Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Copying the first bytes of a SHA1 is duplicated in six places,
however, the implications (the actual value would depend on the
endianness of the platform) is documented only once.

Add a properly documented API for this.

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Whenever the hash table becomes too small then its size is increased,
the original part (and the added space) is zerod out using memset(),
and the table is rebuilt from scratch.

Simplify this proceess by returning the old memory using free() and
allocating the new buffer using xcalloc(), which already clears the
buffer for us.  That way we avoid copying the old hash table contents
needlessly inside xrealloc().

While at it, use the first array member with sizeof instead of a
specific type.  The old code used uint32_t and int, while index is
actually an array of int32_t.  Their sizes are the same basically
everywhere, so it's not actually a problem, but the new code is
cleaner and doesn't have to be touched should the type be changed.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

The hash table that stores the packing list for a given `pack-objects`
run was tightly coupled to the pack-objects code.

In this commit, we refactor the hash table and the underlying storage
array into a `packing_data` struct. The functionality for accessing and
adding entries to the packing list is hence accessible from other parts
of Git besides the `pack-objects` builtin.

This refactoring is a requirement for further patches in this series
that will require accessing the commit packing list from outside of
`pack-objects`.

The hash table implementation has been minimally altered: we now
use table sizes which are always a power of two, to ensure a uniform
index distribution in the array.

Signed-off-by: Vicent Marti <tanoku@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Signed-off-by: Matthias Kestenholz <matthias@spinlock.ch>
Signed-off-by: Junio C Hamano <junkio@cox.net>

For some repositories, deltas simply don't make sense. One can disable
them for git-repack by adding --window, but git-push insists on making
the deltas which can be very CPU-intensive for little benefit.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>

The only visible change is that git-blame doesn't understand
"--compability" anymore, but it does accept "--compatibility" instead,
which is already documented.

Signed-off-by: Pavel Roskin <proski@gnu.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

If no delta is attempted on some objects then it is useless to load them
in memory, neither create any delta index for them.  The best thing to
do is therefore to load and index them only when really needed.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Without this there would never be a chance to improve packing for
previously undeltified objects.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

In the repacking window, if both objects we are looking at already came
from the same (old) pack-file, don't bother delta'ing them against each
other.

That means that we'll still always check for better deltas for (and
against!) _unpacked_ objects, but assuming incremental repacks, you'll
avoid the delta creation 99% of the time.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>