[Mono-dev] Control-C handler

[Robert Jordan]

pablosantosluac wrote:
> Ok, I think I got a bit lost here... how should I proceed then?

Assure that the handler is called once before it gets invoked
from the signal handler:

class Test {
	static volatile bool ctrl_c_pressed;

	static void handler (int sig)
	{
		ctrl_c_pressed = true;
	}

	public static void Main ()
	{
		handler (0);
		ctrl_c_pressed = false;
		
		Stdlib.signal (Signum.SIGINT, handler);

		Console.WriteLine ("Press Ctrl+C to terminate app.");
		while (!ctrl_c_pressed) {
			Thread.Sleep (1);
		}
		Console.WriteLine ("Finished.");
	}
}






> 
> Thanks,
> 
> 
> pablo
> ----- Original Message ----- 
> From: "Jonathan Pryor" <jonpryor at vt.edu>
> To: "Miguel de Icaza" <miguel at novell.com>
> Cc: <mono-devel-list at lists.ximian.com>
> Sent: Thursday, December 20, 2007 8:41 PM
> Subject: Re: [Mono-dev] Control-C handler
> 
> 
>> On Thu, 2007-12-20 at 14:16 -0500, Miguel de Icaza wrote:
>>> Hello,
>>>
>>>> You can use signal(2), which is helpfully exposed by Mono.Posix.dll.
>>>>
>>>> See the attached program.
>>> This actually would corrupt the application state, because the C-c
>>> handler will run the entire JIT at that point and this happens in the
>>> same thread as the executing thread.
>> Isn't there a method that says "JIT this function now"?  (I thought
>> Marshal.Prelink() did that, which is what Stdlib.signal() calls, but I
>> just re-read the documentation and it doesn't do anything of the sort.)
>>
>> Before dropping to C, though, there are two alternatives:
>>
>> 1. Call handler() *before* passing it to Stdlib.signal():
>>
>> handler (-1);
>> Stdlib.signal (Signum.SIGINT, handler);
>> /* ... as before ... */
>>
>> This would require changing handler() to know about this initialization
>> call and NOT set ctrl_c_pressed if the parameter is -1.
>>
>> This would also allow a pure C# signal handler, as the method will be
>> JITed during the first handler() call.
>>
>> 2. Use System.Runtime.ConstrainedExecution.PrePrepareMethodAttribute on
>> the signal handler method.  This would require that Mono have support
>> for Constrained Execution regions, which I believe is currently lacking,
>> but would presumably eventually be supported.
>>
>> - Jon
>>
>>
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