clockwerk-opensim-stable – Blame information for rev 5
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Rev | Author | Line No. | Line |
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1 | vero | 1 | using System; |
2 | using System.Collections.Generic; |
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3 | using System.Threading; |
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4 | |||
5 | namespace Amib.Threading.Internal |
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6 | { |
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7 | #region WorkItemsQueue class |
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8 | |||
9 | /// <summary> |
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10 | /// WorkItemsQueue class. |
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11 | /// </summary> |
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12 | public class WorkItemsQueue : IDisposable |
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13 | { |
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14 | #region Member variables |
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15 | |||
16 | /// <summary> |
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17 | /// Waiters queue (implemented as stack). |
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18 | /// </summary> |
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19 | private readonly WaiterEntry _headWaiterEntry = new WaiterEntry(); |
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20 | |||
21 | /// <summary> |
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22 | /// Waiters count |
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23 | /// </summary> |
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24 | private int _waitersCount = 0; |
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25 | |||
26 | /// <summary> |
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27 | /// Work items queue |
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28 | /// </summary> |
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29 | private readonly PriorityQueue _workItems = new PriorityQueue(); |
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30 | |||
31 | /// <summary> |
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32 | /// Indicate that work items are allowed to be queued |
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33 | /// </summary> |
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34 | private bool _isWorkItemsQueueActive = true; |
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35 | |||
36 | |||
37 | #if (WINDOWS_PHONE) |
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38 | private static readonly Dictionary<int, WaiterEntry> _waiterEntries = new Dictionary<int, WaiterEntry>(); |
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39 | #elif (_WINDOWS_CE) |
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40 | private static LocalDataStoreSlot _waiterEntrySlot = Thread.AllocateDataSlot(); |
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41 | #else |
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42 | |||
43 | [ThreadStatic] |
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44 | private static WaiterEntry _waiterEntry; |
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45 | #endif |
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46 | |||
47 | |||
48 | /// <summary> |
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49 | /// Each thread in the thread pool keeps its own waiter entry. |
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50 | /// </summary> |
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51 | private static WaiterEntry CurrentWaiterEntry |
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52 | { |
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53 | #if (WINDOWS_PHONE) |
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54 | get |
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55 | { |
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56 | lock (_waiterEntries) |
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57 | { |
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58 | WaiterEntry waiterEntry; |
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59 | if (_waiterEntries.TryGetValue(Thread.CurrentThread.ManagedThreadId, out waiterEntry)) |
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60 | { |
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61 | return waiterEntry; |
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62 | } |
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63 | } |
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64 | return null; |
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65 | } |
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66 | set |
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67 | { |
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68 | lock (_waiterEntries) |
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69 | { |
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70 | _waiterEntries[Thread.CurrentThread.ManagedThreadId] = value; |
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71 | } |
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72 | } |
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73 | #elif (_WINDOWS_CE) |
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74 | get |
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75 | { |
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76 | return Thread.GetData(_waiterEntrySlot) as WaiterEntry; |
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77 | } |
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78 | set |
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79 | { |
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80 | Thread.SetData(_waiterEntrySlot, value); |
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81 | } |
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82 | #else |
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83 | get |
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84 | { |
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85 | return _waiterEntry; |
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86 | } |
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87 | set |
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88 | { |
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89 | _waiterEntry = value; |
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90 | } |
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91 | #endif |
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92 | } |
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93 | |||
94 | /// <summary> |
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95 | /// A flag that indicates if the WorkItemsQueue has been disposed. |
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96 | /// </summary> |
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97 | private bool _isDisposed = false; |
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98 | |||
99 | #endregion |
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100 | |||
101 | #region Public properties |
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102 | |||
103 | /// <summary> |
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104 | /// Returns the current number of work items in the queue |
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105 | /// </summary> |
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106 | public int Count |
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107 | { |
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108 | get |
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109 | { |
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110 | return _workItems.Count; |
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111 | } |
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112 | } |
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113 | |||
114 | /// <summary> |
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115 | /// Returns the current number of waiters |
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116 | /// </summary> |
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117 | public int WaitersCount |
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118 | { |
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119 | get |
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120 | { |
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121 | return _waitersCount; |
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122 | } |
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123 | } |
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124 | |||
125 | |||
126 | #endregion |
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127 | |||
128 | #region Public methods |
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129 | |||
130 | /// <summary> |
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131 | /// Enqueue a work item to the queue. |
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132 | /// </summary> |
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133 | public bool EnqueueWorkItem(WorkItem workItem) |
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134 | { |
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135 | // A work item cannot be null, since null is used in the |
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136 | // WaitForWorkItem() method to indicate timeout or cancel |
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137 | if (null == workItem) |
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138 | { |
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139 | throw new ArgumentNullException("workItem" , "workItem cannot be null"); |
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140 | } |
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141 | |||
142 | bool enqueue = true; |
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143 | |||
144 | // First check if there is a waiter waiting for work item. During |
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145 | // the check, timed out waiters are ignored. If there is no |
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146 | // waiter then the work item is queued. |
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147 | lock(this) |
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148 | { |
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149 | ValidateNotDisposed(); |
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150 | |||
151 | if (!_isWorkItemsQueueActive) |
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152 | { |
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153 | return false; |
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154 | } |
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155 | |||
156 | while(_waitersCount > 0) |
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157 | { |
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158 | // Dequeue a waiter. |
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159 | WaiterEntry waiterEntry = PopWaiter(); |
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160 | |||
161 | // Signal the waiter. On success break the loop |
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162 | if (waiterEntry.Signal(workItem)) |
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163 | { |
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164 | enqueue = false; |
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165 | break; |
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166 | } |
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167 | } |
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168 | |||
169 | if (enqueue) |
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170 | { |
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171 | // Enqueue the work item |
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172 | _workItems.Enqueue(workItem); |
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173 | } |
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174 | } |
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175 | return true; |
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176 | } |
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177 | |||
178 | |||
179 | /// <summary> |
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180 | /// Waits for a work item or exits on timeout or cancel |
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181 | /// </summary> |
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182 | /// <param name="millisecondsTimeout">Timeout in milliseconds</param> |
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183 | /// <param name="cancelEvent">Cancel wait handle</param> |
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184 | /// <returns>Returns true if the resource was granted</returns> |
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185 | public WorkItem DequeueWorkItem( |
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186 | int millisecondsTimeout, |
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187 | WaitHandle cancelEvent) |
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188 | { |
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189 | // This method cause the caller to wait for a work item. |
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190 | // If there is at least one waiting work item then the |
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191 | // method returns immidiately with it. |
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192 | // |
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193 | // If there are no waiting work items then the caller |
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194 | // is queued between other waiters for a work item to arrive. |
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195 | // |
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196 | // If a work item didn't come within millisecondsTimeout or |
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197 | // the user canceled the wait by signaling the cancelEvent |
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198 | // then the method returns null to indicate that the caller |
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199 | // didn't get a work item. |
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200 | |||
201 | WaiterEntry waiterEntry; |
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202 | WorkItem workItem = null; |
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203 | lock (this) |
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204 | { |
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205 | ValidateNotDisposed(); |
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206 | |||
207 | // If there are waiting work items then take one and return. |
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208 | if (_workItems.Count > 0) |
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209 | { |
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210 | workItem = _workItems.Dequeue() as WorkItem; |
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211 | return workItem; |
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212 | } |
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213 | |||
214 | // No waiting work items ... |
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215 | |||
216 | // Get the waiter entry for the waiters queue |
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217 | waiterEntry = GetThreadWaiterEntry(); |
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218 | |||
219 | // Put the waiter with the other waiters |
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220 | PushWaiter(waiterEntry); |
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221 | } |
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222 | |||
223 | // Prepare array of wait handle for the WaitHandle.WaitAny() |
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224 | WaitHandle [] waitHandles = new WaitHandle[] { |
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225 | waiterEntry.WaitHandle, |
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226 | cancelEvent }; |
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227 | |||
228 | // Wait for an available resource, cancel event, or timeout. |
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229 | |||
230 | // During the wait we are supposes to exit the synchronization |
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231 | // domain. (Placing true as the third argument of the WaitAny()) |
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232 | // It just doesn't work, I don't know why, so I have two lock(this) |
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233 | // statments instead of one. |
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234 | |||
235 | int index = STPEventWaitHandle.WaitAny( |
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236 | waitHandles, |
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237 | millisecondsTimeout, |
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238 | true); |
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239 | |||
240 | lock(this) |
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241 | { |
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242 | // success is true if it got a work item. |
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243 | bool success = (0 == index); |
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244 | |||
245 | // The timeout variable is used only for readability. |
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246 | // (We treat cancel as timeout) |
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247 | bool timeout = !success; |
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248 | |||
249 | // On timeout update the waiterEntry that it is timed out |
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250 | if (timeout) |
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251 | { |
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252 | // The Timeout() fails if the waiter has already been signaled |
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253 | timeout = waiterEntry.Timeout(); |
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254 | |||
255 | // On timeout remove the waiter from the queue. |
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256 | // Note that the complexity is O(1). |
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257 | if(timeout) |
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258 | { |
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259 | RemoveWaiter(waiterEntry, false); |
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260 | } |
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261 | |||
262 | // Again readability |
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263 | success = !timeout; |
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264 | } |
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265 | |||
266 | // On success return the work item |
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267 | if (success) |
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268 | { |
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269 | workItem = waiterEntry.WorkItem; |
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270 | |||
271 | if (null == workItem) |
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272 | { |
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273 | workItem = _workItems.Dequeue() as WorkItem; |
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274 | } |
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275 | } |
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276 | } |
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277 | // On failure return null. |
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278 | return workItem; |
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279 | } |
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280 | |||
281 | /// <summary> |
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282 | /// Cleanup the work items queue, hence no more work |
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283 | /// items are allowed to be queue |
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284 | /// </summary> |
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285 | private void Cleanup() |
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286 | { |
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287 | lock(this) |
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288 | { |
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289 | // Deactivate only once |
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290 | if (!_isWorkItemsQueueActive) |
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291 | { |
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292 | return; |
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293 | } |
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294 | |||
295 | // Don't queue more work items |
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296 | _isWorkItemsQueueActive = false; |
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297 | |||
298 | foreach(WorkItem workItem in _workItems) |
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299 | { |
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300 | workItem.DisposeOfState(); |
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301 | } |
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302 | |||
303 | // Clear the work items that are already queued |
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304 | _workItems.Clear(); |
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305 | |||
306 | // Note: |
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307 | // I don't iterate over the queue and dispose of work items's states, |
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308 | // since if a work item has a state object that is still in use in the |
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309 | // application then I must not dispose it. |
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310 | |||
311 | // Tell the waiters that they were timed out. |
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312 | // It won't signal them to exit, but to ignore their |
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313 | // next work item. |
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314 | while(_waitersCount > 0) |
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315 | { |
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316 | WaiterEntry waiterEntry = PopWaiter(); |
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317 | waiterEntry.Timeout(); |
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318 | } |
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319 | } |
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320 | } |
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321 | |||
322 | public object[] GetStates() |
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323 | { |
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324 | lock (this) |
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325 | { |
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326 | object[] states = new object[_workItems.Count]; |
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327 | int i = 0; |
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328 | foreach (WorkItem workItem in _workItems) |
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329 | { |
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330 | states[i] = workItem.GetWorkItemResult().State; |
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331 | ++i; |
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332 | } |
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333 | return states; |
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334 | } |
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335 | } |
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336 | |||
337 | #endregion |
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338 | |||
339 | #region Private methods |
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340 | |||
341 | /// <summary> |
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342 | /// Returns the WaiterEntry of the current thread |
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343 | /// </summary> |
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344 | /// <returns></returns> |
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345 | /// In order to avoid creation and destuction of WaiterEntry |
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346 | /// objects each thread has its own WaiterEntry object. |
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347 | private static WaiterEntry GetThreadWaiterEntry() |
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348 | { |
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349 | if (null == CurrentWaiterEntry) |
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350 | { |
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351 | CurrentWaiterEntry = new WaiterEntry(); |
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352 | } |
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353 | CurrentWaiterEntry.Reset(); |
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354 | return CurrentWaiterEntry; |
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355 | } |
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356 | |||
357 | #region Waiters stack methods |
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358 | |||
359 | /// <summary> |
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360 | /// Push a new waiter into the waiter's stack |
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361 | /// </summary> |
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362 | /// <param name="newWaiterEntry">A waiter to put in the stack</param> |
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363 | public void PushWaiter(WaiterEntry newWaiterEntry) |
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364 | { |
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365 | // Remove the waiter if it is already in the stack and |
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366 | // update waiter's count as needed |
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367 | RemoveWaiter(newWaiterEntry, false); |
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368 | |||
369 | // If the stack is empty then newWaiterEntry is the new head of the stack |
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370 | if (null == _headWaiterEntry._nextWaiterEntry) |
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371 | { |
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372 | _headWaiterEntry._nextWaiterEntry = newWaiterEntry; |
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373 | newWaiterEntry._prevWaiterEntry = _headWaiterEntry; |
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374 | |||
375 | } |
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376 | // If the stack is not empty then put newWaiterEntry as the new head |
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377 | // of the stack. |
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378 | else |
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379 | { |
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380 | // Save the old first waiter entry |
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381 | WaiterEntry oldFirstWaiterEntry = _headWaiterEntry._nextWaiterEntry; |
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382 | |||
383 | // Update the links |
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384 | _headWaiterEntry._nextWaiterEntry = newWaiterEntry; |
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385 | newWaiterEntry._nextWaiterEntry = oldFirstWaiterEntry; |
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386 | newWaiterEntry._prevWaiterEntry = _headWaiterEntry; |
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387 | oldFirstWaiterEntry._prevWaiterEntry = newWaiterEntry; |
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388 | } |
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389 | |||
390 | // Increment the number of waiters |
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391 | ++_waitersCount; |
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392 | } |
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393 | |||
394 | /// <summary> |
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395 | /// Pop a waiter from the waiter's stack |
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396 | /// </summary> |
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397 | /// <returns>Returns the first waiter in the stack</returns> |
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398 | private WaiterEntry PopWaiter() |
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399 | { |
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400 | // Store the current stack head |
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401 | WaiterEntry oldFirstWaiterEntry = _headWaiterEntry._nextWaiterEntry; |
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402 | |||
403 | // Store the new stack head |
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404 | WaiterEntry newHeadWaiterEntry = oldFirstWaiterEntry._nextWaiterEntry; |
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405 | |||
406 | // Update the old stack head list links and decrement the number |
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407 | // waiters. |
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408 | RemoveWaiter(oldFirstWaiterEntry, true); |
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409 | |||
410 | // Update the new stack head |
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411 | _headWaiterEntry._nextWaiterEntry = newHeadWaiterEntry; |
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412 | if (null != newHeadWaiterEntry) |
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413 | { |
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414 | newHeadWaiterEntry._prevWaiterEntry = _headWaiterEntry; |
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415 | } |
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416 | |||
417 | // Return the old stack head |
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418 | return oldFirstWaiterEntry; |
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419 | } |
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420 | |||
421 | /// <summary> |
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422 | /// Remove a waiter from the stack |
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423 | /// </summary> |
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424 | /// <param name="waiterEntry">A waiter entry to remove</param> |
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425 | /// <param name="popDecrement">If true the waiter count is always decremented</param> |
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426 | private void RemoveWaiter(WaiterEntry waiterEntry, bool popDecrement) |
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427 | { |
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428 | // Store the prev entry in the list |
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429 | WaiterEntry prevWaiterEntry = waiterEntry._prevWaiterEntry; |
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430 | |||
431 | // Store the next entry in the list |
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432 | WaiterEntry nextWaiterEntry = waiterEntry._nextWaiterEntry; |
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433 | |||
434 | // A flag to indicate if we need to decrement the waiters count. |
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435 | // If we got here from PopWaiter then we must decrement. |
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436 | // If we got here from PushWaiter then we decrement only if |
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437 | // the waiter was already in the stack. |
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438 | bool decrementCounter = popDecrement; |
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439 | |||
440 | // Null the waiter's entry links |
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441 | waiterEntry._prevWaiterEntry = null; |
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442 | waiterEntry._nextWaiterEntry = null; |
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443 | |||
444 | // If the waiter entry had a prev link then update it. |
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445 | // It also means that the waiter is already in the list and we |
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446 | // need to decrement the waiters count. |
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447 | if (null != prevWaiterEntry) |
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448 | { |
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449 | prevWaiterEntry._nextWaiterEntry = nextWaiterEntry; |
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450 | decrementCounter = true; |
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451 | } |
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452 | |||
453 | // If the waiter entry had a next link then update it. |
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454 | // It also means that the waiter is already in the list and we |
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455 | // need to decrement the waiters count. |
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456 | if (null != nextWaiterEntry) |
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457 | { |
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458 | nextWaiterEntry._prevWaiterEntry = prevWaiterEntry; |
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459 | decrementCounter = true; |
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460 | } |
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461 | |||
462 | // Decrement the waiters count if needed |
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463 | if (decrementCounter) |
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464 | { |
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465 | --_waitersCount; |
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466 | } |
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467 | } |
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468 | |||
469 | #endregion |
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470 | |||
471 | #endregion |
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472 | |||
473 | #region WaiterEntry class |
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474 | |||
475 | // A waiter entry in the _waiters queue. |
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476 | public sealed class WaiterEntry : IDisposable |
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477 | { |
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478 | #region Member variables |
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479 | |||
480 | /// <summary> |
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481 | /// Event to signal the waiter that it got the work item. |
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482 | /// </summary> |
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483 | //private AutoResetEvent _waitHandle = new AutoResetEvent(false); |
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484 | private AutoResetEvent _waitHandle = EventWaitHandleFactory.CreateAutoResetEvent(); |
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485 | |||
486 | /// <summary> |
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487 | /// Flag to know if this waiter already quited from the queue |
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488 | /// because of a timeout. |
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489 | /// </summary> |
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490 | private bool _isTimedout = false; |
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491 | |||
492 | /// <summary> |
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493 | /// Flag to know if the waiter was signaled and got a work item. |
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494 | /// </summary> |
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495 | private bool _isSignaled = false; |
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496 | |||
497 | /// <summary> |
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498 | /// A work item that passed directly to the waiter withou going |
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499 | /// through the queue |
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500 | /// </summary> |
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501 | private WorkItem _workItem = null; |
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502 | |||
503 | private bool _isDisposed = false; |
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504 | |||
505 | // Linked list members |
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506 | internal WaiterEntry _nextWaiterEntry = null; |
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507 | internal WaiterEntry _prevWaiterEntry = null; |
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508 | |||
509 | #endregion |
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510 | |||
511 | #region Construction |
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512 | |||
513 | public WaiterEntry() |
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514 | { |
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515 | Reset(); |
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516 | } |
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517 | |||
518 | #endregion |
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519 | |||
520 | #region Public methods |
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521 | |||
522 | public WaitHandle WaitHandle |
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523 | { |
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524 | get { return _waitHandle; } |
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525 | } |
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526 | |||
527 | public WorkItem WorkItem |
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528 | { |
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529 | get |
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530 | { |
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531 | return _workItem; |
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532 | } |
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533 | } |
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534 | |||
535 | /// <summary> |
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536 | /// Signal the waiter that it got a work item. |
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537 | /// </summary> |
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538 | /// <returns>Return true on success</returns> |
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539 | /// The method fails if Timeout() preceded its call |
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540 | public bool Signal(WorkItem workItem) |
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541 | { |
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542 | lock(this) |
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543 | { |
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544 | if (!_isTimedout) |
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545 | { |
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546 | _workItem = workItem; |
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547 | _isSignaled = true; |
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548 | _waitHandle.Set(); |
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549 | return true; |
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550 | } |
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551 | } |
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552 | return false; |
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553 | } |
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554 | |||
555 | /// <summary> |
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556 | /// Mark the wait entry that it has been timed out |
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557 | /// </summary> |
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558 | /// <returns>Return true on success</returns> |
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559 | /// The method fails if Signal() preceded its call |
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560 | public bool Timeout() |
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561 | { |
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562 | lock(this) |
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563 | { |
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564 | // Time out can happen only if the waiter wasn't marked as |
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565 | // signaled |
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566 | if (!_isSignaled) |
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567 | { |
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568 | // We don't remove the waiter from the queue, the DequeueWorkItem |
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569 | // method skips _waiters that were timed out. |
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570 | _isTimedout = true; |
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571 | return true; |
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572 | } |
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573 | } |
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574 | return false; |
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575 | } |
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576 | |||
577 | /// <summary> |
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578 | /// Reset the wait entry so it can be used again |
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579 | /// </summary> |
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580 | public void Reset() |
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581 | { |
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582 | _workItem = null; |
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583 | _isTimedout = false; |
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584 | _isSignaled = false; |
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585 | _waitHandle.Reset(); |
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586 | } |
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587 | |||
588 | /// <summary> |
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589 | /// Free resources |
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590 | /// </summary> |
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591 | public void Close() |
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592 | { |
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593 | if (null != _waitHandle) |
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594 | { |
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595 | _waitHandle.Close(); |
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596 | _waitHandle = null; |
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597 | } |
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598 | } |
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599 | |||
600 | #endregion |
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601 | |||
602 | #region IDisposable Members |
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603 | |||
604 | public void Dispose() |
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605 | { |
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606 | lock (this) |
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607 | { |
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608 | if (!_isDisposed) |
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609 | { |
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610 | Close(); |
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611 | } |
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612 | _isDisposed = true; |
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613 | } |
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614 | } |
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615 | |||
616 | #endregion |
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617 | } |
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618 | |||
619 | #endregion |
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620 | |||
621 | #region IDisposable Members |
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622 | |||
623 | public void Dispose() |
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624 | { |
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625 | if (!_isDisposed) |
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626 | { |
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627 | Cleanup(); |
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628 | } |
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629 | _isDisposed = true; |
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630 | } |
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631 | |||
632 | private void ValidateNotDisposed() |
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633 | { |
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634 | if(_isDisposed) |
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635 | { |
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636 | throw new ObjectDisposedException(GetType().ToString(), "The SmartThreadPool has been shutdown"); |
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637 | } |
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638 | } |
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639 | |||
640 | #endregion |
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641 | } |
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642 | |||
643 | #endregion |
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644 | } |
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645 |