We can easily support BLOB_NONE filters with bitmaps. Since we know the
types of all of the objects, we just need to clear the result bits of
any blobs.
Note two subtleties in the implementation (which I also called out in
comments):
- we have to include any blobs that were specifically asked for (and
not reached through graph traversal) to match the non-bitmap version
- we have to handle in-pack and "ext_index" objects separately.
Arguably prepare_bitmap_walk() could be adding these ext_index
objects to the type bitmaps. But it doesn't for now, so let's match
the rest of the bitmap code here (it probably wouldn't be an
efficiency improvement to do so since the cost of extending those
bitmaps is about the same as our loop here, but it might make the
code a bit simpler).
Here are perf results for the new test on git.git:
Test HEAD^ HEAD
--------------------------------------------------------------------------------
5310.9: rev-list count with blob:none 1.67(1.62+0.05) 0.22(0.21+0.02) -86.8%
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The "--use-bitmap-index" option is usually aspirational: if we have
bitmaps and the request can be fulfilled more quickly using them we'll
do so, but otherwise fall back to a non-bitmap traversal.
The exception is object filtering, which explicitly dies if the two
options are combined. Let's convert this to the usual fallback behavior.
This is a minor convenience for now (since the caller can easily know
that --filter and --use-bitmap-index don't combine), but will become
much more useful as we start to support _some_ filters with bitmaps, but
not others.
The test infrastructure here is bigger than necessary for checking this
one small feature. But it will serve as the basis for more filtering
bitmap tests in future patches.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
