mcs/class/corlib/System.Threading/SemaphoreSlim.cs

   1 // SemaphoreSlim.cs
   2 //
   3 // Copyright (c) 2008 Jérémie "Garuma" Laval
   4 //
   5 // Permission is hereby granted, free of charge, to any person obtaining a copy
   6 // of this software and associated documentation files (the "Software"), to deal
   7 // in the Software without restriction, including without limitation the rights
   8 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   9 // copies of the Software, and to permit persons to whom the Software is
  10 // furnished to do so, subject to the following conditions:
  11 //
  12 // The above copyright notice and this permission notice shall be included in
  13 // all copies or substantial portions of the Software.
  14 //
  15 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  18 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  21 // THE SOFTWARE.
  22 //
  23 //
  24
  25 using System;
  26 using System.Diagnostics;
  27 #if NET_4_5
  28 using System.Threading.Tasks;
  29 #endif
  30
  31 #if NET_4_0
  32 namespace System.Threading
  33 {
  34         [System.Diagnostics.DebuggerDisplayAttribute ("Current Count = {currCount}")]
  35         public class SemaphoreSlim : IDisposable
  36         {
  37                 const int spinCount = 10;
  38                 const int deepSleepTime = 20;
  39
  40                 readonly int maxCount;
  41                 int currCount;
  42                 bool isDisposed;
  43
  44                 EventWaitHandle handle;
  45
  46                 public SemaphoreSlim (int initialCount) : this (initialCount, int.MaxValue)
  47                 {
  48                 }
  49
  50                 public SemaphoreSlim (int initialCount, int maxCount)
  51                 {
  52                         if (initialCount < 0 || initialCount > maxCount || maxCount < 0)
  53                                 throw new ArgumentOutOfRangeException ("The initialCount  argument is negative, initialCount is greater than maxCount, or maxCount is not positive.");
  54
  55                         this.maxCount = maxCount;
  56                         this.currCount = initialCount;
  57                         this.handle = new ManualResetEvent (initialCount > 0);
  58                 }
  59
  60                 public void Dispose ()
  61                 {
  62                         Dispose(true);
  63                 }
  64
  65                 protected virtual void Dispose (bool disposing)
  66                 {
  67                         isDisposed = true;
  68                 }
  69
  70                 void CheckState ()
  71                 {
  72                         if (isDisposed)
  73                                 throw new ObjectDisposedException ("The SemaphoreSlim has been disposed.");
  74                 }
  75
  76                 public int CurrentCount {
  77                         get {
  78                                 return currCount;
  79                         }
  80                 }
  81
  82                 public int Release ()
  83                 {
  84                         return Release(1);
  85                 }
  86
  87                 public int Release (int releaseCount)
  88                 {
  89                         CheckState ();
  90                         if (releaseCount < 1)
  91                                 throw new ArgumentOutOfRangeException ("releaseCount", "releaseCount is less than 1");
  92
  93                         // As we have to take care of the max limit we resort to CAS
  94                         int oldValue, newValue;
  95                         do {
  96                                 oldValue = currCount;
  97                                 newValue = (currCount + releaseCount);
  98                                 newValue = newValue > maxCount ? maxCount : newValue;
  99                         } while (Interlocked.CompareExchange (ref currCount, newValue, oldValue) != oldValue);
 100
 101                         handle.Set ();
 102
 103                         return oldValue;
 104                 }
 105
 106                 public void Wait ()
 107                 {
 108                         Wait (CancellationToken.None);
 109                 }
 110
 111                 public bool Wait (TimeSpan timeout)
 112                 {
 113                         return Wait ((int)timeout.TotalMilliseconds, CancellationToken.None);
 114                 }
 115
 116                 public bool Wait (int millisecondsTimeout)
 117                 {
 118                         return Wait (millisecondsTimeout, CancellationToken.None);
 119                 }
 120
 121                 public void Wait (CancellationToken cancellationToken)
 122                 {
 123                         Wait (-1, cancellationToken);
 124                 }
 125
 126                 public bool Wait (TimeSpan timeout, CancellationToken cancellationToken)
 127                 {
 128                         CheckState();
 129                         return Wait ((int)timeout.TotalMilliseconds, cancellationToken);
 130                 }
 131
 132                 public bool Wait (int millisecondsTimeout, CancellationToken cancellationToken)
 133                 {
 134                         CheckState ();
 135                         if (millisecondsTimeout < -1)
 136                                 throw new ArgumentOutOfRangeException ("millisecondsTimeout",
 137                                                                        "millisecondsTimeout is a negative number other than -1");
 138
 139                         Watch sw = Watch.StartNew ();
 140
 141                         Func<bool> stopCondition = () => millisecondsTimeout >= 0 && sw.ElapsedMilliseconds > millisecondsTimeout;
 142
 143                         do {
 144                                 bool shouldWait;
 145                                 int result;
 146
 147                                 do {
 148                                         cancellationToken.ThrowIfCancellationRequested ();
 149                                         if (stopCondition ())
 150                                                 return false;
 151
 152                                         shouldWait = true;
 153                                         result = currCount;
 154
 155                                         if (result > 0)
 156                                                 shouldWait = false;
 157                                         else
 158                                                 break;
 159                                 } while (Interlocked.CompareExchange (ref currCount, result - 1, result) != result);
 160
 161                                 if (!shouldWait) {
 162                                         if (result == 1)
 163                                                 handle.Reset ();
 164                                         break;
 165                                 }
 166
 167                                 SpinWait wait = new SpinWait ();
 168
 169                                 while (Volatile.Read (ref currCount) <= 0) {
 170                                         cancellationToken.ThrowIfCancellationRequested ();
 171                                         if (stopCondition ())
 172                                                 return false;
 173
 174                                         if (wait.Count > spinCount) {
 175                                                 int timeout = millisecondsTimeout < 0 ? deepSleepTime :
 176                                                         Math.Min (Math.Max (millisecondsTimeout - (int)sw.ElapsedMilliseconds, 1), deepSleepTime);
 177                                                 handle.WaitOne (timeout);
 178                                         } else
 179                                                 wait.SpinOnce ();
 180                                 }
 181                         } while (true);
 182
 183                         return true;
 184                 }
 185
 186                 public WaitHandle AvailableWaitHandle {
 187                         get {
 188                                 return handle;
 189                         }
 190                 }
 191
 192 #if NET_4_5
 193                 public Task WaitAsync ()
 194                 {
 195                         return Task.Factory.StartNew (() => Wait ());
 196                 }
 197
 198                 public Task WaitAsync (CancellationToken cancellationToken)
 199                 {
 200                         return Task.Factory.StartNew (() => Wait (cancellationToken), cancellationToken);
 201                 }
 202
 203                 public Task<bool> WaitAsync (int millisecondsTimeout)
 204                 {
 205                         return Task.Factory.StartNew (() => Wait (millisecondsTimeout));
 206                 }
 207
 208                 public Task<bool> WaitAsync (TimeSpan timeout)
 209                 {
 210                         return Task.Factory.StartNew (() => Wait (timeout));
 211                 }
 212
 213                 public Task<bool> WaitAsync (int millisecondsTimeout, CancellationToken cancellationToken)
 214                 {
 215                         return Task.Factory.StartNew (() => Wait (millisecondsTimeout, cancellationToken), cancellationToken);
 216                 }
 217
 218                 public Task<bool> WaitAsync (TimeSpan timeout, CancellationToken cancellationToken)
 219                 {
 220                         return Task.Factory.StartNew (() => Wait (timeout, cancellationToken), cancellationToken);
 221                 }
 222 #endif
 223
 224         }
 225 }
 226 #endif