On Fri, Jan 08, 2010 at 05:51:51PM +0100, Damien Pollet wrote:
> Hi,
>
> Chaff is a tiny class to intercept the SIGTERM signal and save the
> image http://www.squeaksource.com/Chaff.html
>
> Several problems:
>
> - OSProcess accessor forwardSigTern will only work once. Once the VM
> has registered a handler for a given signal, it can't clean it up or
> register another semaphore, until the image restarts.
Not so. The plugin allows you to reset a signal handler to its default
value for exactly this reason. This is the method comment in
UnixOSProcessPlugin (the part that runs in the VM):
forwardSignal: sigNum toSemaphoreAt: semaphoreIndex
"Set a signal handler in the VM which will signal a Smalltalk semaphore
at
semaphoreIndex whenever an external signal sigNum is received. Answer
the
prior value of the signal handler. If semaphoreIndex is zero, the
handler is
unregistered, and the VM returns to its default behavior for handling
that
signal. A handler must be unregistered before it can be registered
again.
The Smalltalk semaphore is expected to be kept at the same index
location
indefinitely during the lifetime of a Squeak session. If that is not
the case, the
handler must be unregistered prior to unregistering the Smalltalk
semaphore."
Thus in UnixOSProcessAccessor you have #forwardSigInt to set a handler,
and #restoreSigInt to restore the signal handler to its default. After
it has been restored you can set it again.
> - If I have a process waiting on the semaphore, but the image quits
> for a different reason, I guess when it restarts, the process will
> still be there but the semaphore will be invalid??? what's a good way to
> handle that ?
The semaphore will be valid but will receive no signals from the VM.
When you restart the image, you will need to set your signal handlers
at that time. Most likely you will want to just start a new process,
perhaps in a #startUp: method.
Dave
_______________________________________________
Pharo-project mailing list
[email protected]
http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project
