(mqdes);

    printf("Prod: exiting, msgnr=%d\n", msgnr);
    exit(0);
}
/* cons.c - the program reads messages from the POSIX message queue,
 * specified with the first parameter. Optional parameters can specify
 * - delay after reading a message (before an attempt to read again),
 * - timeout -i.e. the maximum waiting time for a meassage.
 * Example call:
 *  ./cons /mq 1 20
 */
#include "mqcommon.h"
#include <signal.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>
static struct sigaction sa;
void alrm(int sig)
{
    return;
}

int main(int argc, char *argv[])
{
    char buf[25], *mq_name;
    int msgnr = 0, sleep_time = 0, timeout = 0;
    mqd_t mqdes;
    struct mq_attr attr;
    struct timespec req_sleep_time, rem;
    unsigned int pri;

    if (argc < 2 || argc > 4)
        err_quit("usage: cons MQ_NAME [sleep_time [timeout]]\n\n");
    mq_name = argv[1];
    if (argc >= 3)
        sleep_time = atoi(argv[2]);
    req_sleep_time.tv_sec = sleep_time;
    req_sleep_time.tv_nsec = 0;
    if (argc >= 4)
        timeout = atoi(argv[3]);

    mqdes = Mq_open_short(mq_name);
    sa.sa_handler = alrm;
    sigaction(SIGALRM, &sa, NULL);
    Mq_getattr(mqdes, &attr);
    fprintf(stderr, "maxmsg=%ld, msgsize=%ld, in queue: %ld\n",
        attr.mq_maxmsg, attr.mq_msgsize, attr.mq_curmsgs);
    if (attr.mq_msgsize > sizeof(buf)) {
        fprintf(stderr, "Buffer is too short\n");
        exit(1);
    }
    while (1) {
        int ret;
        if (timeout > 0)
            alarm(timeout);
        if ((ret = Mq_receive(mqdes, buf, sizeof(buf), &pri)) < 0)
            break;
        alarm(0);
        msgnr++;
        printf("Cons: received msg nr %d, pri=%d, ret=%d\n", msgnr, pri,
               ret);
        buf[sizeof(buf) - 1] = '\0';
        puts(buf);  //write(1,buf,attr.mq_msgsize);
        if (sleep_time > 0) {
            while (nanosleep(&req_sleep_time, &rem) == -1
                   && errno == EINTR) {
                req_sleep_time.tv_sec = rem.tv_sec;
                req_sleep_time.tv_nsec = rem.tv_nsec;
            }
        }
    }

    Mq_close(mqdes);

    printf("Cons: exiting, msgnr=%d\n", msgnr);
    exit(0);
}