[DGD] Object upgrading

[bart at wotf.org]

On Wed, 4 Jul 2018 00:36:32 -0700, Raymond Jennings wrote

> Nope, but the recompilation that triggers the code replacement and
> queues up the patching process also necessitates the sandboxable
> upgrade() call.
> 
> Two separate jobs depending on the same recompile.
> 
> > > This is how it works in kotaka
> >
> > Very similar in concept to how it workd on some other libs but different from
> > what I would expect in one specific detail, the moment where you 'suspend'. I
> > did not read anything in your explanation suggesting that cannot start a bit
> > earlier, only that it should not start later.
> 
> The suspension's side effects only matter once the task invoking it
> completes, since DGD is single threaded (at least from the POV of
> LPC).

But if you start a call_out after the recompile completes, but without
suspending the system, a user action or other pending call_out might fire
before your 'upgrade' call_out fires. So, something could come inbetween
unless you make sure this doesn't happen by suspending everything except for
that one call_out.

> 
> I just personally prefer to defer the suspension until the call_out
> for passing along the call to upgrade is completed.  Technically it
> can be done at any time.

technically it should happen before the task which does the recompile
completes and returns control to dgd. The exact moment within that task
doesn't matter indeed. As I understand from your description of the process
this is indeed the case with your codebase.

Bart.
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