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.hama.ipc; import java.io.DataInput; import java.io.DataOutput; import java.io.IOException; import java.lang.reflect.Array; import java.lang.reflect.InvocationHandler; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.lang.reflect.Proxy; import java.net.ConnectException; import java.net.InetSocketAddress; import java.net.SocketTimeoutException; import java.util.HashMap; import java.util.Map; import javax.net.SocketFactory; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.conf.Configurable; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.io.ObjectWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.io.Writable; import org.apache.hadoop.security.UserGroupInformation; import org.apache.hadoop.security.token.SecretManager; import org.apache.hadoop.security.token.TokenIdentifier; import org.apache.hama.util.BSPNetUtils; /** * A simple RPC mechanism using netty. * * A <i>protocol</i> is a Java interface. All parameters and return types must * be one of: * * <ul> * <li>a primitive type, <code>boolean</code>, <code>byte</code>, * <code>char</code>, <code>short</code>, <code>int</code>, <code>long</code>, * <code>float</code>, <code>double</code>, or <code>void</code>; or</li> * * <li>a {@link String}; or</li> * * <li>a {@link Writable}; or</li> * * <li>an array of the above types</li> * </ul> * * All methods in the protocol should throw only IOException. No field data of * the protocol instance is transmitted. */ public class AsyncRPC { private static final Log LOG = LogFactory.getLog(AsyncRPC.class); private AsyncRPC() { } // no public ctor /** A method invocation, including the method name and its parameters. */ @SuppressWarnings("rawtypes") private static class Invocation implements Writable, Configurable { private String methodName; private Class[] parameterClasses; private Object[] parameters; private Configuration conf; @SuppressWarnings("unused") public Invocation() { } /** * * @param method * @param parameters */ public Invocation(Method method, Object[] parameters) { this.methodName = method.getName(); this.parameterClasses = method.getParameterTypes(); this.parameters = parameters; } /** The name of the method invoked. */ public String getMethodName() { return methodName; } /** The parameter classes. */ public Class[] getParameterClasses() { return parameterClasses; } /** The parameter instances. */ public Object[] getParameters() { return parameters; } /** * * @param in */ public void readFields(DataInput in) throws IOException { methodName = Text.readString(in); parameters = new Object[in.readInt()]; parameterClasses = new Class[parameters.length]; ObjectWritable objectWritable = new ObjectWritable(); for (int i = 0; i < parameters.length; i++) { parameters[i] = ObjectWritable.readObject(in, objectWritable, this.conf); parameterClasses[i] = objectWritable.getDeclaredClass(); } } /** * * @param out */ public void write(DataOutput out) throws IOException { Text.writeString(out, methodName); out.writeInt(parameterClasses.length); for (int i = 0; i < parameterClasses.length; i++) { ObjectWritable.writeObject(out, parameters[i], parameterClasses[i], conf); } } public String toString() { StringBuffer buffer = new StringBuffer(); buffer.append(methodName); buffer.append("("); for (int i = 0; i < parameters.length; i++) { if (i != 0) buffer.append(", "); buffer.append(parameters[i]); } buffer.append(")"); return buffer.toString(); } public void setConf(Configuration conf) { this.conf = conf; } public Configuration getConf() { return this.conf; } } /** Cache a client using its socket factory as the hash key */ static private class ClientCache { private Map<SocketFactory, AsyncClient> clients = new HashMap<SocketFactory, AsyncClient>(); /** * Construct & cache an IPC client with the user-provided SocketFactory if * no cached client exists. * * @param conf Configuration * @return an IPC client */ private synchronized AsyncClient getClient(Configuration conf, SocketFactory factory) { // Construct & cache client. The configuration is only used for timeout, // and Clients have connection pools. So we can either (a) lose some // connection pooling and leak sockets, or (b) use the same timeout for // all // configurations. Since the IPC is usually intended globally, not // per-job, we choose (a) AsyncClient client = clients.get(factory); if (client == null) { client = new AsyncClient(ObjectWritable.class, conf, factory); clients.put(factory, client); } else { client.incCount(); } return client; } /** * Construct & cache an IPC client with the default SocketFactory if no * cached client exists. * * @param conf Configuration * @return an IPC client */ private synchronized AsyncClient getClient(Configuration conf) { return getClient(conf, SocketFactory.getDefault()); } /** * Stop a RPCWithNetty client connection A RPCWithNetty client is closed * only when its reference count becomes zero. * * @param client */ private void stopClient(AsyncClient client) { synchronized (this) { client.decCount(); if (client.isZeroReference()) { clients.remove(client.getSocketFactory()); } } if (client.isZeroReference()) { client.stop(); } } } private static ClientCache CLIENTS = new ClientCache(); /** * for unit testing only * * @param conf * @return */ static AsyncClient getClient(Configuration conf) { return CLIENTS.getClient(conf); } /** * */ private static class Invoker implements InvocationHandler { private AsyncClient.ConnectionId remoteId; private AsyncClient client; private boolean isClosed = false; private Invoker(Class<? extends VersionedProtocol> protocol, InetSocketAddress address, UserGroupInformation ticket, Configuration conf, SocketFactory factory, int rpcTimeout, RetryPolicy connectionRetryPolicy) throws IOException { this.remoteId = AsyncClient.ConnectionId.getConnectionId(address, protocol, ticket, rpcTimeout, connectionRetryPolicy, conf); this.client = CLIENTS.getClient(conf, factory); } public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { final boolean logDebug = LOG.isDebugEnabled(); long startTime = 0; if (logDebug) { startTime = System.currentTimeMillis(); } ObjectWritable value = (ObjectWritable) client.call(new Invocation(method, args), remoteId); if (logDebug) { long callTime = System.currentTimeMillis() - startTime; LOG.debug("Call: " + method.getName() + " " + callTime); } return value.get(); } /** close the RPCWithNetty client that's responsible for this invoker's RPCs */ synchronized private void close() { if (!isClosed) { isClosed = true; CLIENTS.stopClient(client); } } } /** * A version mismatch for the RPC protocol. */ @SuppressWarnings("serial") public static class VersionMismatch extends IOException { private String interfaceName; private long clientVersion; private long serverVersion; /** * Create a version mismatch exception * * @param interfaceName the name of the protocol mismatch * @param clientVersion the client's version of the protocol * @param serverVersion the server's version of the protocol */ public VersionMismatch(String interfaceName, long clientVersion, long serverVersion) { super("Protocol " + interfaceName + " version mismatch. (client = " + clientVersion + ", server = " + serverVersion + ")"); this.interfaceName = interfaceName; this.clientVersion = clientVersion; this.serverVersion = serverVersion; } /** * Get the interface name * * @return the java class name (eg. * org.apache.hadoop.mapred.InterTrackerProtocol) */ public String getInterfaceName() { return interfaceName; } /** * Get the client's preferred version */ public long getClientVersion() { return clientVersion; } /** * Get the server's agreed to version. */ public long getServerVersion() { return serverVersion; } } /** * Get a proxy connection to a remote server */ public static VersionedProtocol waitForProxy(Class<? extends VersionedProtocol> protocol, long clientVersion, InetSocketAddress addr, Configuration conf) throws IOException { return waitForProxy(protocol, clientVersion, addr, conf, 0, Long.MAX_VALUE); } /** * Get a proxy connection to a remote server * * @param protocol protocol class * @param clientVersion client version * @param addr remote address * @param conf configuration to use * @param connTimeout time in milliseconds before giving up * @return the proxy * @throws IOException if the far end through a RemoteException */ static VersionedProtocol waitForProxy(Class<? extends VersionedProtocol> protocol, long clientVersion, InetSocketAddress addr, Configuration conf, long connTimeout) throws IOException { return waitForProxy(protocol, clientVersion, addr, conf, 0, connTimeout); } /** * Get a proxy connection to a remote server * * @param protocol protocol class * @param clientVersion client version * @param addr remote address * @param conf configuration to use * @param rpcTimeout rpc timeout * @param connTimeout time in milliseconds before giving up * @return the proxy * @throws IOException if the far end through a RemoteException */ static VersionedProtocol waitForProxy(Class<? extends VersionedProtocol> protocol, long clientVersion, InetSocketAddress addr, Configuration conf, int rpcTimeout, long connTimeout) throws IOException { long startTime = System.currentTimeMillis(); IOException ioe; while (true) { try { return getProxy(protocol, clientVersion, addr, conf, rpcTimeout); } catch (ConnectException se) { // namenode has not been started LOG.info("Server at " + addr + " not available yet, Zzzzz..."); ioe = se; } catch (SocketTimeoutException te) { // namenode is busy LOG.info("Problem connecting to server: " + addr); ioe = te; } // check if timed out if (System.currentTimeMillis() - connTimeout >= startTime) { throw ioe; } // wait for retry try { Thread.sleep(1000); } catch (InterruptedException ie) { // IGNORE } } } /** * Construct a client-side proxy object that implements the named protocol, * talking to a server at the named address. * * @param protocol * @param clientVersion * @param addr * @param conf * @param factory * @return the proxy * @throws IOException */ public static VersionedProtocol getProxy(Class<? extends VersionedProtocol> protocol, long clientVersion, InetSocketAddress addr, Configuration conf, SocketFactory factory) throws IOException { UserGroupInformation ugi = UserGroupInformation.getCurrentUser(); return getProxy(protocol, clientVersion, addr, ugi, conf, factory, 0); } /** * Construct a client-side proxy object that implements the named protocol, * talking to a server at the named address. * * @param protocol * @param clientVersion * @param addr * @param conf * @param factory * @param rpcTimeout * @return the proxy * @throws IOException */ public static VersionedProtocol getProxy(Class<? extends VersionedProtocol> protocol, long clientVersion, InetSocketAddress addr, Configuration conf, SocketFactory factory, int rpcTimeout) throws IOException { return getProxy(protocol, clientVersion, addr, null, conf, factory, rpcTimeout); } /** * Construct a client-side proxy object that implements the named protocol, * talking to a server at the named address. * * @param protocol * @param clientVersion * @param addr * @param ticket * @param conf * @param factory * @return the proxy * @throws IOException */ public static VersionedProtocol getProxy(Class<? extends VersionedProtocol> protocol, long clientVersion, InetSocketAddress addr, UserGroupInformation ticket, Configuration conf, SocketFactory factory) throws IOException { return getProxy(protocol, clientVersion, addr, ticket, conf, factory, 0); } /** * Construct a client-side proxy object that implements the named protocol, * talking to a server at the named address. * * @param protocol * @param clientVersion * @param addr * @param ticket * @param conf * @param factory * @param rpcTimeout * @return the proxy * @throws IOException */ public static VersionedProtocol getProxy(Class<? extends VersionedProtocol> protocol, long clientVersion, InetSocketAddress addr, UserGroupInformation ticket, Configuration conf, SocketFactory factory, int rpcTimeout) throws IOException { return getProxy(protocol, clientVersion, addr, ticket, conf, factory, rpcTimeout, null, true); } /** * Construct a client-side proxy object that implements the named protocol, * talking to a server at the named address. * * @param protocol * @param clientVersion * @param addr * @param ticket * @param conf * @param factory * @param rpcTimeout * @param connectionRetryPolicy * @param checkVersion * @return the proxy * @throws IOException */ public static VersionedProtocol getProxy(Class<? extends VersionedProtocol> protocol, long clientVersion, InetSocketAddress addr, UserGroupInformation ticket, Configuration conf, SocketFactory factory, int rpcTimeout, RetryPolicy connectionRetryPolicy, boolean checkVersion) throws IOException { final Invoker invoker = new Invoker(protocol, addr, ticket, conf, factory, rpcTimeout, connectionRetryPolicy); VersionedProtocol proxy = (VersionedProtocol) Proxy.newProxyInstance(protocol.getClassLoader(), new Class[] { protocol }, invoker); if (checkVersion) { checkVersion(protocol, clientVersion, proxy); } return proxy; } /** * Get server version and then compare it with client version. * * @param protocol * @param clientVersion * @param proxy * @throws IOException */ public static void checkVersion(Class<? extends VersionedProtocol> protocol, long clientVersion, VersionedProtocol proxy) throws IOException { long serverVersion = proxy.getProtocolVersion(protocol.getName(), clientVersion); if (serverVersion != clientVersion) { throw new VersionMismatch(protocol.getName(), clientVersion, serverVersion); } } /** * Construct a client-side proxy object with the default SocketFactory * * @param protocol * @param clientVersion * @param addr * @param conf * @return a proxy instance * @throws IOException */ public static VersionedProtocol getProxy(Class<? extends VersionedProtocol> protocol, long clientVersion, InetSocketAddress addr, Configuration conf) throws IOException { return getProxy(protocol, clientVersion, addr, conf, BSPNetUtils.getDefaultSocketFactory(conf), 0); } /** * Get VersionedProtocol * * @param protocol * @param clientVersion * @param addr * @param conf * @param rpcTimeout * @return the proxy * @throws IOException */ public static VersionedProtocol getProxy(Class<? extends VersionedProtocol> protocol, long clientVersion, InetSocketAddress addr, Configuration conf, int rpcTimeout) throws IOException { return getProxy(protocol, clientVersion, addr, conf, BSPNetUtils.getDefaultSocketFactory(conf), rpcTimeout); } /** * Stop this proxy and release its invoker's resource * * @param proxy the proxy to be stopped */ public static void stopProxy(VersionedProtocol proxy) { if (proxy != null) { ((Invoker) Proxy.getInvocationHandler(proxy)).close(); } } /** * Expert: Make multiple, parallel calls to a set of servers. * * @param method * @param params * @param addrs * @param ticket * @param conf * @return response object array * @throws IOException * @throws InterruptedException */ public static Object[] call(Method method, Object[][] params, InetSocketAddress[] addrs, UserGroupInformation ticket, Configuration conf) throws IOException, InterruptedException { Invocation[] invocations = new Invocation[params.length]; for (int i = 0; i < params.length; i++) invocations[i] = new Invocation(method, params[i]); AsyncClient client = CLIENTS.getClient(conf); try { Writable[] wrappedValues = client.call(invocations, addrs, method.getDeclaringClass(), ticket, conf); if (method.getReturnType() == Void.TYPE) { return null; } Object[] values = (Object[]) Array.newInstance(method.getReturnType(), wrappedValues.length); for (int i = 0; i < values.length; i++) if (wrappedValues[i] != null) values[i] = ((ObjectWritable) wrappedValues[i]).get(); return values; } finally { CLIENTS.stopClient(client); } } /** * Construct a server for a protocol implementation instance listening on a * port and address. * * @param instance * @param bindAddress * @param port * @param conf * @return server * @throws IOException */ public static NioServer getServer(final Object instance, final String bindAddress, final int port, Configuration conf) throws IOException { return getServer(instance, bindAddress, port, 1, false, conf); } /** * Construct a server for a protocol implementation instance listening on a * port and address. * * @param instance * @param bindAddress * @param port * @param numHandlers * @param verbose * @param conf * @return server * @throws IOException */ public static NioServer getServer(final Object instance, final String bindAddress, final int port, final int numHandlers, final boolean verbose, Configuration conf) throws IOException { return getServer(instance, bindAddress, port, numHandlers, verbose, conf, null); } /** * Construct a server for a protocol implementation instance listening on a * port and address, with a secret manager. * * @param instance * @param bindAddress * @param port * @param numHandlers * @param verbose * @param conf * @param secretManager * @return server * @throws IOException */ public static NioServer getServer(final Object instance, final String bindAddress, final int port, final int numHandlers, final boolean verbose, Configuration conf, SecretManager<? extends TokenIdentifier> secretManager) throws IOException { return new NioServer(instance, conf, bindAddress, port, numHandlers, verbose, secretManager); } /** An RPC Server. */ public static class NioServer extends org.apache.hama.ipc.AsyncServer { private Object instance; private boolean verbose; /** * Construct an RPC server. * * @param instance the instance whose methods will be called * @param conf the configuration to use * @param bindAddress the address to bind on to listen for connection * @param port the port to listen for connections on * @throws IOException */ public NioServer(Object instance, Configuration conf, String bindAddress, int port) throws IOException { this(instance, conf, bindAddress, port, 1, false, null); } private static String classNameBase(String className) { String[] names = className.split("\\.", -1); if (names.length == 0) { return className; } return names[names.length - 1]; } /** * Construct an RPC server. * * @param instance the instance whose methods will be called * @param conf the configuration to use * @param bindAddress the address to bind on to listen for connection * @param port the port to listen for connections on * @param numHandlers the number of method handler threads to run * @param verbose whether each call should be logged * @throws IOException */ public NioServer(Object instance, Configuration conf, String bindAddress, int port, int numHandlers, boolean verbose, SecretManager<? extends TokenIdentifier> secretManager) throws IOException { super(bindAddress, port, Invocation.class, numHandlers, conf, classNameBase(instance.getClass().getName()), secretManager); this.instance = instance; this.verbose = verbose; } public Writable call(Class<?> protocol, Writable param, long receivedTime) throws IOException { try { Invocation call = (Invocation) param; if (verbose) log("Call: " + call); Method method = protocol.getMethod(call.getMethodName(), call.getParameterClasses()); method.setAccessible(true); long startTime = System.currentTimeMillis(); Object value = method.invoke(instance, call.getParameters()); int processingTime = (int) (System.currentTimeMillis() - startTime); int qTime = (int) (startTime - receivedTime); if (LOG.isDebugEnabled()) { LOG.debug("Served: " + call.getMethodName() + " queueTime= " + qTime + " procesingTime= " + processingTime); } if (verbose) log("Return: " + value); return new ObjectWritable(method.getReturnType(), value); } catch (InvocationTargetException e) { Throwable target = e.getTargetException(); if (target instanceof IOException) { throw (IOException) target; } else { IOException ioe = new IOException(target.toString()); ioe.setStackTrace(target.getStackTrace()); throw ioe; } } catch (Throwable e) { if (!(e instanceof IOException)) { LOG.error("Unexpected throwable object ", e); } IOException ioe = new IOException(e.toString()); ioe.setStackTrace(e.getStackTrace()); throw ioe; } } } private static void log(String value) { if (value != null && value.length() > 55) value = value.substring(0, 55) + "..."; LOG.info(value); } }