along with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
-/* Written by Yoann Vandoorselaere <yoann@prelude-ids.org>, 2008. */
+/* Written by Yoann Vandoorselaere <yoann@prelude-ids.org>, 2008,
+ and Bruno Haible <bruno@clisp.org>, 2008. */
#include <config.h>
#endif
/* ========================================================================= */
+
+#if USE_WIN32_THREADS
+
+#include <sys/time.h>
+
+/* -------------------------- gl_cond_t datatype -------------------------- */
+
+/* This implementation is based on the article
+ Douglas C. Schmidt, Irfan Pyarali
+ "Strategies for Implementing POSIX Condition Variables on Win32"
+ <http://www.cs.wustl.edu/~schmidt/win32-cv-1.html> */
+
+int
+glthread_cond_init_func (gl_cond_t *cond)
+{
+ InitializeCriticalSection (&cond->lock);
+ /* Create a manual-reset event. */
+ cond->event = CreateEvent (NULL, TRUE, FALSE, NULL);
+ cond->waiters_count = 0;
+ cond->release_count = 0;
+ cond->wait_generation_count = 0;
+
+ cond->guard.done = 1;
+
+ return 0;
+}
+
+int
+glthread_cond_wait_func (gl_cond_t *cond, gl_lock_t *lock)
+{
+ if (!cond->guard.done)
+ {
+ if (InterlockedIncrement (&cond->guard.started) == 0)
+ /* This thread is the first one to need this condition variable.
+ Initialize it. */
+ glthread_cond_init (cond);
+ else
+ /* Yield the CPU while waiting for another thread to finish
+ initializing this condition variable. */
+ while (!cond->guard.done)
+ Sleep (0);
+ }
+
+ {
+ unsigned old_generation_count;
+ HANDLE event;
+
+ EnterCriticalSection (&cond->lock);
+ /* Increment waiters_count,
+ and get a copy of the current wait_generation_count. */
+ cond->waiters_count++;
+ old_generation_count = cond->wait_generation_count;
+ event = cond->event;
+ LeaveCriticalSection (&cond->lock);
+
+ {
+ /* Now release the lock and let any other thread take it. */
+ int err = glthread_lock_unlock (lock);
+ if (err != 0)
+ {
+ EnterCriticalSection (&cond->lock);
+ cond->waiters_count--;
+ LeaveCriticalSection (&cond->lock);
+ return err;
+ }
+
+ {
+ /* Wait until another thread signals this event. */
+ DWORD result;
+
+ for (;;)
+ {
+ bool wait_done;
+
+ result = WaitForSingleObject (event, INFINITE);
+ if (result != WAIT_OBJECT_0)
+ break;
+ /* Distingish intended from spurious wakeups. */
+ EnterCriticalSection (&cond->lock);
+ wait_done =
+ (cond->release_count > 0
+ && cond->wait_generation_count != old_generation_count);
+ LeaveCriticalSection (&cond->lock);
+ if (wait_done)
+ break;
+ }
+
+ /* Take the lock again. */
+ err = glthread_lock_lock (lock);
+
+ /* Do the bookkeeping. */
+ EnterCriticalSection (&cond->lock);
+ cond->waiters_count--;
+ if (result == WAIT_OBJECT_0)
+ {
+ /* The wait terminated because the event was signaled.
+ Acknowledge the receipt. */
+ if (--cond->release_count == 0)
+ {
+ /* The last waiting thread to be notified has to reset
+ the event. */
+ ResetEvent (cond->event);
+ }
+ }
+ LeaveCriticalSection (&cond->lock);
+
+ return (err ? err :
+ ret == WAIT_OBJECT_0 ? 0 :
+ /* WAIT_FAILED shouldn't happen */ EAGAIN);
+ }
+ }
+ }
+}
+
+int
+glthread_cond_timedwait_func (gl_cond_t *cond, gl_lock_t *lock, struct timespec *abstime)
+{
+ struct timeval currtime;
+
+ gettimeofday (&currtime, NULL);
+ if (currtime.tv_sec > abstime->tv_sec
+ || (currtime.tv_sec == abstime->tv_sec
+ && currtime.tv_usec * 1000 >= abstime->tv_nsec))
+ return ETIMEDOUT;
+
+ if (!cond->guard.done)
+ {
+ if (InterlockedIncrement (&cond->guard.started) == 0)
+ /* This thread is the first one to need this condition variable.
+ Initialize it. */
+ glthread_cond_init (cond);
+ else
+ /* Yield the CPU while waiting for another thread to finish
+ initializing this condition variable. */
+ while (!cond->guard.done)
+ Sleep (0);
+ }
+
+ {
+ unsigned old_generation_count;
+ HANDLE event;
+
+ EnterCriticalSection (&cond->lock);
+ /* Increment waiters_count,
+ and get a copy of the current wait_generation_count. */
+ cond->waiters_count++;
+ old_generation_count = cond->wait_generation_count;
+ event = cond->event;
+ LeaveCriticalSection (&cond->lock);
+
+ {
+ /* Now release the lock and let any other thread take it. */
+ int err = glthread_lock_unlock (lock);
+ if (err != 0)
+ {
+ EnterCriticalSection (&cond->lock);
+ cond->waiters_count--;
+ LeaveCriticalSection (&cond->lock);
+ return err;
+ }
+
+ {
+ /* Wait until another thread signals this event or until the abstime
+ passes. */
+ DWORD result;
+
+ for (;;)
+ {
+ DWORD timeout;
+ bool wait_done;
+
+ gettimeofday (&currtime, NULL);
+ if (currtime.tv_sec > abstime->tv_sec)
+ timeout = 0;
+ else
+ {
+ unsigned long seconds = abstime->tv_sec - currtime.tv_sec;
+ timeout = seconds * 1000;
+ if (timeout / 1000 != seconds) /* overflow? */
+ timeout = INFINITE;
+ else
+ {
+ long milliseconds =
+ abstime->tv_nsec / 1000000 - currtime.tv_usec / 1000;
+ if (milliseconds >= 0)
+ {
+ timeout += milliseconds;
+ if (timeout < milliseconds) /* overflow? */
+ timeout = INFINITE;
+ }
+ else
+ {
+ if (timeout >= - milliseconds)
+ timeout -= (- milliseconds);
+ else
+ timeout = 0;
+ }
+ }
+ }
+
+ result = WaitForSingleObject (event, timeout);
+ if (result != WAIT_OBJECT_0)
+ break;
+ /* Distingish intended from spurious wakeups. */
+ EnterCriticalSection (&cond->lock);
+ wait_done =
+ (cond->release_count > 0
+ && cond->wait_generation_count != old_generation_count);
+ LeaveCriticalSection (&cond->lock);
+ if (wait_done)
+ break;
+ }
+
+ /* Take the lock again. */
+ err = glthread_lock_lock (lock);
+
+ /* Do the bookkeeping. */
+ EnterCriticalSection (&cond->lock);
+ cond->waiters_count--;
+ if (result == WAIT_OBJECT_0)
+ {
+ /* The wait terminated because the event was signaled.
+ Acknowledge the receipt. */
+ if (--cond->release_count == 0)
+ {
+ /* The last waiting thread to be notified has to reset
+ the event. */
+ ResetEvent (cond->event);
+ }
+ }
+ LeaveCriticalSection (&cond->lock);
+
+ return (err ? err :
+ ret == WAIT_OBJECT_0 ? 0 :
+ ret == WAIT_TIMEOUT ? ETIMEDOUT :
+ /* WAIT_FAILED shouldn't happen */ EAGAIN);
+ }
+ }
+ }
+}
+
+int
+glthread_cond_signal_func (gl_cond_t *cond)
+{
+ if (!cond->guard.done)
+ return EINVAL;
+
+ EnterCriticalSection (&cond->lock);
+ /* POSIX says:
+ "The pthread_cond_broadcast() and pthread_cond_signal() functions shall
+ have no effect if there are no threads currently blocked on cond."
+ Also, if waiters_count == release_count > 0, all blocked threads will
+ be unblocked soon anyway; do nothing in this case as well. */
+ if (cond->waiters_count > cond->release_count)
+ {
+ /* Signal the manual-reset event. */
+ SetEvent (cond->event);
+ /* ... and reset it is soon as one of the currently waiting threads has
+ acknowledged the receipt of the signal. */
+ cond->release_count++;
+ cond->wait_generation_count++;
+ }
+ LeaveCriticalSection (&cond->lock);
+
+ return 0;
+}
+
+int
+glthread_cond_broadcast_func (gl_cond_t *cond)
+{
+ if (!cond->guard.done)
+ return EINVAL;
+
+ EnterCriticalSection (&cond->lock);
+ /* POSIX says:
+ "The pthread_cond_broadcast() and pthread_cond_signal() functions shall
+ have no effect if there are no threads currently blocked on cond." */
+ if (cond->waiters_count > 0)
+ {
+ /* Signal the manual-reset event. */
+ SetEvent (cond->event);
+ /* ... and reset it only after all currently waiting threads have
+ acknowledged the receipt of the signal. */
+ cond->release_count = cond->waiters_count;
+ cond->wait_generation_count++;
+ }
+ LeaveCriticalSection (&cond->lock);
+
+ return 0;
+}
+
+int
+glthread_cond_destroy_func (gl_cond_t *cond)
+{
+ if (!cond->guard.done)
+ return EINVAL;
+ if (cond->waiters_count > 0)
+ return EBUSY;
+ CloseHandle (cond->event);
+ DeleteCriticalSection (&cond->lock);
+ cond->guard.done = 0;
+ return 0;
+}
+
+#endif
+
+/* ========================================================================= */
projects / gnulib.git / blobdiff