Re: Safe file update library ready (sort of)
On Fri, Jan 28, 2011 at 07:37:02AM +0100, Olaf van der Spek wrote:
>
> Is there a way to log cases where (potentially) unsafe writes happen?
> Cases like truncation of an existing file, rename on a target that's
> not yet synced, etc.
Not really, because there are plenty of cases where it's perfectly OK
not to sync a file on close or on rename. Any files created during a
build, for example, can easily be reproduced in the unlikely case of a
systme crash. If you are untaring a source tree, it's fine not to
worry about syncing out the files, since presumably you can always
repeat the untar operation. Or take git; when git is checking out
files into the working directory, there's no reason that has to be
done in a super-safe way. On the other hand, when it is writing the
git object files and pack files, those had better be done safely. At
the end of the day the application programmer needs to understand what
is going on, and write his code appropriately based on the needs of
his application with respect to reliability after a power crash.
So how can you just log warnings that the program has just done
something unsafe? It's unsafe only if there's no other way to
reconstitute the data that was just written. But that's not something
which is easily knowable.
(I know, I'm being *so* unfair; I'm expecting application programmers
to be competent...)
- Ted
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