Android中的AutoMutex

在Threads.h文件中定义：

1 /*
2  * Automatic mutex.  Declare one of these at the top of a function.
3  * When the function returns, it will go out of scope, and release the
4  * mutex.
5  */
6  
7 typedef Mutex::Autolock AutoMutex;

其中的Autolock：

 1     // Manages the mutex automatically. It'll be locked when Autolock is
 2     // constructed and released when Autolock goes out of scope.
 3     class Autolock {
 4     public:
 5         inline Autolock(Mutex& mutex) : mLock(mutex)  { mLock.lock(); }
 6         inline Autolock(Mutex* mutex) : mLock(*mutex) { mLock.lock(); }
 7         inline ~Autolock() { mLock.unlock(); }
 8     private:
 9         Mutex& mLock;
10     };

看看AutoMutex的用法：

1、

1 int32_t Asset::getGlobalCount()
2 {
3     AutoMutex _l(gAssetLock);
4     return gCount;
5 }

2、

 1 ResTable* AssetManager::SharedZip::setResourceTable(ResTable* res)
 2 {
 3     {
 4         AutoMutex _l(gLock);
 5         if (mResourceTable == NULL) {
 6             mResourceTable = res;
 7             return res;
 8         }
 9     }
10     delete res;
11     return mResourceTable;
12 }

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。