1. struct ALooperRoster controls every looper.

   deliverMessage

2. Alooper structure:

   friend struct ALooperRoster;

   struct Event {

       int64_t mWhenUs;

       sp<AMessage> mMessage;

   };

   Mutex mLock;

   Condition mQueueChangedCondition;

   AString mName;

   List<Event> mEventQueue;

   struct LooperThread;

   sp<LooperThread> mThread;

   bool mRunningLocally;

 具体看Post实现，

ALooper::registerHandler(const sp<AHandler> &handler) {

   return gLooperRoster.registerHandler(this, handler);

}

3 AMessage

void AMessage::post(int64_t delayUs) {

   gLooperRoster.postMessage(this, delayUs);

}

这里有个流程图可以作为 reference，

http://blog.csdn.net/dtplayer/article/details/12071271