MetricScheduleService.java

/**************************************************************************************
 * Copyright (C) 2008 EsperTech, Inc. All rights reserved.                            *
 * http://esper.codehaus.org                                                          *
 * http://www.espertech.com                                                           *
 * ---------------------------------------------------------------------------------- *
 * The software in this package is published under the terms of the GPL license       *
 * a copy of which has been included with this distribution in the license.txt file.  *
 **************************************************************************************/
package com.espertech.esper.epl.metric;

import com.espertech.esper.schedule.*;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.util.*;

/**
 * Scheduling for metrics execution is handles=d by this service.
 */
public final class MetricScheduleService implements MetricTimeSource
{
    private static final Log log = LogFactory.getLog(MetricScheduleService.class);

    private final SortedMap<Long, List<MetricExec>> timeHandleMap;

    // Current time - used for evaluation as well as for adding new handles
    private volatile Long currentTime;

    private volatile Long nearestTime;

    /**
     * Constructor.
     */
    public MetricScheduleService()
    {
        this.timeHandleMap = new TreeMap<Long, List<MetricExec>>();
    }

    public long getCurrentTime()
    {
        return currentTime;
    }

    /**
     * Clears the schedule.
     */
    public void clear()
    {
        log.debug("Clearing scheduling service");
        timeHandleMap.clear();
        nearestTime = null;
    }

    /**
     * Sets current time.
     * @param currentTime to set
     */
    public synchronized final void setTime(long currentTime)
    {
        this.currentTime = currentTime;
    }

    /**
     * Adds an execution to the schedule.
     * @param afterMSec offset to add at
     * @param execution execution to add
     */
    public synchronized final void add(long afterMSec, MetricExec execution)
    {
        if (execution == null)
        {
            throw new IllegalArgumentException("Unexpected parameters : null execution");
        }
        long triggerOnTime = currentTime + afterMSec;
        List<MetricExec> handleSet = timeHandleMap.get(triggerOnTime);
        if (handleSet == null)
        {
            handleSet = new ArrayList<MetricExec>();
            timeHandleMap.put(triggerOnTime, handleSet);
        }
        handleSet.add(execution);

        nearestTime = timeHandleMap.firstKey();
    }

    /**
     * Evaluate the schedule and populates executions, if any.
     * @param handles to populate
     */
    public synchronized final void evaluate(Collection<MetricExec> handles)
    {
        SortedMap<Long, List<MetricExec>> headMap = timeHandleMap.headMap(currentTime + 1);

        // First determine all triggers to shoot
        List<Long> removeKeys = new LinkedList<Long>();
        for (Map.Entry<Long, List<MetricExec>> entry : headMap.entrySet())
        {
            Long key = entry.getKey();
            List<MetricExec> value = entry.getValue();
            removeKeys.add(key);
            for (MetricExec handle : value)
            {
                handles.add(handle);
            }
        }

        // Remove all triggered msec values
        for (Long key : removeKeys)
        {
            timeHandleMap.remove(key);
        }

        if (!timeHandleMap.isEmpty())
        {
            nearestTime = timeHandleMap.firstKey();
        }
        else
        {
            nearestTime = null;
        }
    }

    /**
     * Returns nearest scheduled time.
     * @return nearest scheduled time, or null if none/empty schedule.
     */
    public Long getNearestTime()
    {
        return nearestTime;
    }

    /**
     * Remove from schedule an execution.
     * @param metricExec to remove
     */
    public void remove(MetricExec metricExec)
    {
        for (Map.Entry<Long, List<MetricExec>> entry : timeHandleMap.entrySet())
        {
            entry.getValue().remove(metricExec);
        }
    }
}