The code to iterate over refs with the reftable backend has seen
some optimization.
* ps/reftable-iteration-perf-part2:
refs/reftable: precompute prefix length
reftable: allow inlining of a few functions
reftable/record: decode keys in place
reftable/record: reuse refname when copying
reftable/record: reuse refname when decoding
reftable/merged: avoid duplicate pqueue emptiness check
reftable/merged: circumvent pqueue with single subiter
reftable/merged: handle subiter cleanup on close only
reftable/merged: remove unnecessary null check for subiters
reftable/merged: make subiters own their records
reftable/merged: advance subiter on subsequent iteration
reftable/merged: make `merged_iter` structure private
reftable/pq: use `size_t` to track iterator index
The implementation in "git clean" that makes "-n" and "-i" ignore
clean.requireForce has been simplified, together with the
documentation.
* so/clean-dry-run-without-force:
clean: further clean-up of implementation around "--force"
clean: improve -n and -f implementation and documentation
Code simplification to one unit-test program.
* rs/t-ctype-simplify:
t-ctype: avoid duplicating class names
t-ctype: align output of i
t-ctype: simplify EOF check
t-ctype: allow NUL anywhere in the specification string
In 24876ebf68 (commit-reach(repo_in_merge_bases_many): report missing
commits, 2024-02-28), I taught `merge_submodule()` to handle errors
reported by `repo_in_merge_bases_many()`.
However, those errors were not passed through to the callers. That was
unintentional, and this commit remedies that.
Note that `find_first_merges()` can now also return -1 (because it
passes through that return value from `repo_in_merge_bases()`), and this
commit also adds the forgotten handling for that scenario.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Acked-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The `merge_submodule()` function returns an integer that indicates
whether the merge was clean (returning 1) or unclean (returning 0).
Like the version in `merge-ort.c`, the version in `merge-recursive.c`
does not report any errors (such as repository corruption) by returning
-1 as of time of writing, even if the callers in `merge-ort.c` are
prepared for exactly such errors.
However, we want to teach (both variants of) the `merge_submodule()`
function that trick: to report errors by returning -1. Therefore,
prepare the caller in `merge-recursive.c` to handle that scenario.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Acked-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The upload-pack program, when talking over v2, accepted the
packfile-uris protocol extension from the client, even if it did
not advertise the capability, which has been corrected.
* jk/upload-pack-v2-capability-cleanup:
upload-pack: only accept packfile-uris if we advertised it
upload-pack: use existing config mechanism for advertisement
upload-pack: centralize setup of sideband-all config
upload-pack: use repository struct to get config
Various parts of upload-pack has been updated to bound the resource
consumption relative to the size of the repository to protect from
abusive clients.
* jk/upload-pack-bounded-resources:
upload-pack: free tree buffers after parsing
upload-pack: use PARSE_OBJECT_SKIP_HASH_CHECK in more places
upload-pack: always turn off save_commit_buffer
upload-pack: disallow object-info capability by default
upload-pack: accept only a single packfile-uri line
upload-pack: use a strmap for want-ref lines
upload-pack: use oidset for deepen_not list
upload-pack: switch deepen-not list to an oid_array
upload-pack: drop separate v2 "haves" array
Clear the fallout from a fix for 2.44 regression.
* ps/reftable-repo-init-fix:
t0610: remove unused variable assignment
refs/reftable: don't fail empty transactions in repo without HEAD
A custom remote helper no longer cannot access the newly created
repository during "git clone", which is a regression in Git 2.44.
This has been corrected.
* ps/remote-helper-repo-initialization-fix:
builtin/clone: allow remote helpers to detect repo
"git log --merge" learned to pay attention to CHERRY_PICK_HEAD and
other kinds of *_HEAD pseudorefs.
* ml/log-merge-with-cherry-pick-and-other-pseudo-heads:
revision: implement `git log --merge` also for rebase/cherry-pick/revert
revision: ensure MERGE_HEAD is a ref in prepare_show_merge
"git commit -v --cleanup=scissors" used to add the scissors line
twice in the log message buffer, which has been corrected.
* jt/commit-redundant-scissors-fix:
commit: unify logic to avoid multiple scissors lines when merging
commit: avoid redundant scissor line with --cleanup=scissors -v
"git merge-tree" has learned that the three trees involved in the
3-way merge only need to be trees, not necessarily commits.
* js/merge-tree-3-trees:
fill_tree_descriptor(): mark error message for translation
cache-tree: avoid an unnecessary check
Always check `parse_tree*()`'s return value
t4301: verify that merge-tree fails on missing blob objects
merge-ort: do check `parse_tree()`'s return value
merge-tree: fail with a non-zero exit code on missing tree objects
merge-tree: accept 3 trees as arguments
"git rev-list --missing=print" has learned to optionally take
"--allow-missing-tips", which allows the objects at the starting
points to be missing.
* cc/rev-list-allow-missing-tips:
revision: fix --missing=[print|allow*] for annotated tags
rev-list: allow missing tips with --missing=[print|allow*]
t6022: fix 'test' style and 'even though' typo
oidset: refactor oidset_insert_from_set()
revision: clarify a 'return NULL' in get_reference()
"git --no-lazy-fetch cmd" allows to run "cmd" while disabling lazy
fetching of objects from the promisor remote, which may be handy
for debugging.
* jc/no-lazy-fetch:
git: extend --no-lazy-fetch to work across subprocesses
git: document GIT_NO_REPLACE_OBJECTS environment variable
git: --no-lazy-fetch option
In b0f6b6b523 (refs/reftable: don't fail empty transactions in repo
without HEAD, 2024-02-27), we have added a new test to t0610. This test
contains a useless assignment to a variable that is never actually used.
Remove it.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Also update the DEF_VER in GIT-VERSION-GEN, which I forgot to do
earlier (it should have been done when we started the new cycle).
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git for-each-ref" learned "--include-root-refs" option to show
even the stuff outside the 'refs/' hierarchy.
* kn/for-all-refs:
for-each-ref: add new option to include root refs
ref-filter: rename 'FILTER_REFS_ALL' to 'FILTER_REFS_REGULAR'
refs: introduce `refs_for_each_include_root_refs()`
refs: extract out `loose_fill_ref_dir_regular_file()`
refs: introduce `is_pseudoref()` and `is_headref()`
When a merge conflicted at a submodule, merge-ort backend used to
unconditionally give a lengthy message to suggest how to resolve
it. Now the message can be squelched as an advice message.
* pb/ort-make-submodule-conflict-message-an-advice:
merge-ort: turn submodule conflict suggestions into an advice
Clarify wording in the CodingGuidelines that requires <git-compat-util.h>
to be the first header file.
* jc/doc-compat-util:
doc: clarify the wording on <git-compat-util.h> requirement
An error message from "git upload-pack", which responds to "git
fetch" requests, had a trialing NUL in it, which has been
corrected.
* sg/upload-pack-error-message-fix:
upload-pack: don't send null character in abort message to the client
Many small allocations "git name-rev" makes have been updated to
allocate from a mem-pool.
* rs/name-rev-with-mempool:
name-rev: use mem_pool_strfmt()
mem-pool: add mem_pool_strfmt()
The logic to access reflog entries by date and number had ugly
corner cases at the boundaries, which have been cleaned up.
* jk/reflog-special-cases-fix:
read_ref_at(): special-case ref@{0} for an empty reflog
get_oid_basic(): special-case ref@{n} for oldest reflog entry
Revert "refs: allow @{n} to work with n-sized reflog"
The code incorrectly attempted to use textconv cache when asked,
even when we are not running in a repository, which has been
corrected.
* jk/textconv-cache-outside-repo-fix:
userdiff: skip textconv caching when not in a repository
We clarified how "clean.requireForce" interacts with the "--dry-run"
option in the previous commit, both in the implementation and in the
documentation. Even when "git clean" (without other options) is
required to be used with "--force" (i.e. either clean.requireForce
is unset, or explicitly set to true) to protect end-users from
casual invocation of the command by mistake, "--dry-run" does not
require "--force" to be used, because it is already its own
protection mechanism by being a no-op to the working tree files.
The previous commit, however, missed another clean-up opportunity
around the same area. Just like in the "--dry-run" mode, the
command in the "--interactive" mode does not require "--force",
either. This is because by going interactive and giving the end
user one more chance to confirm, the mode itself is serving as its
own protection mechanism.
Let's take things one step further, and unify the code that defines
interaction between "--force" and these two other options. Just
like we added explanation for the reason why "--dry-run" does not
honor "clean.requireForce", give an explanation for the reason why
"--interactive" makes "clean.requireForce" to be ignored.
Finally, add some tests to show the interaction between "--force"
and "--interactive". We already have tests that show interaction
between "--force" and "--dry-run", but didn't test "--interactive".
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We're recomputing the prefix length on every iteration of the ref
iterator. Precompute it for another speedup when iterating over 1
million refs:
Benchmark 1: show-ref: single matching ref (revision = HEAD~)
Time (mean ± σ): 100.3 ms ± 3.7 ms [User: 97.3 ms, System: 2.8 ms]
Range (min … max): 97.5 ms … 139.7 ms 1000 runs
Benchmark 2: show-ref: single matching ref (revision = HEAD)
Time (mean ± σ): 95.8 ms ± 3.4 ms [User: 92.9 ms, System: 2.8 ms]
Range (min … max): 93.0 ms … 121.9 ms 1000 runs
Summary
show-ref: single matching ref (revision = HEAD) ran
1.05 ± 0.05 times faster than show-ref: single matching ref (revision = HEAD~)
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We have a few functions which are basically just accessors to
structures. As those functions are executed inside the hot loop when
iterating through many refs, the fact that they cannot be inlined is
costing us some performance.
Move the function definitions into their respective headers so that they
can be inlined. This results in a performance improvement when iterating
over 1 million refs:
Benchmark 1: show-ref: single matching ref (revision = HEAD~)
Time (mean ± σ): 105.9 ms ± 3.6 ms [User: 103.0 ms, System: 2.8 ms]
Range (min … max): 103.1 ms … 133.4 ms 1000 runs
Benchmark 2: show-ref: single matching ref (revision = HEAD)
Time (mean ± σ): 100.7 ms ± 3.4 ms [User: 97.8 ms, System: 2.8 ms]
Range (min … max): 97.8 ms … 124.0 ms 1000 runs
Summary
show-ref: single matching ref (revision = HEAD) ran
1.05 ± 0.05 times faster than show-ref: single matching ref (revision = HEAD~)
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When reading a record from a block, we need to decode the record's key.
As reftable keys are prefix-compressed, meaning they reuse a prefix from
the preceding record's key, this is a bit more involved than just having
to copy the relevant bytes: we need to figure out the prefix and suffix
lengths, copy the prefix from the preceding record and finally copy the
suffix from the current record.
This is done by passing three buffers to `reftable_decode_key()`: one
buffer that holds the result, one buffer that holds the last key, and
one buffer that points to the current record. The final key is then
assembled by calling `strbuf_add()` twice to copy over the prefix and
suffix.
Performing two memory copies is inefficient though. And we can indeed do
better by decoding keys in place. Instead of providing two buffers, the
caller may only call a single buffer that is already pre-populated with
the last key. Like this, we only have to call `strbuf_setlen()` to trim
the record to its prefix and then `strbuf_add()` to add the suffix.
This refactoring leads to a noticeable performance bump when iterating
over 1 million refs:
Benchmark 1: show-ref: single matching ref (revision = HEAD~)
Time (mean ± σ): 112.2 ms ± 3.9 ms [User: 109.3 ms, System: 2.8 ms]
Range (min … max): 109.2 ms … 149.6 ms 1000 runs
Benchmark 2: show-ref: single matching ref (revision = HEAD)
Time (mean ± σ): 106.0 ms ± 3.5 ms [User: 103.2 ms, System: 2.7 ms]
Range (min … max): 103.2 ms … 133.7 ms 1000 runs
Summary
show-ref: single matching ref (revision = HEAD) ran
1.06 ± 0.05 times faster than show-ref: single matching ref (revision = HEAD~)
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Do the same optimization as in the preceding commit, but this time for
`reftable_record_copy()`. While not as noticeable, it still results in a
small speedup when iterating over 1 million refs:
Benchmark 1: show-ref: single matching ref (revision = HEAD~)
Time (mean ± σ): 114.0 ms ± 3.8 ms [User: 111.1 ms, System: 2.7 ms]
Range (min … max): 110.9 ms … 144.3 ms 1000 runs
Benchmark 2: show-ref: single matching ref (revision = HEAD)
Time (mean ± σ): 112.5 ms ± 3.7 ms [User: 109.5 ms, System: 2.8 ms]
Range (min … max): 109.2 ms … 140.7 ms 1000 runs
Summary
show-ref: single matching ref (revision = HEAD) ran
1.01 ± 0.05 times faster than show-ref: single matching ref (revision = HEAD~)
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When decoding a reftable record we will first release the user-provided
record and then decode the new record into it. This is quite inefficient
as we basically need to reallocate at least the refname every time.
Refactor the function to start tracking the refname capacity. Like this,
we can stow away the refname, release, restore and then grow the refname
to the required number of bytes via `REFTABLE_ALLOC_GROW()`.
This refactoring is safe to do because all functions that assigning to
the refname will first call `reftable_ref_record_release()`, which will
zero out the complete record after releasing memory.
This change results in a nice speedup when iterating over 1 million
refs:
Benchmark 1: show-ref: single matching ref (revision = HEAD~)
Time (mean ± σ): 124.0 ms ± 3.9 ms [User: 121.1 ms, System: 2.7 ms]
Range (min … max): 120.4 ms … 152.7 ms 1000 runs
Benchmark 2: show-ref: single matching ref (revision = HEAD)
Time (mean ± σ): 114.4 ms ± 3.7 ms [User: 111.5 ms, System: 2.7 ms]
Range (min … max): 111.0 ms … 152.1 ms 1000 runs
Summary
show-ref: single matching ref (revision = HEAD) ran
1.08 ± 0.05 times faster than show-ref: single matching ref (revision = HEAD~)
Furthermore, with this change we now perform a mostly constant number of
allocations when iterating. Before this change:
HEAP SUMMARY:
in use at exit: 13,603 bytes in 125 blocks
total heap usage: 1,006,620 allocs, 1,006,495 frees, 25,398,363 bytes allocated
After this change:
HEAP SUMMARY:
in use at exit: 13,603 bytes in 125 blocks
total heap usage: 6,623 allocs, 6,498 frees, 509,592 bytes allocated
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When calling `merged_iter_next_void()` we first check whether the iter
has been exhausted already. We already perform this check two levels
down the stack in `merged_iter_next_entry()` though, which makes this
check redundant.
Now if this check was there to accelerate the common case it might have
made sense to keep it. But the iterator being exhausted is rather the
uncommon case because you can expect most reftable stacks to contain
more than two refs.
Simplify the code by removing the check. As `merged_iter_next_void()` is
basically empty except for calling `merged_iter_next()` now, merge these
two functions. This also results in a tiny speedup when iterating over
many refs:
Benchmark 1: show-ref: single matching ref (revision = HEAD~)
Time (mean ± σ): 125.6 ms ± 3.8 ms [User: 122.7 ms, System: 2.8 ms]
Range (min … max): 122.4 ms … 153.4 ms 1000 runs
Benchmark 2: show-ref: single matching ref (revision = HEAD)
Time (mean ± σ): 124.0 ms ± 3.9 ms [User: 121.1 ms, System: 2.8 ms]
Range (min … max): 120.1 ms … 156.4 ms 1000 runs
Summary
show-ref: single matching ref (revision = HEAD) ran
1.01 ± 0.04 times faster than show-ref: single matching ref (revision = HEAD~)
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The merged iterator uses a priority queue to order records so that we
can yielid them in the expected order. This priority queue of course
comes with some overhead as we need to add, compare and remove entries
in that priority queue.
In the general case, that overhead cannot really be avoided. But when we
have a single subiter left then there is no need to use the priority
queue anymore because the order is exactly the same as what that subiter
would return.
While having a single subiter may sound like an edge case, it happens
more frequently than one might think. In the most common scenario, you
can expect a repository to have a single large table that contains most
of the records and then a set of smaller tables which contain later
additions to the reftable stack. In this case it is quite likely that we
exhaust subiters of those smaller stacks before exhausting the large
table.
Special-case this and return records directly from the remaining
subiter. This results in a sizeable speedup when iterating over 1m refs
in a repository with a single table:
Benchmark 1: show-ref: single matching ref (revision = HEAD~)
Time (mean ± σ): 135.4 ms ± 4.4 ms [User: 132.5 ms, System: 2.8 ms]
Range (min … max): 131.0 ms … 166.3 ms 1000 runs
Benchmark 2: show-ref: single matching ref (revision = HEAD)
Time (mean ± σ): 126.3 ms ± 3.9 ms [User: 123.3 ms, System: 2.8 ms]
Range (min … max): 122.7 ms … 157.0 ms 1000 runs
Summary
show-ref: single matching ref (revision = HEAD) ran
1.07 ± 0.05 times faster than show-ref: single matching ref (revision = HEAD~)
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When advancing one of the subiters fails we immediately release
resources associated with that subiter. This is not necessary though as
we will release these resources when closing the merged iterator anyway.
Drop the logic and only release resources when the merged iterator is
done. This is a mere cleanup that should help reduce the cognitive load
when reading through the code.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Whenever we advance a subiter we first call `iterator_is_null()`. This
is not needed though because we only ever advance subiters which have
entries in the priority queue, and we do not end entries to the priority
queue when the subiter has been exhausted.
Drop the check as well as the now-unused function. This results in a
surprisingly big speedup:
Benchmark 1: show-ref: single matching ref (revision = HEAD~)
Time (mean ± σ): 138.1 ms ± 4.4 ms [User: 135.1 ms, System: 2.8 ms]
Range (min … max): 133.4 ms … 167.3 ms 1000 runs
Benchmark 2: show-ref: single matching ref (revision = HEAD)
Time (mean ± σ): 134.4 ms ± 4.2 ms [User: 131.5 ms, System: 2.8 ms]
Range (min … max): 130.0 ms … 164.0 ms 1000 runs
Summary
show-ref: single matching ref (revision = HEAD) ran
1.03 ± 0.05 times faster than show-ref: single matching ref (revision = HEAD~)
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
For each subiterator, the merged table needs to track their current
record. This record is owned by the priority queue though instead of by
the merged iterator. This is not optimal performance-wise.
For one, we need to move around records whenever we add or remove a
record from the priority queue. Thus, the bigger the entries the more
bytes we need to copy around. And compared to pointers, a reftable
record is rather on the bigger side. The other issue is that this makes
it harder to reuse the records.
Refactor the code so that the merged iterator tracks ownership of the
records per-subiter. Instead of having records in the priority queue, we
can now use mere pointers to the per-subiter records. This also allows
us to swap records between the caller and the per-subiter record instead
of doing an actual copy via `reftable_record_copy_from()`, which removes
the need to release the caller-provided record.
This results in a noticeable speedup when iterating through many refs.
The following benchmark iterates through 1 million refs:
Benchmark 1: show-ref: single matching ref (revision = HEAD~)
Time (mean ± σ): 145.5 ms ± 4.5 ms [User: 142.5 ms, System: 2.8 ms]
Range (min … max): 141.3 ms … 177.0 ms 1000 runs
Benchmark 2: show-ref: single matching ref (revision = HEAD)
Time (mean ± σ): 139.0 ms ± 4.7 ms [User: 136.1 ms, System: 2.8 ms]
Range (min … max): 134.2 ms … 182.2 ms 1000 runs
Summary
show-ref: single matching ref (revision = HEAD) ran
1.05 ± 0.05 times faster than show-ref: single matching ref (revision = HEAD~)
This refactoring also allows a subsequent refactoring where we start
reusing memory allocated by the reftable records because we do not need
to release the caller-provided record anymore.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When advancing the merged iterator, we pop the topmost entry from its
priority queue and then advance the sub-iterator that the entry belongs
to, adding the result as a new entry. This is quite sensible in the case
where the merged iterator is used to actually iterate through records.
But the merged iterator is also used when we look up a single record,
only, so advancing the sub-iterator is wasted effort because we would
never even look at the result.
Instead of immediately advancing the sub-iterator, we can also defer
this to the next iteration of the merged iterator by storing the
intent-to-advance. This results in a small speedup when reading many
records. The following benchmark creates 10000 refs, which will also end
up with many ref lookups:
Benchmark 1: update-ref: create many refs (revision = HEAD~)
Time (mean ± σ): 337.2 ms ± 7.3 ms [User: 200.1 ms, System: 136.9 ms]
Range (min … max): 329.3 ms … 373.2 ms 100 runs
Benchmark 2: update-ref: create many refs (revision = HEAD)
Time (mean ± σ): 332.5 ms ± 5.9 ms [User: 197.2 ms, System: 135.1 ms]
Range (min … max): 327.6 ms … 359.8 ms 100 runs
Summary
update-ref: create many refs (revision = HEAD) ran
1.01 ± 0.03 times faster than update-ref: create many refs (revision = HEAD~)
While this speedup alone isn't really worth it, this refactoring will
also allow two additional optimizations in subsequent patches. First, it
will allow us to special-case when there is only a single sub-iter left
to circumvent the priority queue altogether. And second, it makes it
easier to avoid copying records to the caller.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The `merged_iter` structure is not used anywhere outside of "merged.c",
but is declared in its header. Move it into the code file so that it is
clear that its implementation details are never exposed to anything.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The reftable priority queue is used by the merged iterator to yield
records from its sub-iterators in the expected order. Each entry has a
record corresponding to such a sub-iterator as well as an index that
indicates which sub-iterator the record belongs to. But while the
sub-iterators are tracked with a `size_t`, we store the index as an
`int` in the entry.
Fix this and use `size_t` consistently.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
test -(e|d) does not provide a nice error message when we hit test
failures, so use test_path_exists, test_path_is_dir instead.
Signed-off-by: shejialuo <shejialuo@gmail.com>
Acked-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
