package com.tangosol.examples.coherence;


import com.tangosol.net.cache.LocalCache;
import com.tangosol.net.cache.CacheLoader;

import com.tangosol.run.xml.XmlConfigurable;
import com.tangosol.run.xml.XmlElement;

import com.tangosol.util.Base;
import com.tangosol.util.Cache;
import com.tangosol.util.SafeHashMap;

import java.util.Iterator;
import java.util.Map;
import java.util.HashMap;


/**
* A backing map that supports custom expiry based on the type of the object
* placed into the cache.
*
* @author cp 2003-11-25
*/
public class AutoExpiryLocalCache
        extends LocalCache
        implements XmlConfigurable
    {
    // ----- constructors ---------------------------------------------------

    /**
    * Construct the cache manager.
    */
    public AutoExpiryLocalCache()
        {
        super();
        }

    /**
    * Construct the cache manager.
    *
    * @param cUnits         the number of units that the cache manager will
    *                       cache before pruning the cache
    */
    public AutoExpiryLocalCache(int cUnits)
        {
        super(cUnits);
        }

    /**
    * Construct the cache manager.
    *
    * @param cUnits         the number of units that the cache manager will
    *                       cache before pruning the cache
    * @param cExpiryMillis  the number of milliseconds that each cache entry
    *                       lives before being automatically expired
    */
    public AutoExpiryLocalCache(int cUnits, int cExpiryMillis)
        {
        super(cUnits, cExpiryMillis);
        }

    /**
    * Construct the cache manager.
    *
    * @param cUnits         the number of units that the cache manager will
    *                       cache before pruning the cache
    * @param cExpiryMillis  the number of milliseconds that each cache entry
    *                       lives before being automatically expired
    * @param loader         the CacheLoader or CacheStore to use
    */
    public AutoExpiryLocalCache(int cUnits, int cExpiryMillis, CacheLoader loader)
        {
        super(cUnits, cExpiryMillis, loader);
        }


    // ----- XmlConfigurable interface --------------------------------------

    /**
    * Determine the current configuration of the object.
    *
    * @return the XML configuration or null
    */
    public XmlElement getConfig()
        {
        return m_xmlConfig;
        }

    /**
    * Specify the configuration for the object.
    *
    * @param xml  the XML configuration for the object
    *
    * @exception IllegalStateException  if the object is not in a state that
    *            allows the configuration to be set; for example, if the
    *            object has already been configured and cannot be reconfigured
    */
    public void setConfig(XmlElement xml)
        {
        Base.azzert(xml != null);
        Base.azzert(m_xmlConfig == null);

        Map map = null;
        for (Iterator iter = xml.getElementList().iterator(); iter.hasNext(); )
            {
            XmlElement xmlParam = (XmlElement) iter.next();
            String sClass   = xmlParam.getName();
            int    cSeconds = xmlParam.getInt();

            Class clz;
            try
                {
                clz = Class.forName(sClass);
                }
            catch (Throwable e)
                {
                Base.err("AutoExpiryLocalCache.setConfig: Unable to look up class: \"" + sClass + "\"");
                continue;
                }

            if (map == null)
                {
                map = new HashMap();
                }
            map.put(clz, new Integer(cSeconds * 1000));
            }

        if (map != null)
            {
            m_mapClassExpiry = map;
            }

        m_xmlConfig = xml;
        }


    // ----- inner class: Entry ---------------------------------------------

    /**
    * Factory method.  This method exists to allow the Cache class to be
    * easily inherited from by allowing the Entry class to be easily
    * sub-classed.
    *
    * @param oKey    the key with which to associate the cache value
    * @param oValue  the value to cache
    *
    * @return an instance of Entry that holds the passed cache value
    */
    protected SafeHashMap.Entry instantiateEntry()
        {
        return new Entry();
        }

    /**
    * A holder for a cached value.
    *
    * @author cp  2001.04.19
    */
    public class Entry
            extends Cache.Entry
        {
        // ----- constructors -------------------------------------------

        /**
        * Construct the cacheable entry that holds the cached value.
        */
        public Entry()
            {
            super();
            }

        // ----- Cache Entry methods ------------------------------------

        /**
        * Reschedule the cache entry expiration.
        */
        protected void scheduleExpiry()
            {
            long dtExpiry = 0L;

            // get default expiration for all cache entries
            int    cDelay = AutoExpiryLocalCache.this.getExpiryDelay();
            Object oValue = getValue();

            // calculate expiry delay based on object type
            if (oValue != null)
                {
                Map map = m_mapClassExpiry;
                if (map != null)
                    {
                    Class clzValue = oValue.getClass();
                    for (Iterator iter = map.entrySet().iterator(); iter.hasNext(); )
                        {
                        Map.Entry entry = (Map.Entry) iter.next();
                        Class clz = (Class) entry.getKey();
                        if (clz.isAssignableFrom(clzValue))
                            {
                            cDelay = ((Integer) entry.getValue()).intValue();
                            break;
                            }
                        }
                    }
                }

            // convert the expiration delay to an absolute time
            if (cDelay > 0)
                {
                dtExpiry = System.currentTimeMillis() + cDelay;
                }

            setExpiryMillis(dtExpiry);
            }
        }


    // ----- data members ---------------------------------------------------

    /**
    * XML configuration for the cache. 
    */
    private XmlElement m_xmlConfig;

    /**
    * Map from class object to expiration delay for that type (stored as an
    * Integer). 
    */
    private Map m_mapClassExpiry;
    }