/* * Copyright (c) 2002 Apple Computer, Inc. All rights reserved. * * @APPLE_LICENSE_HEADER_START@ * * This file contains Original Code and/or Modifications of Original Code * as defined in and that are subject to the Apple Public Source License * Version 2.0 (the 'License'). You may not use this file except in * compliance with the License. Please obtain a copy of the License at * http://www.opensource.apple.com/apsl/ and read it before using this * file. * * The Original Code and all software distributed under the License are * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. * Please see the License for the specific language governing rights and * limitations under the License. * * @APPLE_LICENSE_HEADER_END@ */ /*! * @header DSMutexSemaphore * Implementation of the DSMutexSemaphore ( mutually exclusive lock ) class. */ #include <errno.h> #include <sys/time.h> // for struct timespec and gettimeofday() #include "DSMutexSemaphore.h" //-------------------------------------------------------------------------------------------------- // DSMutexSemaphore class implementation //-------------------------------------------------------------------------------------------------- DSMutexSemaphore::DSMutexSemaphore ( bool owned ) : DSSemaphore ( owned ? 0 : 1 ), mOwner ( owned ? ::pthread_self() : NULL ) { } DSMutexSemaphore::~DSMutexSemaphore ( void ) { } void DSMutexSemaphore::Signal ( void ) { ::pthread_mutex_lock( &mConditionLock ); // If this is not the owning thread, simply return if ( mOwner != ::pthread_self() ) { ::pthread_mutex_unlock ( &mConditionLock ); return; } // Release the lock as mExcessSignals goes positive. if ( !mExcessSignals++ ) { mOwner = NULL; ::pthread_cond_signal( &mSemaphore ); } ::pthread_mutex_unlock ( &mConditionLock ); } // Signal sInt32 DSMutexSemaphore::Wait ( sInt32 milliSecs ) { // Unlike Mach's mutex_lock(), pthread_mutex_lock() is not a spin lock. // However, locking recursively on the mutex will cause a deadlock. // So, the pthread implementation mimics the cthread implementation: // the mutex locks access to the semaphore/condition. ::pthread_mutex_lock ( &mConditionLock ); // mOwner==NULL implies mExcessSignals==1 if ( mOwner == NULL ) { mOwner = ::pthread_self(); } else if ( mOwner != ::pthread_self() ) { if ( milliSecs == kNever ) { ::pthread_mutex_unlock ( &mConditionLock ); return semTimedOutErr; } if ( milliSecs == kForever ) { while ( !mDestroying && ( mExcessSignals <= 0 ) ) ::pthread_cond_wait ( &mSemaphore, &mConditionLock ); } else { struct timeval tvNow; struct timespec tsTimeout; // Timeout is passed as an absolute time! ::gettimeofday ( &tvNow, NULL ); TIMEVAL_TO_TIMESPEC ( &tvNow, &tsTimeout ); tsTimeout.tv_sec += ( milliSecs / 1000 ); tsTimeout.tv_nsec += ( ( milliSecs % 1000 ) * 1000000 ); while ( !mDestroying && ( mExcessSignals <= 0 ) ) if ( ETIMEDOUT == ::pthread_cond_timedwait ( &mSemaphore, &mConditionLock, &tsTimeout ) ) { ::pthread_mutex_unlock ( &mConditionLock ); return semTimedOutErr; } } if ( mDestroying ) { ::pthread_mutex_unlock ( &mConditionLock ); return semDestroyedErr; } mOwner = ::pthread_self(); } // The executing thread is guaranteed to have the lock at this point. mExcessSignals--; ::pthread_mutex_unlock ( &mConditionLock ); return( semNoErr ); } // Wait