diff options
Diffstat (limited to 'mozilla/nsprpub/pr/src/threads/prsem.c')
| -rw-r--r-- | mozilla/nsprpub/pr/src/threads/prsem.c | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/mozilla/nsprpub/pr/src/threads/prsem.c b/mozilla/nsprpub/pr/src/threads/prsem.c new file mode 100644 index 0000000..d26897c --- /dev/null +++ b/mozilla/nsprpub/pr/src/threads/prsem.c @@ -0,0 +1,170 @@ +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* ***** BEGIN LICENSE BLOCK ***** + * Version: MPL 1.1/GPL 2.0/LGPL 2.1 + * + * The contents of this file are subject to the Mozilla Public License Version + * 1.1 (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * http://www.mozilla.org/MPL/ + * + * Software distributed under the License is distributed on an "AS IS" basis, + * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License + * for the specific language governing rights and limitations under the + * License. + * + * The Original Code is the Netscape Portable Runtime (NSPR). + * + * The Initial Developer of the Original Code is + * Netscape Communications Corporation. + * Portions created by the Initial Developer are Copyright (C) 1998-2000 + * the Initial Developer. All Rights Reserved. + * + * Contributor(s): + * + * Alternatively, the contents of this file may be used under the terms of + * either the GNU General Public License Version 2 or later (the "GPL"), or + * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), + * in which case the provisions of the GPL or the LGPL are applicable instead + * of those above. If you wish to allow use of your version of this file only + * under the terms of either the GPL or the LGPL, and not to allow others to + * use your version of this file under the terms of the MPL, indicate your + * decision by deleting the provisions above and replace them with the notice + * and other provisions required by the GPL or the LGPL. If you do not delete + * the provisions above, a recipient may use your version of this file under + * the terms of any one of the MPL, the GPL or the LGPL. + * + * ***** END LICENSE BLOCK ***** */ + +#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 |