Moving back to trunk!

git-svn-id: http://svn.code.sf.net/p/greenshot/code/trunk@1602 7dccd23d-a4a3-4e1f-8c07-b4c1b4018ab4

GreenshotPlugin/Core/CacheHelper.cs

@@ -0,0 +1,145 @@
+/*
+ * Greenshot - a free and open source screenshot tool
+ * Copyright (C) 2007-2011  Thomas Braun, Jens Klingen, Robin Krom
+ * 
+ * For more information see: http://getgreenshot.org/
+ * The Greenshot project is hosted on Sourceforge: http://sourceforge.net/projects/greenshot/
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 1 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Web;
+using System.Web.Caching;
+
+namespace GreenshotPlugin.Core {
+	public delegate void CacheObjectExpired(string key, object cacheValue);
+
+	/// <summary>
+	/// Description of CacheHelper.
+	/// </summary>
+	public class CacheHelper<T> {
+		private static readonly log4net.ILog LOG = log4net.LogManager.GetLogger("CacheHelper");
+		private Cache cache = HttpRuntime.Cache;
+		private string prefix;
+		private double defaultExpiration = 10*60;	// 10 Minutes
+		private CacheItemRemovedCallback defaultCallback = null;
+		private CacheObjectExpired expiredCallback = null;
+		
+		public CacheHelper(string prefix) {
+			defaultCallback = new CacheItemRemovedCallback(OnRemoved);
+			this.prefix = prefix + ".";
+		}
+
+		public CacheHelper(string prefix, double defaultExpiration) : this(prefix) {
+			this.defaultExpiration = defaultExpiration;
+		}
+
+		public CacheHelper(string prefix, double defaultExpiration, CacheObjectExpired expiredCallback) : this(prefix, defaultExpiration) {
+			this.expiredCallback = expiredCallback;
+		}
+		
+		private void OnRemoved(string key, object cacheValue, CacheItemRemovedReason reason) {
+			LOG.DebugFormat("The item with key '{0}' is being removed from the cache with reason: {1}", key, reason);
+			switch (reason) {
+				case CacheItemRemovedReason.Expired:
+					if (expiredCallback != null) {
+						expiredCallback.Invoke(key, cacheValue);
+					}
+					break;
+				case CacheItemRemovedReason.Underused:
+					break;
+			}
+		}
+
+		/// <summary>
+		/// Insert value into the cache using default expiration & default callback
+		/// </summary>
+		/// <param name="o">Item to be cached</param>
+		/// <param name="key">Name of item</param>
+		public void Add(string key, T o) {
+			if (defaultCallback != null) {
+				cache.Insert(prefix + key, o, null, DateTime.Now.AddSeconds(defaultExpiration), Cache.NoSlidingExpiration, CacheItemPriority.Default, defaultCallback);
+			} else {
+				cache.Insert(prefix + key, o, null, DateTime.Now.AddSeconds(defaultExpiration), Cache.NoSlidingExpiration);
+				
+			}
+		}
+		
+		/// <summary>
+		/// Get all the methods for this cache
+		/// </summary>
+		/// <returns>IEnumerator of the type</returns>
+		public IEnumerable<T> GetElements() {
+			IDictionaryEnumerator cacheEnum = cache.GetEnumerator();
+			while (cacheEnum.MoveNext()) {
+				string key = cacheEnum.Key as string;
+				if (!string.IsNullOrEmpty(key) && key.StartsWith(prefix)) {
+					yield return (T)cacheEnum.Value;
+				}
+			}
+		}
+		
+		/// <summary>
+		/// Insert value into the cache using the supplied expiration time in seconds
+		/// </summary>
+		/// <param name="o">Item to be cached</param>
+		/// <param name="key">Name of item</param>
+		/// <param name="seconds">expiration time in "double" seconds</param>
+		public void Add(string key, T o, double seconds) {
+			cache.Insert(prefix + key, o, null, DateTime.Now.AddSeconds(seconds), Cache.NoSlidingExpiration);
+		}
+
+		/// <summary>
+		/// Insert value into the cache using
+		/// appropriate name/value pairs
+		/// </summary>
+		/// <param name="o">Item to be cached</param>
+		/// <param name="key">Name of item</param>
+		public void Add(string key, T o, CacheItemRemovedCallback callback) {
+			cache.Insert(prefix + key, o, null, DateTime.Now.AddSeconds(defaultExpiration), Cache.NoSlidingExpiration, CacheItemPriority.Default, callback);
+		}
+
+		/// <summary>
+		/// Remove item from cache
+		/// </summary>
+		/// <param name="key">Name of cached item</param>
+		public void Remove(string key) {
+			cache.Remove(prefix + key);
+		}
+
+		/// <summary>
+		/// Check for item in cache
+		/// </summary>
+		/// <param name="key">Name of cached item</param>
+		/// <returns></returns>
+		public bool Exists(string key) {
+			return cache[prefix + key] != null;
+		}
+
+		/// <summary>
+		/// Retrieve cached item
+		/// </summary>
+		/// <param name="key">Name of cached item</param>
+		/// <returns>Cached item as type</returns>
+		public T Get(string key) {
+			try {
+				return (T) cache[prefix + key];
+			} catch {
+				return default(T);
+			}
+		}
+	}
+}