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// Copyright (c) 2007-2009 Nokia Corporation and/or its subsidiary(-ies).
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// All rights reserved.
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// This component and the accompanying materials are made available
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// under the terms of the License "Eclipse Public License v1.0"
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// which accompanies this distribution, and is available
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// at the URL "http://www.eclipse.org/legal/epl-v10.html".
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//
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// Initial Contributors:
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// Nokia Corporation - initial contribution.
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//
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// Contributors:
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//
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// Description:
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//
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/**
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@file
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@internalComponent
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*/
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#ifndef MREFCNTOBJ_H
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#define MREFCNTOBJ_H
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#include <klib.h>
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/**
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Base class for creating reference counted objects.
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This provide basic reference counting and asynchronous cleanup
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for derived classes. An object whose reference count reaches zero
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will be destroyed.
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*/
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class DReferenceCountedObject : public DBase
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{
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public:
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/**
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Constructs this object with an initial reference count of one.
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*/
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DReferenceCountedObject();
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/**
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Atomically increment this object's reference count.
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A fault is raised if the count was initially <= 0.
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@pre Calling thread must be in a critical section
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@pre #iReferenceCount>0
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*/
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void Open();
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/**
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Atomically increment this object's reference count if it
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was initially > 0.
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This is for use in situations where a reference counted object
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is found by looking in a list, and the list may contain
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objects which have had their reference counts decremented
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to zero and are in the process of being cleaned up. A failure
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to open a reference on these objects should be taken as an
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indication that the object should be ignored, and treated as
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though it were never found.
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@return True if the count was incremented.
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False if it wasn't: because it was initially <= 0.
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@pre Calling thread must be in a critical section
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*/
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TBool TryOpen();
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/**
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Decrement this object's reference count and if it reaches zero,
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delete this object.
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@pre Calling thread must be in a critical section.
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@pre No fast mutex can be held.
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@pre No mutexes with order greater less than KMutexOrdKernelHeap can be held.
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*/
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void Close();
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/**
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Decrement this object's reference count and if this reaches zero,
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queue this object for asynchronous deletion.
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@pre Calling thread must be in a critical section.
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@pre No fast mutex can be held.
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*/
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void AsyncClose();
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protected:
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/**
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Destructor which asserts in debug builds that the object's reference count is zero.
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*/
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virtual ~DReferenceCountedObject();
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/**
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Return true if the preconditions for #Close are met.
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This is for use by derived classes which overload the #Close method.
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*/
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TBool CheckCloseIsSafe();
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/**
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Return true if the preconditions for #AsyncClose are met.
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This is for use by derived classes which overload the #AsyncClose method.
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*/
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TBool CheckAsyncCloseIsSafe();
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protected:
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/**
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This object's reference count. Must always be >= 0.
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*/
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TInt iReferenceCount;
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};
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FORCE_INLINE DReferenceCountedObject::DReferenceCountedObject()
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: iReferenceCount(1)
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{
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}
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#endif
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