请问isThrottleBACK的意思是什么，在什么场景下会出现 about fragmentationx HOT 3 CLOSED

public ActionQueue(Handler mainHandler) {
    this.mMainHandler = mainHandler;
}

public void enqueue(final Action action) {
    if (isThrottleBACK(action)){//  如果重复后退 则不处理
        Log.i(TAG,"isThrottleBACK...");
        return;
    }

    if (action.action == Action.ACTION_LOAD && mQueue.isEmpty()
            && Thread.currentThread() == Looper.getMainLooper().getThread()) {
        action.run();
        return;
    }

    mMainHandler.post(new Runnable() {
        @Override
        public void run() {
            enqueueAction(action);
        }
    });
}