1 #if NET_4_0 || BOOTSTRAP_NET_4_0
4 // Copyright (c) 2008 Jérémie "Garuma" Laval
6 // Permission is hereby granted, free of charge, to any person obtaining a copy
7 // of this software and associated documentation files (the "Software"), to deal
8 // in the Software without restriction, including without limitation the rights
9 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 // copies of the Software, and to permit persons to whom the Software is
11 // furnished to do so, subject to the following conditions:
13 // The above copyright notice and this permission notice shall be included in
14 // all copies or substantial portions of the Software.
16 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
28 namespace System.Threading
31 public struct SpinWait
33 // The number of step until SpinOnce yield on multicore machine
35 static readonly bool isSingleCpu = (Environment.ProcessorCount == 1);
39 public void SpinOnce ()
41 // On a single-CPU system, spinning does no good
45 if (Interlocked.Increment (ref ntime) % step == 0) {
48 // Multi-CPU system might be hyper-threaded, let other thread run
49 Thread.SpinWait (2 * (ntime + 1));
54 public static void SpinUntil (Func<bool> predicate)
56 SpinWait sw = new SpinWait ();
61 public static bool SpinUntil (Func<bool> predicate, TimeSpan ts)
63 return SpinUntil (predicate, (int)ts.TotalMilliseconds);
66 public static bool SpinUntil (Func<bool> predicate, int milliseconds)
68 SpinWait sw = new SpinWait ();
69 Watch watch = Watch.StartNew ();
71 while (!predicate ()) {
72 if (watch.ElapsedMilliseconds > milliseconds)
82 // Replace sched_yield by Thread.Sleep(0) which does almost the same thing
83 // (going back in kernel mode and yielding) but avoid the branching and unmanaged bridge
92 public bool NextSpinWillYield {
94 return isSingleCpu ? true : ntime % step == 0;