Re: [gentoo-dev] [PATCH 1/2] Introduce multibuild_merge_root() to merge interim installs.

[Alec Warner <antarus@gentoo.org>]

On Sat, Mar 23, 2013 at 9:26 AM, Michał Górny <mgorny@gentoo.org> wrote:
> This is mostly a copy from distutils-r1. The function does copy all the
> files from one location onto another, preserving whatever possible. It
> can be run in parallel too without the risk of race conditions.
> ---
>  gx86/eclass/distutils-r1.eclass | 41 +------------------------------------
>  gx86/eclass/multibuild.eclass   | 45 +++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 46 insertions(+), 40 deletions(-)
>
> diff --git a/gx86/eclass/distutils-r1.eclass b/gx86/eclass/distutils-r1.eclass
> index 0982e6c..3c21741 100644
> --- a/gx86/eclass/distutils-r1.eclass
> +++ b/gx86/eclass/distutils-r1.eclass
> @@ -449,49 +449,10 @@ distutils-r1_python_install() {
>
>         if [[ ! ${DISTUTILS_SINGLE_IMPL} ]]; then
>                 _distutils-r1_rename_scripts "${root}"
> -               _distutils-r1_merge_root "${root}" "${D}"
> +               multibuild_merge_root "${root}" "${D}"
>         fi
>  }
>
> -# @FUNCTION: distutils-r1_merge_root
> -# @USAGE: <src-root> <dest-root>
> -# @INTERNAL
> -# @DESCRIPTION:
> -# Merge the directory tree from <src-root> to <dest-root>, removing
> -# the <src-root> in the process.
> -_distutils-r1_merge_root() {
> -       local src=${1}
> -       local dest=${2}
> -
> -       local lockfile=${T}/distutils-r1-merge-lock
> -
> -       if type -P lockf &>/dev/null; then
> -               # On BSD, we have 'lockf' wrapper.
> -               tar -C "${src}" -f - -c . \
> -                       | lockf "${lockfile}" tar -x -f - -C "${dest}"
> -       else
> -               local lock_fd
> -               if type -P flock &>/dev/null; then
> -                       # On Linux, we have 'flock' which can lock fd.
> -                       redirect_alloc_fd lock_fd "${lockfile}" '>>'
> -                       flock ${lock_fd}
> -               else
> -                       ewarn "distutils-r1: no locking service found, please report."
> -               fi
> -
> -               cp -a -l -n "${src}"/. "${dest}"/
> -
> -               if [[ ${lock_fd} ]]; then
> -                       # Close the lock file when we are done with it.
> -                       # Prevents deadlock if we aren't in a subshell.
> -                       eval "exec ${lock_fd}>&-"
> -               fi
> -       fi
> -       [[ ${?} == 0 ]] || die "Merging ${EPYTHON} image failed."
> -
> -       rm -rf "${src}"
> -}
> -
>  # @FUNCTION: distutils-r1_python_install_all
>  # @DESCRIPTION:
>  # The default python_install_all(). It installs the documentation.
> diff --git a/gx86/eclass/multibuild.eclass b/gx86/eclass/multibuild.eclass
> index a3f1402..ed837d3 100644
> --- a/gx86/eclass/multibuild.eclass
> +++ b/gx86/eclass/multibuild.eclass
> @@ -238,5 +238,50 @@ run_in_build_dir() {
>         return ${ret}
>  }
>
> +# @FUNCTION: multibuild_merge_root
> +# @USAGE: <src-root> <dest-root>
> +# @DESCRIPTION:
> +# Merge the directory tree (fake root) from <src-root> to <dest-root>
> +# (the real root). Both directories have to be real, absolute paths
> +# (i.e. including ${D}). Source root will be removed.
> +#
> +# This functions uses locking to support merging during parallel
> +# installs.
> +multibuild_merge_root() {
> +       local src=${1}
> +       local dest=${2}
> +
> +       local lockfile=${T}/multibuild_merge_lock
> +
> +       if type -P lockf &>/dev/null; then
> +               # On BSD, we have 'lockf' wrapper.
> +               tar -C "${src}" -f - -c . \
> +                       | lockf "${lockfile}" tar -x -f - -C "${dest}"
> +       else
> +               local lock_fd
> +               if type -P flock &>/dev/null; then
> +                       # On Linux, we have 'flock' which can lock fd.
> +                       redirect_alloc_fd lock_fd "${lockfile}" '>>'
> +                       flock ${lock_fd}
> +               else
> +                       ewarn "multibuild: no locking service found, please report."
> +               fi
> +
> +               cp -a -l -n "${src}"/. "${dest}"/
> +
> +               if [[ ${lock_fd} ]]; then
> +                       # Close the lock file when we are done with it.
> +                       # Prevents deadlock if we aren't in a subshell.
> +                       eval "exec ${lock_fd}>&-"

Not following this bit.

The bash manpage says N>&DIGIT- redirects fd DIGIT to fd N. N may be
unspecified and defaults to 1.

It doesn't say what happens if DIGIT is unspecified. Nor does it say
it closes any file descriptors.

-A

> +               fi
> +       fi
> +
> +       if [[ ${?} -ne 0 ]]; then
> +               die "${MULTIBUILD_VARIANT:-(unknown)}: merging image failed."
> +       fi
> +
> +       rm -rf "${src}"
> +}
> +
>  _MULTIBUILD=1
>  fi
> --
> 1.8.1.5
>
>