# MemoryCacheImpl.java

    /*
     *  Licensed to the Apache Software Foundation (ASF) under one or more
     *  contributor license agreements.  See the NOTICE file distributed with
     *  this work for additional information regarding copyright ownership.
     *  The ASF licenses this file to You 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.test.cache;

    import java.util.concurrent.ConcurrentHashMap;
    import org.qi4j.spi.cache.Cache;

    /**
     * In-Memory Cache implementation based on ConcurrentHashMap.
     */
    public class MemoryCacheImpl<T>
        implements Cache<T>
    {
        private int refCount;

        private final ConcurrentHashMap<String, Object> backingCache;
        private final Class<T> valueType;
        private final String id;

        private int gets;
        private int removes;
        private int puts;
        private int exists;

        public MemoryCacheImpl( String cacheId, ConcurrentHashMap<String, Object> cache, Class<T> valueType )
        {
            this.id = cacheId;
            this.backingCache = cache;
            this.valueType = valueType;
        }

        @Override
        public T get( String key )
        {
            try
            {
                return valueType.cast( backingCache.get( key ) );
            }
            finally
            {
                gets++;
            }
        }

        @Override
        public T remove( String key )
        {
            try
            {
                return valueType.cast( backingCache.remove( key ) );
            }
            finally
            {
                removes++;
            }
        }

        @Override
        public void put( String key, T value )
        {
            try
            {
                backingCache.put( key, value );
            }
            finally
            {
                puts++;
            }
        }

        @Override
        public boolean exists( String key )
        {
            try
            {
                return backingCache.containsKey( key );
            }
            finally
            {
                exists++;
            }
        }

        synchronized void decRefCount()
        {
            refCount--;
        }

        synchronized void incRefCount()
        {
            refCount++;
        }

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

        public String cacheId()
        {
            return id;
        }

        public int size()
        {
            return backingCache.size();
        }

        public int gets()
        {
            return gets;
        }

        public int removes()
        {
            return removes;
        }

        public int puts()
        {
            return puts;
        }

        public int exists()
        {
            return exists;
        }
    }