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