using System;

using System.Web;

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public static class CacheManager

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    {

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       // its used clear cache depend on key value .

        public static void ClearCacheOf<T>(string key)

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        {

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            if (!string.IsNullOrEmpty(key) && HttpContext.Current != null)

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                HttpContext.Current.Cache.Remove(typeof(T) + key);

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        }

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       /// Check if the key correponds to an object saved in cache. 

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       /// <param name="timeToLive">The time to live in minutes (how long the cache will keep the data).</param>

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        /// <param name="identifier">The object's identifier.</param>

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        /// <param name="function">The function to apply if the object is not found in cache wich will do the external call.</param>

        public static T CacheVerification<T>(int timeToLive, string identifier, Func<T> function)

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        {

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            if (HttpContext.Current == null)

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                return function();

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            string key = typeof(T) + identifier;

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            var requestedCachedItem = GetFromCache<T>(key);

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            T response;

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            if (requestedCachedItem != null)

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            {

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                response = requestedCachedItem;

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            }

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            else

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            {

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                response = function();

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                AddToCache(key, response, timeToLive);

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            }

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            return response;

        }

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       private static void AddToCache<T>(string key, T objectToAdd, int ttl)

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        {

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            if (objectToAdd != null)

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            {

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                HttpContext.Current.Cache.Insert(key, objectToAdd, null, System.Web.Caching.Cache.NoAbsoluteExpiration, TimeSpan.FromMinutes(ttl));

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            }

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        }

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        //use existing cache depend on key value   

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        private static T GetFromCache<T>(string key)

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        {

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            return (T)HttpContext.Current.Cache[key];

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        }

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}