Commons DBCP example source code file (AbandonedObjectPool.java)

This example Commons DBCP source code file (AbandonedObjectPool.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 - Commons DBCP tags/keywords

abandonedconfig, abandonedobjectpool, abandonedtrace, abandonedtrace, arraylist, arraylist, exception, exception, iterator, list, object, object, stop, this, util

The Commons DBCP AbandonedObjectPool.java 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.
 */

package org.apache.commons.dbcp;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.apache.commons.pool.PoolableObjectFactory;
import org.apache.commons.pool.impl.GenericObjectPool;

/**
 * <p>An implementation of a Jakarta-Commons ObjectPool which
 * tracks JDBC connections and can recover abandoned db connections.
 * If logAbandoned=true, a stack trace will be printed for any
 * abandoned db connections recovered.
 *                                                                        
 * @author Glenn L. Nielsen
 * @version $Revision: 899987 $ $Date: 2010-01-16 11:51:16 -0500 (Sat, 16 Jan 2010) $
 */
public class AbandonedObjectPool extends GenericObjectPool {

    /** 
     * DBCP AbandonedConfig 
     */
    private final AbandonedConfig config;
    
    /**
     * A list of connections in use
     */
    private final List trace = new ArrayList();

    /**
     * Create an ObjectPool which tracks db connections.
     *
     * @param factory PoolableObjectFactory used to create this
     * @param config configuration for abandoned db connections
     */
    public AbandonedObjectPool(PoolableObjectFactory factory,
                               AbandonedConfig config) {
        super(factory);
        this.config = config;
    }

    /**
     * Get a db connection from the pool.
     *
     * If removeAbandoned=true, recovers db connections which
     * have been idle > removeAbandonedTimeout and
     * getNumActive() > getMaxActive() - 3 and
     * getNumIdle() < 2
     * 
     * @return Object jdbc Connection
     * @throws Exception if an exception occurs retrieving a 
     * connection from the pool
     */
    public Object borrowObject() throws Exception {
        if (config != null
                && config.getRemoveAbandoned()
                && (getNumIdle() < 2)
                && (getNumActive() > getMaxActive() - 3) ) {
            removeAbandoned();
        }
        Object obj = super.borrowObject();
        if (obj instanceof AbandonedTrace) {
            ((AbandonedTrace) obj).setStackTrace();
        }
        if (obj != null && config != null && config.getRemoveAbandoned()) {
            synchronized (trace) {
                trace.add(obj);
            }
        }
        return obj;
    }

    /**
     * Return a db connection to the pool.
     *
     * @param obj db Connection to return
     * @throws Exception if an exception occurs returning the connection
     * to the pool
     */
    public void returnObject(Object obj) throws Exception {
        if (config != null && config.getRemoveAbandoned()) {
            synchronized (trace) {
                boolean foundObject = trace.remove(obj);
                if (!foundObject) {
                    return; // This connection has already been invalidated.  Stop now.
                }
            }
        }
        super.returnObject(obj);
    }

    /**
     * Invalidates an object from the pool.
     *
     * @param obj object to be returned
     * @throws Exception if an exception occurs invalidating the object
     */
    public void invalidateObject(Object obj) throws Exception {
        if (config != null && config.getRemoveAbandoned()) {
            synchronized (trace) {
                boolean foundObject = trace.remove(obj);
                if (!foundObject) {
                    return; // This connection has already been invalidated.  Stop now.
                }
            }
        }
        super.invalidateObject(obj);        
    }

    /**
     * Recover abandoned db connections which have been idle
     * greater than the removeAbandonedTimeout.
     */
    private void removeAbandoned() {
        // Generate a list of abandoned connections to remove
        long now = System.currentTimeMillis();
        long timeout = now - (config.getRemoveAbandonedTimeout() * 1000);
        ArrayList remove = new ArrayList();
        synchronized (trace) {
            Iterator it = trace.iterator();
            while (it.hasNext()) {
                AbandonedTrace pc = (AbandonedTrace) it.next();
                if (pc.getLastUsed() > timeout) {
                    continue;
                }
                if (pc.getLastUsed() > 0) {
                    remove.add(pc);
                }
            }
        }

        // Now remove the abandoned connections
        Iterator it = remove.iterator();
        while (it.hasNext()) {
            AbandonedTrace pc = (AbandonedTrace) it.next();
            if (config.getLogAbandoned()) {
                pc.printStackTrace();
            }             
            try {
                invalidateObject(pc);
            } catch (Exception e) {
                e.printStackTrace();
            }
            
        }
    }
}