linuxthreads/Examples/ex11.c

   1 /* Test program for timedout read/write lock functions.
   2    Copyright (C) 2000 Free Software Foundation, Inc.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 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 Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 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    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser 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 <pthread.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <time.h>
  26 #include <unistd.h>
  27
  28
  29 #define NWRITERS 15
  30 #define WRITETRIES 10
  31 #define NREADERS 15
  32 #define READTRIES 15
  33
  34 #define TIMEOUT 1000000
  35 #define DELAY   1000000
  36
  37 static pthread_rwlock_t lock = PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP;
  38
  39
  40 static void *
  41 writer_thread (void *nr)
  42 {
  43   struct timespec ts;
  44   struct timespec delay;
  45   int n;
  46
  47   ts.tv_sec = 0;
  48   ts.tv_nsec = TIMEOUT;
  49
  50   delay.tv_sec = 0;
  51   delay.tv_nsec = DELAY;
  52
  53   for (n = 0; n < WRITETRIES; ++n)
  54     {
  55       do
  56         {
  57           clock_gettime (CLOCK_REALTIME, &ts);
  58
  59           ts.tv_nsec += 2 * TIMEOUT;
  60
  61           printf ("writer thread %ld tries again\n", (long int) nr);
  62         }
  63       //while (pthread_rwlock_wrlock (&lock), 0);
  64       while (pthread_rwlock_timedwrlock (&lock, &ts) == ETIMEDOUT);
  65
  66       printf ("writer thread %ld succeeded\n", (long int) nr);
  67
  68       nanosleep (&delay, NULL);
  69
  70       pthread_rwlock_unlock (&lock);
  71
  72       printf ("writer thread %ld released\n", (long int) nr);
  73     }
  74
  75   return NULL;
  76 }
  77
  78
  79 static void *
  80 reader_thread (void *nr)
  81 {
  82   struct timespec ts;
  83   struct timespec delay;
  84   int n;
  85
  86   delay.tv_sec = 0;
  87   delay.tv_nsec = DELAY;
  88
  89   for (n = 0; n < READTRIES; ++n)
  90     {
  91       do
  92         {
  93           clock_gettime (CLOCK_REALTIME, &ts);
  94
  95           ts.tv_nsec += TIMEOUT;
  96
  97           printf ("reader thread %ld tries again\n", (long int) nr);
  98         }
  99       //while (pthread_rwlock_rdlock (&lock), 0);
 100       while (pthread_rwlock_timedrdlock (&lock, &ts) == ETIMEDOUT);
 101
 102       printf ("reader thread %ld succeeded\n", (long int) nr);
 103
 104       nanosleep (&delay, NULL);
 105
 106       pthread_rwlock_unlock (&lock);
 107
 108       printf ("reader thread %ld released\n", (long int) nr);
 109     }
 110
 111   return NULL;
 112 }
 113
 114
 115 int
 116 main (void)
 117 {
 118   pthread_t thwr[NWRITERS];
 119   pthread_t thrd[NREADERS];
 120   int n;
 121   void *res;
 122
 123   /* Make standard error the same as standard output.  */
 124   dup2 (1, 2);
 125
 126   /* Make sure we see all message, even those on stdout.  */
 127   setvbuf (stdout, NULL, _IONBF, 0);
 128
 129   for (n = 0; n < NWRITERS; ++n)
 130     {
 131       int err = pthread_create (&thwr[n], NULL, writer_thread,
 132                                 (void *) (long int) n);
 133
 134       if (err != 0)
 135         error (EXIT_FAILURE, err, "cannot create writer thread");
 136     }
 137
 138   for (n = 0; n < NREADERS; ++n)
 139     {
 140       int err = pthread_create (&thrd[n], NULL, reader_thread,
 141                                 (void *) (long int) n);
 142
 143       if (err != 0)
 144         error (EXIT_FAILURE, err, "cannot create reader thread");
 145     }
 146
 147   /* Wait for all the threads.  */
 148   for (n = 0; n < NWRITERS; ++n)
 149     pthread_join (thwr[n], &res);
 150   for (n = 0; n < NREADERS; ++n)
 151     pthread_join (thrd[n], &res);
 152
 153   return 0;
 154 }