Re: [gentoo-dev] Support for multiple ABIs (for Python modules etc.)

[Arfrever Frehtes Taifersar Arahesis]

2009-07-25 12:28:44 Arfrever Frehtes Taifersar Arahesis napisał(a):
> I would like to present the plan of support for multiple ABIs. It should be sufficient for
> Python modules and might be also appropriate for some other ABI types (e.g. for Ruby modules).
>
> 1. Portage will support repository-specific, profile-independent ${REPOSITORY}/profiles/settings
> configuration files (filename can be changed). They will set some variables (similarly to
> make.defaults files). These variables shouldn't be overrideable by profiles, eclasses, ebuilds
> or by user's configuration files (e.g. /etc/portage/*). For future compatibility these files
> could also support lists/indexed arrays and dictionaries/associative arrays/maps.
>
> 2. ${REPOSITORY}/profiles/settings will set ABI_TYPES and ${ABI_TYPE^^}_ABI_SUPPORTED_VALUES variables.
> ABI_TYPES defines supported ABI types. ${ABI_TYPE^^}_ABI_SUPPORTED_VALUES defines supported ABIs
> for given ABI type.
>
>   Example (${REPOSITORY}/profiles/settings):
>     ABI_TYPES="python ruby ..."
>     PYTHON_ABI_SUPPORTED_VALUES="2.4 2.5 2.6 3.0 3.1"
>     RUBY_ABI_SUPPORTED_VALUES="1.8 1.9"
>
> 3. make.defaults files will support ${ABI_TYPE^^}_ABI_FORCED_VALUES/${ABI_TYPE^^}_ABI_MASKED_VALUES
> variables to force/mask specific ABIs in given profiles.
>
>   Example (make.defaults):
>     PYTHON_ABI_MASKED_VALUES="2.4 2.5"
>     PYTHON_ABI_FORCED_VALUES="3.1"
>
> 4. For convenience of developers ABI dependencies will be able to be specified in explicit and
> slightly implicit way. Ebuilds/eclasses, which support multiple ABIs, will set USED_ABI_TYPES.
> Ebuilds/eclasses will be able to set RESTRICT_${ABI_TYPE^^}_ABIS variables which will support
> '*' wildcard. USED_ABI_TYPES and RESTRICT_${ABI_TYPE^^}_ABIS variables should be cumulative
> (across eclasses and ebuild).
>
>   Example (ebuild):
>     USED_ABI_TYPES="python"
>     # This package doesn't work yet with Python 2.6 and 3.*
>     RESTRICT_PYTHON_ABIS="2.6 3*"
>
> 4.1. Implicitly specified ABI dependencies. During calculation of dependencies of given package,
> Portage will verify if all dependencies, which use given ABI type, have been built with enabled
> support for these ABIs, which are enabled for given package.
>
>   Example (ebuild):
>     # dev-python/bsddb3
>     USED_ABI_TYPES="python"
>     RDEPEND=">=sys-libs/db-4.6"
>     DEPEND="${RDEPEND}
>         dev-python/setuptools
>         doc? ( dev-python/sphinx )"
>
>     Assuming that dev-python/setuptools and dev-python/sphinx set USED_ABI_TYPES="python",
>     Portage will verify that, when user runs `USE_PYTHON="2.5 2.6" emerge dev-python/bsddb3`,
>     dev-python/setuptools and dev-python/sphinx (when USE="doc" is enabled) are built with
>     enabled support for at least "2.5" and "2.6" Python ABIs. If they are already installed
>     without support for e.g. "2.5" Python ABI, Portage will print appropriate error message
>     (similarly to unsatisfied USE dependencies) and exit.
>
> 4.2. Explicitly specified ABI dependencies. {,P,R}DEPEND variables will support specifying
> ABI dependencies in explicit way. {,P,R}DEPEND variables will also support ABI conditionals.
> I suggest using {ABI_type[comma-delimited values]} syntax, but it can be changed.
>
>   Example (ebuild):
>     DEPEND="category/package1{python[2.5,2.6],ruby[-1.8]}"
>     RDEPEND="{python[2.6]}? ( category/package2 )
>
>   Example (python.eclass):
>     DEPEND="
>         {python[2.4]}? ( dev-lang/python:2.4 )
>         {python[2.5]}? ( dev-lang/python:2.5 )
>         {python[2.6]}? ( dev-lang/python:2.6 )
>         {python[3.0]}? ( dev-lang/python:3.0 )
>         {python[3.1]}? ( dev-lang/python:3.1 )
>     "
>     RDEPEND="${RDEPEND}"
>
> 5. 18th line of metadata cache files will contain the list of ABI types and values supported
> (i.e. not restricted by RESTRICT_${ABI_TYPE^^}_ABIS variables) by given package.
>
>   Example (18th line of metadata cache file):
>     python[2.5,2.6,3.0,3.1] ruby[1.8,1.9]
>
> Every change to ${REPOSITORY}/profiles/settings should probably invalidate whole metadata
> cache of given repository.
>
> 6. Portage will support USE_${ABI_TYPE^^} variables in /etc/make.conf to specify which ABIs
> should be enabled.

Portage will also allow to set USE_${ABI_TYPE^^} variables per-package etc.

>
>   Example (/etc/make.conf):
>     USE_PYTHON="2.5 2.6 3.1"
>     USE_RUBY="1.8 1.9"
>
> 7. Portage will set ${ABI_TYPE^^}_ABIS variables in ebuild environment. ${ABI_TYPE^^}_ABIS
> should contain ABIs forced by ${ABI_TYPE^^}_ABI_FORCED_VALUES and these ABIs enabled by user
> in /etc/make.conf by USE_${ABI_TYPE^^} which aren't masked by ${ABI_TYPE^^}_ABI_MASKED_VALUES.

${ABI_TYPE^^}_ABIS variables won't contain ABIs restricted by RESTRICT_${ABI_TYPE^^}_ABIS
variables. Eclasses/ebuilds will be able to change the values of ${ABI_TYPE^^}_ABIS variables
in ebuild phases. For example python.eclass will support ignoring of build failures for Python
ABIs specified by user in FAILURE_TOLERANT_PYTHON_ABIS variable. Python ABIs, for which
building has failed, would be removed from PYTHON_ABIS variable.

>
>   Example (ebuild):
>     src_compile() {
>         for abi in ${PYTHON_ABIS}; do
>             emake PYTHON=$(get_PYTHON ${abi})
>         done
>     }
>
> Ebuilds/eclasses should implicitly enable support for one ("default") ABI, when user hasn't
> set appropriate USE_${ABI_TYPE^^} variable. For example Python modules would use ABI of
> /usr/bin/python.
>
> 8. Portage will store the list of supported ABIs in /var/db/pkg/${CATEGORY}/${PF}/SUPPORTED_ABIS
> and the list of enabled ABIs in /var/db/pkg/${CATEGORY}/${PF}/ABIS.

The list of enabled ABIs in /var/db/pkg/${CATEGORY}/${PF}/ABIS will depend on final values of
${ABI_TYPE^^}_ABIS variables after installation.

>
>   Example (/var/db/pkg/${CATEGORY}/${PF}/SUPPORTED_ABIS):
>     python[2.4,2.5,2.6,3.0,3.1] ruby[1.8,1.9]
>
>   Example (/var/db/pkg/${CATEGORY}/${PF}/ABIS):
>     python[2.6,3.1] ruby[1.9]
>
> Names/syntax of specific variables etc. can be changed. Please write constructive comments.

-- 
Arfrever Frehtes Taifersar Arahesis