On 23.01.2014 19:23, Kay Schenk wrote:
On Wed, Jan 22, 2014 at 5:32 AM, Andre Fischer <awf....@gmail.com> wrote:

Not quite a week ago I wrote about an idea to use XML files to store the
declarative part of our makefiles: dependencies of libraries on source
files, which resources are to be created and so on.  In the meantime I have
found the time to do make (conduct?) an experiment.  I am now able to build
module sw from the XML files with the help of the ninja build 'system' [3].
  Most of the work of converting the XML files into one single build.ninja
file was done on one weekend.  You can see the source code at [1] ([2]
contains everything zipped together).

I think link [2] needs to be:

[2] http://people.apache.org/~af/build.zip<http://people.apache.org/build.zip>

instead of --

  http://people.apache.org/build.zip <http://people.apache.org/build.zip>

Yes, thank you.


I am looking forward to checking this out.


Great, but please be aware that this is just an experiment. At the moment it only works on Windows.

-Andre






The results are promising.  It runs faster and the build.ninja generator
looks more maintainable than our solenv/gbuild/... makefiles.  But I am
certainly biased.
Before I give you some numbers, I should say that I have collected the
numbers totally unscientifically and it may be necessary to add some
missing steps to the ninja build.  To the best of my knowledge all C++
files are compiled, libraries linked, resource files built, XML files
copied.  Only the single sw.component file somehow escaped.

I ran my experiments on ani7 2.2GHz, 8GB notebook.

Complete build of a clean module:
     gbuild about 9m30s         (make -sr -j8)
     ninja  about 7m15s         (ninja)

Cleaning up
     gbuild about 40s           (make clean)
     ninja  less then 1s        (ninja -t clean)

rebuild after touching one single header (sw/inc/section.hxx)
     gbuild about 1m10s         (make -sr -j8)
     ninja about    50s         (ninja)

Building an already built module (nothing to do): depends very much on
whether the disk cache is warm or cold.  Best times:
     gbuild   more than 3s (make -sr -j8)
     ninja    about     0.4s    (ninja)


Why is ninja faster than make/gbuild?
- Make runs each recipe in its own shell (bash), ninja executes its
command directly.
- Ninja understands the header dependencies created by gxx/clang and msvc
and stores them in a compact format that can be read in very fast on
startup.
- I avoided some steps of build that are unnecessary in ninja
   = Ninja creates directories for the targets it makes.  Gbuild creates
them explicitly.
   = GBuild first creates empty dependency files and later, in a second
step, fills them with the actual dependency information created by one of
the C/C++ compilers.


But, for me, these numbers are just a welcome side effect.  More important
to me is maintainability.
Ninja follows a very different approach from (GNU) make.  Its lack of even
simplest control structures such as if/then/else or foreach, requires the
generation of the main makefile (by default that is called build.ninja) by
program or script.  This leads to my current approach:
- Use XML to represent the static data (C++ files, libraries, resource
files, XML files).
- Use a Perl script to translate the XML files into the build.ninja file.
The best tool for each job (XML: data representation, Perl: data
processing).  Instead of Perl we could use any language that is part of our
current build requirements (Java, C/C++, Python (we would have to compile
that first, though)).  Look at the Perl files in [1] or [2]
(build/source/ninja/*pm) and compare them to solenv/gbuild/*mk and see
which you can understand better.


I think this could be one way to set up a better maintainable build system
that is even slightly faster then what we currently have.

Best regards,
Andre


[1] http://people.apache.org/~af/build/
[2] http://people.apache.org/build.zip
[3] http://martine.github.io/ninja/manual.html


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