thumbnail mtime, ctime

Dr. Michael J. Chudobiak mjc at
Thu Mar 27 12:02:25 PDT 2008

Hi all,

The thumbnail spec requires the embedding of mtime (with 1 second 
resolution), and the use of mtime as the change-detection parameter.

Unfortunately, the 1-second resolution causes problems sometimes (a file 
can change twice in a second!), and the use of mtime means that 
permissions changes do not trigger a re-thumbnailing. Both of these are 
"real" issues that do occur.

This could be fixed by embedding:

mtime (in seconds - existing method)

and optionally adding

mtime (the microsecond remainder)
ctime (in seconds)
ctime (the microsecond remainder)

Older apps would continue to judge thumbnail freshness based solely on 
mtime in seconds. Newer apps could use the additional parameters (if 
present) to validate a thumbnail more rigorously. There would be no 
significant compatibility or performance issues.

Gnome at least has no UI-based method of fixing broken thumbnails caused 
by the above issues (you have to rm ~/.thumbnails), and the new 
GFileInfo api provides easy access to the microsecond data.

Any reason we shouldn't add this to the standard?

- Mike

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