Added commandline option '-p <timeout>' to enable polling on the writing socket.

Inspired by Marc Kleine-Budde :-)

diff --git a/cangen.c b/cangen.c
index fd9e9a5a3cadcb5cae6916090c131b4334c8409a..df6b77f60d594a07af5f259f93dc1634f78b681f 100644 (file)
--- a/cangen.c
+++ b/cangen.c
@@ -51,6 +51,7 @@
 #include <unistd.h>
 #include <string.h>
 #include <signal.h>
+#include <poll.h>
 #include <ctype.h>
 #include <libgen.h>
 #include <time.h>
@@ -92,6 +93,8 @@ void print_usage(char *prg)
                " generation mode - see below)\n");
        fprintf(stderr, "         -D <mode>     (CAN data (payload)"
                " generation mode - see below)\n");
+       fprintf(stderr, "         -p <timeout>  (poll on -ENOBUFS to write frames"
+               " with <timeout> ms)\n");
        fprintf(stderr, "         -i            (ignore -ENOBUFS return values on"
                " write() syscalls)\n");
        fprintf(stderr, "         -x            (disable local loopback of "
@@ -114,6 +117,8 @@ void print_usage(char *prg)
        fprintf(stderr, "(fixed CAN data payload and length)\n");
        fprintf(stderr, "%s vcan0 -g 0 -i -x                    ", prg);
        fprintf(stderr, "(full load test ignoring -ENOBUFS)\n");
+       fprintf(stderr, "%s vcan0 -g 0 -p 10 -x                 ", prg);
+       fprintf(stderr, "(full load test with polling, 10ms timeout)\n");
        fprintf(stderr, "%s vcan0                               ", prg);
        fprintf(stderr, "(my favourite default :)\n\n");
 }
@@ -126,6 +131,7 @@ void sigterm(int signo)
 int main(int argc, char **argv)
 {
        unsigned long gap = DEFAULT_GAP; 
+       unsigned long polltimeout = 0;
        unsigned char ignore_enobufs = 0;
        unsigned char extended = 0;
        unsigned char id_mode = MODE_RANDOM;
@@ -137,6 +143,7 @@ int main(int argc, char **argv)
 
        int opt;
        int s; /* socket */
+       struct pollfd fds;
 
        struct sockaddr_can addr;
        static struct can_frame frame;
@@ -150,7 +157,7 @@ int main(int argc, char **argv)
        signal(SIGHUP, sigterm);
        signal(SIGINT, sigterm);
 
-       while ((opt = getopt(argc, argv, "ig:eI:L:D:xvh?")) != -1) {
+       while ((opt = getopt(argc, argv, "ig:eI:L:D:xp:vh?")) != -1) {
                switch (opt) {
 
                case 'i':
@@ -209,6 +216,10 @@ int main(int argc, char **argv)
                        loopback_disable = 1;
                        break;
 
+               case 'p':
+                       polltimeout = strtoul(optarg, NULL, 10);
+                       break;
+
                case '?':
                case 'h':
                default:
@@ -284,6 +295,11 @@ int main(int argc, char **argv)
                return 1;
        }
 
+       if (polltimeout) {
+               fds.fd = s;
+               fds.events = POLLOUT;
+       }
+
        while (running) {
 
                if (id_mode == MODE_RANDOM) {
@@ -331,11 +347,18 @@ int main(int argc, char **argv)
                                perror("write");
                                return 1;
                        }
-                       if (!ignore_enobufs) {
+                       if (!ignore_enobufs && !polltimeout) {
                                perror("write");
                                return 1;
                        }
-                       enobufs_count++;
+                       if (polltimeout) {
+                               /* wait for the write socket (with timeout) */
+                               if (poll(&fds, 1, polltimeout) < 0) {
+                                       perror("poll");
+                                       return 1;
+                               }
+                       } else
+                               enobufs_count++;
 
                } else if (nbytes < sizeof(struct can_frame)) {
                        fprintf(stderr, "write: incomplete CAN frame\n");