More on inventory transfer hold ups:

- Added an inventory cache for caching root and system folders
- Synchronized the remote inventory connector, so that all the remote inventory calls are serialized
This will not make much difference in the hold ups. We'd have to move the FireAndForget high up to AddInventoryItem, but that opens up a can of worms regarding the notification of the recipient... the recipient would be notified of the offer before the items are effectively in his inventory, which could lead to surprises.

OpenSim/Region/CoreModules/ServiceConnectorsOut/Inventory/HGInventoryBroker.cs

@@ -58,6 +58,8 @@ namespace OpenSim.Region.CoreModules.ServiceConnectorsOut.Inventory
 
         private List<Scene> m_Scenes = new List<Scene>();
 
+        private InventoryCache m_Cache = new InventoryCache();
+
         protected IUserManagement m_UserManagement;
         protected IUserManagement UserManagementModule
         {
@@ -312,6 +314,9 @@ namespace OpenSim.Region.CoreModules.ServiceConnectorsOut.Inventory
         public InventoryFolderBase GetRootFolder(UUID userID)
         {
             //m_log.DebugFormat("[HG INVENTORY CONNECTOR]: GetRootFolder for {0}", userID);
+            InventoryFolderBase root = m_Cache.GetRootFolder(userID);
+            if (root != null)
+                return root;
 
             string invURL = GetInventoryServiceURL(userID);
 
@@ -320,12 +325,19 @@ namespace OpenSim.Region.CoreModules.ServiceConnectorsOut.Inventory
 
             IInventoryService connector = GetConnector(invURL);
 
-            return connector.GetRootFolder(userID);
+            root = connector.GetRootFolder(userID);
+
+            m_Cache.Cache(userID, root);
+
+            return root;
         }
 
         public InventoryFolderBase GetFolderForType(UUID userID, AssetType type)
         {
             //m_log.DebugFormat("[HG INVENTORY CONNECTOR]: GetFolderForType {0} type {1}", userID, type);
+            InventoryFolderBase f = m_Cache.GetFolderForType(userID, type);
+            if (f != null)
+                return f;
 
             string invURL = GetInventoryServiceURL(userID);
 
@@ -334,7 +346,11 @@ namespace OpenSim.Region.CoreModules.ServiceConnectorsOut.Inventory
 
             IInventoryService connector = GetConnector(invURL);
 
-            return connector.GetFolderForType(userID, type);
+            f = connector.GetFolderForType(userID, type);
+
+            m_Cache.Cache(userID, type, f);
+
+            return f;
         }
 
         public InventoryCollection GetFolderContent(UUID userID, UUID folderID)

OpenSim/Region/CoreModules/ServiceConnectorsOut/Inventory/InventoryCache.cs

@@ -0,0 +1,59 @@
+using System;
+using System.Collections.Generic;
+
+using OpenSim.Framework;
+using OpenMetaverse;
+
+namespace OpenSim.Region.CoreModules.ServiceConnectorsOut.Inventory
+{
+    public class InventoryCache
+    {
+        private const double CACHE_EXPIRATION_SECONDS = 3600.0; // 1 hour
+
+        private static ExpiringCache<UUID, InventoryFolderBase> m_RootFolders = new ExpiringCache<UUID, InventoryFolderBase>();
+        private static ExpiringCache<UUID, Dictionary<AssetType, InventoryFolderBase>> m_FolderTypes = new ExpiringCache<UUID, Dictionary<AssetType, InventoryFolderBase>>();
+
+        public void Cache(UUID userID, InventoryFolderBase root)
+        {
+            lock (m_RootFolders)
+                m_RootFolders.AddOrUpdate(userID, root, CACHE_EXPIRATION_SECONDS);
+        }
+
+        public InventoryFolderBase GetRootFolder(UUID userID)
+        {
+            InventoryFolderBase root = null;
+            if (m_RootFolders.TryGetValue(userID, out root))
+                return root;
+
+            return null;
+        }
+
+        public void Cache(UUID userID, AssetType type, InventoryFolderBase folder)
+        {
+            lock (m_FolderTypes)
+            {
+                Dictionary<AssetType, InventoryFolderBase> ff = null;
+                if (!m_FolderTypes.TryGetValue(userID, out ff))
+                {
+                    ff = new Dictionary<AssetType, InventoryFolderBase>();
+                    m_FolderTypes.Add(userID, ff, CACHE_EXPIRATION_SECONDS);
+                }
+                if (!ff.ContainsKey(type))
+                    ff.Add(type, folder);
+            }
+        }
+
+        public InventoryFolderBase GetFolderForType(UUID userID, AssetType type)
+        {
+            Dictionary<AssetType, InventoryFolderBase> ff = null;
+            if (m_FolderTypes.TryGetValue(userID, out ff))
+            {
+                InventoryFolderBase f = null;
+                if (ff.TryGetValue(type, out f))
+                    return f;
+            }
+
+            return null;
+        }
+    }
+}

OpenSim/Services/Connectors/Inventory/XInventoryConnector.cs

@@ -48,6 +48,8 @@ namespace OpenSim.Services.Connectors
 
         private string m_ServerURI = String.Empty;
 
+        private object m_Lock = new object();
+
         public XInventoryServicesConnector()
         {
         }
@@ -514,7 +516,9 @@ namespace OpenSim.Services.Connectors
         {
             sendData["METHOD"] = method;
 
-            string reply = SynchronousRestFormsRequester.MakeRequest("POST",
+            string reply = string.Empty;
+            lock (m_Lock)
+                reply = SynchronousRestFormsRequester.MakeRequest("POST",
                          m_ServerURI + "/xinventory",
                          ServerUtils.BuildQueryString(sendData));