On code section that rezzes single objects and attachments, reduce CPU use by reading asset XML a single time with a stream reader rather than multiple times.

Reading large XML documents (e.g. complex attachments) is CPU expensive - this must be done as few times as possible (preferably just once).
Reading these documents into XmlDocument is also more resource intensive than using XmlTextReader, as per Microsoft's own publication "Improve .NET Application Performance and Scalability"
Optimization of other cases will follow if this change is successful.

1 files changed, 61 insertions, 36 deletions

diff --git a/OpenSim/Region/Framework/Scenes/Scene.Inventory.cs b/OpenSim/Region/Framework/Scenes/Scene.Inventory.cs
index 542d454..cbb4fe7 100644
--- a/OpenSim/Region/Framework/Scenes/Scene.Inventory.cs
+++ b/OpenSim/Region/Framework/Scenes/Scene.Inventory.cs
@@ -30,6 +30,7 @@ using System.Collections.Generic;
 using System.Collections;
 using System.Reflection;
 using System.Text;
+using System.Threading;
 using System.Timers;
 using System.Xml;
 using OpenMetaverse;
@@ -2192,60 +2193,84 @@ namespace OpenSim.Region.Framework.Scenes
         /// Returns one object if the asset is a regular object, and multiple objects for a coalesced object.
         /// </remarks>
         /// <param name="assetData">Asset data</param>
-        /// <param name="attachment">Whether the item is an attachment</param>
+        /// <param name="isAttachment">True if the object is an attachment.</param>
         /// <param name="objlist">The objects included in the asset</param>
         /// <param name="veclist">Relative positions of the objects</param>
         /// <param name="bbox">Bounding box of all the objects</param>
         /// <param name="offsetHeight">Offset in the Z axis from the centre of the bounding box
         /// to the centre of the root prim (relevant only when returning a single object)</param>
-        /// <returns>true = returning a single object; false = multiple objects</returns>
-        public bool GetObjectsToRez(byte[] assetData, bool attachment, out List<SceneObjectGroup> objlist, out List<Vector3> veclist,
+        /// <returns>
+        /// true if returning a single object or deserialization fails, false if returning the coalesced
+        /// list of objects
+        /// </returns>
+        public bool GetObjectsToRez(
+            byte[] assetData, bool isAttachment, out List<SceneObjectGroup> objlist, out List<Vector3> veclist,
             out Vector3 bbox, out float offsetHeight)
         {
             objlist = new List<SceneObjectGroup>();
             veclist = new List<Vector3>();
 
-            XmlDocument doc = new XmlDocument();
             string xmlData = Utils.BytesToString(assetData);
-            doc.LoadXml(xmlData);
-            XmlElement e = (XmlElement)doc.SelectSingleNode("/CoalescedObject");
 
-            if (e == null || attachment) // Single
+            try
             {
-                SceneObjectGroup g = SceneObjectSerializer.FromOriginalXmlFormat(xmlData);
-                objlist.Add(g);
-                veclist.Add(new Vector3(0, 0, 0));
-                bbox = g.GetAxisAlignedBoundingBox(out offsetHeight);
-                return true;
+                using (XmlTextReader reader = new XmlTextReader(xmlData, XmlNodeType.Element, null))
+                {
+                    reader.Read();
+                    bool isSingleObject = reader.Name != "CoalescedObject";
+
+                    if (isSingleObject || isAttachment)
+                    {
+                        SceneObjectGroup g = SceneObjectSerializer.FromOriginalXmlFormat(reader);
+                        objlist.Add(g);
+                        veclist.Add(Vector3.Zero);
+                        bbox = g.GetAxisAlignedBoundingBox(out offsetHeight);
+                        return true;
+                    }
+                    else
+                    {                
+                        XmlDocument doc = new XmlDocument();
+                        doc.LoadXml(xmlData);
+                        XmlElement e = (XmlElement)doc.SelectSingleNode("/CoalescedObject");
+                        XmlElement coll = (XmlElement)e;
+                        float bx = Convert.ToSingle(coll.GetAttribute("x"));
+                        float by = Convert.ToSingle(coll.GetAttribute("y"));
+                        float bz = Convert.ToSingle(coll.GetAttribute("z"));
+                        bbox = new Vector3(bx, by, bz);
+                        offsetHeight = 0;
+
+                        XmlNodeList groups = e.SelectNodes("SceneObjectGroup");
+                        foreach (XmlNode n in groups)
+                        {
+                            SceneObjectGroup g = SceneObjectSerializer.FromOriginalXmlFormat(n.OuterXml);
+                            objlist.Add(g);
+
+                            XmlElement el = (XmlElement)n;
+                            string rawX = el.GetAttribute("offsetx");
+                            string rawY = el.GetAttribute("offsety");
+                            string rawZ = el.GetAttribute("offsetz");
+
+                            float x = Convert.ToSingle(rawX);
+                            float y = Convert.ToSingle(rawY);
+                            float z = Convert.ToSingle(rawZ);
+                            veclist.Add(new Vector3(x, y, z));
+                        }
+
+                        return false;
+                    }
+                }
             }
-            else
+            catch (Exception e)
             {
-                XmlElement coll = (XmlElement)e;
-                float bx = Convert.ToSingle(coll.GetAttribute("x"));
-                float by = Convert.ToSingle(coll.GetAttribute("y"));
-                float bz = Convert.ToSingle(coll.GetAttribute("z"));
-                bbox = new Vector3(bx, by, bz);
-                offsetHeight = 0;
+                m_log.Error(
+                    "[AGENT INVENTORY]: Deserialization of xml failed when looking for CoalescedObject tag.  Exception ", 
+                    e);
 
-                XmlNodeList groups = e.SelectNodes("SceneObjectGroup");
-                foreach (XmlNode n in groups)
-                {
-                    SceneObjectGroup g = SceneObjectSerializer.FromOriginalXmlFormat(n.OuterXml);
-                    objlist.Add(g);
-
-                    XmlElement el = (XmlElement)n;
-                    string rawX = el.GetAttribute("offsetx");
-                    string rawY = el.GetAttribute("offsety");
-                    string rawZ = el.GetAttribute("offsetz");
-
-                    float x = Convert.ToSingle(rawX);
-                    float y = Convert.ToSingle(rawY);
-                    float z = Convert.ToSingle(rawZ);
-                    veclist.Add(new Vector3(x, y, z));
-                }
+                bbox = Vector3.Zero;
+                offsetHeight = 0;
             }
 
-            return false;
+            return true;
         }
 
         /// <summary>