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.cassandra.transport; import java.io.Closeable; import java.io.IOException; import java.net.InetSocketAddress; import java.nio.ByteBuffer; import java.util.Collections; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.concurrent.BlockingQueue; import java.util.concurrent.LinkedBlockingQueue; import java.util.concurrent.SynchronousQueue; import javax.net.ssl.SSLContext; import javax.net.ssl.SSLEngine; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import io.netty.bootstrap.Bootstrap; import io.netty.channel.ChannelHandler; import io.netty.channel.ChannelInitializer; import io.netty.channel.ChannelOption; import io.netty.channel.SimpleChannelInboundHandler; import io.netty.channel.nio.NioEventLoopGroup; import io.netty.util.internal.logging.InternalLoggerFactory; import io.netty.util.internal.logging.Slf4JLoggerFactory; import org.apache.cassandra.cql3.QueryOptions; import org.apache.cassandra.db.ConsistencyLevel; import org.apache.cassandra.security.SSLFactory; import org.apache.cassandra.transport.messages.CredentialsMessage; import org.apache.cassandra.transport.messages.ErrorMessage; import org.apache.cassandra.transport.messages.EventMessage; import org.apache.cassandra.transport.messages.ExecuteMessage; import org.apache.cassandra.transport.messages.PrepareMessage; import org.apache.cassandra.transport.messages.QueryMessage; import org.apache.cassandra.transport.messages.ResultMessage; import org.apache.cassandra.transport.messages.StartupMessage; import org.apache.cassandra.utils.MD5Digest; import io.netty.channel.Channel; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.ChannelPipeline; import io.netty.handler.ssl.SslHandler; import static org.apache.cassandra.config.EncryptionOptions.ClientEncryptionOptions; public class SimpleClient implements Closeable { static { InternalLoggerFactory.setDefaultFactory(new Slf4JLoggerFactory()); } private static final Logger logger = LoggerFactory.getLogger(SimpleClient.class); public final String host; public final int port; private final ClientEncryptionOptions encryptionOptions; protected final ResponseHandler responseHandler = new ResponseHandler(); protected final Connection.Tracker tracker = new ConnectionTracker(); protected final int version; // We don't track connection really, so we don't need one Connection per channel protected Connection connection; protected Bootstrap bootstrap; protected Channel channel; protected ChannelFuture lastWriteFuture; private final Connection.Factory connectionFactory = new Connection.Factory() { public Connection newConnection(Channel channel, int version) { return connection; } }; public SimpleClient(String host, int port, int version, ClientEncryptionOptions encryptionOptions) { this.host = host; this.port = port; this.version = version; this.encryptionOptions = encryptionOptions; } public SimpleClient(String host, int port, ClientEncryptionOptions encryptionOptions) { this(host, port, Server.CURRENT_VERSION, encryptionOptions); } public SimpleClient(String host, int port, int version) { this(host, port, version, new ClientEncryptionOptions()); } public SimpleClient(String host, int port) { this(host, port, new ClientEncryptionOptions()); } public void connect(boolean useCompression) throws IOException { establishConnection(); Map<String, String> options = new HashMap<>(); options.put(StartupMessage.CQL_VERSION, "3.0.0"); if (useCompression) { options.put(StartupMessage.COMPRESSION, "snappy"); connection.setCompressor(FrameCompressor.SnappyCompressor.instance); } execute(new StartupMessage(options)); } public void setEventHandler(EventHandler eventHandler) { responseHandler.eventHandler = eventHandler; } protected void establishConnection() throws IOException { // Configure the client. bootstrap = new Bootstrap().group(new NioEventLoopGroup()) .channel(io.netty.channel.socket.nio.NioSocketChannel.class) .option(ChannelOption.TCP_NODELAY, true); // Configure the pipeline factory. if (encryptionOptions.enabled) { bootstrap.handler(new SecureInitializer()); } else { bootstrap.handler(new Initializer()); } ChannelFuture future = bootstrap.connect(new InetSocketAddress(host, port)); // Wait until the connection attempt succeeds or fails. channel = future.awaitUninterruptibly().channel(); if (!future.isSuccess()) { bootstrap.group().shutdownGracefully(); throw new IOException("Connection Error", future.cause()); } } public void login(Map<String, String> credentials) { CredentialsMessage msg = new CredentialsMessage(); msg.credentials.putAll(credentials); execute(msg); } public ResultMessage execute(String query, ConsistencyLevel consistency) { return execute(query, Collections.<ByteBuffer>emptyList(), consistency); } public ResultMessage execute(String query, List<ByteBuffer> values, ConsistencyLevel consistencyLevel) { Message.Response msg = execute( new QueryMessage(query, QueryOptions.forInternalCalls(consistencyLevel, values))); assert msg instanceof ResultMessage; return (ResultMessage) msg; } public ResultMessage.Prepared prepare(String query) { Message.Response msg = execute(new PrepareMessage(query)); assert msg instanceof ResultMessage.Prepared; return (ResultMessage.Prepared) msg; } public ResultMessage executePrepared(byte[] statementId, List<ByteBuffer> values, ConsistencyLevel consistency) { Message.Response msg = execute(new ExecuteMessage(MD5Digest.wrap(statementId), QueryOptions.forInternalCalls(consistency, values))); assert msg instanceof ResultMessage; return (ResultMessage) msg; } public void close() { // Wait until all messages are flushed before closing the channel. if (lastWriteFuture != null) lastWriteFuture.awaitUninterruptibly(); // Close the connection. Make sure the close operation ends because // all I/O operations are asynchronous in Netty. channel.close().awaitUninterruptibly(); // Shut down all thread pools to exit. bootstrap.group().shutdownGracefully(); } public Message.Response execute(Message.Request request) { try { request.attach(connection); lastWriteFuture = channel.writeAndFlush(request); Message.Response msg = responseHandler.responses.take(); if (msg instanceof ErrorMessage) throw new RuntimeException((Throwable) ((ErrorMessage) msg).error); return msg; } catch (InterruptedException e) { throw new RuntimeException(e); } } public interface EventHandler { void onEvent(Event event); } public static class SimpleEventHandler implements EventHandler { public final LinkedBlockingQueue<Event> queue = new LinkedBlockingQueue<>(); public void onEvent(Event event) { queue.add(event); } } // Stateless handlers private static final Message.ProtocolDecoder messageDecoder = new Message.ProtocolDecoder(); private static final Message.ProtocolEncoder messageEncoder = new Message.ProtocolEncoder(); private static final Frame.Decompressor frameDecompressor = new Frame.Decompressor(); private static final Frame.Compressor frameCompressor = new Frame.Compressor(); private static final Frame.Encoder frameEncoder = new Frame.Encoder(); private static class ConnectionTracker implements Connection.Tracker { public void addConnection(Channel ch, Connection connection) { } public boolean isRegistered(Event.Type type, Channel ch) { return false; } } private class Initializer extends ChannelInitializer<Channel> { protected void initChannel(Channel channel) throws Exception { connection = new Connection(channel, version, tracker); channel.attr(Connection.attributeKey).set(connection); ChannelPipeline pipeline = channel.pipeline(); pipeline.addLast("frameDecoder", new Frame.Decoder(connectionFactory)); pipeline.addLast("frameEncoder", frameEncoder); pipeline.addLast("frameDecompressor", frameDecompressor); pipeline.addLast("frameCompressor", frameCompressor); pipeline.addLast("messageDecoder", messageDecoder); pipeline.addLast("messageEncoder", messageEncoder); pipeline.addLast("handler", responseHandler); } } private class SecureInitializer extends Initializer { private final SSLContext sslContext; public SecureInitializer() throws IOException { this.sslContext = SSLFactory.createSSLContext(encryptionOptions, true); } protected void initChannel(Channel channel) throws Exception { super.initChannel(channel); SSLEngine sslEngine = sslContext.createSSLEngine(); sslEngine.setUseClientMode(true); sslEngine.setEnabledCipherSuites(encryptionOptions.cipher_suites); sslEngine.setEnabledProtocols(SSLFactory.ACCEPTED_PROTOCOLS); channel.pipeline().addFirst("ssl", new SslHandler(sslEngine)); } } @ChannelHandler.Sharable private static class ResponseHandler extends SimpleChannelInboundHandler<Message.Response> { public final BlockingQueue<Message.Response> responses = new SynchronousQueue<>(true); public EventHandler eventHandler; @Override public void channelRead0(ChannelHandlerContext ctx, Message.Response r) { try { if (r instanceof EventMessage) { if (eventHandler != null) eventHandler.onEvent(((EventMessage) r).event); } else responses.put(r); } catch (InterruptedException ie) { throw new RuntimeException(ie); } } public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { if (this == ctx.pipeline().last()) logger.error("Exception in response", cause); ctx.fireExceptionCaught(cause); } } }