/*
 * %W% %E%
 * 
 * Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * -Redistribution of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 * 
 * -Redistribution 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.
 * 
 * Neither the name of Oracle or the names of contributors may 
 * be used to endorse or promote products derived from this software without 
 * specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL 
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
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 * 
 * You acknowledge that this software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
 * nuclear facility.
 */

/*
 * %W% %E%
 */

import static java.lang.management.ManagementFactory.*;
import java.lang.management.*;
import javax.management.*;
import java.io.*;
import java.util.*;

/**
 * Example of using the java.lang.management API to monitor 
 * the memory usage and garbage collection statistics.
 *
 * @author  Mandy Chung
 * @version %% %G%
 */
public class PrintGCStat {
    private RuntimeMXBean rmbean;
    private MemoryMXBean mmbean;
    private List<MemoryPoolMXBean> pools;
    private List<GarbageCollectorMXBean> gcmbeans;
    
    /**
     * Constructs a PrintGCStat object to monitor a remote JVM.
     */
    public PrintGCStat(MBeanServerConnection server) throws IOException {
        // Create the platform mxbean proxies
        this.rmbean = newPlatformMXBeanProxy(server,
                                             RUNTIME_MXBEAN_NAME,
                                             RuntimeMXBean.class);
        this.mmbean = newPlatformMXBeanProxy(server,
                                             MEMORY_MXBEAN_NAME,
                                             MemoryMXBean.class);
        ObjectName poolName = null;
        ObjectName gcName = null;
        try {
            poolName = new ObjectName(MEMORY_POOL_MXBEAN_DOMAIN_TYPE+",*");
            gcName = new ObjectName(GARBAGE_COLLECTOR_MXBEAN_DOMAIN_TYPE+",*");
        } catch (MalformedObjectNameException e) {
            // should not reach here
            assert(false);
        }

        Set mbeans = server.queryNames(poolName, null);
        if (mbeans != null) {
            pools = new ArrayList<MemoryPoolMXBean>();
            Iterator iterator = mbeans.iterator();
            while (iterator.hasNext()) {
                ObjectName objName = (ObjectName) iterator.next();
                MemoryPoolMXBean p = 
                    newPlatformMXBeanProxy(server,
                                           objName.getCanonicalName(),
                                           MemoryPoolMXBean.class);
                pools.add(p);
            }
        }

        mbeans = server.queryNames(gcName, null);
        if (mbeans != null) {
            gcmbeans = new ArrayList<GarbageCollectorMXBean>();
            Iterator iterator = mbeans.iterator();
            while (iterator.hasNext()) {
                ObjectName objName = (ObjectName) iterator.next();
                GarbageCollectorMXBean gc = 
                    newPlatformMXBeanProxy(server,
                                           objName.getCanonicalName(),
                                           GarbageCollectorMXBean.class);
                gcmbeans.add(gc);
            }
        }
    }

    /**
     * Constructs a PrintGCStat object to monitor the local JVM.
     */
    public PrintGCStat() {
        // Obtain the platform mxbean instances for the running JVM.
        this.rmbean = getRuntimeMXBean();
        this.mmbean = getMemoryMXBean();
        this.pools = getMemoryPoolMXBeans();
        this.gcmbeans = getGarbageCollectorMXBeans();
    }

    /**
     * Prints the verbose GC log to System.out to list the memory usage
     * of all memory pools as well as the GC statistics. 
     */
    public void printVerboseGc() {
        System.out.print("Uptime: " + formatMillis(rmbean.getUptime()));
        for (GarbageCollectorMXBean gc : gcmbeans) {
            System.out.print(" [" + gc.getName() + ": ");
            System.out.print("Count=" + gc.getCollectionCount());
            System.out.print(" GCTime=" + formatMillis(gc.getCollectionTime()));
            System.out.print("]");
        }
        System.out.println();
        for (MemoryPoolMXBean p : pools) {
            System.out.print("  [" + p.getName() + ":");
            MemoryUsage u = p.getUsage();
            System.out.print(" Used=" + formatBytes(u.getUsed()));
            System.out.print(" Committed=" + formatBytes(u.getCommitted()));
            System.out.println("]");
        }
    }

    private String formatMillis(long ms) {
        return String.format("%.4fsec", ms / (double) 1000);
    }
    private String formatBytes(long bytes) {
        long kb = bytes;
        if (bytes > 0) {
            kb = bytes / 1024;
        }
        return kb + "K"; 
    }
}
