Ensure that we apply splits to rewrites, even if we're not
interested in examining it closely for rename/copy detection.
In keeping with core git, status should not display rewrites,
it should simply show files as "modified".
Create a new section of clar tests "stress" that will default to
being off where we can put slow tests that push the library for
performance testing purposes.
After doing further profiling, I found that a lot of time was
being spent attempting to insert hashes into the file hash
signature when using the rolling hash because the rolling hash
approach generates a hash per byte of the file instead of one
per run/line of data.
To optimize this, I decided to convert back to a run-based file
signature algorithm which would be more like core Git.
After changing this, a number of the existing tests started to
fail. In some cases, this appears to have been because the test
was coded to be too specific to the particular results of the file
similarity metric and in some cases there appear to have been bugs
in the core rename detection code where only by the coincidence
of the file similarity scoring were the expected results being
generated.
This renames all the variables in the core rename detection code
to be more consistent and hopefully easier to follow which made it
a bit easier to reason about the behavior of that code and fix the
problems that I was seeing. I think it's in better shape now.
There are a couple of tests now that attempt to stress test the
rename detection code and they are quite slow. Most of the time
is spent setting up the test data on disk and in the index. When
we roll out performance improvements for index insertion, it
should also speed up these tests I hope.
The performance improvements I introduced for rename detection
were not able to run successfully for tree-to-tree diffs because
the blob size was not known early enough and so the file signature
always had to be calculated nonetheless.
This change separates loading blobs into memory from calculating
the signature. I can't avoid having to load the large blobs into
memory, but by moving it forward, I'm able to avoid the signature
calculation if the blob won't come into play for renames.
Before the optimization commits, this test used to take about 20
seconds to run on my machine. Afterwards, there is still a couple
seconds of data setup, but the actual diff and rename detection
runs in a fraction of a second.
This makes the diff rename tracking code more careful about the
order in which it processes renames and more thorough in updating
the mapping of correct renames when an earlier rename update
alters the index of a later matched pair.
A tree to index rename with no changes was getting erased by
the iteration routine (if the routine actually loaded the data
for the unmodified file). This invokes the code path that was
previously messing up the diff and iterates twice to make sure
that the iteration process itself doesn't modify the data.
In a case insensitive index, if you attempt to add a file from
disk with a different case pattern, the old case pattern in the
index should be preserved.
This fixes that (and a couple of minor warnings).
This implements the loading of regular expression pattern lists
for diff drivers that search for function context in that way.
This also changes the way that diff drivers update options and
interface with xdiff APIs to make them a little more flexible.
This is a significant reorganization of the diff code to break it
into a set of more clearly distinct files and to document the new
organization. Hopefully this will make the diff code easier to
understand and to extend.
This adds a new `git_diff_driver` object that looks of diff driver
information from the attributes and the config so that things like
function content in diff headers can be provided. The full driver
spec is not implemented in the commit - this is focused on the
reorganization of the code and putting the driver hooks in place.
This also removes a few #includes from src/repository.h that were
overbroad, but as a result required extra #includes in a variety
of places since including src/repository.h no longer results in
pulling in the whole world.
This extends the rename tests to make sure that every rename
scenario in the inner loop of git_diff_find_similar is actually
exercised. Also, fixes an incorrect assert that was in one of
the clauses that was not previously being exercised.
This adds a couple more tests of different rename scenarios.
Also, this fixes a problem with the case where you have two
"split" deltas and the left half of one matches the right half of
the other. That case was already being handled, but in the wrong
order in a way that could result in bad output. Also, if the swap
also happened to put the other two halves into the correct place
(i.e. two files exchanged places with each other), then the second
delta was left with the SPLIT flag set when it really should be
cleared.
This flips rename detection around so instead of creating a
forward mapping from deltas to possible rename targets, instead
it creates a reverse mapping, looking at possible targets and
trying to find a source that they could have been renamed or
copied from. This is important because each output can only
have a single source, but a given source could map to multiple
outputs (in the form of COPIED records).
Additionally, this makes a couple of tweaks to the public rename
detection APIs, mostly renaming a couple of options that control
the behavior to make more sense and to be more like core Git.
I walked through the tests looking at the exact results and
updated the expectations based on what I saw. The new code is
different from the old because it cannot give some nonsense
results (like A was renamed to both B and C) which were part of
the outputs previously.
This adds a bunch more rename detection tests including checks
vs the working directory, the new exact match options, some more
whitespace variants, etc.
This also adds a git_futils_writebuffer helper function and uses
it in checkout. This is mainly added because I wanted an easy
way to write out a git_buf to disk inside my test code.
There are a number of bugs in the rename code that only were
obvious when I started testing it against large old repos with
more complex patterns. (The code to do that testing is not ready
to merge with libgit2, but I do plan to add more thorough tests.)
This contains a significant number of changes and also tweaks the
public API slightly to make emulating core git easier.
Most notably, this separates the GIT_DIFF_FIND_AND_BREAK_REWRITES
flag into FIND_REWRITES (which adds a self-similarity score to
every modified file) and BREAK_REWRITES (which splits the modified
deltas into add/remove pairs in the diff list). When you do a raw
output of core git, rewrites show up as M090 or such, not at A and
D output, so I wanted to be able to emulate that.
Publicly, this also changes the flags to be uint16_t since we
don't need values out of that range.
Internally, this contains significant changes from a number of
small bug fixes (like using the wrong side of the diff to decide
if the object could be found in the ODB vs the workdir) to larger
issues about which files can and should be compared and how the
various edge cases of similarity scores should be treated.
Honestly, I don't think this is the last update that will have to
be made to this code, but I think this moves us closer to correct
behavior and I tried to document the code so it would be easier
to follow..
If you use rename detection, the renamed and copied files would
not show any text diffs because the function that decides if
data should be loaded didn't know which sides of the diff to
load for those cases.
This adds a test that looks at the patch generated for diff
entries that are COPIED or RENAMED.
`git_diff_get_patch()` would unconditionally load the patch object and
then simply leak it if the user hadn't requested it. Short-circuit
loading the object if the user doesn't want it.
The rest of the plugs are simply calling the free functions of objects
allocated during the tests.
This includes tests for crlf changes, whitespace changes with the
default comparison and with the ignore whitespace comparison, and
more sensitivity checking for the comparison code.
This fixes both a test that I broke in diff::patch where I was
relying on the current state of the working directory for the
renames test data and fixes an unstable test in diff::rename
where the environment setting for the "diff.renames" config was
being allowed to influence the test results.
This adds some new tests that actually exercise the similarity
metric between files to detect renames, copies, and split modified
files that are too heavily modified.
There is still more testing to do - these tests are just partially
covering the cases.
There is also one bug fix in this where a change set with only
MODIFY being broken into ADD/DELETE (due to low self-similarity)
without any additional RENAMED entries would end up not processing
the split requests (because the num_rewrites counter got reset).
This makes the diff functions that take callbacks both take
the payload parameter after the callback function pointers and
pass the payload as the last argument to the callback function
instead of the first. This should make them consistent with
other callbacks across the API.
This improves the naming for the rename related functionality
moving it to be called `git_diff_find_similar()` and renaming
all the associated constants, etc. to make more sense.
I also moved the new code (plus the existing `git_diff_merge`)
into a new file `diff_tform.c` where I can put new functions
related to manipulating git diff lists.
This also updates the implementation significantly from the
last revision fixing some ordering issues (where break-rewrite
needs to be handled prior to copy and rename detection) and
improving config option handling.
This implements the basis for diff rename and copy detection,
although it is based on simple SHA comparison right now instead
of using a matching algortihm. Just as `git_diff_merge` can be
used as a post-pass on diffs to emulate certain command line
behaviors, there is a new API `git_diff_detect` which will
update a diff list in-place, adjusting some deltas to RENAMED
or COPIED state (and also, eventually, splitting MODIFIED deltas
where the change is too large into DELETED/ADDED pairs).
This also adds a new test repo that will hold rename/copy/split
scenarios. Right now, it just has exact-match rename and copy,
but the tests are written to use tree diffs, so we should be able
to add new test scenarios easily without breaking tests.
