Why still calling nativeWake() when the thread not blocking?

Question

Why still calling nativeWake() when the thread not blocking?

when a thread call the method enqueueMessage(), which means the thread is not blocking, but Why still calling nativeWake()?

MessageQueue#enqueueMessage

boolean enqueueMessage(Message msg, long when) {

       ……
            if (needWake) {
                nativeWake(mPtr);
           }
     }

Answer 1

When all messages are waiting, and you call enqueue to one of them, it's just checking the head, in case something important just installed on the top.

        //Log.d("MessageQueue", "Enqueing: " + msg);
        Message p = mMessages;
        if (p == null || when == 0 || when < p.when) {
            msg.next = p;
            mMessages = msg;
            needWake = mBlocked; // new head, might need to wake up
        } else {
            Message prev = null;
            while (p != null && p.when <= when) {
                prev = p;
                p = p.next;
            }
            msg.next = prev.next;
            prev.next = msg;
            needWake = false; // still waiting on head, no need to wake up
        }
    }
    if (needWake) {
        nativeWake(mPtr);
    }

So you just skipped the important part.