Glassfish example source code file (SQLTraceCache.java)

This example Glassfish source code file (SQLTraceCache.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 - Glassfish tags/keywords

arraylist, caching, list, log, logging, sql, sqltrace, sqltrace, sqltracecache, sqltracetimertask, sqltracetimertask, string, string, stringbuffer, trace, trace, util

The Glassfish SQLTraceCache.java source code

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 2010 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at packager/legal/LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
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 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
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 */

package com.sun.gjc.util;

import com.sun.logging.LogDomains;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Timer;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Maintains the Sql Tracing Cache used to store SQL statements used by the
 * applications. This is used by the JDBCRA monitoring to display the most
 * frequently used queries by applications.
 *
 * @author Shalini M
 */
public class SQLTraceCache {

    //List of sql trace objects
    private final List<SQLTrace> list;
    //Maximum size of the cache.
    private int numTopQueriesToReport = 10;
    private long timeToKeepQueries = 60 * 1000;
    private SQLTraceTimerTask sqlTraceTimerTask;
    private String poolName;
    private String appName;
    private String moduleName;
    private final static Logger _logger = LogDomains.getLogger(SQLTraceCache.class,
            LogDomains.RSR_LOGGER);
    private static final String LINE_BREAK = "%%%EOL%%%";

    public SQLTraceCache(String poolName, String appName, String moduleName, int maxSize, long timeToKeepQueries) {
        this.poolName = poolName;
        this.appName = appName;
        this.moduleName = moduleName;
        this.numTopQueriesToReport = maxSize;
        list = new ArrayList<SQLTrace>();
        this.timeToKeepQueries = timeToKeepQueries * 60 * 1000;
    }

    public List<SQLTrace> getSqlTraceList() {
        return list;
    }

    public String getPoolName() {
        return poolName;
    }
    
    /**
     * Schedule timer to perform purgeEntries on the cache after the
     * specified timeToKeepQueries delay and period.
     */
    public void scheduleTimerTask(Timer timer) {

        if(sqlTraceTimerTask != null) {
            sqlTraceTimerTask.cancel();
            sqlTraceTimerTask = null;
        }

        sqlTraceTimerTask = initializeTimerTask();

        if(timer != null) {

            timer.scheduleAtFixedRate(sqlTraceTimerTask, timeToKeepQueries, timeToKeepQueries);
        }
        if(_logger.isLoggable(Level.FINEST)) {
            _logger.finest("Scheduled Sql Trace Caching timer task");
        }
    }

    /**
     * Cancel the timer task used to perform a purgeEntries on the cache.
     */
    public synchronized void cancelTimerTask() {

        if(_logger.isLoggable(Level.FINEST)) {
            _logger.finest("Cancelling Sql Trace Caching timer task");
        }
        if (sqlTraceTimerTask != null) {
            sqlTraceTimerTask.cancel();
        }
        sqlTraceTimerTask = null;
    }

    /**
     * Instantiate the timer task used to perform a purgeEntries on the cache
     *
     * @return SQLTraceTimerTask
     */
    private SQLTraceTimerTask initializeTimerTask() {
        if(_logger.isLoggable(Level.FINEST)) {
            _logger.finest("Initializing Sql Trace Caching timer task");
        }
        return new SQLTraceTimerTask(this);
    }

    /**
     * Request for adding a sql query in the form of SQLTrace to this cache.
     * If the query is already found
     * in the list, the number of times it is executed is incremented by one
     * along with the timestamp.
     * If the query is a new one, it is added to the list.
     * 
     * @param cacheObj
     * @return
     */
    public void checkAndUpdateCache(SQLTrace cacheObj) {
        synchronized (list) {
            if (cacheObj != null) {
                int index = list.indexOf(cacheObj);
                if (index != -1) {
                    //If already found in the cache
                    //equals is invoked here and hence comparison based on query name is done
                    //Get the object at the index to update the numExecutions
                    SQLTrace cache = (SQLTrace) list.get(index);
                    cache.setNumExecutions(cache.getNumExecutions() + 1);
                    cache.setLastUsageTime(System.currentTimeMillis());
                } else {
                    //First occurrence of the query. query to be added.
                    cacheObj.setNumExecutions(1);
                    cacheObj.setLastUsageTime(System.currentTimeMillis());
                    list.add(cacheObj);
                }
            }
        }
    }

    /**
     * Entries are removed from the list after sorting
     * them in the least frequently used order. Only numTopQueriesToReport number of
     * entries are maintained in the list after the purgeEntries.
     */
    public void purgeEntries() {
        synchronized(list) {
            Collections.sort(list, Collections.reverseOrder());
            Iterator i = list.iterator();
            while (i.hasNext()) {
                SQLTrace cacheObj = (SQLTrace) i.next();
                if (list.size() > numTopQueriesToReport) {
                    if(_logger.isLoggable(Level.FINEST)) {
                        _logger.finest("removing sql=" + cacheObj.getQueryName());
                    }
                    i.remove();
                } else {
                    break;
                }
            }
            //sort by most frequently used queries first
            Collections.sort(list);
        }
    }

    /**
     * Returns the String representation of the list of traced sql queries
     * ordered by the number most frequently used, followed by the usage
     * timestamp. Only the top 'n' queries represented by the numTopQueriesToReport are
     * chosen for display.
     *
     * @return string representation of the list of sql queries sorted
     */
    public String getTopQueries() {
        purgeEntries();
        StringBuffer sb = new StringBuffer();
        for(SQLTrace cache : list) {
            sb.append(LINE_BREAK);
            sb.append(cache.getQueryName());
        }
        return sb.toString();
    }
}