[with patch; positive review] notebook -- make it so when you send a kill signal to the notebook server it saves state

[was]

Kill signal does this

2008/03/01 01:10 -0500 [-] Received SIGTERM, shutting down.
2008/03/01 01:10 -0500 [-] (Port 8000 Closed)
2008/03/01 01:10 -0500 [-] Stopping factory <twisted.web2.channel.http.HTTPFactory instance at 0x2a41530>
2008/03/01 01:10 -0500 [-] Main loop terminated.
2008/03/01 01:10 -0500 [-] Server Shut Down.

Control C does this

2008/03/01 01:12 -0500 [-] (Notebook cleanly saved. Press control-C again to exit.)

We should change the notebook so it catches the kill and saves the notebook cleanly. I have no idea how to do this. Maybe some sort of "hook" into Twisted. If anybody knows twisted or reads the docs and figures this out, post here!

[jason]

The python atexit module might help here:

​http://docs.python.org/lib/module-atexit.html

[yi]

If you want to do things the twisted way, here is something that should work:

reactor.addSystemEventTrigger('before', 'shutdown', f)

f is a function you want to be called BEFORE the reactor shuts down. Here is some more documentation about how to properly use this feature:

​http://twistedmatrix.com/documents/current/api/twisted.internet.interfaces.IReactorCore.html#addSystemEventTrigger

Cheers, Yi

​http://yiqiang.org

[was]

The attached patch fixes the issues:

   1. I followed Yi's suggestion which worked like a charm.
   2. As a bonus I also fixed the "have to hit control-c twice to stop the notebook server" crap. Now
      it stops just fine with one single control-c.
   3. I changed twistd.pd to twistd.pid  -- it's a typo since it's supposed to be a pin id.

[yi]

A couple of comments:

1) As far as I can tell the last bit of the patch (involving polynomials) has nothing to do with this issue. Could you explain what that does?

2) Is save_notebook() only used on shutdown? Isn't it possible that in the future, someone would want to call save_notebook while the notebook is running? If that's true, you probably do not want to call reactor.stop() in save_notebook unless you're _certain_ that save_notebook() is the last thing you want to do.

Besides that this patch looks great!

[boothby]

Removed polynomial garbage

[boothby]

works for me -- I uploaded a cleaned up patch.

[mabshoff]

Merged in Sage 3.0.2.alpha1