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本文主要研究一下rocketmq的NettyClientConfig

NettyClientConfig

org/apache/rocketmq/remoting/netty/NettyClientConfig.java

public class NettyClientConfig {
    /**
     * Worker thread number
     */
    private int clientWorkerThreads = 4;
    private int clientCallbackExecutorThreads = Runtime.getRuntime().availableProcessors();
    private int clientOnewaySemaphoreValue = NettySystemConfig.CLIENT_ONEWAY_SEMAPHORE_VALUE;
    private int clientAsyncSemaphoreValue = NettySystemConfig.CLIENT_ASYNC_SEMAPHORE_VALUE;
    private int connectTimeoutMillis = 3000;
    private long channelNotActiveInterval = 1000 * 60;

    /**
     * IdleStateEvent will be triggered when neither read nor write was performed for
     * the specified period of this time. Specify {@code 0} to disable
     */
    private int clientChannelMaxIdleTimeSeconds = 120;

    private int clientSocketSndBufSize = NettySystemConfig.socketSndbufSize;
    private int clientSocketRcvBufSize = NettySystemConfig.socketRcvbufSize;
    private boolean clientPooledByteBufAllocatorEnable = false;
    private boolean clientCloseSocketIfTimeout = false;

    private boolean useTLS;

    //......
}

这里主要有几个参数：

• clientWorkerThreads，默认为4
• clientCallbackExecutorThreads，默认为cpu核数
• clientOnewaySemaphoreValue，默认为NettySystemConfig.CLIENT_ONEWAY_SEMAPHORE_VALUE，如果没有指定，则默认为65535
• clientAsyncSemaphoreValue，默认为NettySystemConfig.CLIENT_ASYNC_SEMAPHORE_VALUE，如果没有指定，则默认为65535
• connectTimeoutMillis，默认为3秒
• channelNotActiveInterval，默认为60秒
• clientChannelMaxIdleTimeSeconds，默认为为120秒
• clientSocketSndBufSize，取NettySystemConfig.socketSndbufSize，如果没有指定，默认为65535
• clientSocketRcvBufSize，取NettySystemConfig.socketRcvbufSize，如果没有指定，默认为65535
• clientPooledByteBufAllocatorEnable，默认为false
• clientCloseSocketIfTimeout，默认为false
• useTLS，默认为false

NettySystemConfig

org/apache/rocketmq/remoting/netty/NettySystemConfig.java

public class NettySystemConfig {
    public static final String COM_ROCKETMQ_REMOTING_NETTY_POOLED_BYTE_BUF_ALLOCATOR_ENABLE =
        "com.rocketmq.remoting.nettyPooledByteBufAllocatorEnable";
    public static final String COM_ROCKETMQ_REMOTING_SOCKET_SNDBUF_SIZE =
        "com.rocketmq.remoting.socket.sndbuf.size";
    public static final String COM_ROCKETMQ_REMOTING_SOCKET_RCVBUF_SIZE =
        "com.rocketmq.remoting.socket.rcvbuf.size";
    public static final String COM_ROCKETMQ_REMOTING_CLIENT_ASYNC_SEMAPHORE_VALUE =
        "com.rocketmq.remoting.clientAsyncSemaphoreValue";
    public static final String COM_ROCKETMQ_REMOTING_CLIENT_ONEWAY_SEMAPHORE_VALUE =
        "com.rocketmq.remoting.clientOnewaySemaphoreValue";

    public static final boolean NETTY_POOLED_BYTE_BUF_ALLOCATOR_ENABLE = //
        Boolean.parseBoolean(System.getProperty(COM_ROCKETMQ_REMOTING_NETTY_POOLED_BYTE_BUF_ALLOCATOR_ENABLE, "false"));
    public static final int CLIENT_ASYNC_SEMAPHORE_VALUE = //
        Integer.parseInt(System.getProperty(COM_ROCKETMQ_REMOTING_CLIENT_ASYNC_SEMAPHORE_VALUE, "65535"));
    public static final int CLIENT_ONEWAY_SEMAPHORE_VALUE =
        Integer.parseInt(System.getProperty(COM_ROCKETMQ_REMOTING_CLIENT_ONEWAY_SEMAPHORE_VALUE, "65535"));
    public static int socketSndbufSize =
        Integer.parseInt(System.getProperty(COM_ROCKETMQ_REMOTING_SOCKET_SNDBUF_SIZE, "65535"));
    public static int socketRcvbufSize =
        Integer.parseInt(System.getProperty(COM_ROCKETMQ_REMOTING_SOCKET_RCVBUF_SIZE, "65535"));
}

• 采取先从系统变量读取，没有则返回默认值

NettyRemotingClient

org/apache/rocketmq/remoting/netty/NettyRemotingClient.java

public class NettyRemotingClient extends NettyRemotingAbstract implements RemotingClient {
    private static final Logger log = LoggerFactory.getLogger(RemotingHelper.ROCKETMQ_REMOTING);

    private static final long LOCK_TIMEOUT_MILLIS = 3000;

    private final NettyClientConfig nettyClientConfig;
    private final Bootstrap bootstrap = new Bootstrap();
    private final EventLoopGroup eventLoopGroupWorker;
    private final Lock lockChannelTables = new ReentrantLock();
    private final ConcurrentMap<String /* addr */, ChannelWrapper> channelTables = new ConcurrentHashMap<String, ChannelWrapper>();

    private final Timer timer = new Timer("ClientHouseKeepingService", true);

    private final AtomicReference<List<String>> namesrvAddrList = new AtomicReference<List<String>>();
    private final AtomicReference<String> namesrvAddrChoosed = new AtomicReference<String>();
    private final AtomicInteger namesrvIndex = new AtomicInteger(initValueIndex());
    private final Lock lockNamesrvChannel = new ReentrantLock();

    private final ExecutorService publicExecutor;

    /**
     * Invoke the callback methods in this executor when process response.
     */
    private ExecutorService callbackExecutor;
    private final ChannelEventListener channelEventListener;
    private DefaultEventExecutorGroup defaultEventExecutorGroup;
    private RPCHook rpcHook;

    public NettyRemotingClient(final NettyClientConfig nettyClientConfig) {
        this(nettyClientConfig, null);
    }

    public NettyRemotingClient(final NettyClientConfig nettyClientConfig,
        final ChannelEventListener channelEventListener) {
        super(nettyClientConfig.getClientOnewaySemaphoreValue(), nettyClientConfig.getClientAsyncSemaphoreValue());
        this.nettyClientConfig = nettyClientConfig;
        this.channelEventListener = channelEventListener;

        int publicThreadNums = nettyClientConfig.getClientCallbackExecutorThreads();
        if (publicThreadNums <= 0) {
            publicThreadNums = 4;
        }

        this.publicExecutor = Executors.newFixedThreadPool(publicThreadNums, new ThreadFactory() {
            private AtomicInteger threadIndex = new AtomicInteger(0);

            @Override
            public Thread newThread(Runnable r) {
                return new Thread(r, "NettyClientPublicExecutor_" + this.threadIndex.incrementAndGet());
            }
        });

        this.eventLoopGroupWorker = new NioEventLoopGroup(1, new ThreadFactory() {
            private AtomicInteger threadIndex = new AtomicInteger(0);

            @Override
            public Thread newThread(Runnable r) {
                return new Thread(r, String.format("NettyClientSelector_%d", this.threadIndex.incrementAndGet()));
            }
        });

        if (nettyClientConfig.isUseTLS()) {
            try {
                sslContext = TlsHelper.buildSslContext(true);
                log.info("SSL enabled for client");
            } catch (IOException e) {
                log.error("Failed to create SSLContext", e);
            } catch (CertificateException e) {
                log.error("Failed to create SSLContext", e);
                throw new RuntimeException("Failed to create SSLContext", e);
            }
        }
    }

    private static int initValueIndex() {
        Random r = new Random();

        return Math.abs(r.nextInt() % 999) % 999;
    }

    @Override
    public void start() {
        this.defaultEventExecutorGroup = new DefaultEventExecutorGroup(
            nettyClientConfig.getClientWorkerThreads(),
            new ThreadFactory() {

                private AtomicInteger threadIndex = new AtomicInteger(0);

                @Override
                public Thread newThread(Runnable r) {
                    return new Thread(r, "NettyClientWorkerThread_" + this.threadIndex.incrementAndGet());
                }
            });

        Bootstrap handler = this.bootstrap.group(this.eventLoopGroupWorker).channel(NioSocketChannel.class)
            .option(ChannelOption.TCP_NODELAY, true)
            .option(ChannelOption.SO_KEEPALIVE, false)
            .option(ChannelOption.CONNECT_TIMEOUT_MILLIS, nettyClientConfig.getConnectTimeoutMillis())
            .option(ChannelOption.SO_SNDBUF, nettyClientConfig.getClientSocketSndBufSize())
            .option(ChannelOption.SO_RCVBUF, nettyClientConfig.getClientSocketRcvBufSize())
            .handler(new ChannelInitializer<SocketChannel>() {
                @Override
                public void initChannel(SocketChannel ch) throws Exception {
                    ChannelPipeline pipeline = ch.pipeline();
                    if (nettyClientConfig.isUseTLS()) {
                        if (null != sslContext) {
                            pipeline.addFirst(defaultEventExecutorGroup, "sslHandler", sslContext.newHandler(ch.alloc()));
                            log.info("Prepend SSL handler");
                        } else {
                            log.warn("Connections are insecure as SSLContext is null!");
                        }
                    }
                    pipeline.addLast(
                        defaultEventExecutorGroup,
                        new NettyEncoder(),
                        new NettyDecoder(),
                        new IdleStateHandler(0, 0, nettyClientConfig.getClientChannelMaxIdleTimeSeconds()),
                        new NettyConnectManageHandler(),
                        new NettyClientHandler());
                }
            });

        this.timer.scheduleAtFixedRate(new TimerTask() {
            @Override
            public void run() {
                try {
                    NettyRemotingClient.this.scanResponseTable();
                } catch (Throwable e) {
                    log.error("scanResponseTable exception", e);
                }
            }
        }, 1000 * 3, 1000);

        if (this.channelEventListener != null) {
            this.nettyEventExecutor.start();
        }
    }

    //......
}

• NettyRemotingClient使用了NettyClientConfig的相关配置来初始化NettyClient
• ChannelOption.CONNECT_TIMEOUT_MILLIS使用的是nettyClientConfig.getConnectTimeoutMillis()
• ChannelOption.SO_SNDBUF使用的是nettyClientConfig.getClientSocketSndBufSize()
• ChannelOption.SO_RCVBUF使用的是nettyClientConfig.getClientSocketRcvBufSize()
• IdleStateHandler的allIdleTimeSeconds参数使用的是nettyClientConfig.getClientChannelMaxIdleTimeSeconds()

小结

rocketmq的NettyClientConfig指定了NettyRemotingClient相关参数，这里除了Netty相关的，还指定了两个信号量，一个是clientOnewaySemaphoreValue，一个是clientAsyncSemaphoreValue。clientOnewaySemaphoreValue指定的是invokeOnewayImpl方法的调用控制，clientAsyncSemaphoreValue指定的是invokeAsyncImpl方法的调用频率。

doc

• NettyClientConfig