lttng_ivc/apps/preload_provider/app.c

   1 /*
   2  * Copyright (C) - 2012 David Goulet <dgoulet@efficios.com>
   3  *
   4  * This library is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU Lesser General Public License as published by the
   6  * Free Software Foundation; version 2.1 of the License.
   7  *
   8  * This library is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
  11  * for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public License
  14  * along with this library; if not, write to the Free Software Foundation,
  15  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  16  */
  17
  18 #include <arpa/inet.h>
  19 #include <assert.h>
  20 #include <time.h>
  21 #include <errno.h>
  22 #include <fcntl.h>
  23 #include <poll.h>
  24 #include <signal.h>
  25 #include <stdarg.h>
  26 #include <stdbool.h>
  27 #include <stdint.h>
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <sys/mman.h>
  32 #include <sys/stat.h>
  33 #include <sys/types.h>
  34 #include <unistd.h>
  35
  36 #define TRACEPOINT_DEFINE
  37 #define TRACEPOINT_PROBE_DYNAMIC_LINKAGE
  38 #include "tp.h"
  39
  40 #define NSEC_PER_USEC 1000
  41 #define NSEC_PER_SEC 1000000000
  42
  43 static inline
  44 int64_t elapsed_time_ns(struct timespec *t1, struct timespec *t2)
  45 {
  46         struct timespec delta;
  47
  48         assert(t1 && t2);
  49         delta.tv_sec = t2->tv_sec - t1->tv_sec;
  50         delta.tv_nsec = t2->tv_nsec - t1->tv_nsec;
  51         return ((int64_t) NSEC_PER_SEC * (int64_t) delta.tv_sec) +
  52                         (int64_t) delta.tv_nsec;
  53 }
  54
  55 static inline
  56 int usleep_safe(useconds_t usec)
  57 {
  58         int ret = 0;
  59         struct timespec t1, t2;
  60         int64_t time_remaining_ns = (int64_t) usec * (int64_t) NSEC_PER_USEC;
  61
  62         ret = clock_gettime(CLOCK_MONOTONIC, &t1);
  63         if (ret) {
  64                 ret = -1;
  65                 perror("clock_gettime");
  66                 goto end;
  67         }
  68
  69         while (time_remaining_ns > 0) {
  70                 ret = usleep(time_remaining_ns / (int64_t) NSEC_PER_USEC);
  71                 if (ret && errno != EINTR) {
  72                         perror("usleep");
  73                         goto end;
  74                 }
  75
  76                 ret = clock_gettime(CLOCK_MONOTONIC, &t2);
  77                 if (ret) {
  78                         perror("clock_gettime");
  79                         goto end;
  80                 }
  81
  82                 time_remaining_ns -= elapsed_time_ns(&t1, &t2);
  83         }
  84 end:
  85         return ret;
  86 }
  87
  88 void create_file(const char *path)
  89 {
  90         static bool file_created = false;
  91         int ret;
  92
  93         if (!path || file_created) {
  94                 return;
  95         }
  96
  97         ret = creat(path, S_IRWXU);
  98         if (ret < 0) {
  99                 fprintf(stderr, "Failed to create file %s\n", path);
 100                 return;
 101         }
 102
 103         (void) close(ret);
 104         file_created = true;
 105 }
 106
 107 static
 108 void wait_on_file(const char *path)
 109 {
 110         if (!path) {
 111                 return;
 112         }
 113         for (;;) {
 114                 int ret;
 115                 struct stat buf;
 116
 117                 ret = stat(path, &buf);
 118                 if (ret == -1 && errno == ENOENT) {
 119                         (void) poll(NULL, 0, 10);       /* 10 ms delay */
 120                         continue;                       /* retry */
 121                 }
 122                 if (ret) {
 123                         perror("stat");
 124                         exit(EXIT_FAILURE);
 125                 }
 126                 break;  /* found */
 127         }
 128 }
 129
 130 int main(int argc, char **argv)
 131 {
 132         unsigned int i, netint;
 133         long values[] = { 1, 2, 3 };
 134         char text[10] = "test";
 135         double dbl = 2.0;
 136         float flt = 2222.0;
 137         int nr_iter = 100, ret = 0;
 138         useconds_t nr_usec = 0;
 139         char *after_first_event_file_path = NULL;
 140         char *before_last_event_file_path = NULL;
 141
 142         if (argc >= 2) {
 143                 /*
 144                  * If nr_iter is negative, do an infinite tracing loop.
 145                  */
 146                 nr_iter = atoi(argv[1]);
 147         }
 148
 149         if (argc >= 3) {
 150                 /* By default, don't wait unless user specifies. */
 151                 nr_usec = atoi(argv[2]);
 152         }
 153
 154         if (argc >= 4) {
 155                 after_first_event_file_path = argv[3];
 156         }
 157
 158         if (argc >= 5) {
 159                 before_last_event_file_path = argv[4];
 160         }
 161
 162         for (i = 0; nr_iter < 0 || i < nr_iter; i++) {
 163                 if (nr_iter >= 0 && i == nr_iter - 1) {
 164                         /*
 165                          * Wait on synchronization before writing last
 166                          * event.
 167                          */
 168                         wait_on_file(before_last_event_file_path);
 169                 }
 170                 netint = htonl(i);
 171                 tracepoint(tp, tptest, i, netint, values, text,
 172                         strlen(text), dbl, flt);
 173                 tracepoint(tp, tpenum, 1);
 174
 175                 /*
 176                  * First loop we create the file if asked to indicate
 177                  * that at least one tracepoint has been hit.
 178                  */
 179                 create_file(after_first_event_file_path);
 180                 if (nr_usec) {
 181                         if (usleep_safe(nr_usec)) {
 182                                 ret = -1;
 183                                 goto end;
 184                         }
 185                 }
 186         }
 187
 188 end:
 189         exit(!ret ? EXIT_SUCCESS : EXIT_FAILURE);
 190 }