Libguestfs - May 2016 - Re: [PATCH] customize: random_seed: avoid one file checking for existing files

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
-- 
2.5.5

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?

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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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