hadoop ClientCache 源码

haddop ClientCache 代码

文件路径：/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/ClientCache.java

/**
 * 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;

import org.apache.hadoop.classification.VisibleForTesting;

/* 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 &amp; 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 &amp; 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 &amp; 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.
   *
   * @param client input client.
   */
  public void stopClient(Client client) {
    if (Client.LOG.isDebugEnabled()) {
      Client.LOG.debug("stopping client from cache: " + client);
    }
    final int count;
    synchronized (this) {
      count = client.decAndGetCount();
      if (count == 0) {
        if (Client.LOG.isDebugEnabled()) {
          Client.LOG.debug("removing client from cache: " + client);
        }
        clients.remove(client.getSocketFactory());
      }
    }
    if (count == 0) {
      if (Client.LOG.isDebugEnabled()) {
        Client.LOG.debug("stopping actual client because no more references remain: "
            + client);
      }
      client.stop();
    }
  }

  @VisibleForTesting
  public void clearCache() {
    clients.values().forEach(c -> c.stop());
    clients.clear();
  }
}

相关信息

hadoop 源码目录

相关文章

hadoop AlignmentContext 源码

hadoop AsyncCallLimitExceededException 源码

hadoop CallQueueManager 源码

hadoop CallerContext 源码

hadoop Client 源码

hadoop ClientId 源码

hadoop CostProvider 源码

hadoop DecayRpcScheduler 源码

hadoop DecayRpcSchedulerMXBean 源码

hadoop DefaultCostProvider 源码