What's wrong with this code #7?

What's wrong with this code #7 - Discussion

Eric Gunnerson's C# Compendium — Sat, 28 May 2005 00:12:50 GMT

In this edition, I presented a small chunk of code that attempted to hook the signal handlers, so that...

re: What's wrong with this code #7?

Phil Hochstetler — Mon, 23 May 2005 21:08:28 GMT

The most obvious thing I see wrong is assuming the count goes from 9 to 10. The count could be incremented twice before the test so it would appear to go from 9 to 11. Either a lock() should be added around the increment / test, or a interlocked call used or just test for >=. All would fix the problem.

re: What's wrong with this code #7?

mgd — Mon, 23 May 2005 20:50:30 GMT

I tend to agree with the idea that delegate may get GC'd; since it's passed into unmanaged code the GC will have no way of telling that it's still required.

But since you can't count of when GC will or won't happen... I would be surprised if it was not usually be the case that it was still around.

re: What's wrong with this code #7?

Felipe Garcia — Mon, 23 May 2005 16:55:01 GMT

I think that "the code" will work fine. The problem I see is related to the Thread.Sleep that will hold the execution of the program for "a while" (100000 / 60) / 60 is like ~27.8 hours.

re: What's wrong with this code #7?

dhananjay singh — Mon, 23 May 2005 12:17:15 GMT

I think SetConsoleCtrlHandler internally creates new thread, so application will keep running even after count>10

re: What's wrong with this code #7?

dhananjay singh — Mon, 23 May 2005 12:07:04 GMT

count++;
if (count == 10)
{
Environment.Exit(0);
}

is not thread safe, so it is possible that even though count > 10 and progam is still running. ;)

Use Interlocked.Increment(ref int)

re: What's wrong with this code #7?

Matt Garven — Sat, 21 May 2005 03:02:02 GMT

Not only may the ControlEventHandler get GC'd, but the ConsoleCtrl instance itself will also be eligible for garbage collection (an optimisation in release mode only - during debug it won't be eligible until the end of the method to allow debuggers to inspect the value). I think :)

re: What's wrong with this code #7?

Sheeshers — Fri, 20 May 2005 21:25:19 GMT

Where are you checking to make sure you only respond to a CTRL-C event? Or maybe you're looking for something more than just such trivial stuff?

re: What's wrong with this code #7?

Versus — Fri, 20 May 2005 20:01:26 GMT

Thread.Sleep(100000);

note:
thats 100000 miliseconds = 100 seconds, not 27 hours

re: What's wrong with this code #7?

Andrew — Fri, 20 May 2005 19:45:14 GMT

The ControlEventHandler delegate should return bool.