3 // Copyright (c) 2008 Jérémie "Garuma" Laval
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:
12 // The above copyright notice and this permission notice shall be included in
13 // all copies or substantial portions of the Software.
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
27 namespace System.Threading
29 public struct SpinWait
31 // The number of step until SpinOnce yield on multicore machine
33 const int maxTime = 200;
34 static readonly bool isSingleCpu = (Environment.ProcessorCount == 1);
38 public void SpinOnce ()
43 // On a single-CPU system, spinning does no good
46 if (ntime % step == 0)
49 // Multi-CPU system might be hyper-threaded, let other thread run
50 Thread.SpinWait (Math.Min (ntime, maxTime) << 1);
54 public static void SpinUntil (Func<bool> condition)
56 SpinWait sw = new SpinWait ();
61 public static bool SpinUntil (Func<bool> condition, TimeSpan timeout)
63 return SpinUntil (condition, (int)timeout.TotalMilliseconds);
66 public static bool SpinUntil (Func<bool> condition, int millisecondsTimeout)
68 SpinWait sw = new SpinWait ();
69 Watch watch = Watch.StartNew ();
71 while (!condition ()) {
72 if (watch.ElapsedMilliseconds > millisecondsTimeout)
85 public bool NextSpinWillYield {
87 return isSingleCpu ? true : ntime % step == 0;