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+/*
+ * stress1.c
+ *
+ *
+ * --------------------------------------------------------------------------
+ *
+ * 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
+ *
+ * --------------------------------------------------------------------------
+ *
+ * Test Synopsis:
+ * - Stress test condition variables, mutexes, semaphores.
+ *
+ * Test Method (Validation or Falsification):
+ * - Validation
+ *
+ * Requirements Tested:
+ * - Correct accounting of semaphore and condition variable waiters.
+ *
+ * Features Tested:
+ * -
+ *
+ * Cases Tested:
+ * -
+ *
+ * Description:
+ * Attempting to expose race conditions in cond vars, semaphores etc.
+ * - Master attempts to signal slave close to when timeout is due.
+ * - Master and slave do battle continuously until main tells them to stop.
+ * - Afterwards, the CV must be successfully destroyed (will return an
+ * error if there are waiters (including any internal semaphore waiters,
+ * which, if there are, cannot not be real waiters).
+ *
+ * Environment:
+ * -
+ *
+ * Input:
+ * - None.
+ *
+ * Output:
+ * - File name, Line number, and failed expression on failure.
+ * - No output on success.
+ *
+ * Assumptions:
+ * -
+ *
+ * Pass Criteria:
+ * - CV is successfully destroyed.
+ *
+ * Fail Criteria:
+ * - CV destroy fails.
+ */
+
+#include "test.h"
+#include <string.h>
+#include <sys/timeb.h>
+
+
+const unsigned int ITERATIONS = 1000;
+
+static pthread_t master, slave;
+typedef struct {
+ int value;
+ pthread_cond_t cv;
+ pthread_mutex_t mx;
+} mysig_t;
+
+static int allExit;
+static mysig_t control = {0, PTHREAD_COND_INITIALIZER, PTHREAD_MUTEX_INITIALIZER};
+static pthread_barrier_t startBarrier, readyBarrier, holdBarrier;
+static int timeoutCount = 0;
+static int signalsTakenCount = 0;
+static int signalsSent = 0;
+static int bias = 0;
+static int timeout = 10; // Must be > 0
+
+enum {
+ CTL_STOP = -1
+};
+
+/*
+ * Returns abstime 'milliseconds' from 'now'.
+ */
+struct timespec *
+millisecondsFromNow (struct timespec * time, int millisecs)
+{
+ struct _timeb currSysTime;
+ int64_t nanosecs, secs;
+ const int64_t NANOSEC_PER_MILLISEC = 1000000;
+ const int64_t NANOSEC_PER_SEC = 1000000000;
+
+ /* get current system time and add millisecs */
+ _ftime(&currSysTime);
+
+ nanosecs = ((int64_t) (millisecs + currSysTime.millitm)) * NANOSEC_PER_MILLISEC;
+ if (nanosecs >= NANOSEC_PER_SEC)
+ {
+ secs = currSysTime.time + 1;
+ nanosecs %= NANOSEC_PER_SEC;
+ }
+ else
+ {
+ secs = currSysTime.time;
+ }
+
+ time->tv_nsec = (long)nanosecs;
+ time->tv_sec = (long)secs;
+
+ return time;
+}
+
+void *
+masterThread (void * arg)
+{
+ int dither = (int) arg;
+
+ timeout = (int) arg;
+
+ pthread_barrier_wait(&startBarrier);
+
+ do
+ {
+ int sleepTime;
+
+ assert(pthread_mutex_lock(&control.mx) == 0);
+ control.value = timeout;
+ assert(pthread_mutex_unlock(&control.mx) == 0);
+
+ /*
+ * We are attempting to send the signal close to when the slave
+ * is due to timeout. We feel around by adding some [non-random] dither.
+ *
+ * with dither added, sleep time range is 2*timeout peak-to-peak centred on timeout,
+ * e.g.
+ * if timeout = 10 then dither = 20 and
+ * sleep millisecs is: 5 <= ms <= 15
+ *
+ * The bias value attempts to apply some negative feedback to keep
+ * the ratio of timeouts to signals taken close to 1:1.
+ * bias changes more slowly than dither so as to average more.
+ */
+ if (signalsSent % timeout == 0)
+ {
+ if (timeoutCount > signalsTakenCount)
+ {
+ bias++;
+ }
+ else if (timeoutCount < signalsTakenCount)
+ {
+ bias--;
+ }
+ if (bias < -timeout || bias > timeout)
+ {
+ timeout++;
+ }
+ }
+ dither = (dither + 1 ) % (timeout * 2);
+ sleepTime = (timeout - bias + dither) / 2;
+ Sleep(sleepTime);
+ assert(pthread_cond_signal(&control.cv) == 0);
+ signalsSent++;
+
+ pthread_barrier_wait(&holdBarrier);
+ pthread_barrier_wait(&readyBarrier);
+ }
+ while (!allExit);
+
+ return NULL;
+}
+
+void *
+slaveThread (void * arg)
+{
+ struct timespec time;
+
+ pthread_barrier_wait(&startBarrier);
+
+ do
+ {
+ assert(pthread_mutex_lock(&control.mx) == 0);
+ if (pthread_cond_timedwait(&control.cv,
+ &control.mx,
+ millisecondsFromNow(&time, control.value)) == ETIMEDOUT)
+ {
+ timeoutCount++;
+ }
+ else
+ {
+ signalsTakenCount++;
+ }
+ assert(pthread_mutex_unlock(&control.mx) == 0);
+
+ pthread_barrier_wait(&holdBarrier);
+ pthread_barrier_wait(&readyBarrier);
+ }
+ while (!allExit);
+
+ return NULL;
+}
+
+int
+main ()
+{
+ unsigned int i;
+
+ assert(pthread_barrier_init(&startBarrier, NULL, 3) == 0);
+ assert(pthread_barrier_init(&readyBarrier, NULL, 3) == 0);
+ assert(pthread_barrier_init(&holdBarrier, NULL, 3) == 0);
+
+ assert(pthread_create(&master, NULL, masterThread, (void *) timeout) == 0);
+ assert(pthread_create(&slave, NULL, slaveThread, NULL) == 0);
+
+ allExit = FALSE;
+
+ pthread_barrier_wait(&startBarrier);
+
+ for (i = 1; !allExit; i++)
+ {
+ pthread_barrier_wait(&holdBarrier);
+ if (i >= ITERATIONS)
+ {
+ allExit = TRUE;
+ }
+ pthread_barrier_wait(&readyBarrier);
+ }
+
+ assert(pthread_join(slave, NULL) == 0);
+ assert(pthread_join(master, NULL) == 0);
+
+ printf("Signals sent = %d\nWait timeouts = %d\nSignals taken = %d\nBias = %d\nTimeout = %d\n",
+ signalsSent,
+ timeoutCount,
+ signalsTakenCount,
+ (int) bias,
+ timeout);
+
+ /* Cleanup */
+ assert(pthread_barrier_destroy(&holdBarrier) == 0);
+ assert(pthread_barrier_destroy(&readyBarrier) == 0);
+ assert(pthread_barrier_destroy(&startBarrier) == 0);
+ assert(pthread_cond_destroy(&control.cv) == 0);
+ assert(pthread_mutex_destroy(&control.mx) == 0);
+
+ /* Success. */
+ return 0;
+}