SqueakMap issues (was Re: Squeak map colours)

goran at krampe.se goran at krampe.se
Wed Sep 27 07:35:00 UTC 2006


Hi Lex!

Lex Spoon <lex at cc.gatech.edu> wrote:
> goran at krampe.se writes:
> > Yes, this is an unfortunate situation that I need to go through. The
> > problem is that after I introduced the server side cache and SHA
> > checksumming apparently lots of releases either were non-available at
> > the time I initially populated the cache (which lead to crap files in
> > the server cache, and to make things worse - crappy checksums!) OR have
> > been unavailable when releases have been registered. I think.
> 
> I run into this as well if SqueakMap downloads while the network is
> unavailable.  It saves to the file an error message, and so of course
> its checksum is wrong.  So, the tool could be more careful about
> checking that the HTTP request worked, before saving the file.

Ah. Yes... I will take a look (if I remember :)).
 
> Recursive delete on the SqueakMap directories works fine in this case.
> You can then restart SqueakMap and it will repopulate its directories
> from the network.

Right, but this is the client side cache you are talking about (just so
other non familiar readers follow).

> I also ran into this when I tried to update the URL of a released
> SqueakMap version.  Maybe this is more in the line of what you discuss
> with bad cached information on the server.  I ended up bumping the
> version number even though the actual file content had not changed.

IIRC the current logic is that when the URL of a release is modified -
it will repopulate the server side cache and update the checksum,
Was that what you tried to do? Because I thought that worked.

But just so that any confused reader understand - if the SM server at
that time downloads a "faulty" file - like say an HTTP error message
instead of a sar-file - then from that moment it will end up being very
inhelpful thinking that any subsequent correct download is in fact bad
(checksum fails) and it will fall back on downloading the faulty file
from the server side cache.

I can't come up with an easy way to sweep and fix this. Any bright
ideas? Except for adding tons of sanity checks on received data - which
on the other hand might not be that hard - recognizing our most popular
formats might be enough.

regards. Göran



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