reactor-netty中TcpClient的create过程

序

本文主要研究一下reactor-netty中TcpClient的create的过程

maven

        
            io.projectreactor.ipc
            reactor-netty
            0.7.3.RELEASE
        

TcpClient

reactor-netty-0.7.3.RELEASE-sources.jar!/reactor/ipc/netty/tcp/TcpClient.java

    protected TcpClient(TcpClient.Builder builder) {
        ClientOptions.Builder clientOptionsBuilder = ClientOptions.builder();
        if (Objects.nonNull(builder.options)) {
            builder.options.accept(clientOptionsBuilder);
        }
        if (!clientOptionsBuilder.isLoopAvailable()) {
            clientOptionsBuilder.loopResources(TcpResources.get());
        }
        if (!clientOptionsBuilder.isPoolAvailable() && !clientOptionsBuilder.isPoolDisabled()) {
            clientOptionsBuilder.poolResources(TcpResources.get());
        }
        this.options = clientOptionsBuilder.build();
    }

loopResources和poolResources其实是通过TcpResources创建
上面loopResources创建完之后，下面的poolResources其实是直接返回

clientOptionsBuilder.isLoopAvailable()

reactor-netty-0.7.3.RELEASE-sources.jar!/reactor/ipc/netty/options/NettyOptions.java

        public final boolean isLoopAvailable() {
            return this.loopResources != null;
        }

一开始是null，于是调用TcpResources.get()创建

TcpResources.get()

reactor-netty-0.7.3.RELEASE-sources.jar!/reactor/ipc/netty/tcp/TcpResources.java

    /**
     * Return the global HTTP resources for event loops and pooling
     *
     * @return the global HTTP resources for event loops and pooling
     */
    public static TcpResources get() {
        return getOrCreate(tcpResources, null, null, ON_TCP_NEW,  "tcp");
    }
    /**
     * Safely check if existing resource exist and proceed to update/cleanup if new
     * resources references are passed.
     *
     * @param ref the resources atomic reference
     * @param loops the eventual new {@link LoopResources}
     * @param pools the eventual new {@link PoolResources}
     * @param onNew a {@link TcpResources} factory
     * @param name a name for resources
     * @param  the reified type of {@link TcpResources}
     *
     * @return an existing or new {@link TcpResources}
     */
    protected static  T getOrCreate(AtomicReference ref,
            LoopResources loops,
            PoolResources pools,
            BiFunction onNew,
            String name) {
        T update;
        for (; ; ) {
            T resources = ref.get();
            if (resources == null || loops != null || pools != null) {
                update = create(resources, loops, pools, name, onNew);
                if (ref.compareAndSet(resources, update)) {
                    if(resources != null){
                        if(loops != null){
                            resources.defaultLoops.dispose();
                        }
                        if(pools != null){
                            resources.defaultPools.dispose();
                        }
                    }
                    return update;
                }
                else {
                    update._dispose();
                }
            }
            else {
                return resources;
            }
        }
    }

这里进入create，创建loops还有pools

    static final AtomicReference                          tcpResources;
    static final BiFunction ON_TCP_NEW;

    static {
        ON_TCP_NEW = TcpResources::new;
        tcpResources  = new AtomicReference<>();
    }

    final PoolResources defaultPools;
    final LoopResources defaultLoops;

    protected TcpResources(LoopResources defaultLoops, PoolResources defaultPools) {
        this.defaultLoops = defaultLoops;
        this.defaultPools = defaultPools;
    }

    static  T create(T previous,
            LoopResources loops,
            PoolResources pools,
            String name,
            BiFunction onNew) {
        if (previous == null) {
            loops = loops == null ? LoopResources.create("reactor-" + name) : loops;
            pools = pools == null ? PoolResources.elastic(name) : pools;
        }
        else {
            loops = loops == null ? previous.defaultLoops : loops;
            pools = pools == null ? previous.defaultPools : pools;
        }
        return onNew.apply(loops, pools);
    }

这里的onNew是创建TcpResources，使用的构造器是TcpResources(LoopResources defaultLoops, PoolResources defaultPools)

LoopResources.create

reactor-netty-0.7.3.RELEASE-sources.jar!/reactor/ipc/netty/resources/LoopResources.java

    /**
     * Default worker thread count, fallback to available processor
     */
    int DEFAULT_IO_WORKER_COUNT = Integer.parseInt(System.getProperty(
            "reactor.ipc.netty.workerCount",
            "" + Math.max(Runtime.getRuntime()
                        .availableProcessors(), 4)));
    /**
     * Default selector thread count, fallback to -1 (no selector thread)
     */
    int DEFAULT_IO_SELECT_COUNT = Integer.parseInt(System.getProperty(
            "reactor.ipc.netty.selectCount",
            "" + -1));
    /**
     * Create a simple {@link LoopResources} to provide automatically for {@link
     * EventLoopGroup} and {@link Channel} factories
     *
     * @param prefix the event loop thread name prefix
     *
     * @return a new {@link LoopResources} to provide automatically for {@link
     * EventLoopGroup} and {@link Channel} factories
     */
    static LoopResources create(String prefix) {
        return new DefaultLoopResources(prefix, DEFAULT_IO_SELECT_COUNT,
                DEFAULT_IO_WORKER_COUNT,
                true);
    }

这里有两个参数，一个是worker thread count，一个是selector thread count

• DEFAULT_IO_WORKER_COUNT

如果环境变量有设置reactor.ipc.netty.workerCount，则用该值；没有设置则取Math.max(Runtime.getRuntime().availableProcessors(), 4)))

• DEFAULT_IO_SELECT_COUNT

如果环境变量有设置reactor.ipc.netty.selectCount，则用该值；没有设置则取-1，表示没有selector thread

DefaultLoopResources

reactor-netty-0.7.3.RELEASE-sources.jar!/reactor/ipc/netty/resources/DefaultLoopResources.java

    DefaultLoopResources(String prefix,
            int selectCount,
            int workerCount,
            boolean daemon) {
        this.running = new AtomicBoolean(true);
        this.daemon = daemon;
        this.workerCount = workerCount;
        this.prefix = prefix;

        this.serverLoops = new NioEventLoopGroup(workerCount,
                threadFactory(this, "nio"));

        this.clientLoops = LoopResources.colocate(serverLoops);

        this.cacheNativeClientLoops = new AtomicReference<>();
        this.cacheNativeServerLoops = new AtomicReference<>();

        if (selectCount == -1) {
            this.selectCount = workerCount;
            this.serverSelectLoops = this.serverLoops;
            this.cacheNativeSelectLoops = this.cacheNativeServerLoops;
        }
        else {
            this.selectCount = selectCount;
            this.serverSelectLoops =
                    new NioEventLoopGroup(selectCount, threadFactory(this, "select-nio"));
            this.cacheNativeSelectLoops = new AtomicReference<>();
        }
    }

这里prefix为reactor-tcp，selectCount为-1，workerCount为4，daemon为true
可以看到这里创建了NioEventLoopGroup，workerCount为4；由于selectCount=-1因此没有单独创建serverSelectLoops

NioEventLoopGroup

netty-transport-4.1.20.Final-sources.jar!/io/netty/channel/nio/NioEventLoopGroup.java

    public NioEventLoopGroup(int nThreads, ThreadFactory threadFactory,
        final SelectorProvider selectorProvider, final SelectStrategyFactory selectStrategyFactory) {
        super(nThreads, threadFactory, selectorProvider, selectStrategyFactory, RejectedExecutionHandlers.reject());
    }

注意这里的rejectHandler是RejectedExecutionHandlers.reject()

netty-common-4.1.20.Final-sources.jar!/io/netty/util/concurrent/MultithreadEventExecutorGroup.java

    /**
     * Create a new instance.
     *
     * @param nThreads          the number of threads that will be used by this instance.
     * @param threadFactory     the ThreadFactory to use, or {@code null} if the default should be used.
     * @param args              arguments which will passed to each {@link #newChild(Executor, Object...)} call
     */
    protected MultithreadEventExecutorGroup(int nThreads, ThreadFactory threadFactory, Object... args) {
        this(nThreads, threadFactory == null ? null : new ThreadPerTaskExecutor(threadFactory), args);
    }

new NioEventLoopGroup的时候调用了MultithreadEventExecutorGroup
这里的threadFactory是reactor.ipc.netty.resources.DefaultLoopResources$EventLoopSelectorFactory
这里的executor是ThreadPerTaskExecutor

netty-common-4.1.20.Final-sources.jar!/io/netty/util/concurrent/ThreadPerTaskExecutor.java

public final class ThreadPerTaskExecutor implements Executor {
    private final ThreadFactory threadFactory;

    public ThreadPerTaskExecutor(ThreadFactory threadFactory) {
        if (threadFactory == null) {
            throw new NullPointerException("threadFactory");
        }
        this.threadFactory = threadFactory;
    }

    @Override
    public void execute(Runnable command) {
        threadFactory.newThread(command).start();
    }
}

MultithreadEventExecutorGroup

    /**
     * Create a new instance.
     *
     * @param nThreads          the number of threads that will be used by this instance.
     * @param executor          the Executor to use, or {@code null} if the default should be used.
     * @param chooserFactory    the {@link EventExecutorChooserFactory} to use.
     * @param args              arguments which will passed to each {@link #newChild(Executor, Object...)} call
     */
    protected MultithreadEventExecutorGroup(int nThreads, Executor executor,
                                            EventExecutorChooserFactory chooserFactory, Object... args) {
        if (nThreads <= 0) {
            throw new IllegalArgumentException(String.format("nThreads: %d (expected: > 0)", nThreads));
        }

        if (executor == null) {
            executor = new ThreadPerTaskExecutor(newDefaultThreadFactory());
        }

        children = new EventExecutor[nThreads];

        for (int i = 0; i < nThreads; i ++) {
            boolean success = false;
            try {
                children[i] = newChild(executor, args);
                success = true;
            } catch (Exception e) {
                // TODO: Think about if this is a good exception type
                throw new IllegalStateException("failed to create a child event loop", e);
            } finally {
                if (!success) {
                    for (int j = 0; j < i; j ++) {
                        children[j].shutdownGracefully();
                    }

                    for (int j = 0; j < i; j ++) {
                        EventExecutor e = children[j];
                        try {
                            while (!e.isTerminated()) {
                                e.awaitTermination(Integer.MAX_VALUE, TimeUnit.SECONDS);
                            }
                        } catch (InterruptedException interrupted) {
                            // Let the caller handle the interruption.
                            Thread.currentThread().interrupt();
                            break;
                        }
                    }
                }
            }
        }

        chooser = chooserFactory.newChooser(children);

        final FutureListener