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authorRasmus Villemoes <rasmus.villemoes@prevas.dk>2018-07-10 14:03:34 +0200
committerRichard Purdie <richard.purdie@linuxfoundation.org>2018-08-16 09:50:42 +0100
commitd4011ce0a37083b19de1769d7f18aa42d7b98137 (patch)
tree16f444fc8f973faf039ae0ff30d060a0dff2a421 /bitbake/lib/bb/utils.py
parent762e6b7b454164a20b11cdf7a1d8c89e94b18e6b (diff)
downloadpoky-d4011ce0a37083b19de1769d7f18aa42d7b98137.tar.gz
bitbake: bb/utils.py: add break_hardlinks helper
bb.utils.copyfile is called in a few places with identical src and dst in order to create an st_nlinks==1 version of the file. That that even works relies on an implementation detail of copyfile (namely, that it creates a temporary file and then does a rename). Moreover, it's a waste of time if the file already has st_nlinks==1. So create a helper that optimizes away the copy in the st_nlinks==1 case. Of course, this helper relies on the same implementation detail, but that's now contained within bb.utils itself. To test that we do at least sometimes hit the no-copy path, I tested locally with if sstat[stat.ST_NLINK] == 1: + bb.note("Woohoo, 2*%d bytes I/O avoided" % sstat[stat.ST_SIZE]) return True (and the obvious places in oe-core patched), and the do_package log files are indeed filled with woohoo notes. (Bitbake rev: 7ae93cf40ab91965147055100432961436bce46c) Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Diffstat (limited to 'bitbake/lib/bb/utils.py')
-rw-r--r--bitbake/lib/bb/utils.py17
1 files changed, 17 insertions, 0 deletions
diff --git a/bitbake/lib/bb/utils.py b/bitbake/lib/bb/utils.py
index b20cdabcf0..56894f130f 100644
--- a/bitbake/lib/bb/utils.py
+++ b/bitbake/lib/bb/utils.py
@@ -906,6 +906,23 @@ def copyfile(src, dest, newmtime = None, sstat = None):
906 newmtime = sstat[stat.ST_MTIME] 906 newmtime = sstat[stat.ST_MTIME]
907 return newmtime 907 return newmtime
908 908
909def break_hardlinks(src, sstat = None):
910 """
911 Ensures src is the only hardlink to this file. Other hardlinks,
912 if any, are not affected (other than in their st_nlink value, of
913 course). Returns true on success and false on failure.
914
915 """
916 try:
917 if not sstat:
918 sstat = os.lstat(src)
919 except Exception as e:
920 logger.warning("break_hardlinks: stat of %s failed (%s)" % (src, e))
921 return False
922 if sstat[stat.ST_NLINK] == 1:
923 return True
924 return copyfile(src, src, sstat=sstat)
925
909def which(path, item, direction = 0, history = False, executable=False): 926def which(path, item, direction = 0, history = False, executable=False):
910 """ 927 """
911 Locate `item` in the list of paths `path` (colon separated string like $PATH). 928 Locate `item` in the list of paths `path` (colon separated string like $PATH).