1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/nsprpub/pr/src/threads/prsem.c Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,138 @@
1.4 +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +#include "primpl.h"
1.10 +#include "obsolete/prsem.h"
1.11 +
1.12 +/************************************************************************/
1.13 +
1.14 +/*
1.15 +** Create a new semaphore.
1.16 +*/
1.17 +PR_IMPLEMENT(PRSemaphore*) PR_NewSem(PRUintn value)
1.18 +{
1.19 + PRSemaphore *sem;
1.20 + PRCondVar *cvar;
1.21 + PRLock *lock;
1.22 +
1.23 + sem = PR_NEWZAP(PRSemaphore);
1.24 + if (sem) {
1.25 +#ifdef HAVE_CVAR_BUILT_ON_SEM
1.26 + _PR_MD_NEW_SEM(&sem->md, value);
1.27 +#else
1.28 + lock = PR_NewLock();
1.29 + if (!lock) {
1.30 + PR_DELETE(sem);
1.31 + return NULL;
1.32 + }
1.33 +
1.34 + cvar = PR_NewCondVar(lock);
1.35 + if (!cvar) {
1.36 + PR_DestroyLock(lock);
1.37 + PR_DELETE(sem);
1.38 + return NULL;
1.39 + }
1.40 + sem->cvar = cvar;
1.41 + sem->count = value;
1.42 +#endif
1.43 + }
1.44 + return sem;
1.45 +}
1.46 +
1.47 +/*
1.48 +** Destroy a semaphore. There must be no thread waiting on the semaphore.
1.49 +** The caller is responsible for guaranteeing that the semaphore is
1.50 +** no longer in use.
1.51 +*/
1.52 +PR_IMPLEMENT(void) PR_DestroySem(PRSemaphore *sem)
1.53 +{
1.54 +#ifdef HAVE_CVAR_BUILT_ON_SEM
1.55 + _PR_MD_DESTROY_SEM(&sem->md);
1.56 +#else
1.57 + PR_ASSERT(sem->waiters == 0);
1.58 +
1.59 + PR_DestroyLock(sem->cvar->lock);
1.60 + PR_DestroyCondVar(sem->cvar);
1.61 +#endif
1.62 + PR_DELETE(sem);
1.63 +}
1.64 +
1.65 +/*
1.66 +** Wait on a Semaphore.
1.67 +**
1.68 +** This routine allows a calling thread to wait or proceed depending upon the
1.69 +** state of the semahore sem. The thread can proceed only if the counter value
1.70 +** of the semaphore sem is currently greater than 0. If the value of semaphore
1.71 +** sem is positive, it is decremented by one and the routine returns immediately
1.72 +** allowing the calling thread to continue. If the value of semaphore sem is 0,
1.73 +** the calling thread blocks awaiting the semaphore to be released by another
1.74 +** thread.
1.75 +**
1.76 +** This routine can return PR_PENDING_INTERRUPT if the waiting thread
1.77 +** has been interrupted.
1.78 +*/
1.79 +PR_IMPLEMENT(PRStatus) PR_WaitSem(PRSemaphore *sem)
1.80 +{
1.81 + PRStatus status = PR_SUCCESS;
1.82 +
1.83 +#ifdef HAVE_CVAR_BUILT_ON_SEM
1.84 + return _PR_MD_WAIT_SEM(&sem->md);
1.85 +#else
1.86 + PR_Lock(sem->cvar->lock);
1.87 + while (sem->count == 0) {
1.88 + sem->waiters++;
1.89 + status = PR_WaitCondVar(sem->cvar, PR_INTERVAL_NO_TIMEOUT);
1.90 + sem->waiters--;
1.91 + if (status != PR_SUCCESS)
1.92 + break;
1.93 + }
1.94 + if (status == PR_SUCCESS)
1.95 + sem->count--;
1.96 + PR_Unlock(sem->cvar->lock);
1.97 +#endif
1.98 +
1.99 + return (status);
1.100 +}
1.101 +
1.102 +/*
1.103 +** This routine increments the counter value of the semaphore. If other threads
1.104 +** are blocked for the semaphore, then the scheduler will determine which ONE
1.105 +** thread will be unblocked.
1.106 +*/
1.107 +PR_IMPLEMENT(void) PR_PostSem(PRSemaphore *sem)
1.108 +{
1.109 +#ifdef HAVE_CVAR_BUILT_ON_SEM
1.110 + _PR_MD_POST_SEM(&sem->md);
1.111 +#else
1.112 + PR_Lock(sem->cvar->lock);
1.113 + if (sem->waiters)
1.114 + PR_NotifyCondVar(sem->cvar);
1.115 + sem->count++;
1.116 + PR_Unlock(sem->cvar->lock);
1.117 +#endif
1.118 +}
1.119 +
1.120 +#if DEBUG
1.121 +/*
1.122 +** Returns the value of the semaphore referenced by sem without affecting
1.123 +** the state of the semaphore. The value represents the semaphore vaule
1.124 +** at the time of the call, but may not be the actual value when the
1.125 +** caller inspects it. (FOR DEBUGGING ONLY)
1.126 +*/
1.127 +PR_IMPLEMENT(PRUintn) PR_GetValueSem(PRSemaphore *sem)
1.128 +{
1.129 + PRUintn rv;
1.130 +
1.131 +#ifdef HAVE_CVAR_BUILT_ON_SEM
1.132 + rv = _PR_MD_GET_VALUE_SEM(&sem->md);
1.133 +#else
1.134 + PR_Lock(sem->cvar->lock);
1.135 + rv = sem->count;
1.136 + PR_Unlock(sem->cvar->lock);
1.137 +#endif
1.138 +
1.139 + return rv;
1.140 +}
1.141 +#endif
