/**
 * Copyright (C) 2010-2017 Gordon Fraser, Andrea Arcuri and EvoSuite
 * contributors
 *
 * This file is part of EvoSuite.
 *
 * EvoSuite is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3.0 of the License, or
 * (at your option) any later version.
 *
 * EvoSuite 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
 * Lesser Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with EvoSuite. If not, see <http://www.gnu.org/licenses/>.
 */
package org.evosuite.utils;

import java.io.Serializable;

import org.evosuite.Properties;
import org.evosuite.ga.Chromosome;
import org.evosuite.ga.metaheuristics.GeneticAlgorithm;
import org.evosuite.ga.metaheuristics.SearchListener;
import org.evosuite.ga.stoppingconditions.StoppingCondition;
import org.evosuite.testcase.execution.TestCaseExecutor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * EvoSuite can run out of resources: eg out of memory, or too many threads that
 * are stalled and cannot be killed.
 * 
 * There can be several ways to handle these cases. The simplest is to to just
 * stop the search. Note: stopping the search when EvoSuite is close to run of
 * memory is important because, if it does actually run out of memory, when it
 * will not be able to write down the results obtained so far!
 * 
 * @author Gordon Fraser
 */
public class ResourceController implements SearchListener, StoppingCondition,
        Serializable {

	private static final long serialVersionUID = -4459807323163275506L;

	private static final Logger logger = LoggerFactory.getLogger(ResourceController.class);

	private GeneticAlgorithm<?> ga;
	private boolean stopComputation;

	private boolean hasExceededResources() {

		if (TestCaseExecutor.getInstance().getNumStalledThreads() >= Properties.MAX_STALLED_THREADS) {
			logger.info("* Too many stalled threads: "
			        + TestCaseExecutor.getInstance().getNumStalledThreads() + " / "
			        + Properties.MAX_STALLED_THREADS);
			return true;
		}

		Runtime runtime = Runtime.getRuntime();

		long freeMem = runtime.maxMemory() - runtime.totalMemory() + runtime.freeMemory();

		if (freeMem < Properties.MIN_FREE_MEM) {
			logger.trace("* Running out of memory, calling GC with memory left: "
			        + freeMem + " / " + runtime.maxMemory());
			System.gc();
			freeMem = runtime.maxMemory() - runtime.totalMemory() + runtime.freeMemory();

			if (freeMem < Properties.MIN_FREE_MEM) {
				logger.info("* Running out of memory, giving up: " + freeMem + " / "
				        + runtime.maxMemory() + " - need " + Properties.MIN_FREE_MEM);
				return true;
			} else {
				logger.trace("* Garbage collection recovered sufficient memory: "
				        + freeMem + " / " + runtime.maxMemory());
			}
		}

		return false;
	}

	/** {@inheritDoc} */
	@Override
	public void searchStarted(GeneticAlgorithm<?> algorithm) {
		ga = algorithm;
	}

	/** {@inheritDoc} */
	@Override
	public void iteration(GeneticAlgorithm<?> algorithm) {
		// TODO Auto-generated method stub

	}

	/** {@inheritDoc} */
	@Override
	public void searchFinished(GeneticAlgorithm<?> algorithm) {
		// TODO Auto-generated method stub

	}

	/** {@inheritDoc} */
	@Override
	public void fitnessEvaluation(Chromosome individual) {
		if (hasExceededResources()) {
			/*
			 * TODO: for now, we just stop the search. in case of running out of memory, other options could
			 * be to reduce the population size, eg by using "removeWorstIndividuals". but before that,
			 * "calculateFitness" need to be-refactored
			 */
			stopComputation = true;
			ga.addStoppingCondition(this);
			logger.warn("Shutting down the search due to running out of computational resources");
		}
	}

	/** {@inheritDoc} */
	@Override
	public void modification(Chromosome individual) {
		// TODO Auto-generated method stub

	}

	/** {@inheritDoc} */
	@Override
	public void forceCurrentValue(long value) {
		// TODO Auto-generated method stub

	}

	/** {@inheritDoc} */
	@Override
	public long getCurrentValue() {
		// TODO Auto-generated method stub
		return 0;
	}

	/** {@inheritDoc} */
	@Override
	public long getLimit() {
		// TODO Auto-generated method stub
		return 0;
	}

	/** {@inheritDoc} */
	@Override
	public boolean isFinished() {
		return stopComputation;
	}

	/** {@inheritDoc} */
	@Override
	public void reset() {
		stopComputation = false;
	}

	/** {@inheritDoc} */
	@Override
	public void setLimit(long limit) {
		// TODO Auto-generated method stub

	}

}