On Thu, Jan 07, 2010 at 10:54:57PM +0100, Johannes Sixt wrote:
> +
> +int pthread_cond_init(pthread_cond_t *cond, const void *unused)
> +{
> + cond->waiters = 0;
> +
> + InitializeCriticalSection(&cond->waiters_lock);
Is waiters_lock really necessary?
> +
> +int pthread_cond_wait(pthread_cond_t *cond, CRITICAL_SECTION *mutex)
> +{
> + /* serialize access to waiters count */
> + EnterCriticalSection(&cond->waiters_lock);
> + ++cond->waiters;
> + LeaveCriticalSection(&cond->waiters_lock);
InterlockedIncrement(&cond->waiters);
> +
> + /*
> + * 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);
> +
> + /* we're done waiting, so make sure we decrease waiters count */
> + EnterCriticalSection(&cond->waiters_lock);
> + --cond->waiters;
> + LeaveCriticalSection(&cond->waiters_lock);
InterlockedDecrement(&cond->waiters);
> +
> + /* lock external mutex again */
> + EnterCriticalSection(mutex);
> +
> + return 0;
> +}
> +
> +int pthread_cond_signal(pthread_cond_t *cond)
> +{
> + int have_waiters;
> +
> + /* serialize access to waiters count */
> + EnterCriticalSection(&cond->waiters_lock);
> + have_waiters = cond->waiters > 0;
> + LeaveCriticalSection(&cond->waiters_lock);
AFAIK, Win32 API assumes that reading LONG is always atomic, so
the critical section is not really necesary here, but you need
to declare 'waiters' as 'volatile':
> + */
> +typedef struct {
> + LONG waiters;
volatile LONG waiters;
> + CRITICAL_SECTION waiters_lock;
> + HANDLE sema;
> +} pthread_cond_t;
> +
Dmitry
--
To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html