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+/* Simple POSIX threads program.
+ *
+ *
+ * --------------------------------------------------------------------------
+ *
+ * Pthreads-win32 - POSIX Threads Library for Win32
+ * Copyright(C) 1998 John E. Bossom
+ * Copyright(C) 1999,2005 Pthreads-win32 contributors
+ *
+ * Contact Email: rpj@callisto.canberra.edu.au
+ *
+ * The current list of contributors is contained
+ * in the file CONTRIBUTORS included with the source
+ * code distribution. The list can also be seen at the
+ * following World Wide Web location:
+ * http://sources.redhat.com/pthreads-win32/contributors.html
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library in the file COPYING.LIB;
+ * if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ *
+ * --------------------------------------------------------------------------
+ *
+ * Author: Eyal Lebedinsky eyal@eyal.emu.id.au
+ * Written: Sep 1998.
+ * Version Date: 12 Sep 1998
+ *
+ * Do we need to lock stdout or is it thread safe?
+ *
+ * Used:
+ * pthread_t
+ * pthread_attr_t
+ * pthread_create()
+ * pthread_join()
+ * pthread_mutex_t
+ * PTHREAD_MUTEX_INITIALIZER
+ * pthread_mutex_init() [not used now]
+ * pthread_mutex_destroy()
+ * pthread_mutex_lock()
+ * pthread_mutex_trylock()
+ * pthread_mutex_unlock()
+ *
+ * What this program does is establish a work queue (implemented using
+ * four mutexes for each thread). It then schedules work (by storing
+ * a number in 'todo') and releases the threads. When the work is done
+ * the threads will block. The program then repeats the same thing once
+ * more (just to test the logic) and when the work is done it destroyes
+ * the threads.
+ *
+ * The 'work' we do is simply burning CPU cycles in a loop.
+ * The 'todo' work queue is trivial - each threads pops one element
+ * off it by incrementing it, the poped number is the 'work' to do.
+ * When 'todo' reaches the limit (nwork) the queue is considered
+ * empty.
+ *
+ * The number displayed at the end is the amount of work each thread
+ * did, so we can see if the load was properly distributed.
+ *
+ * The program was written to test a threading setup (not seen here)
+ * rather than to demonstrate correct usage of the pthread facilities.
+ *
+ * Note how each thread is given access to a thread control structure
+ * (TC) which is used for communicating to/from the main program (e.g.
+ * the threads knows its 'id' and also filles in the 'work' done).
+*/
+
+#include "test.h"
+
+#include <stdlib.h>
+#include <math.h>
+
+struct thread_control {
+ int id;
+ pthread_t thread; /* thread id */
+ pthread_mutex_t mutex_start;
+ pthread_mutex_t mutex_started;
+ pthread_mutex_t mutex_end;
+ pthread_mutex_t mutex_ended;
+ long work; /* work done */
+ int stat; /* pthread_init status */
+};
+
+typedef struct thread_control TC;
+
+static TC *tcs = NULL;
+static int nthreads = 10;
+static int nwork = 100;
+static int quiet = 0;
+
+static int todo = -1;
+
+static pthread_mutex_t mutex_todo = PTHREAD_MUTEX_INITIALIZER;
+static pthread_mutex_t mutex_stdout = PTHREAD_MUTEX_INITIALIZER;
+
+
+static void
+die (int ret)
+{
+ if (NULL != tcs)
+ {
+ free (tcs);
+ tcs = NULL;
+ }
+
+ if (ret)
+ exit (ret);
+}
+
+
+static double
+waste_time (int n)
+{
+ int i;
+ double f, g, h, s;
+
+ s = 0.0;
+
+ /*
+ * Useless work.
+ */
+ for (i = n*100; i > 0; --i)
+ {
+ f = rand ();
+ g = rand ();
+ h = rand ();
+ s += 2.0 * f * g / (h != 0.0 ? (h * h) : 1.0);
+ }
+ return s;
+}
+
+static int
+do_work_unit (int who, int n)
+{
+ int i;
+ static int nchars = 0;
+ double f = 0.0;
+
+ if (quiet)
+ i = 0;
+ else {
+ /*
+ * get lock on stdout
+ */
+ assert(pthread_mutex_lock (&mutex_stdout) == 0);
+
+ /*
+ * do our job
+ */
+ i = printf ("%c", "0123456789abcdefghijklmnopqrstuvwxyz"[who]);
+
+ if (!(++nchars % 50))
+ printf ("\n");
+
+ fflush (stdout);
+
+ /*
+ * release lock on stdout
+ */
+ assert(pthread_mutex_unlock (&mutex_stdout) == 0);
+ }
+
+ n = rand () % 10000; /* ignore incoming 'n' */
+ f = waste_time (n);
+
+ /* This prevents the statement above from being optimised out */
+ if (f > 0.0)
+ return(n);
+
+ return (n);
+}
+
+static int
+print_server (void *ptr)
+{
+ int mywork;
+ int n;
+ TC *tc = (TC *)ptr;
+
+ assert(pthread_mutex_lock (&tc->mutex_started) == 0);
+
+ for (;;)
+ {
+ assert(pthread_mutex_lock (&tc->mutex_start) == 0);
+ assert(pthread_mutex_unlock (&tc->mutex_start) == 0);
+ assert(pthread_mutex_lock (&tc->mutex_ended) == 0);
+ assert(pthread_mutex_unlock (&tc->mutex_started) == 0);
+
+ for (;;)
+ {
+
+ /*
+ * get lock on todo list
+ */
+ assert(pthread_mutex_lock (&mutex_todo) == 0);
+
+ mywork = todo;
+ if (todo >= 0)
+ {
+ ++todo;
+ if (todo >= nwork)
+ todo = -1;
+ }
+ assert(pthread_mutex_unlock (&mutex_todo) == 0);
+
+ if (mywork < 0)
+ break;
+
+ assert((n = do_work_unit (tc->id, mywork)) >= 0);
+ tc->work += n;
+ }
+
+ assert(pthread_mutex_lock (&tc->mutex_end) == 0);
+ assert(pthread_mutex_unlock (&tc->mutex_end) == 0);
+ assert(pthread_mutex_lock (&tc->mutex_started) == 0);
+ assert(pthread_mutex_unlock (&tc->mutex_ended) == 0);
+
+ if (-2 == mywork)
+ break;
+ }
+
+ assert(pthread_mutex_unlock (&tc->mutex_started) == 0);
+
+ return (0);
+}
+
+static void
+dosync (void)
+{
+ int i;
+
+ for (i = 0; i < nthreads; ++i)
+ {
+ assert(pthread_mutex_lock (&tcs[i].mutex_end) == 0);
+ assert(pthread_mutex_unlock (&tcs[i].mutex_start) == 0);
+ assert(pthread_mutex_lock (&tcs[i].mutex_started) == 0);
+ assert(pthread_mutex_unlock (&tcs[i].mutex_started) == 0);
+ }
+
+ /*
+ * Now threads do their work
+ */
+ for (i = 0; i < nthreads; ++i)
+ {
+ assert(pthread_mutex_lock (&tcs[i].mutex_start) == 0);
+ assert(pthread_mutex_unlock (&tcs[i].mutex_end) == 0);
+ assert(pthread_mutex_lock (&tcs[i].mutex_ended) == 0);
+ assert(pthread_mutex_unlock (&tcs[i].mutex_ended) == 0);
+ }
+}
+
+static void
+dowork (void)
+{
+ todo = 0;
+ dosync();
+
+ todo = 0;
+ dosync();
+}
+
+int
+main (int argc, char *argv[])
+{
+ int i;
+
+ assert(NULL != (tcs = (TC *) calloc (nthreads, sizeof (*tcs))));
+
+ /*
+ * Launch threads
+ */
+ for (i = 0; i < nthreads; ++i)
+ {
+ tcs[i].id = i;
+
+ assert(pthread_mutex_init (&tcs[i].mutex_start, NULL) == 0);
+ assert(pthread_mutex_init (&tcs[i].mutex_started, NULL) == 0);
+ assert(pthread_mutex_init (&tcs[i].mutex_end, NULL) == 0);
+ assert(pthread_mutex_init (&tcs[i].mutex_ended, NULL) == 0);
+
+ tcs[i].work = 0;
+
+ assert(pthread_mutex_lock (&tcs[i].mutex_start) == 0);
+ assert((tcs[i].stat =
+ pthread_create (&tcs[i].thread,
+ NULL,
+ (void *(*)(void *))print_server,
+ (void *) &tcs[i])
+ ) == 0);
+
+ /*
+ * Wait for thread initialisation
+ */
+ {
+ int trylock = 0;
+
+ while (trylock == 0)
+ {
+ trylock = pthread_mutex_trylock(&tcs[i].mutex_started);
+ assert(trylock == 0 || trylock == EBUSY);
+
+ if (trylock == 0)
+ {
+ assert(pthread_mutex_unlock (&tcs[i].mutex_started) == 0);
+ }
+ }
+ }
+ }
+
+ dowork ();
+
+ /*
+ * Terminate threads
+ */
+ todo = -2; /* please terminate */
+ dosync();
+
+ for (i = 0; i < nthreads; ++i)
+ {
+ if (0 == tcs[i].stat)
+ assert(pthread_join (tcs[i].thread, NULL) == 0);
+ }
+
+ /*
+ * destroy locks
+ */
+ assert(pthread_mutex_destroy (&mutex_stdout) == 0);
+ assert(pthread_mutex_destroy (&mutex_todo) == 0);
+
+ /*
+ * Cleanup
+ */
+ printf ("\n");
+
+ /*
+ * Show results
+ */
+ for (i = 0; i < nthreads; ++i)
+ {
+ printf ("%2d ", i);
+ if (0 == tcs[i].stat)
+ printf ("%10ld\n", tcs[i].work);
+ else
+ printf ("failed %d\n", tcs[i].stat);
+
+ assert(pthread_mutex_unlock(&tcs[i].mutex_start) == 0);
+
+ assert(pthread_mutex_destroy (&tcs[i].mutex_start) == 0);
+ assert(pthread_mutex_destroy (&tcs[i].mutex_started) == 0);
+ assert(pthread_mutex_destroy (&tcs[i].mutex_end) == 0);
+ assert(pthread_mutex_destroy (&tcs[i].mutex_ended) == 0);
+ }
+
+ die (0);
+
+ return (0);
+}
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