- This document attempts to outline the libvirt project strategy for - the near future. Think of this as a high level vision or to-do list - setting the direction for the project and its developers to take. -
- -- At time of writing libvirt uses the following languages: -
- -- The wide range of languages used present a knowledge burden for - developers involved in libvirt, especially when there are multiple - languages all used in the same problem spaces. This is most notable - in the build system which uses a combination of Meson, shell, awk, - sed, Perl and Python, with debugging requiring - understanding of the interactions between many languages. The - popularity of Perl has declined, while Python has become - more popular. This directly influences the amount and quality of - contributions that can be expected for programs written in the - respective languages. -
-- The C language has served libvirt well over the years, but its age shows - giving rise to limitations which negatively impact the project in terms - of code quality, reliability, and efficiency of development. Most notably - its lack of memory safety means that many code bugs become trivially - exploitable security flaws or denial of service. The lack of a high - level portable runtime results in a lot of effort being spent to - ensure cross platform portability. The modern languages Rust and Go - provide viable options for low level systems programming, in a way that - is not practical with other common languages such as Python and Java. - There is thus a desire to make use of either Rust or Go, or a combination - of both, to incrementally replace existing use of C, and also for - greenfield development. -
-- With this in mind the libvirt project has set a vision for language - usage in the future: -
- -- Some notable points from the above. Whether the core library / daemons - will use Rust or Go internally is still to be decided based on more - detailed evaluation to identify the best fit. The need to link and embed - this functionality in other processes has complex interactions both at a - technical and non-technical level. For standalone helper tools, either - language is viable, but there are fewer concerns around interactions with - other in-process code from 3rd parties. Thus a different decision may be - made for daemons/libraries vs tools. Any rewrite proposed for existing - functionality will have to weigh up the benefits of the new code, - against the risk of introducing regressions with respect to the previous - code. -
- -- Using the RST format for documentation allows for the use of XSLT to be - eliminated from the build process. RST and the Sphinx toolkit are widely - used, as seen by the huge repository of content on - Read The Docs. - The ability to embed raw HTML in the RST docs will greatly facilitate its - adoption, avoiding the need for a big bang conversion of existing content. - Given the desire to eliminate Perl usage, replacing the use of POD - documentation for manual pages is an obvious followup task. RST is the - obvious choice to achieve alignment with the website, allowing the man - pages to be easily published online with other docs. It is further - anticipated that the current API docs generator which uses XSLT to - convert the XML API description would be converted to something which - generates RST using Python instead of XSLT. -
- - diff --git a/docs/strategy.rst b/docs/strategy.rst new file mode 100644 index 0000000000..093764b645 --- /dev/null +++ b/docs/strategy.rst @@ -0,0 +1,105 @@ +================ +Project Strategy +================ + +This document attempts to outline the libvirt project strategy for the near +future. Think of this as a high level vision or to-do list setting the direction +for the project and its developers to take. + +Language consolidation +---------------------- + +At time of writing libvirt uses the following languages: + +C + The core libvirt library, daemons, and helper tools are all written in the C + language. +Python + Various supporting build/test scripts are written in Python, with + compatibility for Python 3. +Perl + Various supporting build/test scripts are written in Perl. It is also used + for many syntax-check inline rules +Shell + Shell is used for some simple build/test scripts. At runtime libvirt avoids + shell except when using SSH tunnels to a remote host +XSLT + The website uses XSLT for its templating system. The API documentation is + also autogenerated from an XML description using XSLT +HTML + The website documentation is all written in plain HTML. Some HTML is also + auto-generated for API documentation +Meson + The core build system uses the new Meson build system +make + The syntax-check uses make recipes +awk/sed + A number of the syntax-check inline rules involve use of awk/sed scripts +POD + The command line manual pages are typically written in Perl's POD format, and + converted to troff + +The wide range of languages used present a knowledge burden for developers +involved in libvirt, especially when there are multiple languages all used in +the same problem spaces. This is most notable in the build system which uses a +combination of Meson, shell, awk, sed, Perl and Python, with debugging requiring +understanding of the interactions between many languages. The popularity of Perl +has declined, while Python has become more popular. This directly influences the +amount and quality of contributions that can be expected for programs written in +the respective languages. + +The C language has served libvirt well over the years, but its age shows giving +rise to limitations which negatively impact the project in terms of code +quality, reliability, and efficiency of development. Most notably its lack of +memory safety means that many code bugs become trivially exploitable security +flaws or denial of service. The lack of a high level portable runtime results in +a lot of effort being spent to ensure cross platform portability. The modern +languages Rust and Go provide viable options for low level systems programming, +in a way that is not practical with other common languages such as Python and +Java. There is thus a desire to make use of either Rust or Go, or a combination +of both, to incrementally replace existing use of C, and also for greenfield +development. + +With this in mind the libvirt project has set a vision for language usage in the +future: + +C + Large parts of the core libvirt library, daemons, and helper tools will + continue to make use in the C language. Integration of other languages will + be an incremental, targeted process where they can bring the greatest + benefit. +Rust / Go + Parts of the core libvirt library, daemons and helper tools are to leverage + Rust or Go or both to replace C. +Meson + The core build system is to be written in Meson. +Python + Various supporting build/test scripts are written in Python 3 compatible mode + only. +reStructuredText + The website and command man pages are to be written in RST, using Sphinx as + the engine to convert to end user formats like HTML, troff, etc + +Some notable points from the above. Whether the core library / daemons will use +Rust or Go internally is still to be decided based on more detailed evaluation +to identify the best fit. The need to link and embed this functionality in other +processes has complex interactions both at a technical and non-technical level. +For standalone helper tools, either language is viable, but there are fewer +concerns around interactions with other in-process code from 3rd parties. Thus a +different decision may be made for daemons/libraries vs tools. Any rewrite +proposed for existing functionality will have to weigh up the benefits of the +new code, against the risk of introducing regressions with respect to the +previous code. + +Using the RST format for documentation allows for the use of XSLT to be +eliminated from the build process. RST and the Sphinx toolkit are widely used, +as seen by the huge repository of content on `Read The +Docs