singrdk/base/Libraries/UnitTest/WatchDogTimer.cs

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2008-03-05 09:52:00 -05:00
///////////////////////////////////////////////////////////////////////////////
//
// Microsoft Research Singularity
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// File: WatchDogTimer.cs
//
// Note:
//
using System;
using System.Threading;
namespace Microsoft.Singularity.UnitTest
{
/// <remarks> A class to watch for timeouts.</remarks>
public sealed class WatchDogTimer
{
private TimeSpan timeout;
private Thread worker;
private volatile bool running;
private AutoResetEvent! workEvent;
public WatchDogTimer(TimeSpan timeout)
{
this.timeout = timeout;
this.running = false;
this.workEvent = new AutoResetEvent(false);
}
public void Start()
{
lock (this) {
if (!this.running) {
this.running = true;
this.worker = new Thread(new ThreadStart(WorkerMain));
this.worker.Start();
}
}
}
public void Stop()
{
Thread toJoin = null;
lock (this) {
if (this.running) {
this.running = false;
this.workEvent.Set();
toJoin = this.worker;
this.worker = null;
}
}
if (toJoin != null) {
toJoin.Join();
}
}
public void Defer()
{
lock (this) {
Assert.True(this.running,
"Watch dog timer expired or stopped.");
workEvent.Set();
}
}
public bool Running
{
get { return this.running; }
}
private void LockedWorkerExpire()
{
try {
Assert.True(false, "Watch-dog timed out.");
}
catch (FailedAssertionException) {
// Expected
}
this.running = false;
}
private void WorkerMain()
{
bool done = false;
while (!done) {
bool signalled = WaitOne(this.workEvent, this.timeout);
lock (this) {
if (signalled) {
done = !this.running;
}
else {
LockedWorkerExpire();
done = true;
}
}
}
}
private static bool WaitOne(WaitHandle /*!*/ w, TimeSpan t)
{
#if SINGULARITY
return w.WaitOne(t);
#else
return w.WaitOne(t, false);
#endif
}
}
}