* Working towards notifying the client if the inventory service has failed, rather than simply returning 0 items.

* This is very early support which would only be triggered in a rather unlikely case (if the user server correctly received an inventory skeleton, but later on failed to return the whole inventory in a timely manner.  Also, this only applies to the 1.19.1.4 client onwards
* Code cleanup and support for other failure cases (failure of inventory caching on region crossing, failure to actually add a folder/item, etc, should follow.

OpenSim/Framework/Communications/Cache/UserProfileCacheService.cs

@@ -340,7 +340,7 @@ namespace OpenSim.Framework.Communications.Cache
         /// <param name="fetchFolders"></param>
         /// <param name="fetchItems"></param>
         /// <param name="sortOrder"></param>
-        /// <returns></returns>
+        /// <returns>null if the inventory look up failed</returns>
         public List<InventoryItemBase> HandleFetchInventoryDescendentsCAPS(LLUUID agentID, LLUUID folderID, LLUUID ownerID,
                                                    bool fetchFolders, bool fetchItems, int sortOrder)
         {
@@ -403,7 +403,7 @@ namespace OpenSim.Framework.Communications.Cache
                 {
                     m_log.ErrorFormat("[INVENTORY CACHE]: Could not find root folder for user {0}", agentID.ToString());
 
-                    return new List<InventoryItemBase>(); ;
+                    return null;
                 }
             }
             else
@@ -412,7 +412,7 @@ namespace OpenSim.Framework.Communications.Cache
                      "[USER CACHE]: HandleFetchInventoryDescendentsCAPS() Could not find user profile for {0}",
                      agentID);
             
-                return new List<InventoryItemBase>();
+                return null;
             }
 
             // If we've reached this point then we couldn't find the folder, even though the client thinks

OpenSim/Framework/Communications/Capabilities/Caps.cs

@@ -57,6 +57,13 @@ namespace OpenSim.Region.Capabilities
     public delegate List<InventoryItemBase> FetchInventoryDescendentsCAPS(LLUUID agentID, LLUUID folderID, LLUUID ownerID,
                                                    bool fetchFolders, bool fetchItems, int sortOrder);
     
+    /// <summary>
+    /// XXX Probably not a particularly nice way of allow us to get the scene presence from the scene (chiefly so that
+    /// we can popup a message on the user's client if the inventory service has permanently failed).  But I didn't want
+    /// to just pass the whole Scene into CAPS.
+    /// </summary>
+    public delegate IClientAPI GetClientDelegate(LLUUID agentID);
+
     public class Caps
     {
         private static readonly log4net.ILog m_log = 
@@ -99,8 +106,8 @@ namespace OpenSim.Region.Capabilities
         public NewInventoryItem AddNewInventoryItem = null;
         public ItemUpdatedCallback ItemUpdatedCall = null;
         public TaskScriptUpdatedCallback TaskScriptUpdatedCall = null;
-        //
         public FetchInventoryDescendentsCAPS CAPSFetchInventoryDescendents = null;
+        public GetClientDelegate GetClient = null;
 
         public Caps(AssetCache assetCache, BaseHttpServer httpServer, string httpListen, uint httpPort, string capsPath,
                     LLUUID agent, bool dumpAssetsToFile)
@@ -240,7 +247,7 @@ namespace OpenSim.Region.Capabilities
 
                 LLSDFetchInventoryDescendents llsdRequest = new LLSDFetchInventoryDescendents();
                 LLSDHelpers.DeserialiseLLSDMap(inventoryhash, llsdRequest);
-                LLSDInventoryDescendents reply = FetchInventory(llsdRequest);
+                LLSDInventoryDescendents reply = FetchInventoryReply(llsdRequest);
 
                 inventoryitemstr = LLSDHelpers.SerialiseLLSDReply(reply);
                 inventoryitemstr = inventoryitemstr.Replace("<llsd><map><key>folders</key><array>", "");
@@ -265,7 +272,7 @@ namespace OpenSim.Region.Capabilities
             return response;
         }
 
-        private LLSDInventoryDescendents FetchInventory(LLSDFetchInventoryDescendents invFetch)
+        private LLSDInventoryDescendents FetchInventoryReply(LLSDFetchInventoryDescendents invFetch)
         {
             LLSDInventoryDescendents reply = new LLSDInventoryDescendents();
             LLSDInventoryFolderContents contents = new LLSDInventoryFolderContents();
@@ -289,6 +296,7 @@ namespace OpenSim.Region.Capabilities
             {
                 itemList = CAPSFetchInventoryDescendents(m_agentID, invFetch.folder_id, invFetch.owner_id, invFetch.fetch_folders, invFetch.fetch_items, invFetch.sort_order);
             }
+            
             if (itemList != null)
             {
                 foreach (InventoryItemBase invItem in itemList)
@@ -296,6 +304,27 @@ namespace OpenSim.Region.Capabilities
                     contents.items.Array.Add(ConvertInventoryItem(invItem));
                 }
             }
+            else
+            {                
+                IClientAPI client = GetClient(m_agentID);
+                    
+                // We're going to both notify the client of inventory service failure and send back a 'no folder contents' response.  
+                // If we don't send back the response,
+                // the client becomes unhappy (see Teravus' comment in FetchInventoryRequest())                
+                if (client != null)
+                {
+                    client.SendAgentAlertMessage(
+                        "AGIN0001E: The inventory service has either failed or is not responding.  Your inventory will not function properly for the rest of this session.  Please clear your cache and relog.",
+                        true);
+                }
+                else
+                {
+                    m_log.ErrorFormat(
+                        "[AGENT INVENTORY]: Could not lookup controlling client for {0} in order to notify them of the inventory service failure", 
+                        m_agentID);
+                }
+            }
+            
             contents.descendents = contents.items.Array.Count;
             return reply;
         }

OpenSim/Region/ClientStack/ClientView.cs

@@ -1576,7 +1576,8 @@ namespace OpenSim.Region.ClientStack
         }
 
         /// <summary>
-        /// 
+        /// Send an alert message to the client.  On the Linden client (tested 1.19.1.4), this pops up a brief duration
+        /// blue information box in the bottom right hand corner.
         /// </summary>
         /// <param name="message"></param>
         public void SendAlertMessage(string message)
@@ -1587,10 +1588,12 @@ namespace OpenSim.Region.ClientStack
         }
 
         /// <summary>
-        /// 
+        /// Send an agent alert message to the client.
         /// </summary>
         /// <param name="message"></param>
-        /// <param name="modal"></param>
+        /// <param name="modal">On the linden client, if this true then it displays a one button text box placed in the
+        /// middle of the window.  If false, the message is displayed in a brief duration blue information box (as for 
+        /// the AlertMessage packet).</param>
         public void SendAgentAlertMessage(string message, bool modal)
         {
             AgentAlertMessagePacket alertPack = (AgentAlertMessagePacket)PacketPool.Instance.GetPacket(PacketType.AgentAlertMessage);

OpenSim/Region/Environment/Scenes/InnerScene.cs

@@ -619,6 +619,28 @@ namespace OpenSim.Region.Environment.Scenes
             return result;
         }
         
+        /// <summary>
+        /// Get the controlling client for the given avatar, if there is one.
+        /// 
+        /// FIXME: The only user of the method right now is Caps.cs, in order to resolve a client API since it can't 
+        /// use the ScenePresence.  This could be better solved in a number of ways - we could establish an
+        /// OpenSim.Framework.IScenePresence, or move the caps code into a region package (which might be the more 
+        /// suitable solution).
+        /// </summary>
+        /// <param name="agentId"></param>
+        /// <returns>null if either the avatar wasn't in the scene, or they do not have a controlling client</returns>
+        public IClientAPI GetControllingClient(LLUUID agentId)
+        {
+            ScenePresence presence = GetScenePresence(agentId);
+            
+            if (presence != null)
+            {
+                return presence.ControllingClient;
+            }
+            
+            return null;
+        }
+
         /// <summary>
         /// Request a filtered list of m_scenePresences in this World
         /// </summary>
@@ -640,16 +662,17 @@ namespace OpenSim.Region.Environment.Scenes
         }
 
         /// <summary>
-        /// Request a Avatar by UUID
+        /// Request a scene presence by UUID
         /// </summary>
         /// <param name="avatarID"></param>
-        /// <returns></returns>
+        /// <returns>null if the agent was not found</returns>
-        public ScenePresence GetScenePresence(LLUUID avatarID)
+        public ScenePresence GetScenePresence(LLUUID agentID)
         {
-            if (ScenePresences.ContainsKey(avatarID))
+            if (ScenePresences.ContainsKey(agentID))
             {
-                return ScenePresences[avatarID];
+                return ScenePresences[agentID];
             }
+            
             return null;
         }
 

OpenSim/Region/Environment/Scenes/Scene.cs

@@ -1884,7 +1884,7 @@ namespace OpenSim.Region.Environment.Scenes
             cap.ItemUpdatedCall = CapsUpdateInventoryItemAsset;
             cap.TaskScriptUpdatedCall = CapsUpdateTaskInventoryScriptAsset;
             cap.CAPSFetchInventoryDescendents = CommsManager.UserProfileCacheService.HandleFetchInventoryDescendentsCAPS;
-
+            cap.GetClient = m_innerScene.GetControllingClient;
             m_capsHandlers[agentId] = cap;
         }