bufp-readwrite.c

/*
 * BUFP-based client/server demo, using the read(2)/write(2)
 * system calls to exchange data over a socket.
 *
 * In this example, two sockets are created.  A server thread (reader)
 * is bound to a real-time port and receives a stream of bytes sent to
 * this port from a client thread (writer).
 *
 * See Makefile in this directory for build directives.
 */
#include <sys/mman.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <string.h>
#include <pthread.h>
#include <errno.h>
#include <rtdk.h>
#include <rtdm/rtipc.h>

pthread_t svtid, cltid;

#define BUFP_SVPORT 12

static const char *msg[] = {
    "Surfing With The Alien",
    "Lords of Karma",
    "Banana Mango",
    "Psycho Monkey",
    "Luminous Flesh Giants",
    "Moroccan Sunset",
    "Satch Boogie",
    "Flying In A Blue Dream",
    "Ride",
    "Summer Song",
    "Speed Of Light",
    "Crystal Planet",
    "Raspberry Jam Delta-V",
    "Champagne?",
    "Clouds Race Across The Sky",
    "Engines Of Creation"
};

static void fail(const char *reason)
{
        perror(reason);
        exit(EXIT_FAILURE);
}

static void *server(void *arg)
{
        struct sockaddr_ipc saddr;
        char buf[128];
        size_t bufsz;
        int ret, s;

        s = socket(AF_RTIPC, SOCK_DGRAM, IPCPROTO_BUFP);
        if (s < 0)
                fail("socket");

        /*
         * Set a 16k buffer for the server endpoint. This
         * configuration must be done prior to binding the socket to a
         * port.
         */
        bufsz = 16384; /* bytes */
        ret = setsockopt(s, SOL_BUFP, BUFP_BUFSZ,
                         &bufsz, sizeof(bufsz));
        if (ret)
                fail("setsockopt");

        saddr.sipc_family = AF_RTIPC;
        saddr.sipc_port = BUFP_SVPORT;
        ret = bind(s, (struct sockaddr *)&saddr, sizeof(saddr));
        if (ret)
                fail("bind");

        for (;;) {
                ret = read(s, buf, sizeof(buf));
                if (ret < 0) {
                        close(s);
                        fail("read");
                }
                rt_printf("%s: received %d bytes, \"%.*s\"\n",
                          __FUNCTION__, ret, ret, buf);
        }

        return NULL;
}

static void *client(void *arg)
{
        struct sockaddr_ipc svsaddr;
        int ret, s, n = 0, len;
        struct timespec ts;

        s = socket(AF_RTIPC, SOCK_DGRAM, IPCPROTO_BUFP);
        if (s < 0)
                fail("socket");

        memset(&svsaddr, 0, sizeof(svsaddr));
        svsaddr.sipc_family = AF_RTIPC;
        svsaddr.sipc_port = BUFP_SVPORT;
        ret = connect(s, (struct sockaddr *)&svsaddr, sizeof(svsaddr));
        if (ret)
                fail("connect");

        for (;;) {
                len = strlen(msg[n]);
                ret = write(s, msg[n], len);
                if (ret < 0) {
                        close(s);
                        fail("write");
                }
                rt_printf("%s: sent %d bytes, \"%.*s\"\n",
                          __FUNCTION__, ret, ret, msg[n]);
                n = (n + 1) % (sizeof(msg) / sizeof(msg[0]));
                /*
                 * We run in full real-time mode (i.e. primary mode),
                 * so we have to let the system breathe between two
                 * iterations.
                 */
                ts.tv_sec = 0;
                ts.tv_nsec = 500000000; /* 500 ms */
                clock_nanosleep(CLOCK_REALTIME, 0, &ts, NULL);
        }

        return NULL;
}

static void cleanup_upon_sig(int sig)
{
        pthread_cancel(svtid);
        pthread_cancel(cltid);
        signal(sig, SIG_DFL);
        pthread_join(svtid, NULL);
        pthread_join(cltid, NULL);
}

int main(int argc, char **argv)
{
        struct sched_param svparam = {.sched_priority = 71 };
        struct sched_param clparam = {.sched_priority = 70 };
        pthread_attr_t svattr, clattr;
        sigset_t mask, oldmask;

        mlockall(MCL_CURRENT | MCL_FUTURE);

        sigemptyset(&mask);
        sigaddset(&mask, SIGINT);
        signal(SIGINT, cleanup_upon_sig);
        sigaddset(&mask, SIGTERM);
        signal(SIGTERM, cleanup_upon_sig);
        sigaddset(&mask, SIGHUP);
        signal(SIGHUP, cleanup_upon_sig);
        pthread_sigmask(SIG_BLOCK, &mask, &oldmask);

        /*
         * This is a real-time compatible printf() package from
         * Xenomai's RT Development Kit (RTDK), that does NOT cause
         * any transition to secondary mode.
         */
        rt_print_auto_init(1);

        pthread_attr_init(&svattr);
        pthread_attr_setdetachstate(&svattr, PTHREAD_CREATE_JOINABLE);
        pthread_attr_setinheritsched(&svattr, PTHREAD_EXPLICIT_SCHED);
        pthread_attr_setschedpolicy(&svattr, SCHED_FIFO);
        pthread_attr_setschedparam(&svattr, &svparam);

        errno = pthread_create(&svtid, &svattr, &server, NULL);
        if (errno)
                fail("pthread_create");

        pthread_attr_init(&clattr);
        pthread_attr_setdetachstate(&clattr, PTHREAD_CREATE_JOINABLE);
        pthread_attr_setinheritsched(&clattr, PTHREAD_EXPLICIT_SCHED);
        pthread_attr_setschedpolicy(&clattr, SCHED_FIFO);
        pthread_attr_setschedparam(&clattr, &clparam);

        errno = pthread_create(&cltid, &clattr, &client, NULL);
        if (errno)
                fail("pthread_create");

        sigsuspend(&oldmask);

        return 0;
}