155 lines
4 KiB
C++
155 lines
4 KiB
C++
//+---------------------------------------------------------------------------
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//
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// Microsoft Windows
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// Copyright (C) Microsoft Corporation, 2000.
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//
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// File: U P S Y N C . H
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//
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// Contents: Synchronization classes
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//
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// Notes:
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//
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// Author: mbend 17 Aug 2000
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//
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//----------------------------------------------------------------------------
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#pragma once
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#include "ncbase.h"
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//+---------------------------------------------------------------------------
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//
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// Class: CUCriticalSection
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//
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// Purpose: Wrapper for Win32 critical sections
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//
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// Author: mbend 17 Aug 2000
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//
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// Notes:
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// The most important and lightweight Windows NT synchronization primitive.
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// Allows only one thread to enter itself at a single time.
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// An important property of critical sections is that they are
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// thread reentrant which means that if a thread owns a critical
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// section and tries to enter it again, the thread is allowed to
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// do so. When exiting the lock, the lock is not freed until it is
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// exited once for each time that it was entered.
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//
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// Critical sections are lightweight because they are not kernel
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// objects. Instead they are implemented through a simple in
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// memory structure CRITICAL_SECTION. If there is no thread
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// contention, they are implemented by simple memory operations
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// and spin locks that are hundreds of times faster than
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// alternative kernel object solutions such as mutexes. However,
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// if there is thread contention, critical sections degraded into
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// kernel objects.
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//
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class CUCriticalSection
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{
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public:
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CUCriticalSection()
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{
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InitializeCriticalSection(&m_critsec);
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}
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~CUCriticalSection()
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{
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DeleteCriticalSection(&m_critsec);
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}
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void Enter()
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{
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EnterCriticalSection(&m_critsec);
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}
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BOOL FTryEnter()
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{
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return TryEnterCriticalSection(&m_critsec);
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}
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void Leave()
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{
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LeaveCriticalSection(&m_critsec);
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}
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DWORD DwSetSpinCount(DWORD dwSpinCount)
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{
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return SetCriticalSectionSpinCount(&m_critsec, dwSpinCount);
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}
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private:
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CUCriticalSection(const CUCriticalSection &);
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CUCriticalSection & operator=(const CUCriticalSection &);
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CRITICAL_SECTION m_critsec;
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};
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//+---------------------------------------------------------------------------
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//
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// Class: CLock
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//
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// Purpose: Used to place an auto lock on a critical section
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//
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// Author: mbend 17 Aug 2000
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//
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// Notes:
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// Typically this class is used in an class object methods like so:
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//
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// class SynchronizedExample {
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// public:
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// void LockedMethod() {
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// CLock lock(m_critSec);
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// ...
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// }
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// private:
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// CUCriticalSection m_critSec;
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// };
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class CLock {
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public:
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// Not attached
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CLock(CUCriticalSection & critsec) : m_critsec(critsec)
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{
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m_critsec.Enter();
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}
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~CLock()
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{
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m_critsec.Leave();
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}
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private:
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CLock(const CLock &);
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CLock & operator=(const CLock &);
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CUCriticalSection & m_critsec;
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};
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#ifdef __ATLCOM_H__
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//+---------------------------------------------------------------------------
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//
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// Class: CALock
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//
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// Purpose: Used to place an auto lock on a CComObjectRootEx<CComMultiThreadModel> derived class
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//
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// Author: mbend 17 Aug 2000
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//
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// Notes:
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// Typically this class is used in an class object methods like so:
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//
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// class SynchronizedExample : public CComObjectRootEx<CComMultiThreadModel> {
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// public:
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// void LockedMethod() {
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// CALock lock(*this);
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// ...
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// }
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// };
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class CALock {
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public:
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// Not attached
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CALock(CComObjectRootEx<CComMultiThreadModel> & object) : m_object(object)
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{
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m_object.Lock();
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}
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~CALock()
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{
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m_object.Unlock();
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}
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private:
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CALock(const CLock &);
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CALock & operator=(const CLock &);
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CComObjectRootEx<CComMultiThreadModel> & m_object;
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};
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#endif // __ATLCOM_H__
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