From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34522) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1enrHl-0002Y1-5H for qemu-devel@nongnu.org; Mon, 19 Feb 2018 14:39:41 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1enrHi-0003oB-PB for qemu-devel@nongnu.org; Mon, 19 Feb 2018 14:39:37 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:45478 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1enrHi-0003mU-Hr for qemu-devel@nongnu.org; Mon, 19 Feb 2018 14:39:34 -0500 Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w1JJcfo3131158 for ; Mon, 19 Feb 2018 14:39:33 -0500 Received: from e36.co.us.ibm.com (e36.co.us.ibm.com [32.97.110.154]) by mx0b-001b2d01.pphosted.com with ESMTP id 2g840atccd-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 19 Feb 2018 14:39:33 -0500 Received: from localhost by e36.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 19 Feb 2018 12:39:31 -0700 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable From: Michael Roth In-Reply-To: <20180211093607.27351-11-armbru@redhat.com> References: <20180211093607.27351-1-armbru@redhat.com> <20180211093607.27351-11-armbru@redhat.com> Date: Sun, 18 Feb 2018 16:43:54 -0600 Message-Id: <151899383495.12376.8016627258791627753@sif> Subject: Re: [Qemu-devel] [PATCH v2 10/29] qapi: Touch generated files only when they change List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster , qemu-devel@nongnu.org Cc: marcandre.lureau@redhat.com, eblake@redhat.com 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 > Reviewed-by: Eric Blake Reviewed-by: Michael Roth > --- > 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 !=3D errno.EEXIST: > raise > - f =3D open(os.path.join(output_dir, fname), 'w') > - f.write(self._top(fname) + self._preamble + self._body > + fd =3D os.open(os.path.join(output_dir, fname), > + os.O_RDWR | os.O_CREAT, 0666) > + f =3D os.fdopen(fd, 'r+') > + text =3D (self._top(fname) + self._preamble + self._body > + self._bottom(fname)) > + oldtext =3D f.read(len(text) + 1) > + if text !=3D oldtext: > + f.seek(0) > + f.truncate(0) > + f.write(text) > f.close() > = > = > -- = > 2.13.6 >=20