/*
 * SSSync, a Simple and Stupid Synchronizer for data with multi-valued attributes
 * Copyright (C) 2014  Ludovic Pouzenc <ludovic@pouzenc.fr>
 *  
 * This file is part of SSSync.
 *
 *  SSSync is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  SSSync 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 SSSync.  If not, see <http://www.gnu.org/licenses/>
 */

package utils;

import java.lang.management.GarbageCollectorMXBean;
import java.lang.management.ManagementFactory;
import java.lang.management.MemoryPoolMXBean;
import java.lang.management.MemoryUsage;
import java.lang.management.RuntimeMXBean;

import org.apache.log4j.Level;
import org.apache.log4j.Logger;

/**
 * TODO javadoc
 * 
 * @author lpouzenc
 */
public class JVMStatsDumper {
	private static final Logger logger = Logger.getLogger(JVMStatsDumper.class.getName());

	public static void logGCStats() {
		// Skip all string construction if will not print this stuff
		if ( logger.getLevel().isGreaterOrEqual(Level.INFO) ) { return; }
	
		long totalGarbageCollections = 0;
		long garbageCollectionTime = 0;
	
		final String gcDumpHeader="Dumping Garbage Collector statistics\n" +
				"+--------------------+-----------------------------+\n" +
				"+      GC Name       +    Count     +   Time (ms)  +\n" +
				"+--------------------+--------------+--------------+\n";
	
		StringBuilder sb = new StringBuilder(1024);
		sb.append(gcDumpHeader);
	
		for(GarbageCollectorMXBean gc : ManagementFactory.getGarbageCollectorMXBeans()) {
	
			long count = gc.getCollectionCount();
			long time = gc.getCollectionTime();
			
			sb.append(String.format("+ %18s + %,12d + %,12d +%n", gc.getName(), count, time));
	
			if(count >= 0) totalGarbageCollections += count;
			if(time >= 0) garbageCollectionTime += time;
		}
	
		sb.append("+                    +              +              +\n");
		sb.append(String.format("+ %18s + %,12d + %,12d +%n",
				"Total", totalGarbageCollections, garbageCollectionTime
				));
		sb.append("+--------------------+--------------+--------------+\n");
		
		sb.append("JVM arguments : ");
		RuntimeMXBean runtimeMxBean = ManagementFactory.getRuntimeMXBean();
		for ( String arg : runtimeMxBean.getInputArguments() ) {
			sb.append(arg + " ");
		}
		
		logger.debug(sb);
	}

	/**
	 * Helper function to log the current memory usage
	 */
	public static void logMemoryUsage() {
		// Skip all string construction if will not print this stuff
		if ( logger.getLevel().isGreaterOrEqual(Level.INFO) ) { return; }
		
		final String memDumpHeader="Dumping memory statistics\n" +
				"+--------------------------------------------------------------------------------+\n" +
				"+                    +         Current (kio)       +           Peak (kio)        +\n" +
				"+        Pool        +-----------------------------------------------------------+\n" +
				"+                    +     Used     +  Committed   +     Used     +  Committed   +\n" +
				"+--------------------+--------------+--------------+--------------+--------------+\n";
		
		StringBuilder sb = new StringBuilder(1024);
		sb.append(memDumpHeader);
		
		for (MemoryPoolMXBean pool : ManagementFactory.getMemoryPoolMXBeans()) {
			MemoryUsage peak = pool.getPeakUsage();
			MemoryUsage curr = pool.getUsage();
			sb.append(String.format("+ %18s + %,12d + %,12d + %,12d + %,12d +%n",
					pool.getName(),curr.getUsed()/1024, curr.getCommitted()/1024, peak.getUsed()/1024, peak.getCommitted()/1024
					));
			pool.resetPeakUsage(); //XXX Maybe this is not a global action and is useless on a temporary object used once
		}
		sb.append("+--------------------+--------------+--------------+--------------+--------------+\n");
		
		logger.debug(sb);
	}

}