在AMS中有仨个广播队列mFgBroadcastQueue，mBgBroadcastQueue，mBgBroadcastQueue，用来分别管理仨类优先级别不同的广播，广播的分类是基于flag:FLAG_RECEIVER_FOREGROUND,FLAG_RECEIVER_OFFLOAD mFgBroadcastQueue，mBgBroadcastQueue，mBgBroadcastQueue,都是BroadcastQueue的对象，在BroadcastQueue.java中有几个比较关键的函数和成员变量
/**
* Lists of all active broadcasts that are to be executed immediately
* (without waiting for another broadcast to finish). Currently this only
* contains broadcasts to registered receivers, to avoid spinning up
* a bunch of processes to execute IntentReceiver components. Background-
* and foreground-priority broadcasts are queued separately.
*/
final ArrayList
/**
* Tracking of the ordered broadcast queue, including deferral policy and alarm
* prioritization.
*/
final BroadcastDispatcher mDispatcher;
public void enqueueParallelBroadcastLocked(BroadcastRecord r) {
mParallelBroadcasts.add(r);
enqueueBroadcastHelper(r);
}
public v