zookeeper源码之客户端网络通信模块

//等待发送的数据包队列
private final LinkedList<Packet> outgoingQueue = new LinkedList<Packet>();
//发送后等待结果的数据包队列
private final LinkedList<Packet> pendingQueue = new LinkedList<Packet>();

class SendThread extends Thread {
        boolean doIO() throws InterruptedException, IOException {
            ...if (!outgoingQueue.isEmpty()) {
                        ByteBuffer pbb = outgoingQueue.getFirst().bb;
                        sock.write(pbb);
                        if (!pbb.hasRemaining()) {
                            sentCount++;
                            Packet p = outgoingQueue.removeFirst();
                            if (p.header != null
                                    && p.header.getType() != OpCode.ping
                                    && p.header.getType() != OpCode.auth) {
                                pendingQueue.add(p);
                            }
                        }
                    }
                }
            ...
        }
　　　　　...
        @Override
        public void run() {
            ...while (zooKeeper.state.isAlive()) {
                ...if (doIO()) {
                                lastHeard = now;
                             }
                ...
            }
            ...

    }