NameValueCache.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / cdf / src / NetFx35 / System.ServiceModel.Web / System / ServiceModel / Dispatcher / NameValueCache.cs / 1305376 / NameValueCache.cs
                        

                        
                            //------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------
using System;
using System.Collections; 
using System.Collections.Concurrent;
using System.Linq; 
using System.Text; 
using System.Threading;
 
namespace System.ServiceModel.Dispatcher
{
    class NameValueCache
    { 
        // The NameValueCache implements a structure that uses a dictionary to map objects to
        // indices of an array of cache entries.  This allows us to store the cache entries in 
        // the order in which they were added to the cache, and yet still lookup any cache entry. 
        // The eviction policy of the cache is to evict the least-recently-added cache entry.
        // Using a pointer to the next available cache entry in the array, we can always be sure 
        // that the given entry is the oldest entry.
        Hashtable cache;
        string[] currentKeys;
        int nextAvailableCacheIndex; 
        object cachelock;
        internal const int maxNumberofEntriesInCache = 16; 
 
        public NameValueCache()
 		: this(maxNumberofEntriesInCache) 
	{
	}

        public NameValueCache(int maxCacheEntries) 
        {
            cache = new Hashtable(); 
            currentKeys = new string[maxCacheEntries]; 
            cachelock = new object();
        } 

        public T Lookup(string key)
        {
            return (T)cache[key]; 
        }
 
        public void AddOrUpdate(string key, T value) 
        {
            lock (cache) 
            {
                if (!cache.ContainsKey(key))
                {
                    if (!String.IsNullOrEmpty(currentKeys[nextAvailableCacheIndex])) 
                    {
                        cache.Remove(currentKeys[nextAvailableCacheIndex]); 
                    } 
                   currentKeys[nextAvailableCacheIndex] = key;
                   nextAvailableCacheIndex = ++nextAvailableCacheIndex % currentKeys.Length; 
                }
                cache[key] = value;
            }
        } 
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.

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