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authorLoo Rong Jie <loorongjie@gmail.com>2018-11-13 18:52:35 (GMT)
committerJunio C Hamano <gitster@pobox.com>2018-11-14 06:14:22 (GMT)
commitc73b7ad5481647545020bcfabb0fe679792b20db (patch)
tree7c4a554dcf4824eac713310fd72e9f24f3aead32 /compat/win32/pthread.c
parentd166e6afe5f257217836ef24a73764eba390c58d (diff)
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win32: replace pthread_cond_*() with much simpler code
The Win32 CONDITION_VARIABLE has better performance and is easier to maintain, as the code is a lot shorter now (the semantics of the CONDITION_VARIABLE matches the pthread_cond_t very well). Note: CONDITION_VARIABLE is not available in Windows XP and below, but the declared minimal Windows version required to build and run Git for Windows is Windows Vista (which is also beyond its end-of-life, but for less long than Windows XP), so that's okay. Signed-off-by: Loo Rong Jie <loorongjie@gmail.com> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'compat/win32/pthread.c')
-rw-r--r--compat/win32/pthread.c138
1 files changed, 0 insertions, 138 deletions
diff --git a/compat/win32/pthread.c b/compat/win32/pthread.c
index e18f5c6..2e7eead 100644
--- a/compat/win32/pthread.c
+++ b/compat/win32/pthread.c
@@ -56,141 +56,3 @@ pthread_t pthread_self(void)
t.tid = GetCurrentThreadId();
return t;
}
-
-int pthread_cond_init(pthread_cond_t *cond, const void *unused)
-{
- cond->waiters = 0;
- cond->was_broadcast = 0;
- InitializeCriticalSection(&cond->waiters_lock);
-
- cond->sema = CreateSemaphore(NULL, 0, LONG_MAX, NULL);
- if (!cond->sema)
- die("CreateSemaphore() failed");
-
- cond->continue_broadcast = CreateEvent(NULL, /* security */
- FALSE, /* auto-reset */
- FALSE, /* not signaled */
- NULL); /* name */
- if (!cond->continue_broadcast)
- die("CreateEvent() failed");
-
- return 0;
-}
-
-int pthread_cond_destroy(pthread_cond_t *cond)
-{
- CloseHandle(cond->sema);
- CloseHandle(cond->continue_broadcast);
- DeleteCriticalSection(&cond->waiters_lock);
- return 0;
-}
-
-int pthread_cond_wait(pthread_cond_t *cond, CRITICAL_SECTION *mutex)
-{
- int last_waiter;
-
- EnterCriticalSection(&cond->waiters_lock);
- cond->waiters++;
- LeaveCriticalSection(&cond->waiters_lock);
-
- /*
- * Unlock external mutex and wait for signal.
- * NOTE: we've held mutex locked long enough to increment
- * waiters count above, so there's no problem with
- * leaving mutex unlocked before we wait on semaphore.
- */
- LeaveCriticalSection(mutex);
-
- /* let's wait - ignore return value */
- WaitForSingleObject(cond->sema, INFINITE);
-
- /*
- * Decrease waiters count. If we are the last waiter, then we must
- * notify the broadcasting thread that it can continue.
- * But if we continued due to cond_signal, we do not have to do that
- * because the signaling thread knows that only one waiter continued.
- */
- EnterCriticalSection(&cond->waiters_lock);
- cond->waiters--;
- last_waiter = cond->was_broadcast && cond->waiters == 0;
- LeaveCriticalSection(&cond->waiters_lock);
-
- if (last_waiter) {
- /*
- * cond_broadcast was issued while mutex was held. This means
- * that all other waiters have continued, but are contending
- * for the mutex at the end of this function because the
- * broadcasting thread did not leave cond_broadcast, yet.
- * (This is so that it can be sure that each waiter has
- * consumed exactly one slice of the semaphor.)
- * The last waiter must tell the broadcasting thread that it
- * can go on.
- */
- SetEvent(cond->continue_broadcast);
- /*
- * Now we go on to contend with all other waiters for
- * the mutex. Auf in den Kampf!
- */
- }
- /* lock external mutex again */
- EnterCriticalSection(mutex);
-
- return 0;
-}
-
-/*
- * IMPORTANT: This implementation requires that pthread_cond_signal
- * is called while the mutex is held that is used in the corresponding
- * pthread_cond_wait calls!
- */
-int pthread_cond_signal(pthread_cond_t *cond)
-{
- int have_waiters;
-
- EnterCriticalSection(&cond->waiters_lock);
- have_waiters = cond->waiters > 0;
- LeaveCriticalSection(&cond->waiters_lock);
-
- /*
- * Signal only when there are waiters
- */
- if (have_waiters)
- return ReleaseSemaphore(cond->sema, 1, NULL) ?
- 0 : err_win_to_posix(GetLastError());
- else
- return 0;
-}
-
-/*
- * DOUBLY IMPORTANT: This implementation requires that pthread_cond_broadcast
- * is called while the mutex is held that is used in the corresponding
- * pthread_cond_wait calls!
- */
-int pthread_cond_broadcast(pthread_cond_t *cond)
-{
- EnterCriticalSection(&cond->waiters_lock);
-
- if ((cond->was_broadcast = cond->waiters > 0)) {
- /* wake up all waiters */
- ReleaseSemaphore(cond->sema, cond->waiters, NULL);
- LeaveCriticalSection(&cond->waiters_lock);
- /*
- * At this point all waiters continue. Each one takes its
- * slice of the semaphor. Now it's our turn to wait: Since
- * the external mutex is held, no thread can leave cond_wait,
- * yet. For this reason, we can be sure that no thread gets
- * a chance to eat *more* than one slice. OTOH, it means
- * that the last waiter must send us a wake-up.
- */
- WaitForSingleObject(cond->continue_broadcast, INFINITE);
- /*
- * Since the external mutex is held, no thread can enter
- * cond_wait, and, hence, it is safe to reset this flag
- * without cond->waiters_lock held.
- */
- cond->was_broadcast = 0;
- } else {
- LeaveCriticalSection(&cond->waiters_lock);
- }
- return 0;
-}