[SAGA-RG] missing(?) method reporting last modification time

[Thilo Kielmann]

Folks,

within our group we are currently delving into issues with accessing
remote file systems. What strikes us is that such access is SLOW.
As such, it would be very beneficial if one could find out when (and
thus whether) a remote file or directory has been modified.

While returning this piece of information sounds to be "trivial", it strikes
us that the SAGA spec has no such call in the name space package (where files
reside).

In POSIX terms, this is the info returned by the stat system call
(see: man 2 stat), with the st_mtime parameter.

In Java, files have a method lastmodified().

Both POSIX and Java report the time in milliseconds since 01/01/1970 (epoch).


Of course, it looks like nobody has ever been thinking about such a use case,
but here we are! Our feeling is that the last modification time is very
essential meta data about files, so such a call should certainly be there.
With our current problem certainly not being the only use case for finding
out how old/new a given file or directory is...

Our favourite proposal is to add a method that returns the last modification
time to both ns_entry and ns_directory as this makes sense with physical as 
well as with logical (replicated) files.


Any reactions/objections ???


Thilo Kielmann
-- 
Thilo Kielmann                                 http://www.cs.vu.nl/~kielmann/