[stellation-res] Recognizing changed files

["Jonathan Gossage" <jgossage@xxxxxxxx>]

I think I may have found another Windows related problem. Currently as I
understand it, you detect that
a file has changed outside of Stellation by checking the timestamp of the
file against the timestamp recorded for the file when it was last checked
out and assuming it has been modified if the timestamp of the file is more
recent than the base. Unforetunately there are a number of cases in Windows
that break that assumption.

In particular, whenever you use any of the Windows command line file copy
commands or if you use Windows Explorer to copy a file, the copy operation
preserves both the attributes and the timestamp of the original file. Thus
if you replace a file in a repository with another file with an earlier
timestamp you will not reognize that the file has changed when a checkin
command has been issued. What's more, in fact, given this scenario, you
delete the apparently older file from the workspace.

This problem is at the root of all the queer behaviour I am currently
observing while trying to test MySQL. A clean solution will take a bit of
thought. One possible solution which would cover all scenarios on both
Windows and UNIX would be to compute a hash for each file when it is checked
out and store this hash in the project data. Then if the timestamp has
changed in any way, compute the hash again on the same file and see if they
are the same. If they are, the file can be treated as unchanged and the
timestamp adjusted appropriately. The major problem with this approach is
that it is somewhat resource intensive.

Regards

Jonathan Gossage

Personal Email
jgossage@xxxxxxxx

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