332218 - Stop processing on instance load error

Status: RESOLVED FIXED

(Core Graveyard :: XForms, defect)

Description

[Allan Beaufour]

If an instance fails to load we just keep on trucking. That's wrong. The spec. says:
"If the link traversal fails, it is treated as an exception (4.5.2 The xforms-link-exception Event)."
[http://www.w3.org/TR/2006/REC-xforms-20060314/slice3.html#structure-model-instance]
So, xforms-link-exception and handleFatalError().

Comment 1

[Allan Beaufour]

Attachment: Testcase

Comment 2

[Allan Beaufour]

Attachment: Patch

This stops processing. I've seen some crashes on trunk, if we do not do this because of some assumptions in other code I think.

It still needs to dispatch the events here.

Comment 3

[Allan Beaufour]

Comment on attachment 216741 [details] [diff] [review]
Patch

I'm blind. It does dispatch the event.

Comment 4

[Olli Pettay [:smaug][[e-mail]]]

Why do you need to move --mPendingInstanceCount ?
If there is an error, doesn't that mean that mPendingInstanceCount will have a wrong value?

Comment 5

[Allan Beaufour]

(In reply to comment #4)
> Why do you need to move --mPendingInstanceCount ?
> If there is an error, doesn't that mean that mPendingInstanceCount will have a
> wrong value?

Yes, and we will not finish model construction, which is what we need to do, because it is a fatal error.

Comment 6

[Olli Pettay [:smaug][[e-mail]]]

Comment on attachment 216741 [details] [diff] [review]
Patch

Ok. Makes sense in this case, I think.

Comment 7

[aaronr]

Comment on attachment 216741 [details] [diff] [review]
Patch

Well, I'd like to discuss this scenario:  What if the author decided to handle xforms-link-exceptions and start changing the instance's @src looking for a server that can serve the instance data.  Perhaps they work in an environment where they have some flakey servers that go up and down a lot, for example.  Do we want to support this scenario?  Where if the author does find a good one that the instance will load and the processor will finish its normal load processing?  Or once we have a fatal exception, is that it (uncorrectable by script)?

Comment 8

[Allan Beaufour]

(In reply to comment #7)
> (From update of attachment 216741 [details] [diff] [review] [edit])
> Well, I'd like to discuss this scenario:  What if the author decided to handle
> xforms-link-exceptions and start changing the instance's @src looking for a
> server that can serve the instance data.  Perhaps they work in an environment
> where they have some flakey servers that go up and down a lot, for example.  Do
> we want to support this scenario?  Where if the author does find a good one
> that the instance will load and the processor will finish its normal load
> processing?  Or once we have a fatal exception, is that it (uncorrectable by
> script)?

That's how I've always interpreted fatal errors: End of story, the processor gives up.

Comment 9

[aaronr]

Comment on attachment 216741 [details] [diff] [review]
Patch

ok, I'm fine with that.  nit: maybe add a comment above mPendingInstanceCount pointing out that in an error we are leaving mPendingInstanceCount > 0 on purpose and why we are doing that (to halt load processing).  Just so that one of us yahoos doesn't try to change it sometime in the future.

with that r=me

Comment 10

[Allan Beaufour]

Attachment: Checked-in version

Comment 11

[Allan Beaufour]

Fixed on trunk