/**
 * NOTE: This copyright does *not* cover user programs that use Hyperic
 * program services by normal system calls through the application
 * program interfaces provided as part of the Hyperic Plug-in Development
 * Kit or the Hyperic Client Development Kit - this is merely considered
 * normal use of the program, and does *not* fall under the heading of
 *  "derived work".
 *
 *  Copyright (C) [2009-2010], VMware, Inc.
 *  This file is part of Hyperic.
 *
 *  Hyperic is free software; you can redistribute it and/or modify
 *  it under the terms version 2 of the GNU General Public License as
 *  published by the Free Software Foundation. This program is distributed
 *  in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
 *  even the implied warranty of MERCHANTABILITY or FITNESS FOR A
 *  PARTICULAR PURPOSE. See the GNU General Public License for more
 *  details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 *  USA.
 *
 *  In addition, as a special exception, the copyright holders give permission to link the code of portions 
 *  of this program with AspectJ under certain conditions as described in each individual source file, 
 *  and distribute linked combinations including the two.
 *
 *  You must obey the GNU General Public License in all respects for all of the code used other than AspectJ.  
 *  If you modify file(s) with this exception, you may extend this exception to your version of the file(s), 
 *  but you are not obligated to do so.  
 *  If you do not wish to do so, delete this exception statement from your version. 
 *
 */
package org.hyperic.hq.monitor.aop.aspects;

import javax.annotation.PostConstruct;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.springframework.util.Assert;
import org.springframework.util.StopWatch;

/**
 * PerformanceMonitor performs around advice on pre-defined service-level
 * methods. Tests if method execution exceeds the injected SLA time.
 * If it does, it logs a warning with the relevant context.
 * @author Helena Edelson
 */
@Aspect
public class PerformanceMonitor {

    private static final Log logger = LogFactory.getLog(PerformanceMonitor.class);

    private long maximumDuration;

    private String warningMessage;

    @PostConstruct
    public void initialize() {
        Assert.hasText("warningMessage should have a value", warningMessage);
        Assert.isTrue(maximumDuration > 0, "threshold for maximumDuration should be > 0");
    }

    /**
     * We could bind the @Transactional annotation to the context but there's no
     * way to know if the method or the type is annotated, causing a false
     * negative.
     * @see org.hyperic.hq.monitor.aop.MonitorArchitecture
     * @param pjp
     */
    @Around("org.hyperic.hq.monitor.aop.MonitorArchitecture.serviceLayerOperationDuration()")
    public Object monitorServiceMethod(ProceedingJoinPoint pjp) throws Throwable {

        Object invocation = null;
        
        final StopWatch timer = new StopWatch(pjp.getSignature() + Thread.currentThread().getName());

        try {
            timer.start();
            invocation = pjp.proceed();
        }
        finally {
            timer.stop();
        }

        long duration = timer.getTotalTimeMillis();

        if (duration > maximumDuration) { 
            logger.warn(new StringBuilder(warningMessage)
                .append(pjp.getSignature()).append(" executed in ").
                append(timer.getTotalTimeMillis()).append(":ms").toString());
        }

        return invocation;
    }

    /**
     *
     * @param warningMessage
     */
    public void setWarningMessage(String warningMessage) {
        this.warningMessage = warningMessage;
    }

    /**
     * Optional - injected from properties file.
     * @param maximumDuration
     */
    public void setMaximumDuration(long maximumDuration) {
        this.maximumDuration = maximumDuration;
    }
}