/*
 * $Header: /home/cvs/commons/dbcp-1.0/ja/src/org/apache/commons/dbcp/AbandonedObjectPool.java,v 1.1.1.1 2004/02/13 10:02:03 hioki Exp $
 * $Revision: 1.1.1.1 $
 * $Date: 2004/02/13 10:02:03 $ 
 *
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999-2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
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 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * 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.commons.dbcp;

import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Date;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;

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

/**
 * <p>
 * JDBC コネクションを追跡し、破棄されたもの回復することのできる Jakarta-Commons ObjectPool の実装です。
 * logAbandoned=true の場合には破棄されたデータベースコネクションを回復した場合にスタックトレースが出力されます。
 * {@primary 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
 * @translator 日置 聡
 * @status firstdraft
 * @update 2003/09/13
 * @version $Revision: 1.1.1.1 $ $Date: 2004/02/13 10:02:03 $
 */
public class AbandonedObjectPool extends GenericObjectPool {

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

    /**
     * データベースコネクションを追跡する ObjectPool を生成します。
     * {@primary Create an ObjectPool which tracks db connections.}
     *
     * @param factory コネクションの生成に使用されるファクトリ
     * {@primary factory used to create this}
     * @param config 破棄されたコネクションに対する設定情報
     * {@primary configuration for abandoned db connections}
     */
    public AbandonedObjectPool(PoolableObjectFactory factory,
                               AbandonedConfig config) {
        super(factory);
        this.config = config;
    }

    /**
     * このプールからコネクションを取得します。
     * removeAbandoned=true の場合にはアイドル時間が
     * removeAbandonedTimeout を超えた場合、データベースコネクションを回復します。
     * {@primary Get a db connection from the pool.
     * If removeAbandoned=true, recovers db connections which
     * have been idle > removeAbandonedTimeout.}
     * 
     * @return JDBCコネクション
     * {@primary Object jdbc Connection}
     */
    public synchronized Object borrowObject() throws Exception {
        try {
            if (config != null
                    && config.getRemoveAbandoned()
                    && (getNumIdle() < 2)
                    && (getNumActive() > getMaxActive() - 3) ) {
                removeAbandoned();
            }
            Object obj = super.borrowObject();
            if (obj != null && config != null && config.getRemoveAbandoned()) {
                trace.add(obj);
            }
            return obj;
        } catch(NoSuchElementException ne) {
            throw new SQLException(
                "DBCP could not obtain an idle db connection, pool exhausted");
        } catch(Exception e) {
            System.out.println("DBCP borrowObject failed: " + e.getMessage());
            throw e;
        }
    }

    /**
     * データベースコネクションをプールに返します。
     * {@primary Return a db connection to the pool.}
     *
     * @param obj プールに返すデータベースコネクション
     * {@primary obj db Connection to return}
     */
    public synchronized void returnObject(Object obj) throws Exception {
        if (config != null && config.getRemoveAbandoned()) {
            trace.remove(obj);
        }
        super.returnObject(obj);
    }

    /**
     * removeAbandonedTimeout の時間以上アイドル状態にある破棄されたデータベースコネクションを回復します。
     * {@primary Recover abandoned db connections which have been idle
     * greater than the removeAbandonedTimeout.}
     */
    private synchronized void removeAbandoned() {
        // Generate a list of abandoned connections to remove
        long now = new Date().getTime();
        long timeout = now - (config.getRemoveAbandonedTimeout() * 1000);
        ArrayList remove = new ArrayList();
        Iterator it = trace.iterator();
        while (it.hasNext()) {
            PoolableConnection pc = (PoolableConnection)it.next();
            if (pc.getLastUsed() > timeout) {
                continue;
            }
            if (pc.getLastUsed() > 0) {
                remove.add(pc);
            }
        }
        // Now remove the abandoned connections
        it = remove.iterator();
        while (it.hasNext()) {
            PoolableConnection pc = (PoolableConnection)it.next();
            if (config.getLogAbandoned()) {
                pc.printStackTrace();
            }             
            try {
                pc.close();
            } catch(SQLException e) {
                e.printStackTrace();
            }             
        }
    }

}