From 75b7e6009a1b30f05a17b9fce0eb3e11c3499f22 Mon Sep 17 00:00:00 2001
From: "Justin Clark-Casey (justincc)" <jjustincc@googlemail.com>
Date: Sat, 15 Sep 2012 01:08:15 +0100
Subject: [PATCH] For FlotsamAssetCache, always update access times of cached
 scene assets before looking for files to expire.

This is to resolve a problem where an asset marked as local but not temporary but still used in the scene would be removed.
The timed expiry scan no longer tries to refetch assets from the scene that are not currently in the cache - this is not helpful since it just drags a lot of data into the cache that may never be referenced.
This removes the DeepScanBeforePurge option since setting this to false will introduce the above problem.  This previously had a default of true.
---
 .../CoreModules/Asset/FlotsamAssetCache.cs    | 37 +++++++++----------
 bin/config-include/FlotsamCache.ini.example   |  7 ----
 2 files changed, 17 insertions(+), 27 deletions(-)

diff --git a/OpenSim/Region/CoreModules/Asset/FlotsamAssetCache.cs b/OpenSim/Region/CoreModules/Asset/FlotsamAssetCache.cs
index fab489dbd4..81f4e0e6c3 100644
--- a/OpenSim/Region/CoreModules/Asset/FlotsamAssetCache.cs
+++ b/OpenSim/Region/CoreModules/Asset/FlotsamAssetCache.cs
@@ -107,8 +107,6 @@ namespace Flotsam.RegionModules.AssetCache
         private IAssetService m_AssetService;
         private List<Scene> m_Scenes = new List<Scene>();
 
-        private bool m_DeepScanBeforePurge;
-
         public FlotsamAssetCache()
         {
             m_InvalidChars.AddRange(Path.GetInvalidPathChars());
@@ -170,8 +168,6 @@ namespace Flotsam.RegionModules.AssetCache
                         m_CacheDirectoryTierLen = assetConfig.GetInt("CacheDirectoryTierLength", m_CacheDirectoryTierLen);
 
                         m_CacheWarnAt = assetConfig.GetInt("CacheWarnAt", m_CacheWarnAt);
-
-                        m_DeepScanBeforePurge = assetConfig.GetBoolean("DeepScanBeforePurge", m_DeepScanBeforePurge);
                     }
 
                     m_log.InfoFormat("[FLOTSAM ASSET CACHE]: Cache Directory {0}", m_CacheDirectory);
@@ -506,13 +502,10 @@ namespace Flotsam.RegionModules.AssetCache
             // Purge all files last accessed prior to this point
             DateTime purgeLine = DateTime.Now - m_FileExpiration;
 
-            // An optional deep scan at this point will ensure assets present in scenes,
-            // or referenced by objects in the scene, but not recently accessed 
-            // are not purged.
-            if (m_DeepScanBeforePurge)
-            {
-                CacheScenes();
-            }
+            // An asset cache may contain local non-temporary assets that are not in the asset service.  Therefore,
+            // before cleaning up expired files we must scan the objects in the scene to make sure that we retain
+            // such local assets if they have not been recently accessed.
+            TouchAllSceneAssets(false);
 
             foreach (string dir in Directory.GetDirectories(m_CacheDirectory))
             {
@@ -705,11 +698,14 @@ namespace Flotsam.RegionModules.AssetCache
 
         /// <summary>
         /// Iterates through all Scenes, doing a deep scan through assets 
-        /// to cache all assets present in the scene or referenced by assets 
-        /// in the scene
+        /// to update the access time of all assets present in the scene or referenced by assets
+        /// in the scene.
         /// </summary>
-        /// <returns></returns>
-        private int CacheScenes()
+        /// <param name="storeUncached">
+        /// If true, then assets scanned which are not found in cache are added to the cache.
+        /// </param>
+        /// <returns>Number of distinct asset references found in the scene.</returns>
+        private int TouchAllSceneAssets(bool storeUncached)
         {
             UuidGatherer gatherer = new UuidGatherer(m_AssetService);
 
@@ -732,7 +728,7 @@ namespace Flotsam.RegionModules.AssetCache
                 {
                     File.SetLastAccessTime(filename, DateTime.Now);
                 }
-                else
+                else if (storeUncached)
                 {
                     m_AssetService.Get(assetID.ToString());
                 }
@@ -860,13 +856,14 @@ namespace Flotsam.RegionModules.AssetCache
 
                         break;
 
-
                     case "assets":
-                        m_log.Info("[FLOTSAM ASSET CACHE]: Caching all assets, in all scenes.");
+                        m_log.Info("[FLOTSAM ASSET CACHE]: Ensuring assets are cached for all scenes.");
 
                         Util.FireAndForget(delegate {
-                            int assetsCached = CacheScenes();
-                            m_log.InfoFormat("[FLOTSAM ASSET CACHE]: Completed Scene Caching, {0} assets found.", assetsCached);
+                            int assetReferenceTotal = TouchAllSceneAssets(true);
+                            m_log.InfoFormat(
+                                "[FLOTSAM ASSET CACHE]: Completed check with {0} assets.",
+                                assetReferenceTotal);
                         });
 
                         break;
diff --git a/bin/config-include/FlotsamCache.ini.example b/bin/config-include/FlotsamCache.ini.example
index b9c6d84808..ad74fc14e9 100644
--- a/bin/config-include/FlotsamCache.ini.example
+++ b/bin/config-include/FlotsamCache.ini.example
@@ -54,10 +54,3 @@
 
     ; Warning level for cache directory size
     ;CacheWarnAt = 30000
-
-    ; Perform a deep scan of all assets within all regions, looking for all assets
-    ; present or referenced.  Mark all assets found that are already present in the
-    ; cache, and request all assets that are found that are not already cached (this
-    ; will cause those assets to be cached)
-    ;
-    DeepScanBeforePurge = true