Quoting Markus Armbruster (2018-02-11 03:35:48) > A massive number of objects depends on QAPI-generated headers. In my > "build everything" tree, it's roughly 4800 out of 5100. This is > particularly annoying when only some of the generated files change, > say for a doc fix. > > Improve qapi-gen.py to touch its output files only if they actually > change. Rebuild time for a QAPI doc fix drops from many minutes to a > few seconds. Rebuilds get faster for certain code changes, too. For > instance, adding a simple QMP event now recompiles less than 200 > instead of 4800 objects. But adding a QAPI type is as bad as ever; > we've clearly got more work to do. > > Signed-off-by: Markus Armbruster <arm...@redhat.com> > Reviewed-by: Eric Blake <ebl...@redhat.com>
Reviewed-by: Michael Roth <mdr...@linux.vnet.ibm.com> > --- > scripts/qapi/common.py | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py > index 8290795dc1..2e58573a39 100644 > --- a/scripts/qapi/common.py > +++ b/scripts/qapi/common.py > @@ -1951,9 +1951,16 @@ class QAPIGen(object): > except os.error as e: > if e.errno != errno.EEXIST: > raise > - f = open(os.path.join(output_dir, fname), 'w') > - f.write(self._top(fname) + self._preamble + self._body > + fd = os.open(os.path.join(output_dir, fname), > + os.O_RDWR | os.O_CREAT, 0666) > + f = os.fdopen(fd, 'r+') > + text = (self._top(fname) + self._preamble + self._body > + self._bottom(fname)) > + oldtext = f.read(len(text) + 1) > + if text != oldtext: > + f.seek(0) > + f.truncate(0) > + f.write(text) > f.close() > > > -- > 2.13.6 >