tests/timeloop.c

   1 #undef G_DISABLE_ASSERT
   2 #undef G_LOG_DOMAIN
   3
   4 #include <errno.h>
   5 #include <stdlib.h>
   6 #include <unistd.h>
   7 #include <stdio.h>
   8 #include <sys/time.h>
   9 #include <sys/resource.h>
  10
  11 #include <glib.h>
  12
  13 static int n_children = 3;
  14 static int n_active_children;
  15 static int n_iters = 10000;
  16 static GMainLoop *loop;
  17
  18 static void
  19 io_pipe (GIOChannel **channels)
  20 {
  21   int fds[2];
  22
  23   if (pipe(fds) < 0)
  24     {
  25       int errsv = errno;
  26       fprintf (stderr, "Cannot create pipe %s\n", g_strerror (errsv));
  27       exit (1);
  28     }
  29
  30   channels[0] = g_io_channel_unix_new (fds[0]);
  31   channels[1] = g_io_channel_unix_new (fds[1]);
  32 }
  33
  34 static gboolean
  35 read_all (GIOChannel *channel, char *buf, int len)
  36 {
  37   gsize bytes_read = 0;
  38   gsize count;
  39   GIOError err;
  40
  41   while (bytes_read < len)
  42     {
  43       err = g_io_channel_read (channel, buf + bytes_read, len - bytes_read, &count);
  44       if (err)
  45         {
  46           if (err != G_IO_ERROR_AGAIN)
  47             return FALSE;
  48         }
  49       else if (count == 0)
  50         return FALSE;
  51
  52       bytes_read += count;
  53     }
  54
  55   return TRUE;
  56 }
  57
  58 static gboolean
  59 write_all (GIOChannel *channel, char *buf, int len)
  60 {
  61   gsize bytes_written = 0;
  62   gsize count;
  63   GIOError err;
  64
  65   while (bytes_written < len)
  66     {
  67       err = g_io_channel_write (channel, buf + bytes_written, len - bytes_written, &count);
  68       if (err && err != G_IO_ERROR_AGAIN)
  69         return FALSE;
  70
  71       bytes_written += count;
  72     }
  73
  74   return TRUE;
  75 }
  76
  77 static void
  78 run_child (GIOChannel *in_channel, GIOChannel *out_channel)
  79 {
  80   int i;
  81   int val = 1;
  82   GTimer *timer = g_timer_new();
  83
  84   for (i = 0; i < n_iters; i++)
  85     {
  86       write_all (out_channel, (char *)&val, sizeof (val));
  87       read_all (in_channel, (char *)&val, sizeof (val));
  88     }
  89
  90   val = 0;
  91   write_all (out_channel, (char *)&val, sizeof (val));
  92
  93   val = g_timer_elapsed (timer, NULL) * 1000;
  94
  95   write_all (out_channel, (char *)&val, sizeof (val));
  96   g_timer_destroy (timer);
  97
  98   exit (0);
  99 }
 100
 101 static gboolean
 102 input_callback (GIOChannel   *source,
 103                 GIOCondition  condition,
 104                 gpointer      data)
 105 {
 106   int val;
 107   GIOChannel *dest = (GIOChannel *)data;
 108
 109   if (!read_all (source, (char *)&val, sizeof(val)))
 110     {
 111       fprintf (stderr, "Unexpected EOF\n");
 112       exit (1);
 113     }
 114
 115   if (val)
 116     {
 117       write_all (dest, (char *)&val, sizeof(val));
 118
 119       return TRUE;
 120     }
 121   else
 122     {
 123       g_io_channel_close (source);
 124       g_io_channel_close (dest);
 125
 126       g_io_channel_unref (source);
 127       g_io_channel_unref (dest);
 128
 129       n_active_children--;
 130       if (n_active_children == 0)
 131         g_main_loop_quit (loop);
 132
 133       return FALSE;
 134     }
 135 }
 136
 137 static void
 138 create_child (void)
 139 {
 140   int pid, errsv;
 141   GIOChannel *in_channels[2];
 142   GIOChannel *out_channels[2];
 143
 144   io_pipe (in_channels);
 145   io_pipe (out_channels);
 146
 147   pid = fork ();
 148   errsv = errno;
 149
 150   if (pid > 0)                  /* Parent */
 151     {
 152       g_io_channel_close (in_channels[0]);
 153       g_io_channel_unref (in_channels[0]);
 154       g_io_channel_close (out_channels[1]);
 155       g_io_channel_unref (out_channels[1]);
 156
 157       g_io_add_watch (out_channels[0], G_IO_IN | G_IO_HUP,
 158                       input_callback, in_channels[1]);
 159     }
 160   else if (pid == 0)            /* Child */
 161     {
 162       g_io_channel_close (in_channels[1]);
 163       g_io_channel_close (out_channels[0]);
 164
 165       setsid ();
 166
 167       run_child (in_channels[0], out_channels[1]);
 168     }
 169   else                          /* Error */
 170     {
 171       fprintf (stderr, "Cannot fork: %s\n", g_strerror (errsv));
 172       exit (1);
 173     }
 174 }
 175
 176 static double
 177 difftimeval (struct timeval *old, struct timeval *new)
 178 {
 179   return
 180     (new->tv_sec - old->tv_sec) * 1000. + (new->tv_usec - old->tv_usec) / 1000;
 181 }
 182
 183 int
 184 main (int argc, char **argv)
 185 {
 186   int i;
 187   struct rusage old_usage;
 188   struct rusage new_usage;
 189
 190   if (argc > 1)
 191     n_children = atoi(argv[1]);
 192
 193   if (argc > 2)
 194     n_iters = atoi(argv[2]);
 195
 196   printf ("Children: %d     Iters: %d\n", n_children, n_iters);
 197
 198   n_active_children = n_children;
 199   for (i = 0; i < n_children; i++)
 200     create_child ();
 201
 202   getrusage (RUSAGE_SELF, &old_usage);
 203   loop = g_main_loop_new (NULL, FALSE);
 204   g_main_loop_run (loop);
 205   getrusage (RUSAGE_SELF, &new_usage);
 206
 207   printf ("Elapsed user: %g\n",
 208           difftimeval (&old_usage.ru_utime, &new_usage.ru_utime));
 209   printf ("Elapsed system: %g\n",
 210           difftimeval (&old_usage.ru_stime, &new_usage.ru_stime));
 211   printf ("Elapsed total: %g\n",
 212           difftimeval (&old_usage.ru_utime, &new_usage.ru_utime) +
 213           difftimeval (&old_usage.ru_stime, &new_usage.ru_stime));
 214   printf ("total / iteration: %g\n",
 215           (difftimeval (&old_usage.ru_utime, &new_usage.ru_utime) +
 216            difftimeval (&old_usage.ru_stime, &new_usage.ru_stime)) /
 217           (n_iters * n_children));
 218
 219   g_main_loop_unref (loop);
 220   return 0;
 221 }