Java example source code file (IdleConnectionHandler.java)

This example source code file (IdleConnectionHandler.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

checking, closing, hashmap, httpconnection, i/o, idleconnectionhandler, io, ioexception, iterator, log, map, notthreadsafe, removing, threading, threads, timeunit, timevalues, util

The IdleConnectionHandler.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;

import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.concurrent.TimeUnit;

import org.apache.http.annotation.NotThreadSafe;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.HttpConnection;

// Currently only used by AbstractConnPool
/**
 * A helper class for connection managers to track idle connections.
 * 
 * <p>This class is not synchronized.

 * 
 * @see org.apache.http.conn.ClientConnectionManager#closeIdleConnections
 * 
 * @since 4.0
 */
@NotThreadSafe
public class IdleConnectionHandler {

    private final Log log = LogFactory.getLog(getClass());
    
    /** Holds connections and the time they were added. */
    private final Map<HttpConnection,TimeValues> connectionToTimes;
    

    public IdleConnectionHandler() {
        super();
        connectionToTimes = new HashMap<HttpConnection,TimeValues>();
    }
    
    /**
     * Registers the given connection with this handler.  The connection will be held until 
     * {@link #remove} or {@link #closeIdleConnections} is called.
     * 
     * @param connection the connection to add
     * 
     * @see #remove
     */
    public void add(HttpConnection connection, long validDuration, TimeUnit unit) {
        
        long timeAdded = System.currentTimeMillis();
        
        if (log.isDebugEnabled()) {
            log.debug("Adding connection at: " + timeAdded);
        }
        
        connectionToTimes.put(connection, new TimeValues(timeAdded, validDuration, unit));
    }
    
    /**
     * Removes the given connection from the list of connections to be closed when idle.
     * This will return true if the connection is still valid, and false
     * if the connection should be considered expired and not used.
     * 
     * @param connection
     * @return True if the connection is still valid.
     */
    public boolean remove(HttpConnection connection) {
        TimeValues times = connectionToTimes.remove(connection);
        if(times == null) {
            log.warn("Removing a connection that never existed!");
            return true;
        } else {
            return System.currentTimeMillis() <= times.timeExpires;
        }
    }

    /**
     * Removes all connections referenced by this handler.
     */
    public void removeAll() {
        this.connectionToTimes.clear();
    }
    
    /**
     * Closes connections that have been idle for at least the given amount of time.
     * 
     * @param idleTime the minimum idle time, in milliseconds, for connections to be closed
     */
    public void closeIdleConnections(long idleTime) {
        
        // the latest time for which connections will be closed
        long idleTimeout = System.currentTimeMillis() - idleTime;

        if (log.isDebugEnabled()) {
            log.debug("Checking for connections, idle timeout: "  + idleTimeout);
        }
        Iterator<HttpConnection> connectionIter = connectionToTimes.keySet().iterator();
        
        while (connectionIter.hasNext()) {
            HttpConnection conn = connectionIter.next();
            TimeValues times = connectionToTimes.get(conn);
            long connectionTime = times.timeAdded;
            if (connectionTime <= idleTimeout) {
                if (log.isDebugEnabled()) {
                    log.debug("Closing idle connection, connection time: "  + connectionTime);
                }
                try {
                    conn.close();
                } catch (IOException ex) {
                    log.debug("I/O error closing connection", ex);
                }
            }
        }
    }
    

    public void closeExpiredConnections() {
        long now = System.currentTimeMillis();
        if (log.isDebugEnabled()) {
            log.debug("Checking for expired connections, now: "  + now);
        }
        
        Iterator<HttpConnection> connectionIter =
            connectionToTimes.keySet().iterator();
        
        while (connectionIter.hasNext()) {
            HttpConnection conn = connectionIter.next();
            TimeValues times = connectionToTimes.get(conn);
            if(times.timeExpires <= now) {
                if (log.isDebugEnabled()) {
                    log.debug("Closing connection, expired @: "  + times.timeExpires);
                }
                try {
                    conn.close();
                } catch (IOException ex) {
                    log.debug("I/O error closing connection", ex);
                }
            }
        }        
    }
    
    private static class TimeValues {
        private final long timeAdded;
        private final long timeExpires;

        /**
         * @param now The current time in milliseconds
         * @param validDuration The duration this connection is valid for
         * @param validUnit The unit of time the duration is specified in.
         */
        TimeValues(long now, long validDuration, TimeUnit validUnit) {
            this.timeAdded = now;
            if(validDuration > 0) {
                this.timeExpires = now + validUnit.toMillis(validDuration);
            } else {
                this.timeExpires = Long.MAX_VALUE;
            }
        }
    }
}