86 lines
1.6 KiB
C++
86 lines
1.6 KiB
C++
//+---------------------------------------------------------------------------
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//
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// Microsoft Windows
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// Copyright (C) Microsoft Corporation, 1994 - 1997.
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//
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// File: Refcount.hxx
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//
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// Contents: For refcounting, under lock
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//
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// Classes: CRefCount
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//
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// History: 09-Feb-94 KyleP Created
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//
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//----------------------------------------------------------------------------
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#pragma once
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class CRefCount
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{
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public:
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inline CRefCount();
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inline ~CRefCount();
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inline void AddRef();
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inline void Release();
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inline void Wait();
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private:
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CMutexSem _mtx; // Refcount incremented under lock
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CEventSem _evt; // Set when _cRef drops to 1
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unsigned _cRef; // RefCount
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};
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inline CRefCount::CRefCount()
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: _cRef( 1 )
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{
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}
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inline CRefCount::~CRefCount()
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{
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//
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// We must take the lock here. Otherwise some other thread may have set
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// _evt (under lock) but not yet have run to completion and
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// released _mtx. If we finish executing this destructor before
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// _mtx is released, _mtx will have been deleted before _mtx.Release()
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// is called. Bad news!
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//
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CLock lock( _mtx );
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}
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inline void CRefCount::AddRef()
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{
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CLock lock( _mtx );
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_cRef++;
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}
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inline void CRefCount::Release()
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{
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CLock lock( _mtx );
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_cRef--;
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if ( _cRef == 1 )
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_evt.Set();
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}
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inline void CRefCount::Wait()
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{
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{
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CLock lock( _mtx );
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if ( _cRef > 1 )
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_evt.Reset();
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else
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return;
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}
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_evt.Wait();
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}
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