michael@0: /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "primpl.h"
michael@0: #include "obsolete/prsem.h"
michael@0: 
michael@0: /************************************************************************/
michael@0: 
michael@0: /*
michael@0: ** Create a new semaphore.
michael@0: */
michael@0: PR_IMPLEMENT(PRSemaphore*) PR_NewSem(PRUintn value)
michael@0: {
michael@0:     PRSemaphore *sem;
michael@0:     PRCondVar *cvar;
michael@0:     PRLock *lock;
michael@0: 
michael@0:     sem = PR_NEWZAP(PRSemaphore);
michael@0:     if (sem) {
michael@0: #ifdef HAVE_CVAR_BUILT_ON_SEM
michael@0:         _PR_MD_NEW_SEM(&sem->md, value);
michael@0: #else
michael@0:         lock = PR_NewLock();
michael@0:         if (!lock) {
michael@0:             PR_DELETE(sem);
michael@0:             return NULL;
michael@0:     	}
michael@0: 
michael@0:         cvar = PR_NewCondVar(lock);
michael@0:         if (!cvar) {
michael@0:             PR_DestroyLock(lock);
michael@0:             PR_DELETE(sem);
michael@0:             return NULL;
michael@0:     	}
michael@0:     	sem->cvar = cvar;
michael@0:     	sem->count = value;
michael@0: #endif
michael@0:     }
michael@0:     return sem;
michael@0: }
michael@0: 
michael@0: /*
michael@0: ** Destroy a semaphore. There must be no thread waiting on the semaphore.
michael@0: ** The caller is responsible for guaranteeing that the semaphore is
michael@0: ** no longer in use.
michael@0: */
michael@0: PR_IMPLEMENT(void) PR_DestroySem(PRSemaphore *sem)
michael@0: {
michael@0: #ifdef HAVE_CVAR_BUILT_ON_SEM
michael@0:     _PR_MD_DESTROY_SEM(&sem->md);
michael@0: #else
michael@0:     PR_ASSERT(sem->waiters == 0);
michael@0: 
michael@0:     PR_DestroyLock(sem->cvar->lock);
michael@0:     PR_DestroyCondVar(sem->cvar);
michael@0: #endif
michael@0:     PR_DELETE(sem);
michael@0: }
michael@0: 
michael@0: /*
michael@0: ** Wait on a Semaphore.
michael@0: ** 
michael@0: ** This routine allows a calling thread to wait or proceed depending upon the 
michael@0: ** state of the semahore sem. The thread can proceed only if the counter value 
michael@0: ** of the semaphore sem is currently greater than 0. If the value of semaphore 
michael@0: ** sem is positive, it is decremented by one and the routine returns immediately 
michael@0: ** allowing the calling thread to continue. If the value of semaphore sem is 0, 
michael@0: ** the calling thread blocks awaiting the semaphore to be released by another 
michael@0: ** thread.
michael@0: ** 
michael@0: ** This routine can return PR_PENDING_INTERRUPT if the waiting thread 
michael@0: ** has been interrupted.
michael@0: */
michael@0: PR_IMPLEMENT(PRStatus) PR_WaitSem(PRSemaphore *sem)
michael@0: {
michael@0: 	PRStatus status = PR_SUCCESS;
michael@0: 
michael@0: #ifdef HAVE_CVAR_BUILT_ON_SEM
michael@0: 	return _PR_MD_WAIT_SEM(&sem->md);
michael@0: #else
michael@0: 	PR_Lock(sem->cvar->lock);
michael@0: 	while (sem->count == 0) {
michael@0: 		sem->waiters++;
michael@0: 		status = PR_WaitCondVar(sem->cvar, PR_INTERVAL_NO_TIMEOUT);
michael@0: 		sem->waiters--;
michael@0: 		if (status != PR_SUCCESS)
michael@0: 			break;
michael@0: 	}
michael@0: 	if (status == PR_SUCCESS)
michael@0: 		sem->count--;
michael@0: 	PR_Unlock(sem->cvar->lock);
michael@0: #endif
michael@0: 	
michael@0: 	return (status);
michael@0: }
michael@0: 
michael@0: /*
michael@0: ** This routine increments the counter value of the semaphore. If other threads 
michael@0: ** are blocked for the semaphore, then the scheduler will determine which ONE 
michael@0: ** thread will be unblocked.
michael@0: */
michael@0: PR_IMPLEMENT(void) PR_PostSem(PRSemaphore *sem)
michael@0: {
michael@0: #ifdef HAVE_CVAR_BUILT_ON_SEM
michael@0: 	_PR_MD_POST_SEM(&sem->md);
michael@0: #else
michael@0: 	PR_Lock(sem->cvar->lock);
michael@0: 	if (sem->waiters)
michael@0: 		PR_NotifyCondVar(sem->cvar);
michael@0: 	sem->count++;
michael@0: 	PR_Unlock(sem->cvar->lock);
michael@0: #endif
michael@0: }
michael@0: 
michael@0: #if DEBUG
michael@0: /*
michael@0: ** Returns the value of the semaphore referenced by sem without affecting
michael@0: ** the state of the semaphore.  The value represents the semaphore vaule
michael@0: ** at the time of the call, but may not be the actual value when the
michael@0: ** caller inspects it. (FOR DEBUGGING ONLY)
michael@0: */
michael@0: PR_IMPLEMENT(PRUintn) PR_GetValueSem(PRSemaphore *sem)
michael@0: {
michael@0: 	PRUintn rv;
michael@0: 
michael@0: #ifdef HAVE_CVAR_BUILT_ON_SEM
michael@0: 	rv = _PR_MD_GET_VALUE_SEM(&sem->md);
michael@0: #else
michael@0: 	PR_Lock(sem->cvar->lock);
michael@0: 	rv = sem->count;
michael@0: 	PR_Unlock(sem->cvar->lock);
michael@0: #endif
michael@0: 	
michael@0: 	return rv;
michael@0: }
michael@0: #endif