The second round similarity estimator simply used the size of
the xdelta itself to estimate the extent of damage. This patch
keeps that logic to detect big insertions to terminate the check
early, but otherwise looks at the generated delta in order to
estimate the extent of edit more accurately.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Earlier implementation had a major screw-up in the memory
management area. Rename/copy logic sometimes borrowed a pointer
to a structure without any provision for downstream to determine
which pointer is shared and which is not. This resulted in the
later clean-up code to sometimes double free such structure,
resulting in a segfault. This made -M and -C useless.
Another problem the earlier implementation had was that it
reordered the patches, and forced the logic to differentiate
renames and copies to depend on that particular order. This
problem was fixed by teaching rename/copy detection logic not to
do any reordering, and rename-copy differentiator not to depend
on the order of the patches. The diffs will leave rename/copy
detector in the same destination path order as the patch that
was fed into it. Some test vectors have been reordered to
accommodate this change.
It also adds a sanity check logic to the human-readable diff-raw
output to detect paths with embedded TAB and LF characters,
which cannot be expressed with that format. This idea came up
during a discussion with Chris Wedgwood.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
For later stages to reorder patches, pruning logic and rename detection
logic should not decide which delete to discard (because another entry
said it will take over the file as a rename) until the very end.
Also fix some tests that were assuming the earlier "last one is rename
or keep everything else is copy" semantics of diff-raw format, which no
longer is true.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The rename/copy detection logic in earlier round was only good
enough to show patch output and discussion on the mailing list
about the diff-raw format updates revealed many problems with
it. This patch fixes all the ones known to me, without making
things I want to do later impossible, mostly related to patch
reordering.
(1) Earlier rename/copy detector determined which one is rename
and which one is copy too early, which made it impossible
to later introduce diffcore transformers to reorder
patches. This patch fixes it by moving that logic to the
very end of the processing.
(2) Earlier output routine diff_flush() was pruning all the
"no-change" entries indiscriminatingly. This was done due
to my false assumption that one of the requirements in the
diff-raw output was not to show such an entry (which
resulted in my incorrect comment about "diff-helper never
being able to be equivalent to built-in diff driver"). My
special thanks go to Linus for correcting me about this.
When we produce diff-raw output, for the downstream to be
able to tell renames from copies, sometimes it _is_
necessary to output "no-change" entries, and this patch
adds diffcore_prune() function for doing it.
(3) Earlier diff_filepair structure was trying to be not too
specific about rename/copy operations, but the purpose of
the structure was to record one or two paths, which _was_
indeed about rename/copy. This patch discards xfrm_msg
field which was trying to be generic for this wrong reason,
and introduces a couple of fields (rename_score and
rename_rank) that are explicitly specific to rename/copy
logic. One thing to note is that the information in a
single diff_filepair structure _still_ does not distinguish
renames from copies, and it is deliberately so. This is to
allow patches to be reordered in later stages.
(4) This patch also adds some tests about diff-raw format
output and makes sure that necessary "no-change" entries
appear on the output.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Earlier round was not treating symbolic links carefully enough,
and would have produced diff output that renamed/copied then
edited the contents of a symbolic link, which made no practical
sense. Change it to detect only pure renames.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This moves the path selection logic from individual programs to a new
diffcore transformer (diff-tree still needs to have its own for
performance reasons). Also the header printing code in diff-tree was
tweaked not to produce anything when pickaxe is in effect and there is
nothing interesting to report. An interesting example is the following
in the GIT archive itself:
$ git-whatchanged -p -C -S'or something in a real script'
Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
When the minimum score is specified as 0 (meaning "use default
value"), set it to the default as we are told.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
There was a screwy math bug in the estimator that confused what
-C1 meant and what -C9 meant, only in one of the early "cheap"
check, which resulted in quite confusing behaviour.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Update the diff-raw format as Linus and I discussed, except that
it does not use sequence of underscore '_' letters to express
nonexistence. All '0' mode is used for that purpose instead.
The new diff-raw format can express rename/copy, and the earlier
restriction that -M and -C _must_ be used with the patch format
output is no longer necessary. The patch makes -M and -C flags
independent of -p flag, so you need to say git-whatchanged -M -p
to get the diff/patch format.
Updated are both documentations and tests.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This does not actually supress the extra headers when pickaxe is
used, but prepares enough support for diff-tree to implement it.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The heuristics so far was to compare file size change and xdelta
size against the average of file size before and after the
change. This patch uses the smaller of pre- and post- change
file size instead.
It also makes a very small performance fix. I didn't measure
it; I do not expect it to make any practical difference, but
while scanning an already sorted list, breaking out in the
middle is the right thing.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This steals the "pickaxe" feature from JIT and make it available
to the bare Plumbing layer. From the command line, the user
gives a string he is intersted in.
Using the diff-core infrastructure previously introduced, it
filters the differences to limit the output only to the diffs
between <src> and <dst> where the string appears only in one but
not in the other. For example:
$ ./git-rev-list HEAD | ./git-diff-tree -Sdiff-tree-helper --stdin -M
would show the diffs that touch the string "diff-tree-helper".
In real software-archaeologist application, you would typically
look for a few to several lines of code and see where that code
came from.
The "pickaxe" module runs after "rename/copy detection" module,
so it even crosses the file rename boundary, as the above
example demonstrates.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This introduces the diff-core, the layer between the diff-tree
family and the external diff interface engine. The calls to the
interface diff-tree family uses (diff_change and diff_addremove)
have not changed and will not change. The purpose of the
diff-core layer is to provide an infrastructure to transform the
set of differences sent from the applications, before sending
them to the external diff interface.
The recently introduced rename detection code has been rewritten
to use the diff-core facility. When applications send in
separate creates and deletes, matching ones are transformed into
a single rename-and-edit diff, and sent out to the external diff
interface as such.
This patch also enhances the rename detection code further to be
able to detect copies. Currently this happens only as long as
copy sources appear as part of the modified files, but there
already is enough provision for callers to report unmodified
files to diff-core, so that they can be also used as copy source
candidates. Extending the callers this way will be done in a
separate patch.
Please see and marvel at how well this works by trying out the
newly added t/t4003-diff-rename-1.sh test script.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
