AbstractCacheableService.java

/*
 * Copyright (c) 2002-2022, City of Paris
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *  1. Redistributions of source code must retain the above copyright notice
 *     and the following disclaimer.
 *
 *  2. Redistributions in binary form must reproduce the above copyright notice
 *     and the following disclaimer in the documentation and/or other materials
 *     provided with the distribution.
 *
 *  3. Neither the name of 'Mairie de Paris' nor 'Lutece' nor the names of its
 *     contributors may be used to endorse or promote products derived from
 *     this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * License 1.0
 */
package fr.paris.lutece.portal.service.cache;

import fr.paris.lutece.portal.service.util.AppLogService;

import net.sf.ehcache.Cache;
import net.sf.ehcache.CacheException;
import net.sf.ehcache.Ehcache;
import net.sf.ehcache.Element;
import net.sf.ehcache.Statistics;
import net.sf.ehcache.event.CacheEventListener;

import java.util.ArrayList;
import java.util.List;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

/**
 * Base implementation for a cacheable service
 */
public abstract class AbstractCacheableService implements CacheableService, CacheEventListener
{
    private Cache _cache;
    private boolean _bEnable;
    private Logger _logger = LogManager.getLogger( "lutece.cache" );

    /**
     * Init the cache. Should be called by the service at its initialization.
     */
    public void initCache( )
    {
        initCache( getName( ) );
    }

    /**
     * Init the cache. Should be called by the service at its initialization.
     * 
     * @param strCacheName
     *            The cache name
     */
    public void initCache( String strCacheName )
    {
        createCache( strCacheName );
        _bEnable = true;
        CacheService.registerCacheableService( this );
    }

    /**
     * Create a cache
     * 
     * @param strCacheName
     *            The cache name
     */
    private void createCache( String strCacheName )
    {
        _cache = CacheService.getInstance( ).createCache( strCacheName );
        _cache.getCacheEventNotificationService( ).registerListener( this );
    }

    /**
     * Put an object into the cache
     * 
     * @param strKey
     *            The key of the object to put into the cache
     * @param object
     *            The object to put into the cache
     */
    public void putInCache( String strKey, Object object )
    {
        if ( ( _cache != null ) && isCacheEnable( ) )
        {
            Element element = new Element( strKey, object );
            _cache.put( element );
        }
    }

    /**
     * Gets an object from the cache
     * 
     * @param strKey
     *            The key of the object to retrieve from the cache
     * @return The object from the cache
     */
    public Object getFromCache( String strKey )
    {
        Object object = null;

        if ( ( _cache != null ) && isCacheEnable( ) )
        {
            Element element = _cache.get( strKey );

            if ( element != null )
            {
                object = element.getObjectValue( );
            }
        }

        return object;
    }

    /**
     * Gets the current cache status.
     *
     * @return true if enable, otherwise false
     */
    @Override
    public boolean isCacheEnable( )
    {
        return _bEnable;
    }

    /**
     * {@inheritDoc }
     */
    @Override
    public void enableCache( boolean bEnable )
    {
        _bEnable = bEnable;

        if ( ( !_bEnable ) && ( _cache != null ) )
        {
            _cache.removeAll( );
        }

        if ( ( _bEnable ) && ( _cache == null ) )
        {
            createCache( getName( ) );
        }

        CacheService.updateCacheStatus( this );
    }

    /**
     * Reset the cache.
     */
    @Override
    public void resetCache( )
    {
        try
        {
            if ( _cache != null )
            {
                _cache.removeAll( );
            }
        }
        catch( CacheException | IllegalStateException e )
        {
            AppLogService.error( e.getMessage( ), e );
        }
    }

    /**
     * Gets the number of item currently in the cache.
     *
     * @return the number of item currently in the cache.
     */
    @Override
    public int getCacheSize( )
    {
        return ( _cache != null ) ? _cache.getSize( ) : 0;
    }

    /**
     * Return a cache object
     * 
     * @return cache object
     */
    public Cache getCache( )
    {
        return _cache;
    }

    /**
     * {@inheritDoc }
     */
    @Override
    public List<String> getKeys( )
    {
        if ( _cache != null )
        {
            return _cache.getKeys( );
        }

        return new ArrayList<>( );
    }

    /**
     * {@inheritDoc }
     */
    @Override
    public int getMaxElements( )
    {
        return _cache.getCacheConfiguration( ).getMaxElementsInMemory( );
    }

    /**
     * {@inheritDoc }
     */
    @Override
    public long getTimeToLive( )
    {
        return _cache.getCacheConfiguration( ).getTimeToLiveSeconds( );
    }

    /**
     * {@inheritDoc }
     */
    @Override
    public long getMemorySize( )
    {
        return _cache.calculateInMemorySize( );
    }

    /**
     * {@inheritDoc }
     */
    @Override
    public String getInfos( )
    {
        return CacheService.getInfos( _cache );
    }

    /**
     * Get cache statistics.
     * 
     * The string representation is susceptible to change
     * 
     * @return a string representation of cache statistics
     * 
     * @since 7.0.10
     */
    public String getStatistics( )
    {
        if ( !( isCacheEnable( ) && _cache.getCacheConfiguration( ).getStatistics( ) ) )
        {
            return null;
        }
        Statistics stats = _cache.getStatistics( );
        StringBuilder buidler = new StringBuilder( );
        buidler.append( "name = " ).append( stats.getAssociatedCacheName( ) ).append( "\ncacheHits = " )
                .append( stats.getCacheHits( ) ).append( "\nonDiskHits = " ).append( stats.getOnDiskHits( ) )
                .append( "\noffHeapHits = " ).append( stats.getOffHeapHits( ) ).append( "\ninMemoryHits = " )
                .append( stats.getInMemoryHits( ) ).append( "\nmisses = " ).append( stats.getCacheMisses( ) )
                .append( "\nonDiskMisses = " ).append( stats.getOnDiskMisses( ) ).append( "\noffHeapMisses = " )
                .append( stats.getOffHeapMisses( ) ).append( "\ninMemoryMisses = " )
                .append( stats.getInMemoryMisses( ) ).append( "\nsize = " ).append( stats.getObjectCount( ) )
                .append( "\naverageGetTime = " ).append( stats.getAverageGetTime( ) ).append( "\nevictionCount = " )
                .append( stats.getEvictionCount( ) );
        return buidler.toString( );
    }

    // CacheEventListener implementation

    /**
     * @see java.lang.Object#clone()
     * @return the instance
     */
    @Override
    public Object clone( )
    {
        throw new UnsupportedOperationException( "This class shouldn't be cloned" );
    }

    /**
     * {@inheritDoc }
     */
    @Override
    public void notifyElementExpired( Ehcache cache, Element element )
    {
        // Remove the element from the cache
        _cache.remove( element.getKey( ) );
        _logger.debug( "Object removed from the cache : {}  - key : {}", cache.getName( ), element.getKey( ) );
    }

    /**
     * {@inheritDoc }
     */
    @Override
    public void notifyElementRemoved( Ehcache ehch, Element elmnt )
    {
        // Do nothing
    }

    /**
     * {@inheritDoc }
     */
    @Override
    public void notifyElementEvicted( Ehcache ehch, Element elmnt )
    {
        // Do nothing
    }

    /**
     * {@inheritDoc }
     */
    @Override
    public void notifyRemoveAll( Ehcache ehch )
    {
        // Do nothing
    }

    /**
     * {@inheritDoc }
     */
    @Override
    public void notifyElementPut( Ehcache ehch, Element elmnt )
    {
        // Do nothing
    }

    /**
     * {@inheritDoc }
     */
    @Override
    public void notifyElementUpdated( Ehcache ehch, Element elmnt )
    {
        // Do nothing
    }

    /**
     * {@inheritDoc }
     */
    @Override
    public void dispose( )
    {
        // Do nothing
    }

    /**
     * Remove a key from the cache
     * 
     * @param strKey
     *            The key to remove
     */
    public void removeKey( String strKey )
    {
        getCache( ).remove( strKey );
    }
}