Code cleanup.

* tk/diffcore-delta-remove-unused:
  diffcore-delta: remove unused parameter to diffcore_count_changes()

The delta_limit parameter to diffcore_count_changes() has been unused
since commit ba23bbc8e ("diffcore-delta: make change counter to byte
oriented again.", 2006-03-04).

Remove the parameter and adjust all callers.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Now that this struct's sha1 member is called "oid", update the comment
and the sha1_valid member to be called "oid_valid" instead.  The
following Coccinelle semantic patch was used to implement this, followed
by the transformations in object_id.cocci:

@@
struct diff_filespec o;
@@
- o.sha1_valid
+ o.oid_valid

@@
struct diff_filespec *p;
@@
- p->sha1_valid
+ p->oid_valid

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Convert struct diff_filespec's sha1 member to use a struct object_id
called "oid" instead.  The following Coccinelle semantic patch was used
to implement this, followed by the transformations in object_id.cocci:

@@
struct diff_filespec o;
@@
- o.sha1
+ o.oid.hash

@@
struct diff_filespec *p;
@@
- p->sha1
+ p->oid.hash

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Starting from a single file, A, if you create B as a copy of A (and
possibly make some edit) and then make extensive change to A, you
will see:

    $ git diff -C --name-status
    C89    A    B
    M      A

which is expected.  However, if you ask the same question in a
different way, you see this:

    $ git diff -B -M --name-status
    R89    A    B
    M100   A

telling us that A was rename-edited into B (as if "A will no longer
exist as the result") and at the same time A itself was extensively
edited.

In this case, because the resulting tree still does have file A
(even if it has contents vastly different from the original), we
should use "C"opy, not "R"ename, to avoid hinting that A somehow
goes away.

Two existing tests were depending on the wrong behaviour, and fixed.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

When the source file is empty, the calculation of the merge score
results in a division by zero.  In the situation:

     == preimage ==             == postimage ==

     F (empty file)             F (a large file)
                                E (a new empty file)

it does not make sense to consider F->E as a rename, so it is better not
to break the pre- and post-image of F.

Bail out early in this case to avoid hitting the divide-by-zero.  This
causes the merge score to be left at zero.

Signed-off-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Refactor the diff_queue_struct code, this macro help
to reset the structure.

Signed-off-by: Bo Yang <struggleyb.nku@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

The "break" phase works by counting changes between two
blobs with the same path. We do this by splitting the file
into chunks (or lines for text oriented files) and then
keeping a count of chunk hashes.

The "rename" phase counts changes between blobs at two
different paths. However, it uses the exact same set of
chunk hashes (which are immutable for a given sha1).

The rename phase can therefore use the same hash data as
break. Unfortunately, we were throwing this data away after
computing it in the break phase. This patch instead attaches
it to the filespec and lets it live through the rename
phase, working under the assumption that most of the time
that breaks are being computed, renames will be too.

We only do this optimization for files which have actually
been broken, as those ones will be candidates for rename
detection (and it is a time-space tradeoff, so we don't want
to waste space keeping useless data).

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

As we look at each changed file and consider breaking it, we
load the blob data and make a decision about whether to
break, which is independent of any other blobs that might
have changed. However, we keep the data in memory while we
consider breaking all of the other files. Which means that
both versions of every file you are diffing are in memory at
the same time.

This patch instead frees the blob data as we finish with
each file pair, leading to much lower memory usage.

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

These variables were unused and can be removed safely:

  builtin-clone.c::cmd_clone(): use_local_hardlinks, use_separate_remote
  builtin-fetch-pack.c::find_common(): len
  builtin-remote.c::mv(): symref
  diff.c::show_stats():show_stats(): total
  diffcore-break.c::should_break(): base_size
  fast-import.c::validate_raw_date(): date, sign
  fsck.c::fsck_tree(): o_sha1, sha1
  xdiff-interface.c::parse_num(): read_some

Signed-off-by: Benjamin Kramer <benny.kra@googlemail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>