aboutsummaryrefslogtreecommitdiffstatshomepage
path: root/OpenSim/Region/ClientStack/LindenUDP/PriorityQueue.cs
blob: 364ce4ba9ee5c41b8bb2628ff1a5d100b4de490f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
/*
 * 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.Region.ClientStack.LindenUDP
{
    public class PriorityQueue
    {
        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);

        internal delegate bool UpdatePriorityHandler(ref uint priority, ISceneEntity entity);

        // Heap[0] for self updates
        // Heap[1..12] for entity updates

        internal const uint m_numberOfQueues = 12;

        private MinHeap<MinHeapItem>[] m_heaps = new MinHeap<MinHeapItem>[m_numberOfQueues];
        private Dictionary<uint, LookupItem> m_lookupTable;
        private uint m_nextQueue = 0;
        private UInt64 m_nextRequest = 0;

        private object m_syncRoot = new object();
        public object SyncRoot {
            get { return this.m_syncRoot; }
        }

        internal PriorityQueue() : this(MinHeap<MinHeapItem>.DEFAULT_CAPACITY) { }

        internal 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);
        }

        internal int Count
        {
            get
            {
                int count = 0;
                for (int i = 0; i < m_heaps.Length; ++i)
                    count += m_heaps[i].Count;
                return count;
            }
        }

        public bool Enqueue(uint pqueue, EntityUpdate 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.Flags |=  lookup.Heap[lookup.Handle].Value.Flags;
                lookup.Heap.Remove(lookup.Handle);
            }

            pqueue = Util.Clamp<uint>(pqueue, 0, m_numberOfQueues - 1);
            lookup.Heap = m_heaps[pqueue];
            lookup.Heap.Add(new MinHeapItem(pqueue, entry, value), ref lookup.Handle);
            m_lookupTable[localid] = lookup;

            return true;
        }

        internal bool TryDequeue(out EntityUpdate value, out Int32 timeinqueue)
        {
            for (int i = 0; i < m_numberOfQueues; ++i)
            {
                // To get the fair queing, we cycle through each of the
                // queues when finding an element to dequeue, this code
                // assumes that the distribution of updates in the queues
                // is polynomial, probably quadractic (eg distance of PI * R^2)
                uint h = (uint)((m_nextQueue + i) % m_numberOfQueues);
                if (m_heaps[h].Count > 0)
                {
                    m_nextQueue = (uint)((h + 1) % m_numberOfQueues);

                    MinHeapItem item = m_heaps[h].RemoveMin();
                    m_lookupTable.Remove(item.Value.Entity.LocalId);
                    timeinqueue = Util.EnvironmentTickCountSubtract(item.EntryTime);
                    value = item.Value;

                    return true;
                }
            }

            timeinqueue = 0;
            value = default(EntityUpdate);
            return false;
        }

        internal 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, m_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);
                    }
                }
            }
        }

        public override string ToString()
        {
            string s = "";
            for (int i = 0; i < m_numberOfQueues; i++)
            {
                if (s != "") s += ",";
                s += m_heaps[i].Count.ToString();
            }
            return s;
        }

#region MinHeapItem
        private struct MinHeapItem : IComparable<MinHeapItem>
        {
            private EntityUpdate value;
            internal EntityUpdate 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, EntityUpdate 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
    }
}