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Java example source code file (ThreadSafeClientConnManager.java)

This example source code file (ThreadSafeClientConnManager.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java tags/keywords

abstractconnpool, basicpooledconnadapter, basicpoolentry, clientconnectionrequest, closing, defaultclientconnectionoperator, httproute, illegalargumentexception, io, ioexception, released, schemeregistry, threading, threads, threadsafe, threadsafeclientconnmanager, timeunit

The ThreadSafeClientConnManager.java example source code

/*
 * ====================================================================
 *
 *  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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.impl.conn.tsccm;

import java.io.IOException;
import java.util.concurrent.TimeUnit;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.conn.routing.HttpRoute;
import org.apache.http.conn.scheme.SchemeRegistry;
import org.apache.http.conn.ClientConnectionManager;
import org.apache.http.conn.ClientConnectionOperator;
import org.apache.http.conn.ClientConnectionRequest;
import org.apache.http.conn.ConnectionPoolTimeoutException;
import org.apache.http.conn.ManagedClientConnection;
import org.apache.http.conn.OperatedClientConnection;
import org.apache.http.params.HttpParams;
import org.apache.http.impl.conn.DefaultClientConnectionOperator;

/**
 * Manages a pool of {@link OperatedClientConnection client connections} and 
 * is able to service connection requests from multiple execution threads. 
 * Connections are pooled on a per route basis. A request for a route which 
 * already the manager has persistent connections for available in the pool 
 * will be services by leasing a connection from the pool rather than 
 * creating a brand new connection.
 * <p>
 * ThreadSafeClientConnManager maintains a maximum limit of connection on 
 * a per route basis and in total. Per default this implementation will
 * create no more than than 2 concurrent connections per given route 
 * and no more 20 connections in total. For many real-world applications
 * these limits may prove too constraining, especially if they use HTTP
 * as a transport protocol for their services. Connection limits, however,
 * can be adjusted using HTTP parameters.
 * <p>
 * The following parameters can be used to customize the behavior of this 
 * class: 
 * <ul>
 *  <li>{@link org.apache.http.conn.params.ConnManagerPNames#MAX_TOTAL_CONNECTIONS}
 *  <li>{@link org.apache.http.conn.params.ConnManagerPNames#MAX_CONNECTIONS_PER_ROUTE}
 * </ul>
 *
 * @see org.apache.http.conn.params.ConnPerRoute 
 * @see org.apache.http.conn.params.ConnPerRouteBean
 *
 * @since 4.0
 */
public class ThreadSafeClientConnManager implements ClientConnectionManager {

    private final Log log = LogFactory.getLog(getClass());

    /** The schemes supported by this connection manager. */
    protected final SchemeRegistry schemeRegistry; // @ThreadSafe
    
    /** The pool of connections being managed. */
    protected final AbstractConnPool connectionPool;

    /** The operator for opening and updating connections. */
    protected final ClientConnectionOperator connOperator; // DefaultClientConnectionOperator is @ThreadSafe
    
    /**
     * Creates a new thread safe connection manager.
     *
     * @param params    the parameters for this manager.
     * @param schreg    the scheme registry.
     */
    public ThreadSafeClientConnManager(HttpParams params,
                                       SchemeRegistry schreg) {

        if (params == null) {
            throw new IllegalArgumentException("HTTP parameters may not be null");
        }
        if (schreg == null) {
            throw new IllegalArgumentException("Scheme registry may not be null");
        }
        this.schemeRegistry = schreg;
        this.connOperator   = createConnectionOperator(schreg);
        this.connectionPool = createConnectionPool(params);

    }

    @Override
    protected void finalize() throws Throwable {
        try {
            shutdown();
        } finally {
            super.finalize();
        }
    }

    /**
     * Hook for creating the connection pool.
     *
     * @return  the connection pool to use
     */
    protected AbstractConnPool createConnectionPool(final HttpParams params) {
        return new ConnPoolByRoute(connOperator, params);
    }

    /**
     * Hook for creating the connection operator.
     * It is called by the constructor.
     * Derived classes can override this method to change the
     * instantiation of the operator.
     * The default implementation here instantiates
     * {@link DefaultClientConnectionOperator DefaultClientConnectionOperator}.
     *
     * @param schreg    the scheme registry.
     *
     * @return  the connection operator to use
     */
    protected ClientConnectionOperator
        createConnectionOperator(SchemeRegistry schreg) {

        return new DefaultClientConnectionOperator(schreg);// @ThreadSafe
    }

    public SchemeRegistry getSchemeRegistry() {
        return this.schemeRegistry;
    }

    public ClientConnectionRequest requestConnection(
            final HttpRoute route, 
            final Object state) {
        
        final PoolEntryRequest poolRequest = connectionPool.requestPoolEntry(
                route, state);
        
        return new ClientConnectionRequest() {
            
            public void abortRequest() {
                poolRequest.abortRequest();
            }
            
            public ManagedClientConnection getConnection(
                    long timeout, TimeUnit tunit) throws InterruptedException,
                    ConnectionPoolTimeoutException {
                if (route == null) {
                    throw new IllegalArgumentException("Route may not be null.");
                }

                if (log.isDebugEnabled()) {
                    log.debug("Get connection: " + route + ", timeout = " + timeout);
                }

                BasicPoolEntry entry = poolRequest.getPoolEntry(timeout, tunit);
                return new BasicPooledConnAdapter(ThreadSafeClientConnManager.this, entry);
            }
            
        };
        
    }

    public void releaseConnection(ManagedClientConnection conn, long validDuration, TimeUnit timeUnit) {

        if (!(conn instanceof BasicPooledConnAdapter)) {
            throw new IllegalArgumentException
                ("Connection class mismatch, " +
                 "connection not obtained from this manager.");
        }
        BasicPooledConnAdapter hca = (BasicPooledConnAdapter) conn;
        if ((hca.getPoolEntry() != null) && (hca.getManager() != this)) {
            throw new IllegalArgumentException
                ("Connection not obtained from this manager.");
        }
        synchronized (hca) {
            BasicPoolEntry entry = (BasicPoolEntry) hca.getPoolEntry();
            if (entry == null) {
                return;
            }
            try {
                // make sure that the response has been read completely
                if (hca.isOpen() && !hca.isMarkedReusable()) {
                    // In MTHCM, there would be a call to
                    // SimpleHttpConnectionManager.finishLastResponse(conn);
                    // Consuming the response is handled outside in 4.0.

                    // make sure this connection will not be re-used
                    // Shut down rather than close, we might have gotten here
                    // because of a shutdown trigger.
                    // Shutdown of the adapter also clears the tracked route.
                    hca.shutdown();
                }
            } catch (IOException iox) {
                if (log.isDebugEnabled())
                    log.debug("Exception shutting down released connection.",
                              iox);
            } finally {
                boolean reusable = hca.isMarkedReusable();
                if (log.isDebugEnabled()) {
                    if (reusable) {
                        log.debug("Released connection is reusable.");
                    } else {
                        log.debug("Released connection is not reusable.");
                    }
                }
                hca.detach();
                connectionPool.freeEntry(entry, reusable, validDuration, timeUnit);
            }
        }
    }

    public void shutdown() {
        log.debug("Shutting down");
        connectionPool.shutdown();
    }

    /**
     * Gets the total number of pooled connections for the given route.
     * This is the total number of connections that have been created and
     * are still in use by this connection manager for the route.
     * This value will not exceed the maximum number of connections per host.
     * 
     * @param route     the route in question
     *
     * @return  the total number of pooled connections for that route
     */
    public int getConnectionsInPool(HttpRoute route) {
        return ((ConnPoolByRoute)connectionPool).getConnectionsInPool(
                route);
    }

    /**
     * Gets the total number of pooled connections.  This is the total number of 
     * connections that have been created and are still in use by this connection 
     * manager.  This value will not exceed the maximum number of connections
     * in total.
     * 
     * @return the total number of pooled connections
     */
    public int getConnectionsInPool() {
        connectionPool.poolLock.lock();
        try {
            return connectionPool.numConnections;
        } finally {
            connectionPool.poolLock.unlock();
        }
    }

    public void closeIdleConnections(long idleTimeout, TimeUnit tunit) {
        if (log.isDebugEnabled()) {
            log.debug("Closing connections idle for " + idleTimeout + " " + tunit);
        }
        connectionPool.poolLock.lock();
        try {
            connectionPool.closeIdleConnections(idleTimeout, tunit);
            connectionPool.deleteClosedConnections();
        } finally {
            connectionPool.poolLock.unlock();
        }
    }
    
    public void closeExpiredConnections() {
        log.debug("Closing expired connections");
        connectionPool.poolLock.lock();
        try {
            connectionPool.closeExpiredConnections();
            connectionPool.deleteClosedConnections();
        } finally {
            connectionPool.poolLock.unlock();
        }
    }

}

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