[Mono-bugs] [Bug 79484][Nor] Changed - null reference exception in System.Timers.StartTimer()

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Changed by psingh at fnfr.com.

http://bugzilla.ximian.com/show_bug.cgi?id=79484

--- shadow/79484	2006-09-24 18:13:26.000000000 -0400
+++ shadow/79484.tmp.17557	2006-09-26 04:00:23.000000000 -0400
@@ -30,6 +30,35 @@
 
 How often does this happen? 
 Very often - on one machine it happens 99% of the time, on another it
 happens 50% of the time. I tried running our app with mono -v option to get
 more information, but it prints mostly useless information about "emitting"
 code.
+
+------- Additional Comments From psingh at fnfr.com  2006-09-26 04:00 -------
+We looked at the source code for System.Timers.Timer class and here is
+the problem. If Timer.AutoReset = false, the loop exits and sets wait
+= null. If the user has called Timer.Start() again, a new thread can
+get into the while condition after the previous thread has set the
+wait to null just after this new thread created new "wait" object. The
+fix can be simple.
+
+-Pawan
+
+void StartTimer ()
+                {
+                        wait = new ManualResetEvent (false);
+
+                        WaitCallback wc = new WaitCallback (Callback);
+                        while (enabled && wait.WaitOne ((int)
+interval, false) == false) {
+                                if (autoReset == false)
+                                        enabled = false;
+
+                                ThreadPool.QueueUserWorkItem (wc, this);
+                        }
+
+                        wc = null;
+                        ((IDisposable) wait).Dispose ();
+                     ==>   wait = null;
+                }
+