Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.activemq.transport.netty; import java.io.IOException; import java.net.URI; import java.security.Principal; import java.util.concurrent.CountDownLatch; import java.util.concurrent.TimeUnit; import java.util.concurrent.atomic.AtomicBoolean; import org.apache.activemq.transport.amqp.client.util.IOExceptionSupport; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import io.netty.bootstrap.Bootstrap; import io.netty.buffer.ByteBuf; import io.netty.channel.Channel; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelFutureListener; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.ChannelInboundHandlerAdapter; import io.netty.channel.ChannelInitializer; import io.netty.channel.ChannelOption; import io.netty.channel.ChannelPipeline; import io.netty.channel.EventLoopGroup; import io.netty.channel.FixedRecvByteBufAllocator; import io.netty.channel.SimpleChannelInboundHandler; import io.netty.channel.nio.NioEventLoopGroup; import io.netty.channel.socket.nio.NioSocketChannel; import io.netty.handler.logging.LoggingHandler; import io.netty.handler.ssl.SslHandler; import io.netty.util.concurrent.Future; import io.netty.util.concurrent.GenericFutureListener; /** * TCP based transport that uses Netty as the underlying IO layer. */ public class NettyTcpTransport implements NettyTransport { private static final Logger LOG = LoggerFactory.getLogger(NettyTcpTransport.class); private static final int SHUTDOWN_TIMEOUT = 100; public static final int DEFAULT_MAX_FRAME_SIZE = 65535; protected Bootstrap bootstrap; protected EventLoopGroup group; protected Channel channel; protected NettyTransportListener listener; protected final NettyTransportOptions options; protected final URI remote; protected int maxFrameSize = DEFAULT_MAX_FRAME_SIZE; private final AtomicBoolean connected = new AtomicBoolean(); private final AtomicBoolean closed = new AtomicBoolean(); private final CountDownLatch connectLatch = new CountDownLatch(1); private volatile IOException failureCause; /** * Create a new transport instance * * @param remoteLocation * the URI that defines the remote resource to connect to. * @param options * the transport options used to configure the socket connection. */ public NettyTcpTransport(URI remoteLocation, NettyTransportOptions options) { this(null, remoteLocation, options); } /** * Create a new transport instance * * @param listener * the TransportListener that will receive events from this Transport. * @param remoteLocation * the URI that defines the remote resource to connect to. * @param options * the transport options used to configure the socket connection. */ public NettyTcpTransport(NettyTransportListener listener, URI remoteLocation, NettyTransportOptions options) { if (options == null) { throw new IllegalArgumentException("Transport Options cannot be null"); } if (remoteLocation == null) { throw new IllegalArgumentException("Transport remote location cannot be null"); } this.options = options; this.listener = listener; this.remote = remoteLocation; } @Override public void connect() throws IOException { if (listener == null) { throw new IllegalStateException("A transport listener must be set before connection attempts."); } final SslHandler sslHandler; if (isSSL()) { try { sslHandler = NettyTransportSupport.createSslHandler(getRemoteLocation(), getSslOptions()); } catch (Exception ex) { // TODO: can we stop it throwing Exception? throw IOExceptionSupport.create(ex); } } else { sslHandler = null; } group = new NioEventLoopGroup(1); bootstrap = new Bootstrap(); bootstrap.group(group); bootstrap.channel(NioSocketChannel.class); bootstrap.handler(new ChannelInitializer<Channel>() { @Override public void initChannel(Channel connectedChannel) throws Exception { configureChannel(connectedChannel, sslHandler); } }); configureNetty(bootstrap, getTransportOptions()); ChannelFuture future = bootstrap.connect(getRemoteHost(), getRemotePort()); future.addListener(new ChannelFutureListener() { @Override public void operationComplete(ChannelFuture future) throws Exception { if (!future.isSuccess()) { handleException(future.channel(), IOExceptionSupport.create(future.cause())); } } }); try { connectLatch.await(); } catch (InterruptedException ex) { LOG.debug("Transport connection was interrupted."); Thread.interrupted(); failureCause = IOExceptionSupport.create(ex); } if (failureCause != null) { // Close out any Netty resources now as they are no longer needed. if (channel != null) { channel.close().syncUninterruptibly(); channel = null; } if (group != null) { Future<?> fut = group.shutdownGracefully(0, SHUTDOWN_TIMEOUT, TimeUnit.MILLISECONDS); if (!fut.awaitUninterruptibly(2 * SHUTDOWN_TIMEOUT)) { LOG.trace("Channel group shutdown failed to complete in allotted time"); } group = null; } throw failureCause; } else { // Connected, allow any held async error to fire now and close the transport. channel.eventLoop().execute(new Runnable() { @Override public void run() { if (failureCause != null) { channel.pipeline().fireExceptionCaught(failureCause); } } }); } } @Override public boolean isConnected() { return connected.get(); } @Override public boolean isSSL() { return options.isSSL(); } @Override public void close() throws IOException { if (closed.compareAndSet(false, true)) { connected.set(false); try { if (channel != null) { channel.close().syncUninterruptibly(); } } finally { if (group != null) { Future<?> fut = group.shutdownGracefully(0, SHUTDOWN_TIMEOUT, TimeUnit.MILLISECONDS); if (!fut.awaitUninterruptibly(2 * SHUTDOWN_TIMEOUT)) { LOG.trace("Channel group shutdown failed to complete in allotted time"); } } } } } @Override public ByteBuf allocateSendBuffer(int size) throws IOException { checkConnected(); return channel.alloc().ioBuffer(size, size); } @Override public ChannelFuture send(ByteBuf output) throws IOException { checkConnected(); int length = output.readableBytes(); if (length == 0) { return null; } LOG.trace("Attempted write of: {} bytes", length); return channel.writeAndFlush(output); } @Override public NettyTransportListener getTransportListener() { return listener; } @Override public void setTransportListener(NettyTransportListener listener) { this.listener = listener; } @Override public NettyTransportOptions getTransportOptions() { return options; } @Override public URI getRemoteLocation() { return remote; } @Override public Principal getLocalPrincipal() { Principal result = null; if (isSSL()) { SslHandler sslHandler = channel.pipeline().get(SslHandler.class); result = sslHandler.engine().getSession().getLocalPrincipal(); } return result; } @Override public void setMaxFrameSize(int maxFrameSize) { if (connected.get()) { throw new IllegalStateException("Cannot change Max Frame Size while connected."); } this.maxFrameSize = maxFrameSize; } @Override public int getMaxFrameSize() { return maxFrameSize; } // ----- Internal implementation details, can be overridden as needed -----// protected String getRemoteHost() { return remote.getHost(); } protected int getRemotePort() { if (remote.getPort() != -1) { return remote.getPort(); } else { return isSSL() ? getSslOptions().getDefaultSslPort() : getTransportOptions().getDefaultTcpPort(); } } protected void addAdditionalHandlers(ChannelPipeline pipeline) { } protected ChannelInboundHandlerAdapter createChannelHandler() { return new NettyTcpTransportHandler(); } // ----- Event Handlers which can be overridden in subclasses -------------// protected void handleConnected(Channel channel) throws Exception { LOG.trace("Channel has become active! Channel is {}", channel); connectionEstablished(channel); } protected void handleChannelInactive(Channel channel) throws Exception { LOG.trace("Channel has gone inactive! Channel is {}", channel); if (connected.compareAndSet(true, false) && !closed.get()) { LOG.trace("Firing onTransportClosed listener"); listener.onTransportClosed(); } } protected void handleException(Channel channel, Throwable cause) throws Exception { LOG.trace("Exception on channel! Channel is {}", channel); if (connected.compareAndSet(true, false) && !closed.get()) { LOG.trace("Firing onTransportError listener"); if (failureCause != null) { listener.onTransportError(failureCause); } else { listener.onTransportError(cause); } } else { // Hold the first failure for later dispatch if connect succeeds. // This will then trigger disconnect using the first error reported. if (failureCause == null) { LOG.trace("Holding error until connect succeeds: {}", cause.getMessage()); failureCause = IOExceptionSupport.create(cause); } connectionFailed(channel, failureCause); } } // ----- State change handlers and checks ---------------------------------// protected final void checkConnected() throws IOException { if (!connected.get()) { throw new IOException("Cannot send to a non-connected transport."); } } /* * Called when the transport has successfully connected and is ready for use. */ private void connectionEstablished(Channel connectedChannel) { channel = connectedChannel; connected.set(true); connectLatch.countDown(); } /* * Called when the transport connection failed and an error should be returned. */ private void connectionFailed(Channel failedChannel, IOException cause) { failureCause = cause; channel = failedChannel; connected.set(false); connectLatch.countDown(); } private NettyTransportSslOptions getSslOptions() { return (NettyTransportSslOptions) getTransportOptions(); } private void configureNetty(Bootstrap bootstrap, NettyTransportOptions options) { bootstrap.option(ChannelOption.TCP_NODELAY, options.isTcpNoDelay()); bootstrap.option(ChannelOption.CONNECT_TIMEOUT_MILLIS, options.getConnectTimeout()); bootstrap.option(ChannelOption.SO_KEEPALIVE, options.isTcpKeepAlive()); bootstrap.option(ChannelOption.SO_LINGER, options.getSoLinger()); if (options.getSendBufferSize() != -1) { bootstrap.option(ChannelOption.SO_SNDBUF, options.getSendBufferSize()); } if (options.getReceiveBufferSize() != -1) { bootstrap.option(ChannelOption.SO_RCVBUF, options.getReceiveBufferSize()); bootstrap.option(ChannelOption.RCVBUF_ALLOCATOR, new FixedRecvByteBufAllocator(options.getReceiveBufferSize())); } if (options.getTrafficClass() != -1) { bootstrap.option(ChannelOption.IP_TOS, options.getTrafficClass()); } } private void configureChannel(final Channel channel, final SslHandler sslHandler) throws Exception { if (isSSL()) { channel.pipeline().addLast(sslHandler); } if (getTransportOptions().isTraceBytes()) { channel.pipeline().addLast("logger", new LoggingHandler(getClass())); } addAdditionalHandlers(channel.pipeline()); channel.pipeline().addLast(createChannelHandler()); } // ----- Handle connection events -----------------------------------------// protected abstract class NettyDefaultHandler<E> extends SimpleChannelInboundHandler<E> { @Override public void channelRegistered(ChannelHandlerContext context) throws Exception { channel = context.channel(); } @Override public void channelActive(ChannelHandlerContext context) throws Exception { // In the Secure case we need to let the handshake complete before we // trigger the connected event. if (!isSSL()) { handleConnected(context.channel()); } else { SslHandler sslHandler = context.pipeline().get(SslHandler.class); sslHandler.handshakeFuture().addListener(new GenericFutureListener<Future<Channel>>() { @Override public void operationComplete(Future<Channel> future) throws Exception { if (future.isSuccess()) { LOG.trace("SSL Handshake has completed: {}", channel); handleConnected(channel); } else { LOG.trace("SSL Handshake has failed: {}", channel); handleException(channel, future.cause()); } } }); } } @Override public void channelInactive(ChannelHandlerContext context) throws Exception { handleChannelInactive(context.channel()); } @Override public void exceptionCaught(ChannelHandlerContext context, Throwable cause) throws Exception { handleException(context.channel(), cause); } } // ----- Handle Binary data from connection -------------------------------// protected class NettyTcpTransportHandler extends NettyDefaultHandler<ByteBuf> { @Override protected void channelRead0(ChannelHandlerContext ctx, ByteBuf buffer) throws Exception { LOG.trace("New data read: {} bytes incoming: {}", buffer.readableBytes(), buffer); listener.onData(buffer); } } }