[Libguestfs] [PATCH] customize: random_seed: avoid one file checking for existing files

[Pino Toscano]

On Thursday 26 May 2016 15:23:53 Richard W.M. Jones wrote:
> On Thu, May 26, 2016 at 01:45:05PM +0200, Pino Toscano wrote:
> > When the random-seed file is found, then avoid checking its existance
> > again.
> > ---
> >  customize/random_seed.ml | 9 ++++++---
> >  1 file changed, 6 insertions(+), 3 deletions(-)
> > 
> > diff --git a/customize/random_seed.ml b/customize/random_seed.ml
> > index e4c955e..1633aed 100644
> > --- a/customize/random_seed.ml
> > +++ b/customize/random_seed.ml
> > @@ -35,7 +35,7 @@ let rec set_random_seed (g : Guestfs.guestfs) root =
> >      List.iter (
> >        fun file ->
> >          if g#is_file file then (
> > -          make_random_seed_file g file;
> > +          make_random_seed_file g file ~exists:true;
> >            created := true
> >          )
> >      ) files;
> > @@ -71,8 +71,11 @@ let rec set_random_seed (g : Guestfs.guestfs) root =
> >  
> >    !created
> >  
> > -and make_random_seed_file g file =
> > -  let file_exists = g#is_file file in
> > +and make_random_seed_file ?exists g file =
> > +  let file_exists =
> > +    match exists with
> > +    | None -> g#is_file file
> > +    | Some b -> b in
> >    let n =
> >      if file_exists then (
> >        let n = Int64.to_int (g#filesize file) in
> 
> Seems to be quite a detailed optimization, but sure, ACK.  What was
> the problem this was trying to address?

Not a problem at all -- while reading a verbose+trace log of
virt-customize, I noticed two g#is_file done (one right after the
other) for the existing random-seed file of the guest.

-- 
Pino Toscano
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