Re: [PATCH 5/5] blame: use xdi_diff_hunks(), get rid of struct patch

> Based on a patch by Brian Downing, this replaces the struct patch based
> code for blame passing with calls to xdi_diff_hunks().  This way we
> avoid generating and then parsing patches; we only let the interesting
> infos be passed to our callbacks instead.  This makes blame a bit faster:
>
>    $ blame="./git blame -M -C -C -p --incremental v1.6.0"
>
>    # master
>    $ /usr/bin/time $blame Makefile >/dev/null
>    1.38user 0.14system 0:01.52elapsed 100%CPU (0avgtext+0avgdata 0maxresident)k
>    0inputs+0outputs (0major+12226minor)pagefaults 0swaps
>    $ /usr/bin/time $blame cache.h >/dev/null
>    1.66user 0.13system 0:01.80elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
>    0inputs+0outputs (0major+12262minor)pagefaults 0swaps
>
>    # this patch series
>    $ /usr/bin/time $blame Makefile >/dev/null
>    1.27user 0.12system 0:01.40elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
>    0inputs+0outputs (0major+11836minor)pagefaults 0swaps
>    $ /usr/bin/time $blame cache.h >/dev/null
>    1.52user 0.12system 0:01.70elapsed 97%CPU (0avgtext+0avgdata 0maxresident)k
>    0inputs+0outputs (0major+12052minor)pagefaults 0swaps
>
> Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>

> Brian, your numbers looked much more impressive.  Could you please clock
> this code with your repository and the file server.c?  I wonder if this
> callback mechanism is just too complicated or if your case simply benefits
> lots more than the two files from git mentioned above.
>
> The patch series ends here without adding xdiff caching, for two reasons.
> It's quite easy to add it; patch 4 from your series applies unchanged and
> patch 5 is just needs a few small changes to account for the absence of
> compare_buffer().  More importantly, speed actually went down with caching
> for the test case.  The common tail optimization (xdi_diff() vs. xdl_diff())
> seems to beat caching for cache.h and Makefile..