From efd7093b9cd19be36f48b523f9fbaf4df84f602d Mon Sep 17 00:00:00 2001
From: James South <james_south@hotmail.com>
Date: Mon, 6 Apr 2015 15:04:42 +0100
Subject: [PATCH] Upgrade locker

Former-commit-id: 9605c3095790426c6a99f7c8625fe26d8d6311a6
Former-commit-id: d5e76ef95bf0c9093821c589d509d2a9223c9244
Former-commit-id: 161948a997047b2ed3239ea36ca42d1da6d44d93
---
 src/ImageProcessor.Web/Caching/MemCache.cs | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/src/ImageProcessor.Web/Caching/MemCache.cs b/src/ImageProcessor.Web/Caching/MemCache.cs
index 192a7b7b7..060a3e805 100644
--- a/src/ImageProcessor.Web/Caching/MemCache.cs
+++ b/src/ImageProcessor.Web/Caching/MemCache.cs
@@ -14,6 +14,9 @@ namespace ImageProcessor.Web.Caching
     using System.Collections.Concurrent;
     using System.Collections.Generic;
     using System.Runtime.Caching;
+    using System.Threading;
+
+    using ImageProcessor.Common.Helpers;
 
     /// <summary>
     /// Encapsulates methods that allow the caching and retrieval of objects from the in memory cache.
@@ -25,6 +28,11 @@ namespace ImageProcessor.Web.Caching
         /// </summary>
         private static readonly ObjectCache Cache = MemoryCache.Default;
 
+        /// <summary>
+        /// The reader-writer lock implementation.
+        /// </summary>
+        private static readonly ReaderWriterLockSlim Locker = new ReaderWriterLockSlim();
+
         /// <summary>
         /// An internal list of cache keys to allow bulk removal.
         /// </summary>
@@ -56,8 +64,7 @@ namespace ImageProcessor.Web.Caching
         public static bool AddItem(string key, object value, CacheItemPolicy policy = null, string regionName = null)
         {
             bool isAdded;
-
-            lock (Cache)
+            using (new WriteLock(Locker))
             {
                 if (policy == null)
                 {
@@ -100,7 +107,7 @@ namespace ImageProcessor.Web.Caching
         /// </returns>
         public static object GetItem(string key, string regionName = null)
         {
-            lock (Cache)
+            using (new UpgradeableReadLock(Locker))
             {
                 return Cache.Get(key, regionName);
             }
@@ -173,7 +180,7 @@ namespace ImageProcessor.Web.Caching
         {
             bool isRemoved;
 
-            lock (Cache)
+            using (new WriteLock(Locker))
             {
                 isRemoved = Cache.Remove(key, regionName) != null;
 
@@ -200,7 +207,7 @@ namespace ImageProcessor.Web.Caching
         {
             bool isCleared = false;
 
-            lock (CacheItems)
+            using (new WriteLock(Locker))
             {
                 // You can't remove items from a collection whilst you are iterating over it so you need to 
                 // create a collection to store the items to remove.