org.jactr.core.concurrent.ExecutorServices.java Source code

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Here is the source code for org.jactr.core.concurrent.ExecutorServices.java

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/*
 * Created on Nov 20, 2006 Copyright (C) 2001-6, Anthony Harrison anh23@pitt.edu
 * (jactr.org) This library 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 2.1 of the License,
 * or (at your option) any later version. This library 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 General Public License for more details. You should have
 * received a copy of the GNU Lesser General Public License along with this
 * library; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place, Suite 330, Boston, MA 02111-1307 USA
 */
package org.jactr.core.concurrent;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import java.util.concurrent.AbstractExecutorService;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.commonreality.executor.GeneralThreadFactory;

public class ExecutorServices {
    /**
     * logger definition
     */
    static private final Log LOGGER = LogFactory.getLog(ExecutorServices.class);

    static final public String INLINE = "Inline";

    static final public String BACKGROUND = "Background";

    static final public String PERIODIC = "Periodic";

    static final public ExecutorService INLINE_EXECUTOR = new InlineExecutor();

    static private Map<String, ExecutorService> _executors = new TreeMap<String, ExecutorService>();

    static private boolean _isShuttingDown = false;

    static protected void initialize() {
        addExecutor(INLINE, INLINE_EXECUTOR);
        addExecutor(BACKGROUND, Executors.newSingleThreadExecutor(new GeneralThreadFactory("jACTR-Background")));
        addExecutor(PERIODIC,
                Executors.newSingleThreadScheduledExecutor(new GeneralThreadFactory("jACT-R Periodic")));
    }

    static public void removeExecutor(String name) {
        synchronized (_executors) {
            ExecutorService service = _executors.remove(name);
            if (LOGGER.isDebugEnabled())
                LOGGER.debug("Removed " + name + " : " + service);
        }
    }

    static public void addExecutor(String name, ExecutorService service) {
        synchronized (_executors) {
            if (_executors.containsKey(name) && !_executors.get(name).isShutdown())
                throw new RuntimeException("Cannot overwrite active executors [" + name + "]");

            if (LOGGER.isDebugEnabled())
                LOGGER.debug("Adding executor " + name + " : " + service);
            _executors.put(name, service);
        }
    }

    static public ExecutorService getExecutor(String name) {
        synchronized (_executors) {
            if (!_isShuttingDown && !_executors.containsKey(BACKGROUND))
                initialize();
            return _executors.get(name);
        }
    }

    static private void getExecutorNames(Collection<String> container) {
        synchronized (_executors) {
            container.addAll(_executors.keySet());
        }
    }

    /**
     * shutdown and wait for the shutdown of all the executors that are currently
     * installed. if millisecondsToWait is 0, it will wait indefinitely
     */
    static public void shutdown(long millisecondsToWait) {
        synchronized (_executors) {
            _isShuttingDown = true;
        }

        Collection<String> executorNames = new ArrayList<String>();
        getExecutorNames(executorNames);

        /*
         * issue shutdown
         */
        for (String name : executorNames) {
            ExecutorService executor = getExecutor(name);
            if (executor != null && !executor.isShutdown())
                executor.shutdown();
        }

        /*
         * and wait
         */
        long interval = 500;
        long abortAt = System.currentTimeMillis() + millisecondsToWait;
        if (millisecondsToWait == 0)
            abortAt = Long.MAX_VALUE;
        while (abortAt > System.currentTimeMillis() && executorNames.size() != 0) {
            for (String name : executorNames) {
                ExecutorService executor = getExecutor(name);
                if (executor != null)
                    try {
                        if (executor.awaitTermination(interval, TimeUnit.MILLISECONDS))
                            removeExecutor(name);
                        else if (LOGGER.isDebugEnabled())
                            LOGGER.debug(name + " did not terminate after " + interval + "ms");
                    } catch (Exception e) {
                        if (LOGGER.isWarnEnabled())
                            LOGGER.warn("Failed to terminate " + name, e);
                        removeExecutor(name);
                    }
            }

            /*
             * get the current names again..
             */
            executorNames.clear();
            getExecutorNames(executorNames);
        }

        if (executorNames.size() != 0) {
            if (LOGGER.isWarnEnabled())
                LOGGER.warn("Forcing unresponsive executors to terminate " + executorNames + " after "
                        + millisecondsToWait + "ms");
            for (String name : executorNames) {
                ExecutorService executor = getExecutor(name);
                if (executor != null)
                    executor.shutdownNow();
            }
        }

        synchronized (_executors) {
            _executors.clear();
            _isShuttingDown = false;
        }

    }

    static private class InlineExecutor extends AbstractExecutorService {
        public boolean awaitTermination(long arg0, TimeUnit arg1) throws InterruptedException {
            return true;
        }

        public boolean isShutdown() {
            return false;
        }

        public boolean isTerminated() {
            return false;
        }

        public void shutdown() {
        }

        @SuppressWarnings("unchecked")
        public List<Runnable> shutdownNow() {
            return Collections.EMPTY_LIST;
        }

        public void execute(Runnable arg0) {
            arg0.run();
        }
    }
}