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Message-ID: <20231027223408.1865704-1-kuba@kernel.org>
Date: Fri, 27 Oct 2023 15:34:08 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org,
edumazet@...gle.com,
pabeni@...hat.com,
jiri@...nulli.us,
Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH net-next] tools: ynl-gen: don't touch the output file if content is the same
I often regenerate all YNL files in the tree to make sure they
are in sync with the codegen and specs. Generator rewrites
the files unconditionally, so since make looks at file modification
time to decide what to rebuild - my next build takes longer.
We already generate the code to a tempfile most of the time,
only overwrite the target when we have to.
Before:
$ stat include/uapi/linux/netdev.h
File: include/uapi/linux/netdev.h
Size: 2307 Blocks: 8 IO Block: 4096 regular file
Access: 2023-10-27 15:19:56.347071940 -0700
Modify: 2023-10-27 15:19:45.089000900 -0700
Change: 2023-10-27 15:19:45.089000900 -0700
Birth: 2023-10-27 15:19:45.088000894 -0700
$ ./tools/net/ynl/ynl-regen.sh -f
[...]
$ stat include/uapi/linux/netdev.h
File: include/uapi/linux/netdev.h
Size: 2307 Blocks: 8 IO Block: 4096 regular file
Access: 2023-10-27 15:19:56.347071940 -0700
Modify: 2023-10-27 15:22:18.417968446 -0700
Change: 2023-10-27 15:22:18.417968446 -0700
Birth: 2023-10-27 15:19:45.088000894 -0700
After:
$ stat include/uapi/linux/netdev.h
File: include/uapi/linux/netdev.h
Size: 2307 Blocks: 8 IO Block: 4096 regular file
Access: 2023-10-27 15:22:41.520114221 -0700
Modify: 2023-10-27 15:22:18.417968446 -0700
Change: 2023-10-27 15:22:18.417968446 -0700
Birth: 2023-10-27 15:19:45.088000894 -0700
$ ./tools/net/ynl/ynl-regen.sh -f
[...]
$ stat include/uapi/linux/netdev.h
File: include/uapi/linux/netdev.h
Size: 2307 Blocks: 8 IO Block: 4096 regular file
Access: 2023-10-27 15:22:41.520114221 -0700
Modify: 2023-10-27 15:22:18.417968446 -0700
Change: 2023-10-27 15:22:18.417968446 -0700
Birth: 2023-10-27 15:19:45.088000894 -0700
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
tools/net/ynl/ynl-gen-c.py | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/tools/net/ynl/ynl-gen-c.py b/tools/net/ynl/ynl-gen-c.py
index 13427436bfb7..c4003a83cd5d 100755
--- a/tools/net/ynl/ynl-gen-c.py
+++ b/tools/net/ynl/ynl-gen-c.py
@@ -3,6 +3,7 @@
import argparse
import collections
+import filecmp
import os
import re
import shutil
@@ -1168,7 +1169,7 @@ from lib import SpecFamily, SpecAttrSet, SpecAttr, SpecOperation, SpecEnumSet, S
if out_file is None:
self._out = os.sys.stdout
else:
- self._out = tempfile.TemporaryFile('w+')
+ self._out = tempfile.NamedTemporaryFile('w+')
self._out_file = out_file
def __del__(self):
@@ -1177,6 +1178,10 @@ from lib import SpecFamily, SpecAttrSet, SpecAttr, SpecOperation, SpecEnumSet, S
def close_out_file(self):
if self._out == os.sys.stdout:
return
+ # Avoid modifying the file if contents didn't change
+ self._out.flush()
+ if os.path.isfile(self._out_file) and filecmp.cmp(self._out.name, self._out_file, shallow=False):
+ return
with open(self._out_file, 'w+') as out_file:
self._out.seek(0)
shutil.copyfileobj(self._out, out_file)
--
2.41.0
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