/*
 * Copyright (c) 2014, 2015, Dynatrace and/or its affiliates. All rights reserved.
 * 
 * This file is part of the Lock Contention Tracing Subsystem for the HotSpot
 * Virtual Machine, which is developed at Christian Doppler Laboratory on
 * Monitoring and Evolution of Very-Large-Scale Software Systems. Please
 * contact us at <http://mevss.jku.at/> if you need additional information
 * or have any questions.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work. If not, see <http://www.gnu.org/licenses/>.
 *
 */ 
package sun.evtracing.processing.statistics;

import sun.evtracing.parser.MonitorContendedEnterEvent;
import sun.evtracing.parser.MonitorContendedEnteredEvent;
import sun.evtracing.parser.MonitorContendedExitedEvent;
import sun.evtracing.parser.MonitorEnterWait;
import sun.evtracing.parser.MonitorEnteredFlags;
import sun.evtracing.parser.MonitorEvent;
import sun.evtracing.parser.TraceEventType;
import sun.evtracing.parser.metadata.JavaStack;
import sun.evtracing.parser.metadata.JavaThread;
import sun.evtracing.processing.Sanity;
import sun.evtracing.processing.statistics.aggregator.ContentionProcessor;
import sun.evtracing.processing.statistics.metadata.Contention;
import sun.evtracing.processing.statistics.metadata.Group;
import sun.evtracing.processing.statistics.metadata.JavaObjectStack;

public class MonitorContender {

	private final JavaObjectStack objectStack;
	private final ContentionProcessor processor;
	private final MonitorContendedEnterEvent enter;

	private MonitorEvent lastEvent;

	public static MonitorContender forEnter(JavaObjectStack objectStack, MonitorContendedEnterEvent event, ContentionProcessor processor) {
		return new MonitorContender(objectStack, event, processor);
	}

	private MonitorContender(JavaObjectStack objectStack, MonitorContendedEnterEvent event, ContentionProcessor processor) {
		this.objectStack = objectStack;
		this.enter = event;
		this.processor = processor;
		this.lastEvent = event;
	}

	private Group group() {
		if (enter.afterWait() != MonitorEnterWait.NoWait) {
			return Group.MonitorWaitReentry;
		}
		return Group.Monitors;
	}

	private boolean wasEntered() {
		return (lastEvent.type() == TraceEventType.MonitorContendedEntered);
	}

	void contenderExitedMonitor(MonitorContendedExitedEvent exit) {
		assert !wasEntered();
		long startTime = lastEvent.timestamp();
		long duration = exit.timestamp() - startTime;
		processor.submit(new Contention(group(), enter.thread().metadata(), exit.thread().metadata(), enter.stack().metadata(), exit.stack().metadata(), objectStack, startTime, duration));
		lastEvent = exit;
	}

	void monitorContendedEntered(MonitorContendedEnteredEvent entered) {
		assert !wasEntered();
		if (entered.flags().contains(MonitorEnteredFlags.Queued)) {
			if (entered.flags().contains(MonitorEnteredFlags.Parked)) {
				Sanity.warnIf(lastEvent == enter, "entered monitor after parking without prior contender exit (rare race)");					
			} else {
				Sanity.warnIf(lastEvent == enter, "entered monitor after queueing without prior contender exit (race)");					
			}
		} else {
			// the thread managed to obtain the lock only by spinning, not entering
			// itself on any queue. therefore, the contender could not have noticed it
			// and has not written an exit event unless another thread was waiting.
		}
		// attribute period between last exit and entered to unknown
		long startTime = lastEvent.timestamp();
		long duration = entered.timestamp() - startTime;
		processor.submit(new Contention(group(), enter.thread().metadata(), JavaThread.UNKNOWN, enter.stack().metadata(), JavaStack.UNKNOWN, objectStack, startTime, duration));
		lastEvent = entered;
	}

	void monitorContendedExited(long time) {
		// nothing to do so far
	}

	@Override
	public String toString() {
		return enter.thread().metadata().toString() + " blocking on " + objectStack.toString();
	}

}