Re: [PATCH] deb-dl-dir class rework to use faster ln -P or fallback to cp

["Roberto A. Foglietta" <roberto.foglietta@gmail.com>]

On Tue, 7 Feb 2023 at 07:32, Uladzimir Bely <ubely@ilbers.de> wrote:
>
> In the email from понедельник, 6 февраля 2023 г. 16:09:19 +03 user
> roberto.foglietta@linuxteam.org wrote:
> > From: "Roberto A. Foglietta" <roberto.foglietta@gmail.com>
> >
> > deb-dl-dir, feature: faster when using ln -P otherwise fallback to cp
> >
> > The original class functions deb_dl_dir_import/export were using cp to
> > copy debian package to the target rootfs but this approach is quite slow
> > while using hard link does not work if the destination and source dirs
> > are not lying on the same filesystem. Thus, ln -P should fallback to cp
> > when it does not work (which is different from complaining on stderr).
> >
> > Moreover, these two functions have been reworked to reach a straight
> > forward and more compact form. In particular, export function was using
> > bashism to do some kind of comparison which after all is useless
> > because copying back without overwriting just fulfills that part.
> >
> > Signed-off-by: Roberto A. Foglietta <roberto.foglietta@gmail.com>
> > ---
> >  meta/classes/deb-dl-dir.bbclass | 41 ++++++++++++++++++---------------
> >  1 file changed, 23 insertions(+), 18 deletions(-)
> >
> > diff --git a/meta/classes/deb-dl-dir.bbclass
> > b/meta/classes/deb-dl-dir.bbclass index 3b1517dc..22de7bf6 100644
> > --- a/meta/classes/deb-dl-dir.bbclass
> > +++ b/meta/classes/deb-dl-dir.bbclass
> > @@ -78,39 +78,44 @@ debsrc_download() {
> >
> >  deb_dl_dir_import() {
> >      export pc="${DEBDIR}/${2}"
> > -    export rootfs="${1}"
> > -    sudo mkdir -p "${rootfs}"/var/cache/apt/archives/
> > +    export sc="${1}/var/cache/apt/archives/"
> > +    sudo mkdir -p "${sc}"
> >      [ ! -d "${pc}" ] && return 0
> > +    export tf=$(ls -1 "${pc}"/*.deb | head -n1)
> > +    [ ! -e "${tf}" ] && return 0
> >      flock -s "${pc}".lock -c '
> >          set -e
> >          printenv | grep -q BB_VERBOSE_LOGS && set -x
> >
> > -        sudo find "${pc}" -type f -iname "*\.deb" -exec \
> > -            cp -n --no-preserve=owner -t
> > "${rootfs}"/var/cache/apt/archives/ {} + +        sudo ln -Pf -t "${sc}"
> > "${tf}" 2>/dev/null ||:
>
> I'm not sure that assumption "if one hardlink failed, other also will fail"
> (and vice versa) would always be true.

Yes, it is true. If further failures happen it is not because of the
destination/source nature. Instead of the opposite, the return code
does not always lead to a failure in a way we suppose.

Best regards, R-