linuxthreads/Examples/ex10.c

   1 /* Tests for pthread_mutex_timedlock function.
   2    Copyright (C) 2000 Free Software Foundation, Inc.
   3    Contributed by Kaz Kylheku <kaz@ashi.footprints.net>, 2000.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <errno.h>
  21 #include <error.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <pthread.h>
  25 #include <time.h>
  26
  27 #define NUM_THREADS 10
  28 #define NUM_ITERS   50
  29 #define TIMEOUT_NS  100000000L
  30
  31 static void *thread (void *);
  32 static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
  33
  34 int
  35 main (void)
  36 {
  37   pthread_t th;
  38   int i;
  39
  40   for (i = 0; i < NUM_THREADS; i++)
  41     {
  42       if (pthread_create (&th, NULL, thread, NULL) != 0)
  43         error (EXIT_FAILURE, 0, "cannot create thread");
  44     }
  45
  46   (void) thread (NULL);
  47   /* notreached */
  48   return 0;
  49 }
  50
  51
  52 static void *
  53 thread (void *arg)
  54 {
  55   int i;
  56   pthread_t self = pthread_self ();
  57   static int linecount; /* protected by flockfile(stdout) */
  58
  59   for (i = 0; i < NUM_ITERS; i++)
  60     {
  61       struct timespec ts;
  62
  63       for (;;)
  64         {
  65
  66           clock_gettime (CLOCK_REALTIME, &ts);
  67
  68           ts.tv_nsec += TIMEOUT_NS;
  69
  70           if (ts.tv_nsec > 1000000000L) {
  71              ts.tv_sec++;
  72              ts.tv_nsec -= 1000000000L;
  73           }
  74
  75           switch (pthread_mutex_timedlock (&mutex, &ts))
  76             {
  77             case 0:
  78               flockfile (stdout);
  79               printf ("%04d: thread %lu got mutex\n", ++linecount,
  80                       (unsigned long) self);
  81               funlockfile (stdout);
  82               break;
  83             case ETIMEDOUT:
  84               flockfile (stdout);
  85               printf ("%04d: thread %lu timed out on mutex\n", ++linecount,
  86                       (unsigned long) self);
  87               funlockfile (stdout);
  88               continue;
  89             }
  90           break;
  91         }
  92
  93       ts.tv_sec = 0;
  94       ts.tv_nsec = TIMEOUT_NS;
  95       nanosleep (&ts, NULL);
  96
  97       flockfile (stdout);
  98       printf ("%04d: thread %lu releasing mutex\n", ++linecount,
  99               (unsigned long) self);
 100       funlockfile (stdout);
 101       pthread_mutex_unlock (&mutex);
 102     }
 103
 104   pthread_exit (NULL);
 105 }