Cache.cs

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/* 
 * 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.
 */

using System;

namespace Lucene.Net.Util.Cache
{
    
    
    /// <summary> Base class for cache implementations.</summary>
    public abstract class Cache<TKey, TValue> : IDisposable
    {
        
        /// <summary> Simple Cache wrapper that synchronizes all
        /// calls that access the cache. 
        /// </summary>
        internal class SynchronizedCache_Renamed_Class : Cache<TKey, TValue>
        {
            internal System.Object mutex;
            internal Cache<TKey,TValue> cache;

            internal SynchronizedCache_Renamed_Class(Cache<TKey, TValue> cache)
            {
                this.cache = cache;
                this.mutex = this;
            }

            internal SynchronizedCache_Renamed_Class(Cache<TKey, TValue> cache, System.Object mutex)
            {
                this.cache = cache;
                this.mutex = mutex;
            }
            
            public override void Put(TKey key, TValue value_Renamed)
            {
                lock (mutex)
                {
                    cache.Put(key, value_Renamed);
                }
            }
            
            public override TValue Get(System.Object key)
            {
                lock (mutex)
                {
                    return cache.Get(key);
                }
            }
            
            public override bool ContainsKey(System.Object key)
            {
                lock (mutex)
                {
                    return cache.ContainsKey(key);
                }
            }
            
            protected override void Dispose(bool disposing)
            {
                lock (mutex)
                {
                    cache.Dispose();
                }
            }
            
            internal override Cache<TKey,TValue> GetSynchronizedCache()
            {
                return this;
            }
        }
        
        /// <summary> Returns a thread-safe cache backed by the specified cache. 
        /// In order to guarantee thread-safety, all access to the backed cache must
        /// be accomplished through the returned cache.
        /// </summary>
        public static Cache<TKey, TValue> SynchronizedCache(Cache<TKey, TValue> cache)
        {
            return cache.GetSynchronizedCache();
        }
        
        /// <summary> Called by <see cref="SynchronizedCache(Cache{TKey,TValue})" />. This method
        /// returns a <see cref="SynchronizedCache" /> instance that wraps
        /// this instance by default and can be overridden to return
        /// e. g. subclasses of <see cref="SynchronizedCache" /> or this
        /// in case this cache is already synchronized.
        /// </summary>
        internal virtual Cache<TKey, TValue> GetSynchronizedCache()
        {
            return new SynchronizedCache_Renamed_Class(this);
        }
        
        /// <summary> Puts a (key, value)-pair into the cache. </summary>
        public abstract void  Put(TKey key, TValue value_Renamed);
        
        /// <summary> Returns the value for the given key. </summary>
        public abstract TValue Get(System.Object key);
        
        /// <summary> Returns whether the given key is in this cache. </summary>
        public abstract bool ContainsKey(System.Object key);

        /// <summary> Closes the cache.</summary>
        [Obsolete("Use Dispose() instead")]
        public void Close()
        {
            Dispose();
        }

        public void Dispose()
        {
            Dispose(true);
        }

        protected abstract void Dispose(bool disposing);
    }
}