| /** |
| * 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.hadoop.ipc; |
| |
| import java.util.HashMap; |
| import java.util.Map; |
| |
| import javax.net.SocketFactory; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.io.ObjectWritable; |
| import org.apache.hadoop.io.Writable; |
| |
| /* Cache a client using its socket factory as the hash key */ |
| @InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"}) |
| @InterfaceStability.Evolving |
| public class ClientCache { |
| private Map<SocketFactory, Client> clients = |
| new HashMap<SocketFactory, Client>(); |
| |
| /** |
| * Construct & cache an IPC client with the user-provided SocketFactory |
| * if no cached client exists. |
| * |
| * @param conf Configuration |
| * @param factory SocketFactory for client socket |
| * @param valueClass Class of the expected response |
| * @return an IPC client |
| */ |
| public synchronized Client getClient(Configuration conf, |
| SocketFactory factory, Class<? extends Writable> valueClass) { |
| // 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). |
| Client client = clients.get(factory); |
| if (client == null) { |
| client = new Client(valueClass, conf, factory); |
| clients.put(factory, client); |
| } else { |
| client.incCount(); |
| } |
| if (Client.LOG.isDebugEnabled()) { |
| Client.LOG.debug("getting client out of cache: " + client); |
| } |
| return client; |
| } |
| |
| /** |
| * Construct & cache an IPC client with the default SocketFactory |
| * and default valueClass if no cached client exists. |
| * |
| * @param conf Configuration |
| * @return an IPC client |
| */ |
| public synchronized Client getClient(Configuration conf) { |
| return getClient(conf, SocketFactory.getDefault(), ObjectWritable.class); |
| } |
| |
| /** |
| * Construct & cache an IPC client with the user-provided SocketFactory |
| * if no cached client exists. Default response type is ObjectWritable. |
| * |
| * @param conf Configuration |
| * @param factory SocketFactory for client socket |
| * @return an IPC client |
| */ |
| public synchronized Client getClient(Configuration conf, SocketFactory factory) { |
| return this.getClient(conf, factory, ObjectWritable.class); |
| } |
| |
| /** |
| * Stop a RPC client connection |
| * A RPC client is closed only when its reference count becomes zero. |
| */ |
| public void stopClient(Client client) { |
| if (Client.LOG.isDebugEnabled()) { |
| Client.LOG.debug("stopping client from cache: " + client); |
| } |
| synchronized (this) { |
| client.decCount(); |
| if (client.isZeroReference()) { |
| if (Client.LOG.isDebugEnabled()) { |
| Client.LOG.debug("removing client from cache: " + client); |
| } |
| clients.remove(client.getSocketFactory()); |
| } |
| } |
| if (client.isZeroReference()) { |
| if (Client.LOG.isDebugEnabled()) { |
| Client.LOG.debug("stopping actual client because no more references remain: " |
| + client); |
| } |
| client.stop(); |
| } |
| } |
| } |