Make it possible to chain another asset service underneath the de-duplicating XAssetService.

This makes it possible to use the dedupliicating service without needing to migrate all the existing asset data beforehand.
Currently controlled by a ChainedServiceModule setting in [AssetService] (e.g. ChainedServiceModule = "OpenSim.Services.AssetService.dll:AssetService")
Not yet ready for use.

OpenSim/Services/AssetService/XAssetService.cs

@@ -39,8 +39,7 @@ using OpenMetaverse;
 namespace OpenSim.Services.AssetService
 {
     /// <summary>
-    /// This will be developed into a de-duplicating asset service.
+    /// A de-duplicating asset service.
-    /// XXX: Currently it's a just a copy of the existing AssetService. so please don't attempt to use it.
     /// </summary>
     public class XAssetService : XAssetServiceBase, IAssetService
     {
@@ -48,7 +47,9 @@ namespace OpenSim.Services.AssetService
 
         protected static XAssetService m_RootInstance;
 
-        public XAssetService(IConfigSource config) : base(config)
+        public XAssetService(IConfigSource config) : this(config, "AssetService") {}
+
+        public XAssetService(IConfigSource config, string configName) : base(config, configName)
         {
             if (m_RootInstance == null)
             {
@@ -56,22 +57,21 @@ namespace OpenSim.Services.AssetService
 
                 if (m_AssetLoader != null)
                 {
-                    IConfig assetConfig = config.Configs["AssetService"];
+                    IConfig assetConfig = config.Configs[configName];
                     if (assetConfig == null)
                         throw new Exception("No AssetService configuration");
 
-                    string loaderArgs = assetConfig.GetString("AssetLoaderArgs",
+                    string loaderArgs = assetConfig.GetString("AssetLoaderArgs", String.Empty);
-                            String.Empty);
 
                     bool assetLoaderEnabled = assetConfig.GetBoolean("AssetLoaderEnabled", true);
 
-                    if (assetLoaderEnabled)
+                    if (assetLoaderEnabled && !HasChainedAssetService)
                     {
                         m_log.DebugFormat("[XASSET SERVICE]: Loading default asset set from {0}", loaderArgs);
 
                         m_AssetLoader.ForEachDefaultXmlAsset(
                             loaderArgs,
-                            delegate(AssetBase a)
+                            a =>
                             {
                                 AssetBase existingAsset = Get(a.ID);
 //                                AssetMetadata existingMetadata = GetMetadata(a.ID);
@@ -103,7 +103,14 @@ namespace OpenSim.Services.AssetService
 
             try
             {
-                return m_Database.GetAsset(assetID);
+                AssetBase asset = m_Database.GetAsset(assetID);
+
+                if (asset != null)
+                    return asset;
+                else if (HasChainedAssetService)
+                    return m_ChainedAssetService.Get(id);
+                else
+                    return null;
             }
             catch (Exception e)
             {
@@ -128,9 +135,17 @@ namespace OpenSim.Services.AssetService
 
             AssetBase asset = m_Database.GetAsset(assetID);
             if (asset != null)
+            {
                 return asset.Metadata;
-
+            }
-            return null;
+            else if (HasChainedAssetService)
+            {
+                return m_ChainedAssetService.GetMetadata(id);
+            }
+            else
+            {
+                return null;
+            }
         }
 
         public virtual byte[] GetData(string id)
@@ -143,7 +158,13 @@ namespace OpenSim.Services.AssetService
                 return null;
 
             AssetBase asset = m_Database.GetAsset(assetID);
-            return asset.Data;
+
+            if (asset != null)
+                return asset.Data;
+            else if (HasChainedAssetService)
+                return m_ChainedAssetService.GetData(id);
+            else
+                return null;
         }
 
         public virtual bool Get(string id, Object sender, AssetRetrieved handler)
@@ -157,6 +178,9 @@ namespace OpenSim.Services.AssetService
 
             AssetBase asset = m_Database.GetAsset(assetID);
 
+            if (asset == null && HasChainedAssetService)
+                asset = m_ChainedAssetService.Get(id);
+
             //m_log.DebugFormat("[XASSET SERVICE]: Got asset {0}", asset);
             
             handler(id, sender, asset);
@@ -194,6 +218,9 @@ namespace OpenSim.Services.AssetService
             if (!UUID.TryParse(id, out assetID))
                 return false;
 
+            // Don't bother deleting from a chained asset service.  This isn't a big deal since deleting happens
+            // very rarely.
+
             return m_Database.Delete(id);
         }
     }

OpenSim/Services/AssetService/XAssetServiceBase.cs

@@ -27,9 +27,11 @@
 
 using System;
 using System.Reflection;
+using log4net;
 using Nini.Config;
 using OpenSim.Framework;
 using OpenSim.Data;
+using OpenSim.Server.Base;
 using OpenSim.Services.Interfaces;
 using OpenSim.Services.Base;
 
@@ -37,10 +39,15 @@ namespace OpenSim.Services.AssetService
 {
     public class XAssetServiceBase : ServiceBase
     {
-        protected IXAssetDataPlugin m_Database = null;
+        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
-        protected IAssetLoader m_AssetLoader = null;
 
-        public XAssetServiceBase(IConfigSource config) : base(config)
+        protected IXAssetDataPlugin m_Database;
+        protected IAssetLoader m_AssetLoader;
+        protected IAssetService m_ChainedAssetService;
+
+        protected bool HasChainedAssetService { get { return m_ChainedAssetService != null; } }
+
+        public XAssetServiceBase(IConfigSource config, string configName) : base(config)
         {
             string dllName = String.Empty;
             string connString = String.Empty;
@@ -48,7 +55,7 @@ namespace OpenSim.Services.AssetService
             //
             // Try reading the [AssetService] section first, if it exists
             //
-            IConfig assetConfig = config.Configs["AssetService"];
+            IConfig assetConfig = config.Configs[configName];
             if (assetConfig != null)
             {
                 dllName = assetConfig.GetString("StorageProvider", dllName);
@@ -77,17 +84,35 @@ namespace OpenSim.Services.AssetService
             if (m_Database == null)
                 throw new Exception("Could not find a storage interface in the given module");
 
+            string chainedAssetServiceDesignator = assetConfig.GetString("ChainedServiceModule", null);
+
+            if (chainedAssetServiceDesignator != null)
+            {
+                m_log.InfoFormat(
+                    "[XASSET SERVICE BASE]: Loading chained asset service from {0}", chainedAssetServiceDesignator);
+
+                Object[] args = new Object[] { config, configName };
+                m_ChainedAssetService = ServerUtils.LoadPlugin<IAssetService>(chainedAssetServiceDesignator, args);
+
+                if (!HasChainedAssetService)
+                    throw new Exception(
+                        String.Format("Failed to load ChainedAssetService from {0}", chainedAssetServiceDesignator));
+            }
+
             m_Database.Initialise(connString);
 
-            string loaderName = assetConfig.GetString("DefaultAssetLoader",
+            if (HasChainedAssetService)
-                    String.Empty);
-
-            if (loaderName != String.Empty)
             {
-                m_AssetLoader = LoadPlugin<IAssetLoader>(loaderName);
+                string loaderName = assetConfig.GetString("DefaultAssetLoader",
+                        String.Empty);
 
-                if (m_AssetLoader == null)
+                if (loaderName != String.Empty)
-                    throw new Exception("Asset loader could not be loaded");
+                {
+                    m_AssetLoader = LoadPlugin<IAssetLoader>(loaderName);
+
+                    if (m_AssetLoader == null)
+                        throw new Exception("Asset loader could not be loaded");
+                }
             }
         }
     }

prebuild.xml

@@ -899,6 +899,7 @@
       <Reference name="OpenSim.Framework"/>
       <Reference name="OpenSim.Framework.Console"/>
       <Reference name="OpenSim.Framework.Servers.HttpServer"/>
+      <Reference name="OpenSim.Server.Base"/>
       <Reference name="OpenSim.Services.Interfaces"/>
       <Reference name="OpenSim.Services.Base"/>
       <Reference name="OpenSim.Services.Connectors"/>