00001 // Copyright (c) 2008-2009 Nokia Corporation and/or its subsidiary(-ies). +00002 // All rights reserved. +00003 // This component and the accompanying materials are made available +00004 // under the terms of "Eclipse Public License v1.0" +00005 // which accompanies this distribution, and is available +00006 // at the URL "http://www.eclipse.org/legal/epl-v10.html". +00007 // +00008 // Initial Contributors: +00009 // Nokia Corporation - initial contribution. +00010 // +00011 // Contributors: +00012 // +00013 // Description: +00014 // Contains the definition of member functions of the CQueue class. +00015 // +00016 +00017 +00018 +00023 #include "queue.h" +00024 +00029 CQueue* CQueue::NewL() +00030 { +00031 CQueue* self = new (ELeave)CQueue; +00032 CleanupStack::PushL(self); +00033 self->ConstructL(); +00034 CleanupStack::Pop(self); +00035 return self; +00036 } +00037 +00043 void CQueue::ConstructL() +00044 { +00045 // Create the local RMutex variable. +00046 User::LeaveIfError(iMutex.CreateLocal()); +00047 // Create the local RCondVar variable. +00048 User::LeaveIfError(iCondVar.CreateLocal()); +00049 } +00050 +00054 CQueue::CQueue() +00055 { +00056 } +00057 +00062 void CQueue::Insert() +00063 { +00064 // Wait for the mutex. +00065 // The mutex is required to ensure that only one thread updates iArray at a time. +00066 iMutex.Wait(); +00067 // Insertion operation. +00068 // Insert some random number as a token into the queue. +00069 iArray.Append(Math::Random()%10); +00070 // Signal the local condition variable to indicate that queue has new data. +00071 iCondVar.Signal(); +00072 // release the mutex so that the other thread has access to iArray. +00073 iMutex.Signal(); +00074 // RCondVar::Broadcast() can be used as an alternative to the RCondVar::Signal() function. +00075 // It is more relevant to use Broadcast() when more than two threads are blocking on single condition variable. +00076 // The following code block illustrates the use of the Broadcast() function. +00077 // +00078 //if(!IsEmpty()) +00079 // { +00080 // iCondVar.Broadcast(); +00081 // iMutex.Signal(); +00082 // } +00083 // +00084 } +00085 +00090 void CQueue::Remove() +00091 { +00092 // Ensures that mutex is held by the current thread. +00093 iMutex.Wait(); +00094 // Test to see whether there is anything in the queue before attempting to remove an item. +00095 // If the queue is empty wait for a signal on the Condition Variable before proceeding +00096 while(!IsEmpty()) +00097 { +00098 // The following call blocks this thread and releases the mutex so that the other thread can update the shared data. +00099 // When the other thread signals iCondVar and releases the mutex this thread continues. +00100 iCondVar.Wait(iMutex); +00101 // If there were more than one consumer waiting for the same signal +00102 // it would be essential to test IsEmpty() again because another thread, or threads, +00103 // might have got the mutex before this one and emptied the array. +00104 // For this reason if is good practise to use while( IsEmpty() ) instead of if( IsEmpty() ). +00105 } +00106 // Deletion operation. +00107 iArray.Remove(0); +00108 // Release the mutex. +00109 iMutex.Signal(); +00110 } +00111 +00116 TBool CQueue::IsEmpty() +00117 { +00118 if(iArray.Count() > 0) +00119 { +00120 return ETrue; +00121 } +00122 return EFalse; +00123 } +00124 +00129 void CQueue::GetTokens(RArray<TInt>& aArray) +00130 { +00131 for(TInt ix = 0; ix < iArray.Count(); ix++) +00132 { +00133 aArray.Append(iArray[ix]); +00134 } +00135 } +00136 +00140 CQueue::~CQueue() +00141 { +00142 iMutex.Close(); +00143 iCondVar.Close(); +00144 } +
1.6.2
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