Hi Thomas, Hi Max,
On Thu, Mar 21, 2019 at 3:35 AM Max Leske <[email protected]> wrote:
> On 21 Mar 2019, at 11:06, Thomas Dupriez wrote:
>
> Hi Thomas,
>
> > Hello,
> >
> > While looking at the DebugSession>>isContextPostMortem: method (code
> > below), I got three questions:
> >
> > 1) There is a check for whether the suspendedContext (top context) of
> > the process is nil. Does it even make sense for a process not to have
> > any top context?
>
> Yes, only suspended processes have a suspendedContext. Also, the process
> might have been terminated already.
>
> >
> > 2) It seems that all the last 3 lines are doing is to check whether
> > selectedContext is in the context chain of the process. Could they be
> > rewritten into this simpler one-liner? `|^ (suspendedContext
> > hasContext: selectedContext) not`|
>
> Yes, I think that would work.
>
> >
> > 3) Overall, this method says that a context C is "post mortem" if the
> > process controlled by the DebugSession has a top context and C is not
> > in its context chain. That's the practical definition. Could someone
> > shed some light on the high-level definition of "post mortem"? Because
> > "post mortem" is like "after death", but the death of what? A context
> > that merely belongs to another context chain would be considered "post
> > mortem" by the practical definition, but there's no death in this
> > case...
> > ||
> >
>
> You can create a copy of a process' stack. That stack will behave like a
> process in the debugger but it can't run, as the VM doesn't have a
> process to which the context are attached, hence it's considered
> post-mortem.
>
> >
> > ```
> >
> > |DebugSession>>isContextPostMortem: selectedContext "return whether
> > we're inspecting a frozen exception without a process attached" |
> > suspendedContext | suspendedContext := interruptedProcess
> > suspendedContext. suspendedContext ifNil: [ ^ false ].
> > (suspendedContext == selectedContext) ifTrue: [ ^ false ]. ^
> > (suspendedContext findContextSuchThat: [:c | c sender ==
> > selectedContext]) isNil ``` |
>
In addition a context is post-mortem if its pc is nil, which at least in
Squeak is answered by the Context>>isDead method. So I might look at
writing that method as
DebugSession>>isContextPostMortem: selectedContext
"Answer if we're inspecting a frozen exception without a process
attached."
^selectedContext isDead
or: [(interruptedProcess suspendedContext hasContext:
selectedContext) not]
> >
> > Does someone know the answer to some (or all) of these questions?
> >
> > Thomas
>
>
> Hope that helps.
>
> Max
>
>
--
_,,,^..^,,,_
best, Eliot
