[KCP] Thoughts on adding system changes and refactoring ChangeSet

Avi Bryant avi at beta4.com
Tue Jun 24 19:05:34 UTC 2003


On Tue, 24 Jun 2003, Andreas Raab wrote:

> > I managed to hose an image by installing a client that
> > caused a MNU error after method compilation, but before
> > the installation of the compiled method. It may be that
> > all I needed was to evaluate the action with an ensure:
> > block, but I'm not sure that's bulletproof.
>
> It's definitely not bullet-proof as it may open a debugger (and at this
> point it can be too late already). If you handle the errors silently (e.g.,
> using some catch-all rule) you _may_ be better off but it's still a hard
> problem as things may screw up while the callback is completing (in
> particular if there has been some error along the way). Most code in this
> area is written under the assumption of being run atomically so whatever
> hooks in there can cause some severe problems.

But Roel was using exactly this example as to why the currently available
notifications were problematic - they sometimes happen halfway through the
process.  Since his notifications will always fire only once the atomic
operation has completed, it should be much harder to thoroughly hose an
image, right?



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