add a Check method to flotsamAssetCache, so to check if a asset is in

cache without actually loading it. Make use limited use of it in
avatarfactory textures check. Also on llclientview
HandleAgentTextureCached that now should work. Other asset cache modules
for now will return false, so are broken. baked textures logic
still unchanged. *UNTESTED*

OpenSim/Region/CoreModules/Asset/FlotsamAssetCache.cs

@@ -348,6 +348,17 @@ namespace OpenSim.Region.CoreModules.Asset
             return asset;
         }
 
+        private bool CheckFromMemoryCache(string id)
+        {
+            AssetBase asset = null;
+
+            if (m_MemoryCache.TryGetValue(id, out asset))
+                return true;
+
+            return false;
+        }
+
+
         /// <summary>
         /// Try to get an asset from the file cache.
         /// </summary>
@@ -420,6 +431,50 @@ namespace OpenSim.Region.CoreModules.Asset
             return asset;
         }
 
+        private bool CheckFromFileCache(string id)
+        {
+            bool found = false;
+
+            string filename = GetFileName(id);
+            if (File.Exists(filename))
+            {
+                // actually check if we can open it, and so update expire
+                FileStream stream = null;
+                try
+                {
+                    stream = File.Open(filename, FileMode.Open, FileAccess.Read, FileShare.Read);
+                    if (stream != null)
+                    {
+                        found = true;
+                        stream.Close();
+                    }
+
+                }
+                catch (System.Runtime.Serialization.SerializationException e)
+                {
+                    found = false;
+                    m_log.ErrorFormat(
+                        "[FLOTSAM ASSET CACHE]: Failed to check file {0} for asset {1}.  Exception {2} {3}",
+                        filename, id, e.Message, e.StackTrace);
+
+                    // If there was a problem deserializing the asset, the asset may
+                    // either be corrupted OR was serialized under an old format
+                    // {different version of AssetBase} -- we should attempt to
+                    // delete it and re-cache
+                    File.Delete(filename);
+                }
+                catch (Exception e)
+                {
+                    found = false;
+                    m_log.ErrorFormat(
+                        "[FLOTSAM ASSET CACHE]: Failed to check file {0} for asset {1}.  Exception {2} {3}",
+                        filename, id, e.Message, e.StackTrace);
+                }
+            }
+
+            return found;
+        }
+
         public AssetBase Get(string id)
         {
             m_Requests++;
@@ -456,11 +511,26 @@ namespace OpenSim.Region.CoreModules.Asset
             return asset;
         }
 
+        public bool Check(string id)
+        {
+            if (m_MemoryCacheEnabled && CheckFromMemoryCache(id))
+                return true;
+
+            if (m_FileCacheEnabled && CheckFromFileCache(id))
+                return true;
+            return false;
+        }
+
         public AssetBase GetCached(string id)
         {
             return Get(id);
         }
 
+        public AssetBase CheckCached(string id)
+        {
+            return Get(id);
+        }
+
         public void Expire(string id)
         {
             if (m_LogLevel >= 2)
@@ -941,6 +1011,11 @@ namespace OpenSim.Region.CoreModules.Asset
             return asset.Data;
         }
 
+        public bool CheckData(string id)
+        {
+            return Check(id); ;
+        }
+
         public bool Get(string id, object sender, AssetRetrieved handler)
         {
             AssetBase asset = Get(id);