linuxthreads/Examples/ex9.c

   1 /* Tests for pthread_barrier_* functions.
   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
  26 #define NUM_THREADS 10
  27 #define NUM_ITERS   500
  28
  29 static void *thread (void *);
  30 static pthread_barrier_t barrier;
  31
  32 int
  33 main (void)
  34 {
  35   pthread_t th;
  36   int i;
  37
  38   if (pthread_barrier_init (&barrier, NULL, NUM_THREADS + 1) != 0)
  39     error (EXIT_FAILURE, 0, "cannot initialize barrier");
  40
  41   for (i = 0; i < NUM_THREADS; i++)
  42     {
  43       if (pthread_create (&th, NULL, thread, NULL) != 0)
  44         error (EXIT_FAILURE, 0, "cannot create thread");
  45     }
  46
  47   (void) thread (NULL);
  48   /* notreached */
  49   return 0;
  50 }
  51
  52
  53 static void *
  54 thread (void *arg)
  55 {
  56   int i;
  57   pthread_t self = pthread_self ();
  58   static pthread_t last_serial_thread;
  59   static int linecount; /* protected by flockfile(stdout) */
  60
  61   for (i = 0; i < NUM_ITERS; i++)
  62     {
  63       switch (pthread_barrier_wait (&barrier))
  64         {
  65         case 0:
  66           flockfile (stdout);
  67           printf ("%04d: non-serial thread %lu\n", ++linecount,
  68                   (unsigned long) self);
  69           funlockfile (stdout);
  70           break;
  71         case PTHREAD_BARRIER_SERIAL_THREAD:
  72           flockfile (stdout);
  73           printf ("%04d: serial thread %lu\n", ++linecount,
  74                   (unsigned long) self);
  75           funlockfile (stdout);
  76           last_serial_thread = self;
  77           break;
  78         default:
  79           /* Huh? */
  80           error (EXIT_FAILURE, 0, "unexpected return value from barrier wait");
  81         }
  82     }
  83
  84   if (pthread_equal (self, last_serial_thread))
  85   {
  86     flockfile (stdout);
  87     printf ("%04d: last serial thread %lu terminating process\n",
  88             ++linecount, (unsigned long) self);
  89     funlockfile (stdout);
  90     exit (0);
  91   }
  92
  93   pthread_exit(NULL);
  94 }