elasticsearch节点间通信的基础transport启动过程

protected void doStart() throws ElasticsearchException {
       clientBootstrap = createClientBootstrap();//根据配置启动客户端
       ……//省略了无关分代码
　　　　createServerBootstrap(name, mergedSettings);//启动server端
       bindServerBootstrap(name, mergedSettings);//绑定ip
        }

public void connectToNode(DiscoveryNode node, boolean light) {
　　　　　//transport的模块必须要启动
        if (!lifecycle.started()) {
            throw new ElasticsearchIllegalStateException("can't add nodes to a stopped transport");
        }
　　　　　//获取读锁，每个节点可以和多个节点建立连接，因此这里用读锁
        globalLock.readLock().lock();
        try {
　　　　　　　　//以node.id为基础获取一个锁，这保证对于每个node只能建立一次连接
            connectionLock.acquire(node.id());
            try {
                if (!lifecycle.started()) {
                    throw new ElasticsearchIllegalStateException("can't add nodes to a stopped transport");
                }
                NodeChannels nodeChannels = connectedNodes.get(node);
                if (nodeChannels != null) {
                    return;
                }
                try {
                    if (light) {//这里的light，就是对该节点只获取一个channel，所有类型（5种连接类型下面会说到）都使用者一个channel
                        nodeChannels = connectToChannelsLight(node);
                    } else {
                        nodeChannels = new NodeChannels(new Channel[connectionsPerNodeRecovery], new Channel[connectionsPerNodeBulk], new Channel[connectionsPerNodeReg], new Channel[connectionsPerNodeState], new Channel[connectionsPerNodePing]);
                        try {
                            connectToChannels(nodeChannels, node);
                        } catch (Throwable e) {
                            logger.trace("failed to connect to [{}], cleaning dangling connections", e, node);
                            nodeChannels.close();
                            throw e;
                        }
                    }
                    // we acquire a connection lock, so no way there is an existing connection
                    connectedNodes.put(node, nodeChannels);
                    if (logger.isDebugEnabled()) {
                        logger.debug("connected to node [{}]", node);
                    }
                    transportServiceAdapter.raiseNodeConnected(node);
                } catch (ConnectTransportException e) {
                    throw e;
                } catch (Exception e) {
                    throw new ConnectTransportException(node, "general node connection failure", e);
                }
            } finally {
                connectionLock.release(node.id());
            }
        } finally {
            globalLock.readLock().unlock();
        }
    }

protected void connectToChannels(NodeChannels nodeChannels, DiscoveryNode node) {
　　　　//五种连接方式，不同的连接方式对应不同的集群操作
        ChannelFuture[] connectRecovery = new ChannelFuture[nodeChannels.recovery.length];
        ChannelFuture[] connectBulk = new ChannelFuture[nodeChannels.bulk.length];
        ChannelFuture[] connectReg = new ChannelFuture[nodeChannels.reg.length];
        ChannelFuture[] connectState = new ChannelFuture[nodeChannels.state.length];
        ChannelFuture[] connectPing = new ChannelFuture[nodeChannels.ping.length];
        InetSocketAddress address = ((InetSocketTransportAddress) node.address()).address();
　　　　//尝试建立连接
        for (int i = 0; i < connectRecovery.length; i++) {
            connectRecovery[i] = clientBootstrap.connect(address);
        }
        for (int i = 0; i < connectBulk.length; i++) {
            connectBulk[i] = clientBootstrap.connect(address);
        }
        for (int i = 0; i < connectReg.length; i++) {
            connectReg[i] = clientBootstrap.connect(address);
        }
        for (int i = 0; i < connectState.length; i++) {
            connectState[i] = clientBootstrap.connect(address);
        }
        for (int i = 0; i < connectPing.length; i++) {
            connectPing[i] = clientBootstrap.connect(address);
        }
　　　　//获取每个连接的channel存入到相应的channels中便于后面使用。
        try {
            for (int i = 0; i < connectRecovery.length; i++) {
                connectRecovery[i].awaitUninterruptibly((long) (connectTimeout.millis() * 1.5));
                if (!connectRecovery[i].isSuccess()) {
                    throw new ConnectTransportException(node, "connect_timeout[" + connectTimeout + "]", connectRecovery[i].getCause());
                }
                nodeChannels.recovery[i] = connectRecovery[i].getChannel();
                nodeChannels.recovery[i].getCloseFuture().addListener(new ChannelCloseListener(node));
            }
            for (int i = 0; i < connectBulk.length; i++) {
                connectBulk[i].awaitUninterruptibly((long) (connectTimeout.millis() * 1.5));
                if (!connectBulk[i].isSuccess()) {
                    throw new ConnectTransportException(node, "connect_timeout[" + connectTimeout + "]", connectBulk[i].getCause());
                }
                nodeChannels.bulk[i] = connectBulk[i].getChannel();
                nodeChannels.bulk[i].getCloseFuture().addListener(new ChannelCloseListener(node));
            }
            for (int i = 0; i < connectReg.length; i++) {
                connectReg[i].awaitUninterruptibly((long) (connectTimeout.millis() * 1.5));
                if (!connectReg[i].isSuccess()) {
                    throw new ConnectTransportException(node, "connect_timeout[" + connectTimeout + "]", connectReg[i].getCause());
                }
                nodeChannels.reg[i] = connectReg[i].getChannel();
                nodeChannels.reg[i].getCloseFuture().addListener(new ChannelCloseListener(node));
            }
            for (int i = 0; i < connectState.length; i++) {
                connectState[i].awaitUninterruptibly((long) (connectTimeout.millis() * 1.5));
                if (!connectState[i].isSuccess()) {
                    throw new ConnectTransportException(node, "connect_timeout[" + connectTimeout + "]", connectState[i].getCause());
                }
                nodeChannels.state[i] = connectState[i].getChannel();
                nodeChannels.state[i].getCloseFuture().addListener(new ChannelCloseListener(node));
            }
            for (int i = 0; i < connectPing.length; i++) {
                connectPing[i].awaitUninterruptibly((long) (connectTimeout.millis() * 1.5));
                if (!connectPing[i].isSuccess()) {
                    throw new ConnectTransportException(node, "connect_timeout[" + connectTimeout + "]", connectPing[i].getCause());
                }
                nodeChannels.ping[i] = connectPing[i].getChannel();
                nodeChannels.ping[i].getCloseFuture().addListener(new ChannelCloseListener(node));
            }
            if (nodeChannels.recovery.length == 0) {
                if (nodeChannels.bulk.length > 0) {
                    nodeChannels.recovery = nodeChannels.bulk;
                } else {
                    nodeChannels.recovery = nodeChannels.reg;
                }
            }
            if (nodeChannels.bulk.length == 0) {
                nodeChannels.bulk = nodeChannels.reg;
            }
        } catch (RuntimeException e) {
            // clean the futures
            for (ChannelFuture future : ImmutableList.<ChannelFuture>builder().add(connectRecovery).add(connectBulk).add(connectReg).add(connectState).add(connectPing).build()) {
                future.cancel();
                if (future.getChannel() != null && future.getChannel().isOpen()) {
                    try {
                        future.getChannel().close();
                    } catch (Exception e1) {
                        // ignore
                    }
                }
            }
            throw e;
        }
    }