Re: Idea for reducing disk IO on tagging operations

[Dr. David Alan Gilbert]

* Jim Hyslop (address@hidden) wrote:
> Dr. David Alan Gilbert wrote:
> >  2) I could do with a better under standing of the directory locks;
> >  pointers? I've read the top of lock.c but it still doesn't tell me
> >  enough; for example there seem to be multiple lock files used - but
> >  then surely the creation of them isn't atomic? Or is there one lock
> >  file used for both reading and writing?
> The locking process is explained in the manual, at 
> https://www.cvshome.org/docs/manual/cvs-1.11.19/cvs_2.html#SEC17

Thanks Jim for pointing me at that (I'd had a good search through
the FAQ rather than the manual....).

(and to Paul - apologies if I misquoted in that last email)

OK; this convinces me that I don't need to worry about cvs reading
my file while it is being modified.  Together with the restriction
of me only performing my trick if the write is entirely within
a block then I feel reasonably safe.

I'm going to have a crack at making this optimisation and will
forward a copy here for discussion when I've done it.

Dave
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