[bitbake-devel] [PATCH] bb/utils.py: add break_hardlinks helper

[Rasmus Villemoes]

On 2018-07-10 14:03, Rasmus Villemoes wrote:
> 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.

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