Android中的AutoMutex

在Threads.h文件中定义：

/*
 * Automatic mutex.  Declare one of these at the top of a function.
 * When the function returns, it will go out of scope, and release the
 * mutex.
 */
 
typedef Mutex::Autolock AutoMutex;

其中的Autolock：

    // Manages the mutex automatically. It'll be locked when Autolock is
    // constructed and released when Autolock goes out of scope.
    class Autolock {
    public:
        inline Autolock(Mutex& mutex) : mLock(mutex)  { mLock.lock(); }
        inline Autolock(Mutex* mutex) : mLock(*mutex) { mLock.lock(); }
        inline ~Autolock() { mLock.unlock(); }
    private:
        Mutex& mLock;
    };

看看AutoMutex的用法：

1、

int32_t Asset::getGlobalCount()
{
    AutoMutex _l(gAssetLock);
    return gCount;
}

2、

ResTable* AssetManager::SharedZip::setResourceTable(ResTable* res)
{
 3     {
 4         AutoMutex _l(gLock);
 5         if (mResourceTable == NULL) {
 6             mResourceTable = res;
 7             return res;
 8         }
 9     }
    delete res;
    return mResourceTable;
}

我认为特别是第二种用法，完全是对变量存在域的一种精辟理解。学习了。