Message

AndroidSource

Message 回收机制

void recycleUnchecked() {
    // Mark the message as in use while it remains in the recycled object pool.
    // Clear out all other details.
    flags = FLAG_IN_USE;
    what = 0;
    arg1 = 0;
    arg2 = 0;
    obj = null;
    replyTo = null;
    sendingUid = -1;
    when = 0;
    target = null;
    callback = null;
    data = null;
    synchronized (sPoolSync) {
        if (sPoolSize < MAX_POOL_SIZE) {
            // 把当前的Message插入表头
            next = sPool;
            sPool = this;
            sPoolSize++;
        }
    }
}

public static Message obtain() {
    synchronized (sPoolSync) {
        if (sPool != null) {
            // 从表头取出一个Message，原先下个的Message成为新的表头
            Message m = sPool;
            sPool = m.next;
            m.next = null;
            m.flags = 0; // clear in-use flag
            sPoolSize--;
            return m;
        }
    }
    return new Message();
}