The reftable format includes support for an (OID => ref) map. This map can speed
up visibility and reachability checks. In particular, various operations along
the fetch/push path within Gerrit have ben sped up by using this structure.
The map is constructed with help of a binary tree. Object IDs are hashes, so
they are uniformly distributed. Hence, the tree does not attempt forced
rebalancing.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The reftable format is structured as a sequence of block. Within a block,
records are prefix compressed, with an index of offsets for fully expand keys to
enable binary search within blocks.
This commit provides the logic to read and write these blocks.
Helped-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This will be needed for reading reflog blocks in reftable.
Helped-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The reftable format is structured as a sequence of blocks, and each block
contains a sequence of prefix-compressed key-value records. There are 4 types of
records, and they have similarities in how they must be handled. This is
achieved by introducing a polymorphic 'record' type that encapsulates ref, log,
index and object records.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The reftable format is usually used with files for storage. However, we abstract
away this using the blocksource data structure. This has two advantages:
* log blocks are zlib compressed, and handling them is simplified if we can
discard byte segments from within the block layer.
* for unittests, it is useful to read and write in-memory. The blocksource
allows us to abstract the data away from on-disk files.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit provides basic utility classes for the reftable library.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Helped-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The reftable/ directory is structured as a library, so it cannot
crash on misuse. Instead, it returns an error code.
In addition to signaling errors, the error code can be used to signal
conditions from lower levels of the library to be handled by higher
levels of the library. For example, in a transaction we might
legitimately write an empty reftable file, but in that case, we want to
shortcut the transaction.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The objective of this code is to be usable as a C library, so it can be reused
in libgit2.
This is currently using a BSD license as it is the liberal license I could find,
but this could be changed to whatever fits the stated goal above.
This code is currently imported from github.com/hanwen/reftable. Once this code
lands in git.git, the C code will be removed from github.com/hanwen/reftable,
and the git.git code will be the source of truth.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This will simplify referencing them from code that is not deeply integrated with
Git, in particular, the reftable library.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Loading of ref tips to prepare for common ancestry negotiation in
"git fetch-pack" has been optimized by taking advantage of the
commit graph when available.
* ps/fetch-pack-load-refs-optim:
fetch-pack: speed up loading of refs via commit graph
Bugfix for common ancestor negotiation recently introduced in "git
push" code path.
* jt/push-negotiation-fixes:
fetch: die on invalid --negotiation-tip hash
send-pack: fix push nego. when remote has refs
send-pack: fix push.negotiate with remote helper
trace2 logs learned to show parent process name to see in what
context Git was invoked.
* es/trace2-log-parent-process-name:
tr2: log parent process name
tr2: make process info collection platform-generic
A handful of tests that assumed implementation details of files
backend for refs have been cleaned up.
* hn/refs-test-cleanup:
t6001: avoid direct file system access
t6500: use "ls -1" to snapshot ref database state
t7064: use update-ref -d to remove upstream branch
t1410: mark test as REFFILES
t1405: mark test for 'git pack-refs' as REFFILES
t1405: use 'git reflog exists' to check reflog existence
t2402: use ref-store test helper to create broken symlink
t3320: use git-symbolic-ref rather than filesystem access
t6120: use git-update-ref rather than filesystem access
t1503: mark symlink test as REFFILES
t6050: use git-update-ref rather than filesystem access
Final batch for "merge -sort" optimization.
* en/ort-perf-batch-15:
merge-ort: remove compile-time ability to turn off usage of memory pools
merge-ort: reuse path strings in pool_alloc_filespec
merge-ort: store filepairs and filespecs in our mem_pool
diffcore-rename, merge-ort: add wrapper functions for filepair alloc/dealloc
merge-ort: switch our strmaps over to using memory pools
merge-ort: set up a memory pool
merge-ort: add pool_alloc, pool_calloc, and pool_strndup wrappers
diffcore-rename: use a mem_pool for exact rename detection's hashmap
merge-ort: rename str{map,intmap,set}_func()
Pathname expansion (like "~username/") learned a way to specify a
location relative to Git installation (e.g. its $sharedir which is
$(prefix)/share), with "%(prefix)".
* js/expand-runtime-prefix:
expand_user_path: allow in-flight topics to keep using the old name
interpolate_path(): allow specifying paths relative to the runtime prefix
Use a better name for the function interpolating paths
expand_user_path(): clarify the role of the `real_home` parameter
expand_user_path(): remove stale part of the comment
tests: exercise the RUNTIME_PREFIX feature
Prepare the "ref-filter" machinery that drives the "--format"
option of "git for-each-ref" and its friends to be used in "git
cat-file --batch".
* zh/ref-filter-raw-data:
ref-filter: add %(rest) atom
ref-filter: use non-const ref_format in *_atom_parser()
ref-filter: --format=%(raw) support --perl
ref-filter: add %(raw) atom
ref-filter: add obj-type check in grab contents
Input validation of "git pack-objects --stdin-packs" has been
corrected.
* ab/pack-stdin-packs-fix:
pack-objects: fix segfault in --stdin-packs option
pack-objects tests: cover blindspots in stdin handling
Support for ancient versions of cURL library (pre 7.19.4) has been
dropped.
* ab/http-drop-old-curl:
http: rename CURLOPT_FILE to CURLOPT_WRITEDATA
http: drop support for curl < 7.19.3 and < 7.17.0 (again)
http: drop support for curl < 7.19.4
http: drop support for curl < 7.16.0
http: drop support for curl < 7.11.1
"git add" can work better with the sparse index.
* ds/add-with-sparse-index:
add: remove ensure_full_index() with --renormalize
add: ignore outside the sparse-checkout in refresh()
pathspec: stop calling ensure_full_index
add: allow operating on a sparse-only index
t1092: test merge conflicts outside cone
"git bisect" spawned "git show-branch" only to pretty-print the
title of the commit after checking out the next version to be
tested; this has been rewritten in C.
* jc/bisect-sans-show-branch:
bisect: simplify return code from bisect_checkout()
bisect: do not run show-branch just to show the current commit
Codepath to access recently added oidtree data structure had
to make unaligned accesses to oids, which has been corrected.
* rs/oidtree-alignment-fix:
oidtree: avoid unaligned access to crit-bit tree
Also fixed some typos reported by "git-po-helper".
Signed-off-by: Peter Krefting <peter@softwolves.pp.se>
Signed-off-by: Jiang Xin <worldhello.net@gmail.com>
The flexible array member "k" of struct cb_node is used to store the key
of the crit-bit tree node. It offers no alignment guarantees -- in fact
the current struct layout puts it one byte after a 4-byte aligned
address, i.e. guaranteed to be misaligned.
oidtree uses a struct object_id as cb_node key. Since cf0983213c (hash:
add an algo member to struct object_id, 2021-04-26) it requires 4-byte
alignment. The mismatch is reported by UndefinedBehaviorSanitizer at
runtime like this:
hash.h:277:2: runtime error: member access within misaligned address 0x00015000802d for type 'struct object_id', which requires 4 byte alignment
0x00015000802d: note: pointer points here
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
^
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior hash.h:277:2 in
We can fix that by:
1. eliminating the alignment requirement of struct object_id,
2. providing the alignment in struct cb_node, or
3. avoiding the issue by only using memcpy to access "k".
Currently we only store one of two values in "algo" in struct object_id.
We could use a uint8_t for that instead and widen it only once we add
support for our twohundredth algorithm or so. That would not only avoid
alignment issues, but also reduce the memory requirements for each
instance of struct object_id by ca. 9%.
Supporting keys with alignment requirements might be useful to spread
the use of crit-bit trees. It can be achieved by using a wider type for
"k" (e.g. uintmax_t), using different types for the members "byte" and
"otherbits" (e.g. uint16_t or uint32_t for each), or by avoiding the use
of flexible arrays like khash.h does.
This patch implements the third option, though, because it has the least
potential for causing side-effects and we're close to the next release.
If one of the other options is implemented later as well to get their
additional benefits we can get rid of the extra copies introduced here.
Reported-by: Andrzej Hunt <andrzej@ahunt.org>
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Translate 48 new messages (5230t0f0u) for git 2.33.0, and also fixed
typos found by "git-po-helper".
Signed-off-by: Jiang Xin <worldhello.net@gmail.com>
Signed-off-by: Fangyi Zhou <me@fangyi.io>
Format README.md using GFM (GitHub Flavored Markdown) syntax.
- In order to use more than 3 level headings, use ATX style headings
instead of setext style headings.
- In order to add highlights for code blocks, use fenced code blocks
instead of indented code blocks.
Signed-off-by: Jiang Xin <worldhello.net@gmail.com>
Update translation for following component:
* builtin/submodule--helper.c
Translate following new component:
* builtin/revert.c
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
