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Author SHA1 Message Date
Michael Lohmann f3fc5d9c91 revision: implement git log --merge also for rebase/cherry-pick/revert
'git log' learned in ae3e5e1ef2 (git log -p --merge [[--] paths...],
2006-07-03) to show commits touching conflicted files in the range
HEAD...MERGE_HEAD, an addition documented in d249b45547 (Document
rev-list's option --merge, 2006-08-04).

It can be useful to look at the commit history to understand what lead
to merge conflicts also for other mergy operations besides merges, like
cherry-pick, revert and rebase.

For rebases and cherry-picks, an interesting range to look at is
HEAD...{REBASE_HEAD,CHERRY_PICK_HEAD}, since even if all the commits
included in that range are not directly part of the 3-way merge,
conflicts encountered during these operations can indeed be caused by
changes introduced in preceding commits on both sides of the history.

For revert, as we are (most likely) reversing changes from a previous
commit, an appropriate range is REVERT_HEAD..HEAD, which is equivalent
to REVERT_HEAD...HEAD and to HEAD...REVERT_HEAD, if we keep HEAD and its
parents on the left side of the range.

As such, adjust the code in prepare_show_merge so it constructs the
range HEAD...$OTHER for OTHER={MERGE_HEAD, CHERRY_PICK_HEAD, REVERT_HEAD
or REBASE_HEAD}. Note that we try these pseudorefs in order, so keep
REBASE_HEAD last since the three other operations can be performed
during a rebase. Note also that in the uncommon case where $OTHER and
HEAD do not share a common ancestor, this will show the complete
histories of both sides since their root commits, which is the same
behaviour as currently happens in that case for HEAD and MERGE_HEAD.

Adjust the documentation of this option accordingly.

Co-authored-by: Johannes Sixt <j6t@kdbg.org>
Co-authored-by: Philippe Blain <levraiphilippeblain@gmail.com>
Signed-off-by: Michael Lohmann <mi.al.lohmann@gmail.com>
[jc: tweaked in j6t's precedence fix that tries REBASE_HEAD last]
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-02-28 10:04:39 -08:00
Michael Lohmann f476143ee6 revision: ensure MERGE_HEAD is a ref in prepare_show_merge
This is done to

 (1) ensure MERGE_HEAD is a ref,
 (2) obtain the oid without any prefixing by refs.c:repo_dwim_ref()
 (3) error out when MERGE_HEAD is a symref.

Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Michael Lohmann <mi.al.lohmann@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-02-28 10:02:46 -08:00
Junio C Hamano 186b115d30 The eighth batch
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-16 10:11:58 -08:00
Junio C Hamano a57da6bfee Merge branch 'ib/rebase-reschedule-doc'
Doc update.

* ib/rebase-reschedule-doc:
  rebase: clarify --reschedule-failed-exec default
2024-01-16 10:11:58 -08:00
Junio C Hamano 4cc0f8e8fa Merge branch 'jk/commit-graph-slab-clear-fix'
Clearing in-core repository (happens during e.g., "git fetch
--recurse-submodules" with commit graph enabled) made in-core
commit object in an inconsistent state by discarding the necessary
data from commit-graph too early, which has been corrected.

* jk/commit-graph-slab-clear-fix:
  commit-graph: retain commit slab when closing NULL commit_graph
2024-01-16 10:11:58 -08:00
Junio C Hamano b27f67aa93 Merge branch 'jk/index-pack-lsan-false-positive-fix'
Fix false positive reported by leak sanitizer.

* jk/index-pack-lsan-false-positive-fix:
  index-pack: spawn threads atomically
2024-01-16 10:11:58 -08:00
Junio C Hamano 6484eb9a97 Merge branch 'cp/sideband-array-index-comment-fix'
In-code comment fix.

* cp/sideband-array-index-comment-fix:
  sideband.c: remove redundant 'NEEDSWORK' tag
2024-01-16 10:11:57 -08:00
Junio C Hamano 32c6fc3e30 Merge branch 'ps/refstorage-extension'
Introduce a new extension "refstorage" so that we can mark a
repository that uses a non-default ref backend, like reftable.

* ps/refstorage-extension:
  t9500: write "extensions.refstorage" into config
  builtin/clone: introduce `--ref-format=` value flag
  builtin/init: introduce `--ref-format=` value flag
  builtin/rev-parse: introduce `--show-ref-format` flag
  t: introduce GIT_TEST_DEFAULT_REF_FORMAT envvar
  setup: introduce GIT_DEFAULT_REF_FORMAT envvar
  setup: introduce "extensions.refStorage" extension
  setup: set repository's formats on init
  setup: start tracking ref storage format
  refs: refactor logic to look up storage backends
  worktree: skip reading HEAD when repairing worktrees
  t: introduce DEFAULT_REPO_FORMAT prereq
2024-01-16 10:11:57 -08:00
Junio C Hamano 481d69dd63 Merge branch 'ps/reftable-fixes-and-optims'
More fixes and optimizations to the reftable backend.

* ps/reftable-fixes-and-optims:
  reftable/merged: transfer ownership of records when iterating
  reftable/merged: really reuse buffers to compute record keys
  reftable/record: store "val2" hashes as static arrays
  reftable/record: store "val1" hashes as static arrays
  reftable/record: constify some parts of the interface
  reftable/writer: fix index corruption when writing multiple indices
  reftable/stack: do not auto-compact twice in `reftable_stack_add()`
  reftable/stack: do not overwrite errors when compacting
2024-01-16 10:11:57 -08:00
Junio C Hamano d4dbce1db5 The seventh batch
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-12 16:09:57 -08:00
Junio C Hamano b3049bbb97 Merge branch 'cp/git-flush-is-an-env-bool'
Unlike other environment variables that took the usual
true/false/yes/no as well as 0/1, GIT_FLUSH only understood 0/1,
which has been corrected.

* cp/git-flush-is-an-env-bool:
  write-or-die: make GIT_FLUSH a Boolean environment variable
2024-01-12 16:09:57 -08:00
Junio C Hamano 566471105c Merge branch 'ms/rebase-insnformat-doc-fix'
Docfix.

* ms/rebase-insnformat-doc-fix:
  Documentation: fix statement about rebase.instructionFormat
2024-01-12 16:09:57 -08:00
Junio C Hamano 15df15fe07 Merge branch 'jx/sideband-chomp-newline-fix'
Sideband demultiplexer fixes.

* jx/sideband-chomp-newline-fix:
  pkt-line: do not chomp newlines for sideband messages
  pkt-line: memorize sideband fragment in reader
  test-pkt-line: add option parser for unpack-sideband
2024-01-12 16:09:56 -08:00
Junio C Hamano 0fea6b73f1 Merge branch 'tb/multi-pack-verbatim-reuse'
Streaming spans of packfile data used to be done only from a
single, primary, pack in a repository with multiple packfiles.  It
has been extended to allow reuse from other packfiles, too.

* tb/multi-pack-verbatim-reuse: (26 commits)
  t/perf: add performance tests for multi-pack reuse
  pack-bitmap: enable reuse from all bitmapped packs
  pack-objects: allow setting `pack.allowPackReuse` to "single"
  t/test-lib-functions.sh: implement `test_trace2_data` helper
  pack-objects: add tracing for various packfile metrics
  pack-bitmap: prepare to mark objects from multiple packs for reuse
  pack-revindex: implement `midx_pair_to_pack_pos()`
  pack-revindex: factor out `midx_key_to_pack_pos()` helper
  midx: implement `midx_preferred_pack()`
  git-compat-util.h: implement checked size_t to uint32_t conversion
  pack-objects: include number of packs reused in output
  pack-objects: prepare `write_reused_pack_verbatim()` for multi-pack reuse
  pack-objects: prepare `write_reused_pack()` for multi-pack reuse
  pack-objects: pass `bitmapped_pack`'s to pack-reuse functions
  pack-objects: keep track of `pack_start` for each reuse pack
  pack-objects: parameterize pack-reuse routines over a single pack
  pack-bitmap: return multiple packs via `reuse_partial_packfile_from_bitmap()`
  pack-bitmap: simplify `reuse_partial_packfile_from_bitmap()` signature
  ewah: implement `bitmap_is_empty()`
  pack-bitmap: pass `bitmapped_pack` struct to pack-reuse functions
  ...
2024-01-12 16:09:56 -08:00
Junio C Hamano 0ebbaa07d0 Merge branch 'jk/t1006-cat-file-objectsize-disk'
Test update.

* jk/t1006-cat-file-objectsize-disk:
  t1006: prefer shell loop to awk for packed object sizes
  t1006: add tests for %(objectsize:disk)
2024-01-12 16:09:56 -08:00
Junio C Hamano 3e8558438d Merge branch 'jw/builtin-objectmode-attr'
The builtin_objectmode attribute is populated for each path
without adding anything in .gitattributes files, which would be
useful in magic pathspec, e.g., ":(attr:builtin_objectmode=100755)"
to limit to executables.

* jw/builtin-objectmode-attr:
  attr: add builtin objectmode values support
2024-01-12 16:09:55 -08:00
Junio C Hamano 99bb88a6f6 Merge branch 'js/contributor-docs-updates'
Doc update.

* js/contributor-docs-updates:
  SubmittingPatches: hyphenate non-ASCII
  SubmittingPatches: clarify GitHub artifact format
  SubmittingPatches: clarify GitHub visual
  SubmittingPatches: provide tag naming advice
  SubmittingPatches: update extra tags list
  SubmittingPatches: discourage new trailers
  SubmittingPatches: drop ref to "What's in git.git"
  CodingGuidelines: write punctuation marks
  CodingGuidelines: move period inside parentheses
2024-01-12 16:09:55 -08:00
Junio C Hamano a54a84b333 The sixth batch
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-08 14:05:24 -08:00
Junio C Hamano bdfa7a2445 Merge branch 'rs/mem-pool-improvements'
MemPool allocator fixes.

* rs/mem-pool-improvements:
  mem-pool: simplify alignment calculation
  mem-pool: fix big allocations
2024-01-08 14:05:17 -08:00
Junio C Hamano 8a48cd484f Merge branch 'rs/fast-import-simplify-mempool-allocation'
Code simplification.

* rs/fast-import-simplify-mempool-allocation:
  fast-import: use mem_pool_calloc()
2024-01-08 14:05:16 -08:00
Junio C Hamano d73db002b5 Merge branch 'en/sparse-checkout-eoo'
"git sparse-checkout (add|set) --[no-]cone --end-of-options" did
not handle "--end-of-options" correctly after a recent update.

* en/sparse-checkout-eoo:
  sparse-checkout: be consistent with end of options markers
2024-01-08 14:05:16 -08:00
Junio C Hamano 863c596e68 Merge branch 'jc/sparse-checkout-set-default-fix'
"git sparse-checkout set" added default patterns even when the
patterns are being fed from the standard input, which has been
corrected.

* jc/sparse-checkout-set-default-fix:
  sparse-checkout: use default patterns for 'set' only !stdin
2024-01-08 14:05:16 -08:00
Junio C Hamano 492ee03f60 Merge branch 'en/header-cleanup'
Remove unused header "#include".

* en/header-cleanup:
  treewide: remove unnecessary includes in source files
  treewide: add direct includes currently only pulled in transitively
  trace2/tr2_tls.h: remove unnecessary include
  submodule-config.h: remove unnecessary include
  pkt-line.h: remove unnecessary include
  line-log.h: remove unnecessary include
  http.h: remove unnecessary include
  fsmonitor--daemon.h: remove unnecessary includes
  blame.h: remove unnecessary includes
  archive.h: remove unnecessary include
  treewide: remove unnecessary includes in source files
  treewide: remove unnecessary includes from header files
2024-01-08 14:05:15 -08:00
Junio C Hamano 9decd56cc9 Merge branch 'ml/doc-merge-updates'
Doc update.

* ml/doc-merge-updates:
  Documentation/git-merge.txt: use backticks for command wrapping
  Documentation/git-merge.txt: fix reference to synopsis
2024-01-08 14:05:15 -08:00
Junio C Hamano 6bf317df4b Merge branch 'jc/archive-list-with-extra-args'
"git archive --list extra garbage" silently ignored excess command
line parameters, which has been corrected.

* jc/archive-list-with-extra-args:
  archive: "--list" does not take further options
2024-01-08 14:05:14 -08:00
Illia Bobyr 25aec06326 rebase: clarify --reschedule-failed-exec default
Documentation should mention the default behavior.

It is better to explain the persistent nature of the
--reschedule-failed-exec flag from the user standpoint, rather than from
the implementation standpoint.

Signed-off-by: Illia Bobyr <illia.bobyr@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-05 09:41:25 -08:00
Jeff King 993d38a066 index-pack: spawn threads atomically
The t5309 script triggers a racy false positive with SANITIZE=leak on a
multi-core system. Running with "--stress --run=6" usually fails within
10 seconds or so for me, complaining with something like:

    + git index-pack --fix-thin --stdin
    fatal: REF_DELTA at offset 46 already resolved (duplicate base 01d7713666f4de822776c7622c10f1b07de280dc?)

    =================================================================
    ==3904583==ERROR: LeakSanitizer: detected memory leaks

    Direct leak of 32 byte(s) in 1 object(s) allocated from:
        #0 0x7fa790d01986 in __interceptor_realloc ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:98
        #1 0x7fa790add769 in __pthread_getattr_np nptl/pthread_getattr_np.c:180
        #2 0x7fa790d117c5 in __sanitizer::GetThreadStackTopAndBottom(bool, unsigned long*, unsigned long*) ../../../../src/libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cpp:150
        #3 0x7fa790d11957 in __sanitizer::GetThreadStackAndTls(bool, unsigned long*, unsigned long*, unsigned long*, unsigned long*) ../../../../src/libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cpp:598
        #4 0x7fa790d03fe8 in __lsan::ThreadStart(unsigned int, unsigned long long, __sanitizer::ThreadType) ../../../../src/libsanitizer/lsan/lsan_posix.cpp:51
        #5 0x7fa790d013fd in __lsan_thread_start_func ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:440
        #6 0x7fa790adc3eb in start_thread nptl/pthread_create.c:444
        #7 0x7fa790b5ca5b in clone3 ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81

    SUMMARY: LeakSanitizer: 32 byte(s) leaked in 1 allocation(s).
    Aborted

What happens is this:

  0. We construct a bogus pack with a duplicate object in it and trigger
     index-pack.

  1. We spawn a bunch of worker threads to resolve deltas (on my system
     it is 16 threads).

  2. One of the threads sees the duplicate object and bails by calling
     exit(), taking down all of the threads. This is expected and is the
     point of the test.

  3. At the time exit() is called, we may still be spawning threads from
     the main process via pthread_create(). LSan hooks thread creation
     to update its book-keeping; it has to know where each thread's
     stack is (so it can find entry points for reachable memory). So it
     calls pthread_getattr_np() to get information about the new thread.
     That may allocate memory that must be freed with a matching call to
     pthread_attr_destroy(). Probably LSan does that immediately, but
     if you're unlucky enough, the exit() will happen while it's between
     those two calls, and the allocated pthread_attr_t appears as a
     leak.

This isn't a real leak. It's not even in our code, but rather in the
LSan instrumentation code. So we could just ignore it. But the false
positive can cause people to waste time tracking it down.

It's possibly something that LSan could protect against (e.g., cover the
getattr/destroy pair with a mutex, and then in the final post-exit()
check for leaks try to take the same mutex). But I don't know enough
about LSan to say if that's a reasonable approach or not (or if my
analysis is even completely correct).

In the meantime, it's pretty easy to avoid the race by making creation
of the worker threads "atomic". That is, we'll spawn all of them before
letting any of them start to work. That's easy to do because we already
have a work_lock() mutex for handing out that work. If the main process
takes it, then all of the threads will immediately block until we've
finished spawning and released it.

This shouldn't make any practical difference for non-LSan runs. The
thread spawning is quick, and could happen before any worker thread gets
scheduled anyway.

Probably other spots that use threads are subject to the same issues.
But since we have to manually insert locking (and since this really is
kind of a hack), let's not bother with them unless somebody experiences
a similar racy false-positive in practice.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-05 08:40:56 -08:00
Jeff King d70f554cdf commit-graph: retain commit slab when closing NULL commit_graph
This fixes a regression introduced in ac6d45d11f (commit-graph: move
slab-clearing to close_commit_graph(), 2023-10-03), in which running:

  git -c fetch.writeCommitGraph=true fetch --recurse-submodules

multiple times in a freshly cloned repository causes a segfault. What
happens in the second (and subsequent) runs is this:

  1. We make a "struct commit" for any ref tips which we're storing
     (even if we already have them, they still go into FETCH_HEAD).

     Because the first run will have created a commit graph, we'll find
     those commits in the graph.

     The commit struct is therefore created with a NULL "maybe_tree"
     entry, because we can load its oid from the graph later. But to do
     that we need to remember that we got the commit from the graph,
     which is recorded in a global commit_graph_data_slab object.

  2. Because we're using --recurse-submodules, we'll try to fetch each
     of the possible submodules. That implies creating a separate
     "struct repository" in-process for each submodule, which will
     require a later call to repo_clear().

     The call to repo_clear() calls raw_object_store_clear(), which in
     turn calls close_object_store(), which in turn calls
     close_commit_graph(). And the latter frees the commit graph data
     slab.

  3. Later, when trying to write out a new commit graph, we'll ask for
     their tree oid via get_commit_tree_oid(), which will see that the
     object is parsed but with a NULL maybe_tree field. We'd then
     usually pull it from the graph file, but because the slab was
     cleared, we don't realize that we can do so! We end up returning
     NULL and segfaulting.

     (It seems questionable that we'd write a graph entry for such a
     commit anyway, since we know we already have one. I didn't
     double-check, but that may simply be another side effect of having
     cleared the slab).

The bug is in step (2) above. We should not be clearing the slab when
cleaning up the submodule repository structs. Prior to ac6d45d11f, we
did not do so because it was done inside a helper function that returned
early when it saw NULL. So the behavior change from that commit is that
we'll now _always_ clear the slab via repo_clear(), even if the
repository being closed did not have a commit graph (and thus would have
a NULL commit_graph struct).

The most immediate fix is to add in a NULL check in close_commit_graph(),
making it a true noop when passed in an object_store with a NULL
commit_graph (it's OK to just return early, since the rest of its code
is already a noop when passed NULL). That restores the pre-ac6d45d11f
behavior. And that's what this patch does, along with a test that
exercises it (we already have a test that uses submodules along with
fetch.writeCommitGraph, but the bug only triggers when there is a
subsequent fetch and when that fetch uses --recurse-submodules).

So that fixes the regression in the least-risky way possible.

I do think there's some fragility here that we might want to follow up
on. We have a global commit_graph_data_slab that contains graph
positions, and our global commit structs depend on the that slab
remaining valid. But close_commit_graph() is just about closing _one_
object store's graph. So it's dangerous to call that function and clear
the slab without also throwing away any "struct commit" we might have
parsed that depends on it.

Which at first glance seems like a bug we could already trigger. In the
situation described here, there is no commit graph in the submodule
repository, so our commit graph is NULL (in fact, in our test script
there is no submodule repo at all, so we immediately return from
repo_init() and call repo_clear() only to free up memory). But what
would happen if there was one? Wouldn't we see a non-NULL commit_graph
entry, and then clear the global slab anyway?

The answer is "no", but for very bizarre reasons. Remember that
repo_clear() calls raw_object_store_clear(), which then calls
close_object_store() and thus close_commit_graph(). But before it does
so, raw_object_store_clear() does something else: it frees the commit
graph and sets it to NULL! So by this code path we'll _never_ see a
non-NULL commit_graph struct, and thus never clear the slab.

So it happens to work out. But it still seems questionable to me that we
would clear a global slab (which might still be in use) when closing the
commit graph. This clearing comes from 957ba814bf (commit-graph: when
closing the graph, also release the slab, 2021-09-08), and was fixing a
case where we really did need it to be closed (and in that case we
presumably call close_object_store() more directly).

So I suspect there may still be a bug waiting to happen there, as any
object loaded before the call to close_object_store() may be stranded
with a bogus maybe_tree entry (and thus looking at it after the call
might cause an error). But I'm not sure how to trigger it, nor what the
fix should look like (you probably would need to "unparse" any objects
pulled from the graph). And so this patch punts on that for now in favor
of fixing the recent regression in the most direct way, which should not
have any other fallouts.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-05 08:35:26 -08:00
Chandra Pratap 556e68032f write-or-die: make GIT_FLUSH a Boolean environment variable
Among Git's environment variables, the ones marked as "Boolean"
accept values in a way similar to Boolean configuration variables,
i.e. values like 'yes', 'on', 'true' and positive numbers are
taken as "on" and values like 'no', 'off', 'false' are taken as
"off".

GIT_FLUSH can be used to force Git to use non-buffered I/O when
writing to stdout. It can only accept two values, '1' which causes
Git to flush more often and '0' which makes all output buffered.
Make GIT_FLUSH accept more values besides '0' and '1' by turning it
into a Boolean environment variable, modifying the required logic.
Update the related documentation.

Signed-off-by: Chandra Pratap <chandrapratap3519@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-04 10:32:21 -08:00
Maarten van der Schrieck 9cd30af991 Documentation: fix statement about rebase.instructionFormat
Since commit 62db5247 (rebase -i: generate the script via
rebase--helper, 2017-07-14), the short hash is given in
rebase-todo. Specifying rebase.instructionFormat does not alter this
behavior, contrary to what the documentation implies.

Signed-off-by: Maarten van der Schrieck <maarten@thingsconnected.nl>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-03 11:21:15 -08:00
Patrick Steinhardt 19b9496c1f reftable/merged: transfer ownership of records when iterating
When iterating over records with the merged iterator we put the records
into a priority queue before yielding them to the caller. This means
that we need to allocate the contents of these records before we can
pass them over to the caller.

The handover to the caller is quite inefficient though because we first
deallocate the record passed in by the caller and then copy over the new
record, which requires us to reallocate memory.

Refactor the code to instead transfer ownership of the new record to the
caller. So instead of reallocating all contents, we now release the old
record and then copy contents of the new record into place.

The following benchmark of `git show-ref --quiet` in a repository with
around 350k refs shows a clear improvement. Before:

    HEAP SUMMARY:
        in use at exit: 21,163 bytes in 193 blocks
      total heap usage: 708,058 allocs, 707,865 frees, 36,783,255 bytes allocated

After:

    HEAP SUMMARY:
        in use at exit: 21,163 bytes in 193 blocks
      total heap usage: 357,007 allocs, 356,814 frees, 24,193,602 bytes allocated

This shows that we now have roundabout a single allocation per record
that we're yielding from the iterator. Ideally, we'd also get rid of
this allocation so that the number of allocations doesn't scale with the
number of refs anymore. This would require some larger surgery though
because the memory is owned by the priority queue before transferring it
over to the caller.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-03 09:54:21 -08:00
Patrick Steinhardt 5473aca376 reftable/merged: really reuse buffers to compute record keys
In 829231dc20 (reftable/merged: reuse buffer to compute record keys,
2023-12-11), we have refactored the merged iterator to reuse a pair of
long-living strbufs by relying on the fact that `reftable_record_key()`
tries to reuse already allocated strbufs by calling `strbuf_reset()`,
which should give us significantly fewer reallocations compared to the
old code that used on-stack strbufs that are allocated for each and
every iteration. Unfortunately, we called `strbuf_release()` on these
long-living strbufs that we meant to reuse on each iteration, defeating
the optimization.

Fix this performance issue by not releasing those buffers on iteration
anymore, where we instead rely on `merged_iter_close()` to release the
buffers for us.

Using `git show-ref --quiet` in a repository with ~350k refs this leads
to a significant drop in allocations. Before:

    HEAP SUMMARY:
        in use at exit: 21,163 bytes in 193 blocks
      total heap usage: 1,410,148 allocs, 1,409,955 frees, 61,976,068 bytes allocated

After:

    HEAP SUMMARY:
        in use at exit: 21,163 bytes in 193 blocks
      total heap usage: 708,058 allocs, 707,865 frees, 36,783,255 bytes allocated

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-03 09:54:21 -08:00
Patrick Steinhardt b31e3cc620 reftable/record: store "val2" hashes as static arrays
Similar to the preceding commit, convert ref records of type "val2" to
store their object IDs in static arrays instead of allocating them for
every single record.

We're using the same benchmark as in the preceding commit, with `git
show-ref --quiet` in a repository with ~350k refs. This time around
though the effects aren't this huge. Before:

    HEAP SUMMARY:
        in use at exit: 21,163 bytes in 193 blocks
      total heap usage: 1,419,040 allocs, 1,418,847 frees, 62,153,868 bytes allocated

After:

    HEAP SUMMARY:
        in use at exit: 21,163 bytes in 193 blocks
      total heap usage: 1,410,148 allocs, 1,409,955 frees, 61,976,068 bytes allocated

This is because "val2"-type records are typically only stored for peeled
tags, and the number of annotated tags in the benchmark repository is
rather low. Still, it can be seen that this change leads to a reduction
of allocations overall, even if only a small one.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-03 09:54:21 -08:00
Patrick Steinhardt 7af607c58d reftable/record: store "val1" hashes as static arrays
When reading ref records of type "val1", we store its object ID in an
allocated array. This results in an additional allocation for every
single ref record we read, which is rather inefficient especially when
iterating over refs.

Refactor the code to instead use an embedded array of `GIT_MAX_RAWSZ`
bytes. While this means that `struct ref_record` is bigger now, we
typically do not store all refs in an array anyway and instead only
handle a limited number of records at the same point in time.

Using `git show-ref --quiet` in a repository with ~350k refs this leads
to a significant drop in allocations. Before:

    HEAP SUMMARY:
        in use at exit: 21,098 bytes in 192 blocks
      total heap usage: 2,116,683 allocs, 2,116,491 frees, 76,098,060 bytes allocated

After:

    HEAP SUMMARY:
        in use at exit: 21,098 bytes in 192 blocks
      total heap usage: 1,419,031 allocs, 1,418,839 frees, 62,145,036 bytes allocated

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-03 09:54:20 -08:00
Patrick Steinhardt 88f59d9e31 reftable/record: constify some parts of the interface
We're about to convert reftable records to stop storing their object IDs
as allocated hashes. Prepare for this refactoring by constifying some
parts of the interface that will be impacted by this.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-03 09:54:20 -08:00
Patrick Steinhardt ddac965965 reftable/writer: fix index corruption when writing multiple indices
Each reftable may contain multiple types of blocks for refs, objects and
reflog records, where each of these may have an index that makes it more
efficient to find the records. It was observed that the index for log
records can become corrupted under certain circumstances, where the
first entry of the index points into the object index instead of to the
log records.

As it turns out, this corruption can occur whenever we write a log index
as well as at least one additional index. Writing records and their index
is basically a two-step process:

  1. We write all blocks for the corresponding record. Each block that
     gets written is added to a list of blocks to index.

  2. Once all blocks were written we finish the section. If at least two
     blocks have been added to the list of blocks to index then we will
     now write the index for those blocks and flush it, as well.

When we have a very large number of blocks then we may decide to write a
multi-level index, which is why we also keep track of the list of the
index blocks in the same way as we previously kept track of the blocks
to index.

Now when we have finished writing all index blocks we clear the index
and flush the last block to disk. This is done in the wrong order though
because flushing the block to disk will re-add it to the list of blocks
to be indexed. The result is that the next section we are about to write
will have an entry in the list of blocks to index that points to the
last block of the preceding section's index, which will corrupt the log
index.

Fix this corruption by clearing the index after having written the last
block.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-03 09:54:20 -08:00
Patrick Steinhardt 75d790608f reftable/stack: do not auto-compact twice in reftable_stack_add()
In 5c086453ff (reftable/stack: perform auto-compaction with
transactional interface, 2023-12-11), we fixed a bug where the
transactional interface to add changes to a reftable stack did not
perform auto-compaction by calling `reftable_stack_auto_compact()` in
`reftable_stack_addition_commit()`. While correct, this change may now
cause us to perform auto-compaction twice in the non-transactional
interface `reftable_stack_add()`:

  - It performs auto-compaction by itself.

  - It now transitively performs auto-compaction via the transactional
    interface.

Remove the first instance so that we only end up doing auto-compaction
once.

Reported-by: Han-Wen Nienhuys <hanwenn@gmail.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-03 09:54:20 -08:00
Patrick Steinhardt d26c21483d reftable/stack: do not overwrite errors when compacting
In order to compact multiple stacks we iterate through the merged ref
and log records. When there is any error either when reading the records
from the old merged table or when writing the records to the new table
then we break out of the respective loops. When breaking out of the loop
for the ref records though the error code will be overwritten, which may
cause us to inadvertently skip over bad ref records. In the worst case,
this can lead to a compacted stack that is missing records.

Fix the code by using `goto done` instead so that any potential error
codes are properly returned to the caller.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-03 09:54:20 -08:00
René Scharfe 54d8a2531b t1006: prefer shell loop to awk for packed object sizes
To compute the expected on-disk size of packed objects, we sort the
output of show-index by pack offset and then compute the difference
between adjacent entries using awk. This works but has a few readability
problems:

  1. Reading the index in pack order means don't find out the size of an
     oid's entry until we see the _next_ entry. So we have to save it to
     print later.

     We can instead iterate in reverse order, so we compute each oid's
     size as we see it.

  2. Since the awk invocation is inside a text_expect block, we can't
     easily use single-quotes to hold the script. So we use
     double-quotes, but then have to escape the dollar signs in the awk
     script.

     We can swap this out for a shell loop instead (which is made much
     easier by the first change).

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-03 09:26:53 -08:00
Junio C Hamano a26002b628 The fifth batch
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-02 13:51:30 -08:00
Junio C Hamano dbf668a1b7 Merge branch 'ps/pseudo-refs'
Assorted changes around pseudoref handling.

* ps/pseudo-refs:
  bisect: consistently write BISECT_EXPECTED_REV via the refdb
  refs: complete list of special refs
  refs: propagate errno when reading special refs fails
  wt-status: read HEAD and ORIG_HEAD via the refdb
2024-01-02 13:51:30 -08:00
Junio C Hamano 601b1571e8 Merge branch 'jc/orphan-unborn'
Doc updates to clarify what an "unborn branch" means.

* jc/orphan-unborn:
  orphan/unborn: fix use of 'orphan' in end-user facing messages
  orphan/unborn: add to the glossary and use them consistently
2024-01-02 13:51:30 -08:00
Junio C Hamano cce4778520 Merge branch 'rj/status-bisect-while-rebase'
"git status" is taught to show both the branch being bisected and
being rebased when both are in effect at the same time.

* rj/status-bisect-while-rebase:
  status: fix branch shown when not only bisecting
2024-01-02 13:51:29 -08:00
Junio C Hamano 59a29e1274 Merge branch 'la/trailer-cleanups'
Code clean-up.

* la/trailer-cleanups:
  trailer: use offsets for trailer_start/trailer_end
  trailer: find the end of the log message
  commit: ignore_non_trailer computes number of bytes to ignore
2024-01-02 13:51:29 -08:00
Junio C Hamano 43ec879169 Merge branch 'jc/retire-cas-opt-name-constant'
Code clean-up.

* jc/retire-cas-opt-name-constant:
  remote.h: retire CAS_OPT_NAME
2024-01-02 13:51:29 -08:00
Junio C Hamano 9cc710098b Merge branch 'rs/rebase-use-strvec-pushf'
Code clean-up.

* rs/rebase-use-strvec-pushf:
  rebase: use strvec_pushf() for format-patch revisions
2024-01-02 13:51:29 -08:00
Junio C Hamano 72e6a61c40 Merge branch 'sh/completion-with-reftable'
Command line completion script (in contrib/) learned to work better
with the reftable backend.

* sh/completion-with-reftable:
  completion: support pseudoref existence checks for reftables
  completion: refactor existence checks for pseudorefs
2024-01-02 13:51:28 -08:00
Patrick Steinhardt 1b2234079b t9500: write "extensions.refstorage" into config
In t9500 we're writing a custom configuration that sets up gitweb. This
requires us to manually ensure that the repository format is configured
as required, including both the repository format version and
extensions. With the introduction of the "extensions.refStorage"
extension we need to update the test to also write this new one.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-02 09:24:49 -08:00
Patrick Steinhardt 5ed860f51b builtin/clone: introduce --ref-format= value flag
Introduce a new `--ref-format` value flag for git-clone(1) that allows
the user to specify the ref format that is to be used for a newly
initialized repository.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-02 09:24:48 -08:00
Patrick Steinhardt 48fa45f5fb builtin/init: introduce --ref-format= value flag
Introduce a new `--ref-format` value flag for git-init(1) that allows
the user to specify the ref format that is to be used for a newly
initialized repository.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-02 09:24:48 -08:00