[Yum] A couple of problems and RFE for Yum

[Michael Stenner]

On Tue, Oct 21, 2003 at 03:17:27PM -0400, seth vidal wrote:
> > That COULD be atomic, but it may or may not be worth it.  If I
> > understand correctly, you currently do this:
> > 
> > 1) write to .newheaders
> > 2) rename headers to .oldheaders
> > 3) rename .newheaders to headers
> > 
> > If you instead do
> > 
> > 1) write to .newheaders
> > 2) COPY headers to .oldheaders
> > 3) rename .newheaders to headers
> 
> the copy operation could take forever and a day is my concern.
> and in that time, depending on what changed on the repo, the headers are
> out of date to the rpms.

Yep... that's what I meant by heavy.

> > Then it should be atomic.  That's a significantly heavier operation,
> > though.
> 
> and you'd have to remove headers at some point. 

This discussion is only relevant when you're replacing a file with
another of the same name.

> > Another alternative is:
> > 
> > 1) write to .newheaders
> > 2) HARD LINK headers to .oldheaders
> > 3) rename .newheaders to headers
> > 
> > That's efficient, but requires hard links :)
> 
> which not all filesystems have, right.

I was never really _proposing_ these ideas.  I was simply pointing out
how it _could_ be done.  The goal was simply to list the options so
the tradeoffs would be clear.  I'm with you that the current solution
is probably the most sensible.

					-Michael
-- 
  Michael Stenner                       Office Phone: 919-660-2513
  Duke University, Dept. of Physics       mstenner at phy.duke.edu
  Box 90305, Durham N.C. 27708-0305