加锁基类LockImpl

最新推荐文章于 2021-06-14 18:06:50 发布

原创最新推荐文章于 2021-06-14 18:06:50 发布 · 586 阅读

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#variables #os #chrome #linux #class

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LockImpl是一个用于Chrome的加锁基类，它定义了尝试获取锁、锁定、解锁以及在调试模式下检查锁是否已被当前线程持有的方法。该类基于CRITICAL_SECTION实现，并使用InitializeCriticalSectionAndSpinCount进行初始化，DeleteCriticalSection进行销毁。

chrome中的加锁基类,去掉不用的部分

#pragma once

#define DISALLOW_COPY_AND_ASSIGN(TypeName) /
TypeName(const TypeName&); /
void operator=(const TypeName&)

class LockImpl
{
typedef CRITICAL_SECTION OSLockType;

public:
LockImpl(void);
virtual ~LockImpl(void);

// If the lock is not held, take it and return true. If the lock is already
// held by something else, immediately return false.
bool Try();

// Take the lock, blocking until it is available if necessary.
void Lock();

// Release the lock. This must only be called by the lock's holder: after
// a successful call to Try, or a call to Lock.
void Unlock();

// Debug-only method that will DCHECK() if the lock is not acquired by the
// current thread. In non-debug builds, no check is performed.
// Because linux and mac condition variables modify the underlyning lock
// through the os_lock() method, runtime assertions can not be done on those
// builds.
#ifdef DEBUG
void AssertAcquired() const;
#endif

private:
OSLockType os_lock_;
DISALLOW_COPY_AND_ASSIGN(LockImpl);
};

#include "stdafx.h"
#include "LockImpl.h"

LockImpl::LockImpl(void)
{
::InitializeCriticalSectionAndSpinCount(&os_lock_, 2000);
}

LockImpl::~LockImpl(void)
{
::DeleteCriticalSection(&os_lock_);
}

bool LockImpl::Try() {
if (::TryEnterCriticalSection(&os_lock_) != FALSE) {
return true;
}
return false;
}

void LockImpl::Lock() {
::EnterCriticalSection(&os_lock_);
}

void LockImpl::Unlock() {
::LeaveCriticalSection(&os_lock_);
}