100 lines
2.6 KiB
C#
100 lines
2.6 KiB
C#
// SpinWait.cs
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//
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// Copyright (c) 2008 Jérémie "Garuma" Laval
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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//
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//
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#if NET_4_0
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using System;
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namespace System.Threading
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{
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public struct SpinWait
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{
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// The number of step until SpinOnce yield on multicore machine
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const int step = 10;
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const int maxTime = 200;
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static readonly bool isSingleCpu = (Environment.ProcessorCount == 1);
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int ntime;
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public void SpinOnce ()
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{
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ntime += 1;
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if (isSingleCpu) {
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// On a single-CPU system, spinning does no good
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Thread.Yield ();
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} else {
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if (ntime % step == 0)
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Thread.Yield ();
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else
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// Multi-CPU system might be hyper-threaded, let other thread run
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Thread.SpinWait (Math.Min (ntime, maxTime) << 1);
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}
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}
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public static void SpinUntil (Func<bool> condition)
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{
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SpinWait sw = new SpinWait ();
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while (!condition ())
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sw.SpinOnce ();
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}
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public static bool SpinUntil (Func<bool> condition, TimeSpan timeout)
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{
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return SpinUntil (condition, (int)timeout.TotalMilliseconds);
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}
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public static bool SpinUntil (Func<bool> condition, int millisecondsTimeout)
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{
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SpinWait sw = new SpinWait ();
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Watch watch = Watch.StartNew ();
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while (!condition ()) {
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if (watch.ElapsedMilliseconds > millisecondsTimeout)
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return false;
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sw.SpinOnce ();
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}
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return true;
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}
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public void Reset ()
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{
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ntime = 0;
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}
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public bool NextSpinWillYield {
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get {
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return isSingleCpu ? true : ntime % step == 0;
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}
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}
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public int Count {
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get {
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return ntime;
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}
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}
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}
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}
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#endif
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