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When running unpack_trees() with a sparse index, we attempt to operate
on the index without expanding the sparse directory entries. Thus, we
operate by manipulating entire directories and passing them to the
unpack function. In the case of the 'git checkout' command, this is the
twoway_merge() function.
There are several cases in twoway_merge() that handle different
situations. One new one to add is the case of a directory/file conflict
where the directory is sparse. Before the sparse index, such a conflict
would appear as a list of file additions and deletions. Now,
twoway_merge() initializes 'current', 'oldtree', and 'newtree' from
src[0], src[1], and src[2], then sets 'oldtree' to NULL because it is
equal to the df_conflict_entry. The way to determine that we have a
directory/file conflict is to test that 'current' and 'newtree' disagree
on being sparse directory entries.
When we are in this case, we want to resolve the situation by calling
merged_entry(). This allows replacing the 'current' entry with the
'newtree' entry. This is important for cases where we want to run 'git
checkout' across the conflict and have the new HEAD represent the new
file type at that path. The first NEEDSWORK comment dropped in t1092
demonstrates this necessary behavior.
However, we still are in a confusing state when 'current' corresponds to
a staged change within a sparse directory that is not present at HEAD.
This should be atypical, because it requires adding a change outside of
the sparse-checkout cone, but it is possible. Since we are unable to
determine that this is a staged change within twoway_merge(), we cannot
add a case to reject the merge at this point. I believe this is due to
the use of df_conflict_entry in the place of 'oldtree' instead of using
the valud at HEAD, which would provide some perspective to this
decision. Any change that would allow this differentiation for staged
entries would need to involve information further up in unpack_trees().
That work should be done, sometime, because we are further confusing the
behavior of a directory/file conflict when staging a change in the
directory. The two cases 'checkout behaves oddly with df-conflict-?' in
t1092 demonstrate that even without a sparse-checkout, Git is not
consistent in its behavior. Neither of the two options seems correct,
either. This change makes the sparse-index behave differently than the
typcial sparse-checkout case, but it does match the full checkout
behavior in the df-conflict-2 case.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Add new branches to the test repo that demonstrate directory/file
conflicts in different ways. Since the directory 'folder1/' has
adjacent files 'folder1-', 'folder1.txt', and 'folder10' it causes
searches for 'folder1/' to land in a different place in the index than a
search for 'folder1'. This causes a change in behavior when working with
the df-conflict-1 and df-conflict-2 branches, whose only difference is
that the first uses 'folder1' as the conflict and the other uses
'folder2' which does not have these adjacent files.
We can extend two tests that compare the behavior across different 'git
checkout' commands, and we see already that the behavior will be
different in some cases and not in others. The difference between the
two test loops is that one uses 'git reset --hard' between iterations.
Further, we isolate the behavior of creating a staged change within a
directory and then checking out a branch where that directory is
replaced with a file. A full checkout behaves differently across these
two cases, while a sparse-checkout cone behaves consistently. In both
cases, the behavior is wrong. In one case, the staged change is dropped
entirely. The other case the staged change is kept, replacing the file
at that location, but none of the other files in the directory are kept.
Likely, the correct behavior in this case is to reject the checkout and
report the conflict, leaving HEAD in its previous location. None of the
cases behave this way currently. Use comments to demonstrate that the
tested behavior is only a documentation of the current, incorrect
behavior to ensure we do not _accidentally_ change it. Instead, we would
prefer to change it on purpose with a future change.
At this point, the sparse-index does not handle these 'git checkout'
commands correctly. Or rather, it _does_ reject the 'git checkout' when
we have the staged change, but for the wrong reason. It also rejects the
'git checkout' commands when there is no staged change and we want to
replace a directory with a file. A fix for that unstaged case will
follow in the next change, but that will make the sparse-index agree
with the full checkout case in these documented incorrect behaviors.
Helped-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Previous changes did the necessary improvements to unpack-trees.c and
diff-lib.c in order to modify a sparse index based on its comparision
with a tree. The only remaining work is to remove some
ensure_full_index() calls and add tests that verify that the index is
not expanded in our interesting cases. Include 'switch' and 'restore' in
these tests, as they share a base implementation with 'checkout'.
Here are the relevant performance results from
p2000-sparse-operations.sh:
Test HEAD~1 HEAD
--------------------------------------------------------------------------------
2000.18: git checkout -f - (full-v3) 0.49(0.43+0.03) 0.47(0.39+0.05) -4.1%
2000.19: git checkout -f - (full-v4) 0.45(0.37+0.06) 0.42(0.37+0.05) -6.7%
2000.20: git checkout -f - (sparse-v3) 0.76(0.71+0.07) 0.04(0.03+0.04) -94.7%
2000.21: git checkout -f - (sparse-v4) 0.75(0.72+0.04) 0.05(0.06+0.04) -93.3%
It is important to compare the full index case to the sparse index case,
as the previous results for the sparse index were inflated by the index
expansion. For index v4, this is an 88% improvement.
On an internal repository with over two million paths at HEAD and a
sparse-checkout definition containing ~60,000 of those paths, 'git
checkout' went from 3.5s to 297ms with this change. The theoretical
optimum where only those ~60,000 paths exist was 275ms, so the extra
sparse directory entries contribute a 22ms overhead.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Update 'git commit' to allow using the sparse-index in memory without
expanding to a full one. The only place that had an ensure_full_index()
call was in cache_tree_update(). The recursive algorithm for
update_one() was already updated in 2de37c536 (cache-tree: integrate
with sparse directory entries, 2021-03-03) to handle sparse directory
entries in the index.
Most of this change involves testing different command-line options that
allow specifying which on-disk changes should be included in the commit.
This includes no options (only take currently-staged changes), -a (take
all tracked changes), and --include (take a list of specific changes).
To simplify testing that these options do not expand the index, update
the test that previously verified that 'git status' does not expand the
index with a helper method, ensure_not_expanded().
This allows 'git commit' to operate much faster when the sparse-checkout
cone is much smaller than the full list of files at HEAD.
Here are the relevant lines from p2000-sparse-operations.sh:
Test HEAD~1 HEAD
----------------------------------------------------------------------------------
2000.14: git commit -a -m A (full-v3) 0.35(0.26+0.06) 0.36(0.28+0.07) +2.9%
2000.15: git commit -a -m A (full-v4) 0.32(0.26+0.05) 0.34(0.28+0.06) +6.3%
2000.16: git commit -a -m A (sparse-v3) 0.63(0.59+0.06) 0.04(0.05+0.05) -93.7%
2000.17: git commit -a -m A (sparse-v4) 0.64(0.59+0.08) 0.04(0.04+0.04) -93.8%
It is important to compare the full-index case to the sparse-index case,
so the improvement for index version v4 is actually an 88% improvement in
this synthetic example.
In a real repository with over two million files at HEAD and 60,000
files in the sparse-checkout definition, the time for 'git commit -a'
went from 2.61 seconds to 134ms. I compared this to the result if the
index only contained the paths in the sparse-checkout definition and
found the theoretical optimum to be 120ms, so the out-of-cone paths only
add a 12% overhead.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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There are several situations where a repository with sparse-checkout
enabled will act differently than a normal repository, and in ways that
are not intentional. The test t1092-sparse-checkout-compatibility.sh
documents some of these deviations, but a casual reader might think
these are intentional behavior changes.
Add comments on these tests that make it clear that these behaviors
should be updated. Using 'NEEDSWORK' helps contributors find that these
are potential areas for improvement.
Helped-by: Elijah Newren <newren@gmail.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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It is difficult, but possible, to get into a state where we intend to
add a directory that is outside of the sparse-checkout definition. Add a
test to t1092-sparse-checkout-compatibility.sh that demonstrates this
using a combination of 'git reset --mixed' and 'git checkout --orphan'.
This test failed before because the output of 'git status
--porcelain=v2' would not match on the lines for folder1/:
* The sparse-checkout repo (with a full index) would output each path
name that is intended to be added.
* The sparse-index repo would only output that "folder1/" is staged for
addition.
The status should report the full list of files to be added, and so this
sparse-directory entry should be expanded to a full list when reaching
it inside the wt_status_collect_changes_initial() method. Use
read_tree_at() to assist.
Somehow, this loop over the cache entries was not guarded by
ensure_full_index() as intended.
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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By testing 'git -c core.fsmonitor= status -uno', we can check for the
simplest index operations that can be made sparse-aware. The necessary
implementation details are already integrated with sparse-checkout, so
modify command_requires_full_index to be zero for cmd_status().
In refresh_index(), we loop through the index entries to refresh their
stat() information. However, sparse directories have no stat()
information to populate. Ignore these entries.
This allows 'git status' to no longer expand a sparse index to a full
one. This is further tested by dropping the "-uno" option and adding an
untracked file into the worktree.
The performance test p2000-sparse-checkout-operations.sh demonstrates
these improvements:
Test HEAD~1 HEAD
-----------------------------------------------------------------------------
2000.2: git status (full-index-v3) 0.31(0.30+0.05) 0.31(0.29+0.06) +0.0%
2000.3: git status (full-index-v4) 0.31(0.29+0.07) 0.34(0.30+0.08) +9.7%
2000.4: git status (sparse-index-v3) 2.35(2.28+0.10) 0.04(0.04+0.05) -98.3%
2000.5: git status (sparse-index-v4) 2.35(2.24+0.15) 0.05(0.04+0.06) -97.9%
Note that since HEAD~1 was expanding the sparse index by parsing trees,
it was artificially slower than the full index case. Thus, the 98%
improvement is misleading, and instead we should celebrate the 0.34s to
0.05s improvement of 85%. This is more indicative of the peformance
gains we are expecting by using a sparse index.
Note: we are dropping the assignment of core.fsmonitor here. This is not
necessary for the test script as we are not altering the config any
other way. Correct integration with FS Monitor will be validated in
later changes.
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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'git status' began reporting a percentage of populated paths when
sparse-checkout is enabled in 051df3cf (wt-status: show sparse
checkout status as well, 2020-07-18). This percentage is incorrect when
the index has sparse directories. It would also be expensive to
calculate as we would need to parse trees to count the total number of
possible paths.
Avoid the expensive computation by simplifying the output to only report
that a sparse checkout exists, without the percentage.
This change is the reason we use 'git status --porcelain=v2' in
t1092-sparse-checkout-compatibility.sh. We don't want to ensure that
this message is equal across both modes, but instead just the important
information about staged, modified, and untracked files are compared.
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Before moving to update 'git status' and 'git add' to work with sparse
indexes, add an explicit test that ensures the sparse-index works the
same as a normal sparse-checkout when the worktree contains directories
and files outside of the sparse cone.
Specifically, 'folder1/a' is a file in our test repo, but 'folder1' is
not in the sparse cone. When 'folder1/a' is modified, the file is not
shown as modified and adding it will fail. This is new behavior as of
a20f704 (add: warn when asked to update SKIP_WORKTREE entries,
2021-04-08). Before that change, these adds would be silently ignored.
Untracked files are fine: adding new files both with 'git add .' and
'git add folder1/' works just as in a full checkout. This may not be
entirely desirable, but we are not intending to change behavior at the
moment, only document it. A future change could alter the behavior to
be more sensible, and this test could be modified to satisfy the new
expected behavior.
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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As more features integrate with the sparse-index feature, more and more
special cases arise that require different data shapes within the tree
structure of the repository in order to demonstrate those cases.
Add several interesting special cases all at once instead of sprinkling
them across several commits. The interesting cases being added here are:
* Add sparse-directory entries on both sides of directories within the
sparse-checkout definition.
* Add directories outside the sparse-checkout definition who have only
one entry and are the first entry of a directory with multiple
entries.
* Add filenames adjacent to a sparse directory entry that sort before
and after the trailing slash.
Later tests will take advantage of these shapes, but they also deepen
the tests that already exist.
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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This fixes the test data shape to be as expected, allowing rename
detection to work properly now that the 'larger-content' file actually
has meaningful lines.
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The sparse-index format is designed to be compatible with merge
conflicts, even those outside the sparse-checkout definition. The reason
is that when converting a full index to a sparse one, a cache entry with
nonzero stage will not be collapsed into a sparse directory entry.
However, this behavior was not tested, and a different behavior within
convert_to_sparse() fails in this scenario. Specifically,
cache_tree_update() will fail when unmerged entries exist.
convert_to_sparse_rec() uses the cache-tree data to recursively walk the
tree structure, but also to compute the OIDs used in the
sparse-directory entries.
Add an index scan to convert_to_sparse() that will detect if these merge
conflict entries exist and skip the conversion before trying to update
the cache-tree. This is marked as NEEDSWORK because this can be removed
with a suitable update to cache_tree_update() or a similar method that
can construct a cache-tree with invalid nodes, but still allow creating
the nodes necessary for creating sparse directory entries.
It is possible that in the future we will not need to make such an
update, since if we do not expand a sparse-index into a full one, this
conversion does not need to happen. Thus, this can be deferred until the
merge machinery is made to integrate with the sparse-index.
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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This looked like a good idea, but it seems to break tests on 32-bit
builds rather badly. Revert to just use "100 thousands must be big
enough" for now.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The t1092-sparse-checkout-compatibility.sh tests compare the stdout and
stderr for several Git commands across both full checkouts, sparse
checkouts with a full index, and sparse checkouts with a sparse index.
Since these are direct comparisons, sometimes a progress indicator can
flush at unpredictable points, especially on slower machines. This
causes the tests to be flaky.
One standard way to avoid this is to add GIT_PROGRESS_DELAY=0 to the Git
commands that are run, as this will force every progress indicator
created with start_progress_delay() to be created immediately. However,
there are some progress indicators that are created in the case of a
full index that are not created with a sparse index. Moreover, their
values may be different as those indexes have a different number of
entries.
Instead, use GIT_PROGRESS_DELAY=-1 (which will turn into UINT_MAX)
to ensure that any reasonable machine running these tests would
never display delayed progress indicators.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The cache_tree_verify() method is run when GIT_TEST_CHECK_CACHE_TREE
is enabled, which it is by default in the test suite. The logic must
be adjusted for the presence of these directory entries.
For now, leave the test as a simple check for whether the directory
entry is sparse. Do not go any further until needed.
This allows us to re-enable GIT_TEST_CHECK_CACHE_TREE in
t1092-sparse-checkout-compatibility.sh. Further,
p2000-sparse-operations.sh uses the test suite and hence this is enabled
for all tests. We need to integrate with it before we run our
performance tests with a sparse-index.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The sparse index extension is used to signal that index writes should be
in sparse mode. This was only updated using GIT_TEST_SPARSE_INDEX=1.
Add a '--[no-]sparse-index' option to 'git sparse-checkout init' that
specifies if the sparse index should be used. It also updates the index
to use the correct format, either way. Add a warning in the
documentation that the use of a repository extension might reduce
compatibility with third-party tools. 'git sparse-checkout init' already
sets extension.worktreeConfig, which places most sparse-checkout users
outside of the scope of most third-party tools.
Update t1092-sparse-checkout-compatibility.sh to use this CLI instead of
GIT_TEST_SPARSE_INDEX=1.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Add a test case that uses test_region to ensure that we are truly
expanding a sparse index to a full one, then converting back to sparse
when writing the index. As we integrate more Git commands with the
sparse index, we will convert these commands to check that we do _not_
convert the sparse index to a full index and instead stay sparse the
entire time.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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A submodule is stored as a "Git link" that actually points to a commit
within a submodule. Submodules are populated or not depending on
submodule configuration, not sparse-checkout. To ensure that the
sparse-index feature integrates correctly with submodules, we should not
collapse a directory if there is a Git link within its range.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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If we have a full index, then we can convert it to a sparse index by
replacing directories outside of the sparse cone with sparse directory
entries. The convert_to_sparse() method does this, when the situation is
appropriate.
For now, we avoid converting the index to a sparse index if:
1. the index is split.
2. the index is already sparse.
3. sparse-checkout is disabled.
4. sparse-checkout does not use cone mode.
Finally, we currently limit the conversion to when the
GIT_TEST_SPARSE_INDEX environment variable is enabled. A mode using Git
config will be added in a later change.
The trickiest thing about this conversion is that we might not be able
to mark a directory as a sparse directory just because it is outside the
sparse cone. There might be unmerged files within that directory, so we
need to look for those. Also, if there is some strange reason why a file
is not marked with CE_SKIP_WORKTREE, then we should give up on
converting that directory. There is still hope that some of its
subdirectories might be able to convert to sparse, so we keep looking
deeper.
The conversion process is assisted by the cache-tree extension. This is
calculated from the full index if it does not already exist. We then
abandon the cache-tree as it no longer applies to the newly-sparse
index. Thus, this cache-tree will be recalculated in every
sparse-full-sparse round-trip until we integrate the cache-tree
extension with the sparse index.
Some Git commands use the index after writing it. For example, 'git add'
will update the index, then write it to disk, then read its entries to
report information. To keep the in-memory index in a full state after
writing, we re-expand it to a full one after the write. This is wasteful
for commands that only write the index and do not read from it again,
but that is only the case until we make those commands "sparse aware."
We can compare the behavior of the sparse-index in
t1092-sparse-checkout-compability.sh by using GIT_TEST_SPARSE_INDEX=1
when operating on the 'sparse-index' repo. We can also compare the two
sparse repos directly, such as comparing their indexes (when expanded to
full in the case of the 'sparse-index' repo). We also verify that the
index is actually populated with sparse directory entries.
The 'checkout and reset (mixed)' test is marked for failure when
comparing a sparse repo to a full repo, but we can compare the two
sparse-checkout cases directly to ensure that we are not changing the
behavior when using a sparse index.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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We will use 'test-tool read-cache --table' to check that a sparse
index is written as part of init_repos. Since we will no longer always
expand a sparse index into a full index, add an '--expand' parameter
that adds a call to ensure_full_index() so we can compare a sparse index
directly against a full index, or at least what the in-memory index
looks like when expanded in this way.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Add a new 'sparse-index' repo alongside the 'full-checkout' and
'sparse-checkout' repos in t1092-sparse-checkout-compatibility.sh. Also
add run_on_sparse and test_sparse_match helpers. These helpers will be
used when the sparse index is implemented.
Add the GIT_TEST_SPARSE_INDEX environment variable to enable the
sparse-index by default. This can be enabled across all tests, but that
will only affect cases where the sparse-checkout feature is enabled.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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This test was introduced in 19a0acc83e4 (t1092: test interesting
sparse-checkout scenarios, 2021-01-23), but it contains issues with quoting
that were not noticed until starting this follow-up series. The old
mechanism would drop quoting such as in
test_all_match git commit -m "touch README.md"
The above happened to work because README.md is a file in the
repository, so 'git commit -m touch REAMDE.md' would succeed by
accident.
Other cases included quoting for no good reason, so clean that up now.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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These also document some behaviors that differ from a full checkout, and
possibly in a way that is not intended.
The test is designed to be run with "--run=1,X" where 'X' is an
interesting test case. Each test uses 'init_repos' to reset the full and
sparse copies of the initial-repo that is created by the first test
case. This also makes it possible to have test cases leave the working
directory or index in unusual states without disturbing later cases.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Derrick Stolee
Junio C Hamano