# EhCacheImpl.java

    /*
     * Copyright 2010 Niclas Hedhman.
     *
     * Licensed  under the  Apache License,  Version 2.0  (the "License");
     * you may not use  this file  except in  compliance with the License.
     * You may obtain a copy of the License at
     *
     *   http://www.apache.org/licenses/LICENSE-2.0
     *
     * Unless required by applicable law or agreed to in writing, software
     * distributed  under the  License is distributed on an "AS IS" BASIS,
     * WITHOUT  WARRANTIES OR CONDITIONS  OF ANY KIND, either  express  or
     * implied.
     *
     * See the License for the specific language governing permissions and
     * limitations under the License.
     */
    package org.qi4j.cache.ehcache;

    import net.sf.ehcache.Element;
    import org.qi4j.spi.cache.Cache;

    public class EhCacheImpl<T>
        implements Cache<T>
    {
        private int refCount;
        private final net.sf.ehcache.Cache backingCache;
        private final Class<T> valueType;
        private final String id;

        public EhCacheImpl( String cacheId, net.sf.ehcache.Cache cache, Class<T> valueType )
        {
            this.id = cacheId;
            this.backingCache = cache;
            this.valueType = valueType;
        }

        @Override
        public T get( String key )
        {
            Element element = backingCache.get( key );
            if( element == null )
            {
                return null;
            }
            return valueType.cast( element.getObjectValue() );
        }

        @Override
        public T remove( String key )
        {
            T old = valueType.cast( backingCache.get( key ).getObjectValue() );
            backingCache.remove( key );
            return old;
        }

        @Override
        public void put( String key, T value )
        {
            Element element = new Element( key, value );
            backingCache.put( element );
        }

        @Override
        public boolean exists( String key )
        {
            return backingCache.isKeyInCache( key );
        }

        synchronized void decRefCount()
        {
            refCount--;
        }

        synchronized void incRefCount()
        {
            refCount++;
        }

        synchronized boolean isNotUsed()
        {
            return refCount == 0;
        }

        public String cacheId()
        {
            return id;
        }
    }