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