com.alibaba.wasp.ipc.ClientCache.java Source code

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Here is the source code for com.alibaba.wasp.ipc.ClientCache.java

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/**
 * 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 com.alibaba.wasp.ipc;

import com.alibaba.wasp.FConstants;
import org.apache.hadoop.conf.Configuration;

import javax.net.SocketFactory;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.net.InetSocketAddress;
import java.util.HashMap;
import java.util.Map;

/**
 * Cache a client using its socket factory as the hash key. Enables
 * reuse/sharing of clients on a per SocketFactory basis. A client establishes
 * certain configuration dependent characteristics like timeouts, tcp-keepalive
 * (true or false), etc. For more details on the characteristics. Creation of
 * dynamic proxies to protocols creates the clients (and increments reference
 * count once created), and stopping of the proxies leads to clearing out
 * references and when the reference drops to zero, the cache mapping is
 * cleared.
 */
class ClientCache {
    private Map<String, NettyTransceiver> clients = new HashMap<String, NettyTransceiver>();

    protected ClientCache() {
    }

    /**
     * Construct & cache an IPC client with the user-provided SocketFactory if no
     * cached client exists.
     * 
     * @param conf
     *          Configuration
     * @param factory
     *          socket factory
     * @return an IPC client
     */
    protected synchronized NettyTransceiver getClient(InetSocketAddress addr, SocketFactory factory,
            Configuration conf) {

        NettyTransceiver client = clients.get(addr.toString());
        if (client == null) {
            Class<? extends NettyTransceiver> waspClientClass = NettyTransceiver.class;

            // Make an wasp rpc client.
            try {
                Constructor<? extends NettyTransceiver> cst = waspClientClass
                        .getConstructor(InetSocketAddress.class, Long.class);
                client = cst.newInstance(addr, conf.getLong(FConstants.WASP_CONNECTION_TIMEOUT_MILLIS,
                        FConstants.DEFAULT_CONNECTION_TIMEOUT_MILLIS));
                client.setConf(conf);
            } catch (InvocationTargetException e) {
                throw new RuntimeException(e);
            } catch (InstantiationException e) {
                throw new RuntimeException(e);
            } catch (IllegalAccessException e) {
                throw new RuntimeException(e);
            } catch (NoSuchMethodException e) {
                throw new RuntimeException("No matching constructor in " + waspClientClass.getName(), e);
            }

            clients.put(addr.toString(), client);
        } else {
            client.incCount();
        }
        return client;
    }

    /**
     * Stop a RPC client connection A RPC client is closed only when its reference
     * count becomes zero.
     * 
     * @param client
     *          client to stop
     */
    protected void stopClient(NettyTransceiver client) {
        synchronized (this) {
            client.decCount();
            if (client.isZeroReference()) {
                clients.remove(client.getRemoteAddr().toString());
            }
        }
        if (client.isZeroReference()) {
            client.close();
        }
    }
}