From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40481) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1erU6o-0000ot-Bs for qemu-devel@nongnu.org; Thu, 01 Mar 2018 14:43:19 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1erU6n-0007WG-G5 for qemu-devel@nongnu.org; Thu, 01 Mar 2018 14:43:18 -0500 Received: from mx1.redhat.com ([209.132.183.28]:55700) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1erU6n-0007Uh-9C for qemu-devel@nongnu.org; Thu, 01 Mar 2018 14:43:17 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 872A94E4C5 for ; Thu, 1 Mar 2018 19:43:16 +0000 (UTC) From: Eric Blake Date: Thu, 1 Mar 2018 13:42:25 -0600 Message-Id: <20180301194245.29854-11-eblake@redhat.com> In-Reply-To: <20180301194245.29854-1-eblake@redhat.com> References: <20180301194245.29854-1-eblake@redhat.com> Subject: [Qemu-devel] [PULL 10/30] qapi: Touch generated files only when they change List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Markus Armbruster From: Markus Armbruster 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 Message-Id: <20180211093607.27351-11-armbru@redhat.com> Reviewed-by: Michael Roth [eblake: fix octal constant for python3] Signed-off-by: Eric Blake --- 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 c3ae590202a..47673928dcc 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, 0o666) + 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() -- 2.14.3