sl@0: // Copyright (c) 2005-2009 Nokia Corporation and/or its subsidiary(-ies).
sl@0: // All rights reserved.
sl@0: // This component and the accompanying materials are made available
sl@0: // under the terms of "Eclipse Public License v1.0"
sl@0: // which accompanies this distribution, and is available
sl@0: // at the URL "http://www.eclipse.org/legal/epl-v10.html".
sl@0: //
sl@0: // Initial Contributors:
sl@0: // Nokia Corporation - initial contribution.
sl@0: //
sl@0: // Contributors:
sl@0: //
sl@0: // Description:
sl@0: // Name        : condvar.cpp
sl@0: // Part of     : pthread
sl@0: // Interface   : POSIX, pthread
sl@0: // POSIX implementation of pthread on Symbian
sl@0: // Version     :
sl@0: //
sl@0: 
sl@0: 
sl@0: 
sl@0: #include "condvartypes.h"
sl@0: 
sl@0: /*
sl@0: This internal function initializes the passed queue to be an empty queue
sl@0: */
sl@0: bool _QueueInit(_CondQueue* aQueue)
sl@0: {
sl@0:     if(!aQueue)
sl@0:     {
sl@0:         return false;
sl@0:     }
sl@0:     pthread_mutex_init(&aQueue->iMutex,NULL);
sl@0:     aQueue->iHead = aQueue->iTail = NULL;
sl@0:     return true;
sl@0: }
sl@0: 
sl@0: /*
sl@0: This internal function destroys the passed 
sl@0: */
sl@0: int _QueueDestroy(_CondQueue* aQueue)
sl@0: {
sl@0:     if(!aQueue)
sl@0:     {
sl@0:         return EINVAL;
sl@0:     }
sl@0:     pthread_mutex_lock(&aQueue->iMutex);
sl@0:     _CondNode* head = aQueue->iHead;
sl@0:     pthread_mutex_unlock(&aQueue->iMutex);
sl@0:     if (head) 
sl@0:     {
sl@0:         return EBUSY;   
sl@0:     }
sl@0:     else
sl@0:     {
sl@0:         return pthread_mutex_destroy(&aQueue->iMutex);
sl@0:     }
sl@0: }
sl@0: 
sl@0: 
sl@0: /*
sl@0: This internal function atomically adds a element
sl@0: to the passed queue
sl@0: */
sl@0: bool _QueueAdd(_CondQueue* aQueue, _CondNode* aNode)
sl@0: {
sl@0:     if( (!aQueue) || (!aNode) )
sl@0:     {
sl@0:         return false;
sl@0:     }
sl@0:     aNode->iNext = NULL;
sl@0:     pthread_mutex_lock(&aQueue->iMutex);
sl@0:     if(!(aQueue->iHead))
sl@0:     {
sl@0:         aQueue->iHead = aQueue->iTail = aNode;
sl@0:     }
sl@0:     else
sl@0:     {
sl@0:         aQueue->iTail->iNext = aNode;
sl@0:         aQueue->iTail = aNode;
sl@0:     }
sl@0:     pthread_mutex_unlock(&aQueue->iMutex);
sl@0:     return true;
sl@0: }
sl@0:   
sl@0:     
sl@0: /*
sl@0: This internal function atomically removes the pased element
sl@0: from the queue
sl@0: */
sl@0: bool _QueueRemove(_CondQueue* aQueue, _CondNode* aNode)
sl@0: {
sl@0:     if( (!aQueue) || (!aNode) )
sl@0:     {
sl@0:         return false;
sl@0:     }
sl@0:     pthread_mutex_lock(&aQueue->iMutex);
sl@0:         
sl@0:     _CondNode* prev = NULL;
sl@0:     _CondNode* node = aQueue->iHead;
sl@0:     for(; node; node = node->iNext)
sl@0:     {
sl@0:         if(node == aNode)
sl@0:         {
sl@0:             break;
sl@0:         }
sl@0:         prev = node;
sl@0:     }
sl@0:     if(node)
sl@0:     {
sl@0:         if(node == aQueue->iHead)
sl@0:         {
sl@0:             aQueue->iHead = node->iNext;
sl@0:         }
sl@0:         if(node == aQueue->iTail)
sl@0:         {
sl@0:             aQueue->iTail = prev;
sl@0:         }
sl@0:         if(prev)
sl@0:         {
sl@0:             prev->iNext = node->iNext;
sl@0:         }
sl@0:     }// node found
sl@0:     pthread_mutex_unlock(&aQueue->iMutex);
sl@0:     return (node) ? true : false;
sl@0: }
sl@0: 
sl@0: /*
sl@0: This internal function atomically removes the head of the queue, and
sl@0: returns a pointer to this node
sl@0: */
sl@0: _CondNode* _QueueRemoveHead(_CondQueue* aQueue)
sl@0: {
sl@0:     _CondNode* retNode = NULL;
sl@0:     pthread_mutex_lock(&aQueue->iMutex);
sl@0:     retNode = aQueue->iHead;
sl@0:     if(retNode)
sl@0:     {
sl@0:         aQueue->iHead = retNode->iNext;
sl@0:         if(aQueue->iTail == retNode)
sl@0:         {
sl@0:             aQueue->iTail = aQueue->iHead = NULL;
sl@0:         }
sl@0:     }
sl@0:     pthread_mutex_unlock(&aQueue->iMutex);
sl@0:     return retNode;
sl@0: }
sl@0: 
sl@0: 
sl@0: /*
sl@0: This internal function  removes the head of the queue, and
sl@0: returns a pointer to this node WITHOUT locking the associated mutex
sl@0: */
sl@0: _CondNode* _QueueRemoveHeadNoLock(_CondQueue* aQueue)
sl@0: {
sl@0:     _CondNode* retNode = NULL;
sl@0:     retNode = aQueue->iHead;
sl@0:     if(retNode)
sl@0:     {
sl@0:         aQueue->iHead = retNode->iNext;
sl@0:         if(aQueue->iTail == retNode)
sl@0:         {
sl@0:             aQueue->iTail = aQueue->iHead = NULL;
sl@0:         }
sl@0:     }
sl@0:     return retNode;
sl@0: }
sl@0: 
sl@0: /*
sl@0: This internal function  locks the queue mutex
sl@0: */
sl@0: void  _QueueLock(_CondQueue* aQueue)
sl@0: {
sl@0:     pthread_mutex_lock(&aQueue->iMutex);
sl@0: }
sl@0: 
sl@0: /*
sl@0: This internal function  unlocks the queue mutex
sl@0: */
sl@0: void  _QueueUnlock(_CondQueue* aQueue)
sl@0: {
sl@0:     pthread_mutex_unlock(&aQueue->iMutex);
sl@0: }
sl@0: 
sl@0: /*
sl@0: This internal function atomically resolves the race to dynamically initialize a static cond var
sl@0: */
sl@0: bool _staticCondInit(pthread_cond_t* cond)
sl@0: {
sl@0:     if(!cond)
sl@0:     {
sl@0:         return false;
sl@0:     }
sl@0:     if(cond->iState == _EInitialized)
sl@0:     {
sl@0:         return true;
sl@0:     }
sl@0: 
sl@0: 
sl@0:     if(cond->iState != _ENeedsNormalInit)
sl@0:     {
sl@0:         return false;
sl@0:     }
sl@0:     int retval=0;
sl@0: 
sl@0:     #ifndef NOUSE_INTERNALS
sl@0:     void* tlsPtr;
sl@0: 
sl@0:     // Get the TLS pointer
sl@0:     tlsPtr = _pthread_getTls();  
sl@0:     if(NULL == tlsPtr)
sl@0:     {
sl@0:         return false;
sl@0:     }
sl@0:     _pthread_atomicMutexLock(tlsPtr);
sl@0:     #endif
sl@0: 
sl@0:     //another thread might win race
sl@0:     if(cond->iState != _EInitialized)
sl@0:     {
sl@0:         retval = pthread_cond_init(cond,NULL);
sl@0:     }
sl@0: 
sl@0:     #ifndef NOUSE_INTERNALS
sl@0:     _pthread_atomicMutexUnlock(tlsPtr);
sl@0:     #endif
sl@0:     if(retval == 0)
sl@0:     {
sl@0:         return true;
sl@0:     }
sl@0:     else
sl@0:     {
sl@0:         return false;
sl@0:     }
sl@0: }
sl@0: 
sl@0: /*
sl@0: This internal function provides the functionality to wait on a condition variable,
sl@0: */
sl@0: int _internalCondWait(pthread_cond_t *cond, pthread_mutex_t *mutex,const struct timespec *abstime)
sl@0: {
sl@0:     if(!_staticCondInit(cond))
sl@0:     {
sl@0:         return EINVAL;
sl@0:     }
sl@0:     
sl@0:     _CondNode* newNode = new _CondNode;  
sl@0:     if(!newNode)
sl@0:     {
sl@0:         return ENOMEM;
sl@0:     }
sl@0:     sem_init(&newNode->iSemaphore,0,0);
sl@0:       
sl@0:     _QueueAdd(&cond->iQueue,newNode);
sl@0: 
sl@0:     int retval=0;
sl@0:     
sl@0:     //unlock passed mutex
sl@0:     retval = pthread_mutex_unlock(mutex);
sl@0:     if(retval != 0)
sl@0:     {
sl@0:         _QueueRemove(&cond->iQueue,newNode);
sl@0:         sem_destroy(&newNode->iSemaphore);
sl@0:         delete newNode; 
sl@0:         errno = 0; // Condition variables should not set errno
sl@0:         return retval;
sl@0:     }    
sl@0: 
sl@0:     //node removed from queue by pthread_cond_signal or pthread_cond_broadcast
sl@0:     //by timeout below
sl@0:     if(abstime)
sl@0:     {
sl@0:         retval = sem_timedwait(&newNode->iSemaphore,abstime);   
sl@0:         if(retval != 0)
sl@0:         {
sl@0:             _QueueRemove(&cond->iQueue,newNode);
sl@0:         }//timed_wait timedout
sl@0:     }
sl@0:     else
sl@0:     {
sl@0:         retval = sem_wait(&newNode->iSemaphore);    
sl@0:     }
sl@0:     if(retval != 0)
sl@0:     {
sl@0:         retval = errno;
sl@0:     }
sl@0:     sem_destroy(&newNode->iSemaphore);
sl@0:     delete newNode; 
sl@0:     /* This is a cancellation point */
sl@0:     //test for cancel
sl@0:     pthread_testcancel();
sl@0: 
sl@0:     //lock the passed mutex
sl@0:     pthread_mutex_lock(mutex);
sl@0: 
sl@0:     errno = 0; // Condition variables should not set errno
sl@0:     return retval;
sl@0: }
sl@0: 
sl@0: //End of File