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| author | Markus Armbruster <armbru@redhat.com> | 2018-02-11 10:35:48 +0100 |
|---|---|---|
| committer | Eric Blake <eblake@redhat.com> | 2018-03-02 13:14:09 -0600 |
| commit | 907b846653fb3757bf2ab98d6d66f92df34d875f (patch) | |
| tree | d4ea513585b3435789c3f5bccb6ff1b6cc8c0cf3 /scripts | |
| parent | 3b446a1817289d89844ad77c719bdc44bbcd1198 (diff) | |
| download | qemu-907b846653fb3757bf2ab98d6d66f92df34d875f.zip qemu-907b846653fb3757bf2ab98d6d66f92df34d875f.tar.gz qemu-907b846653fb3757bf2ab98d6d66f92df34d875f.tar.bz2 | |
qapi: Touch generated files only when they change
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 <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180211093607.27351-11-armbru@redhat.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
[eblake: fix octal constant for python3]
Signed-off-by: Eric Blake <eblake@redhat.com>
Diffstat (limited to 'scripts')
| -rw-r--r-- | scripts/qapi/common.py | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py index c3ae590..4767392 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() |