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diff --git a/OpenSim/Framework/PriorityQueue.cs b/OpenSim/Framework/PriorityQueue.cs
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+/*
+ * Copyright (c) Contributors, http://opensimulator.org/
+ * See CONTRIBUTORS.TXT for a full list of copyright holders.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of the OpenSimulator Project nor the
+ *       names of its contributors may be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Reflection;
+
+using OpenSim.Framework;
+using OpenSim.Framework.Client;
+using log4net;
+
+namespace OpenSim.Framework
+{
+    public class PriorityQueue
+    {
+        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
+
+        public delegate bool UpdatePriorityHandler(ref uint priority, ISceneEntity entity);
+
+        /// <summary>
+        /// Total number of queues (priorities) available
+        /// </summary>
+        public const uint NumberOfQueues = 12;
+
+        /// <summary>
+        /// Number of queuest (priorities) that are processed immediately
+        /// </summary.
+        public const uint NumberOfImmediateQueues = 2;
+
+        private MinHeap<MinHeapItem>[] m_heaps = new MinHeap<MinHeapItem>[NumberOfQueues];
+        private Dictionary<uint, LookupItem> m_lookupTable;
+
+        // internal state used to ensure the deqeues are spread across the priority
+        // queues "fairly". queuecounts is the amount to pull from each queue in 
+        // each pass. weighted towards the higher priority queues
+        private uint m_nextQueue = 0;
+        private uint m_countFromQueue = 0;
+        private uint[] m_queueCounts = { 8, 4, 4, 2, 2, 2, 2, 1, 1, 1, 1, 1 };
+
+        // next request is a counter of the number of updates queued, it provides
+        // a total ordering on the updates coming through the queue and is more
+        // lightweight (and more discriminating) than tick count
+        private UInt64 m_nextRequest = 0;
+
+        /// <summary>
+        /// Lock for enqueue and dequeue operations on the priority queue
+        /// </summary>
+        private object m_syncRoot = new object();
+        public object SyncRoot {
+            get { return this.m_syncRoot; }
+        }
+
+#region constructor
+        public PriorityQueue() : this(MinHeap<MinHeapItem>.DEFAULT_CAPACITY) { }
+
+        public PriorityQueue(int capacity)
+        {
+            m_lookupTable = new Dictionary<uint, LookupItem>(capacity);
+
+            for (int i = 0; i < m_heaps.Length; ++i)
+                m_heaps[i] = new MinHeap<MinHeapItem>(capacity);
+
+            m_nextQueue = NumberOfImmediateQueues;
+            m_countFromQueue = m_queueCounts[m_nextQueue];
+        }
+#endregion Constructor
+
+#region PublicMethods
+        /// <summary>
+        /// Return the number of items in the queues
+        /// </summary>
+        public int Count
+        {
+            get
+            {
+                int count = 0;
+                for (int i = 0; i < m_heaps.Length; ++i)
+                    count += m_heaps[i].Count;
+                
+                return count;
+            }
+        }
+
+        /// <summary>
+        /// Enqueue an item into the specified priority queue
+        /// </summary>
+        public bool Enqueue(uint pqueue, IEntityUpdate value)
+        {
+            LookupItem lookup;
+
+            uint localid = value.Entity.LocalId;
+            UInt64 entry = m_nextRequest++;
+            if (m_lookupTable.TryGetValue(localid, out lookup))
+            {
+                entry = lookup.Heap[lookup.Handle].EntryOrder;
+                value.Update(lookup.Heap[lookup.Handle].Value);
+                lookup.Heap.Remove(lookup.Handle);
+            }
+
+            pqueue = Util.Clamp<uint>(pqueue, 0, NumberOfQueues - 1);
+            lookup.Heap = m_heaps[pqueue];
+            lookup.Heap.Add(new MinHeapItem(pqueue, entry, value), ref lookup.Handle);
+            m_lookupTable[localid] = lookup;
+
+            return true;
+        }
+
+        /// <summary>
+        /// Remove an item from one of the queues. Specifically, it removes the
+        /// oldest item from the next queue in order to provide fair access to
+        /// all of the queues
+        /// </summary>
+        public bool TryDequeue(out IEntityUpdate value, out Int32 timeinqueue)
+        {
+            // If there is anything in priority queue 0, return it first no
+            // matter what else. Breaks fairness. But very useful.
+            for (int iq = 0; iq < NumberOfImmediateQueues; iq++)
+            {
+                if (m_heaps[iq].Count > 0)
+                {
+                    MinHeapItem item = m_heaps[iq].RemoveMin();
+                    m_lookupTable.Remove(item.Value.Entity.LocalId);
+                    timeinqueue = Util.EnvironmentTickCountSubtract(item.EntryTime);
+                    value = item.Value;
+
+                    return true;
+                }
+            }
+            
+            // To get the fair queing, we cycle through each of the
+            // queues when finding an element to dequeue. 
+            // We pull (NumberOfQueues - QueueIndex) items from each queue in order
+            // to give lower numbered queues a higher priority and higher percentage
+            // of the bandwidth. 
+            
+            // Check for more items to be pulled from the current queue
+            if (m_heaps[m_nextQueue].Count > 0 && m_countFromQueue > 0)
+            {
+                m_countFromQueue--;
+                
+                MinHeapItem item = m_heaps[m_nextQueue].RemoveMin();
+                m_lookupTable.Remove(item.Value.Entity.LocalId);
+                timeinqueue = Util.EnvironmentTickCountSubtract(item.EntryTime);
+                value = item.Value;
+                
+                return true;
+            }
+            
+            // Find the next non-immediate queue with updates in it
+            for (int i = 0; i < NumberOfQueues; ++i)
+            {
+                m_nextQueue = (uint)((m_nextQueue + 1) % NumberOfQueues);
+                m_countFromQueue = m_queueCounts[m_nextQueue];
+
+                // if this is one of the immediate queues, just skip it
+                if (m_nextQueue < NumberOfImmediateQueues)
+                    continue;
+                
+                if (m_heaps[m_nextQueue].Count > 0)
+                {
+                    m_countFromQueue--;
+
+                    MinHeapItem item = m_heaps[m_nextQueue].RemoveMin();
+                    m_lookupTable.Remove(item.Value.Entity.LocalId);
+                    timeinqueue = Util.EnvironmentTickCountSubtract(item.EntryTime);
+                    value = item.Value;
+
+                    return true;
+                }
+            }
+
+            timeinqueue = 0;
+            value = default(IEntityUpdate);
+            return false;
+        }
+
+        /// <summary>
+        /// Reapply the prioritization function to each of the updates currently
+        /// stored in the priority queues. 
+        /// </summary
+        public void Reprioritize(UpdatePriorityHandler handler)
+        {
+            MinHeapItem item;
+            foreach (LookupItem lookup in new List<LookupItem>(this.m_lookupTable.Values))
+            {
+                if (lookup.Heap.TryGetValue(lookup.Handle, out item))
+                {
+                    uint pqueue = item.PriorityQueue;
+                    uint localid = item.Value.Entity.LocalId;
+
+                    if (handler(ref pqueue, item.Value.Entity))
+                    {
+                        // unless the priority queue has changed, there is no need to modify
+                        // the entry
+                        pqueue = Util.Clamp<uint>(pqueue, 0, NumberOfQueues - 1);
+                        if (pqueue != item.PriorityQueue)
+                        {
+                            lookup.Heap.Remove(lookup.Handle);
+
+                            LookupItem litem = lookup;
+                            litem.Heap = m_heaps[pqueue];
+                            litem.Heap.Add(new MinHeapItem(pqueue, item), ref litem.Handle);
+                            m_lookupTable[localid] = litem;
+                        }
+                    }
+                    else
+                    {
+                        // m_log.WarnFormat("[PQUEUE]: UpdatePriorityHandler returned false for {0}",item.Value.Entity.UUID);
+                        lookup.Heap.Remove(lookup.Handle);
+                        this.m_lookupTable.Remove(localid);
+                    }
+                }
+            }
+        }
+
+        /// <summary>
+        /// </summary>
+        public override string ToString()
+        {
+            string s = "";
+            for (int i = 0; i < NumberOfQueues; i++)
+                s += String.Format("{0,7} ",m_heaps[i].Count);
+            return s;
+        }
+
+#endregion PublicMethods
+
+#region MinHeapItem
+        private struct MinHeapItem : IComparable<MinHeapItem>
+        {
+            private IEntityUpdate value;
+            internal IEntityUpdate Value {
+                get {
+                    return this.value;
+                }
+            }
+
+            private uint pqueue;
+            internal uint PriorityQueue {
+                get {
+                    return this.pqueue;
+                }
+            }
+
+            private Int32 entrytime;
+            internal Int32 EntryTime {
+                get {
+                    return this.entrytime;
+                }
+            }
+
+            private UInt64 entryorder;
+            internal UInt64 EntryOrder
+            {
+                get {
+                    return this.entryorder;
+                }
+            }
+
+            internal MinHeapItem(uint pqueue, MinHeapItem other)
+            {
+                this.entrytime = other.entrytime;
+                this.entryorder = other.entryorder;
+                this.value = other.value;
+                this.pqueue = pqueue;
+            }
+
+            internal MinHeapItem(uint pqueue, UInt64 entryorder, IEntityUpdate value)
+            {
+                this.entrytime = Util.EnvironmentTickCount();
+                this.entryorder = entryorder;
+                this.value = value;
+                this.pqueue = pqueue;
+            }
+
+            public override string ToString()
+            {
+                return String.Format("[{0},{1},{2}]",pqueue,entryorder,value.Entity.LocalId);
+            }
+
+            public int CompareTo(MinHeapItem other)
+            {
+                // I'm assuming that the root part of an SOG is added to the update queue
+                // before the component parts
+                return Comparer<UInt64>.Default.Compare(this.EntryOrder, other.EntryOrder);
+            }
+        }
+#endregion
+
+#region LookupItem
+        private struct LookupItem
+        {
+            internal MinHeap<MinHeapItem> Heap;
+            internal IHandle Handle;
+        }
+#endregion
+    }
+}