[libvirt PATCH 342/351] meson: add syntax-check

[Pavel Hrdina]

On Tue, Jul 28, 2020 at 04:19:56PM +0200, Peter Krempa wrote:
> On Tue, Jul 28, 2020 at 15:08:11 +0100, Daniel Berrange wrote:
> > On Tue, Jul 28, 2020 at 04:04:39PM +0200, Pavel Hrdina wrote:
> > > On Tue, Jul 28, 2020 at 03:48:29PM +0200, Peter Krempa wrote:
> > > > On Thu, Jul 16, 2020 at 11:59:38 +0200, Pavel Hrdina wrote:
> > > > > Signed-off-by: Pavel Hrdina <phrdina at redhat.com>
> > > > > ---
> > > > >  build-aux/Makefile.in                         |  9 +++
> > > > >  .../Makefile.nonreentrant                     |  0
> > > > >  build-aux/meson.build                         | 30 +++++++++
> > > > >  build-aux/syntax-check.mk                     | 62 +++++++++----------
> > > > >  meson.build                                   |  2 +
> > > > >  5 files changed, 72 insertions(+), 31 deletions(-)
> > > > >  create mode 100644 build-aux/Makefile.in
> > > > >  rename Makefile.nonreentrant => build-aux/Makefile.nonreentrant (100%)
> > > > >  create mode 100644 build-aux/meson.build
> > > > 
> > > > [...]
> > > > 
> > > > > +make_prog = find_program('make')
> > > > > +
> > > > > +# There is no way how to pass value to -j using run_target so let's use
> > > > > +# it without any value to run all tests in parallel.
> > > > > +run_target(
> > > > > +  'syntax-check',
> > > > > +  command: [
> > > > > +    make_prog, '-C', meson.current_build_dir(), '-j', 'syntax-check',
> > > > > +  ],
> > > > 
> > > > While I do run syntax check with unlimited '-j'. I don't think it's
> > > > entirely cool to impose that on everybody. Specifically overcommiting
> > > > the system is not cool. Since meson is automagically scaling can't we
> > > > use the meson-detected cpu number here?
> > > 
> > > Unfortunately no, that was the first thing I was trying to figure out
> > > by going through meson code as well. It's not ideal I know.
> > > 
> > > Other options are to not use -j at all which is no-go or we can add some
> > > code to detect the available number of CPUs. But again it would not
> > > reflect the fact if user runs 'ninja -j N'.
> > 
> > In libosinfo we put "syntax-check" as part of the unit tests, rather
> > than as a separate meson target. With that you don't need to pass
> > -j to syntax-check, because other unit tests are running in parallel
> > already, and chances are syntax-check will finish first even when
> > serialized.
> 
> Unfortunately it's not even close.
> 
> Serialized syntax-check:
> real	0m22.139s
> user	0m24.209s
> sys	0m6.788s
> 
> test suite:
> real	0m4.833s
> user	0m12.408s
> sys	0m3.918s
> 
> syntax-check with -j == ncpus: (24 thread box)
> 
> real	0m2.099s
> user	0m28.558s
> sys	0m7.739s
> 
> 
> As said, I'm a big fan of -jncpus or -j. so I really want to keep it
> especially given the data above, but on the other hand I don't want to
> set the CI boxes on fire.

So I was trying to figure out what to do with our syntax-check and this
could be one solution:


rc = run_command(
  'sed', '-n',
  's/^\\(sc_[a-zA-Z0-9_-]*\\):.*/\\1/p',
  meson.current_source_dir() / 'syntax-check.mk',
  check: true,
)

sc_tests = rc.stdout().strip().split()


This is how syntax-check.mk gets the list of targets to run for
syntax-check target. We can use the same list to define tests like this:


foreach target : sc_tests
  rc = run_command(
    python3_prog, '-c',
    'print("@0@".replace("sc_", ""))'.format(target),
    check: true,
    env: runutf8,
  )
  name = rc.stdout().strip()

  test(
    name,
    make_prog,
    args: [ '-C', meson.current_build_dir(), target ],
    depends: [
      potfiles_dep,
    ],
    suite: 'syntax-check',
  )
endforeach


It could be simplified if we don't care that all the syntax-check tests
would have 'sc_' prefix.


To use it with meson/ninja would be possible with the following
commands:


ninja test

    - will run all tests regardless of the test suite, it is not
      possible to specify test suite

meson test
    - same as ninja test

meson test --no-suite syntax-check
    - this would be equivalent to make check

meson test --suite syntax-check
    - this would be equivalent to make syntax-check


In addition we can add `suite: 'check'` to the remaining test() calls to
make `meson test --suite check` available as well.

With this change running `meson test --suite syntax-check` takes on my
machine 3.037s compared to `ninja syntax-check` which takes 2.256s.

Pavel
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