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2020-04-10rebase: generify reset_head()Denton Liu1-27/+37
In the future, we plan on lib-ifying reset_head() so we need it to be more generic. Make it more generic by making it accept a `struct repository` argument instead of implicitly using the non-repo functions. Also, make it accept a `const char *default_reflog_action` argument so that the default action of "rebase" isn't hardcoded in. Signed-off-by: Denton Liu <liu.denton@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-10rebase: use apply_autostash() from sequencer.cDenton Liu3-48/+5
The apply_autostash() function in builtin/rebase.c is similar enough to the apply_autostash() function in sequencer.c that they are almost interchangeable, except for the type of arg they accept. Make the sequencer.c version extern and use it in rebase. The rebase version was introduced in 6defce2b02 (builtin rebase: support `--autostash` option, 2018-09-04) as part of the shell to C conversion. It opted to duplicate the function because, at the time, there was another in-progress project converting interactive rebase from shell to C as well and they did not want to clash with them by refactoring sequencer.c version of apply_autostash(). Since both efforts are long done, we can freely combine them together now. Signed-off-by: Denton Liu <liu.denton@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-10sequencer: rename stash_sha1 to stash_oidDenton Liu1-8/+8
The preferred terminology is to refer to object identifiers as "OIDs". Rename the `stash_sha1` variable to `stash_oid` in order to conform to this. Signed-off-by: Denton Liu <liu.denton@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-10sequencer: make apply_autostash() accept a pathDenton Liu1-7/+7
In order to make apply_autostash() more generic for future extraction, make it accept a `path` argument so that the location from where to read the reference to the autostash commit can be customized. Remove the `opts` argument since it was unused before anyway. Signed-off-by: Denton Liu <liu.denton@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-10rebase: use read_oneliner()Denton Liu1-20/+17
Since in sequencer.c, read_one() basically duplicates the functionality of read_oneliner(), reduce code duplication by replacing read_one() with read_oneliner(). This was done with the following Coccinelle script @@ expression a, b; @@ - read_one(a, b) + !read_oneliner(b, a, READ_ONELINER_WARN_MISSING) and long lines were manually broken up. Signed-off-by: Denton Liu <liu.denton@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-09repository: mark the "refs" pointer as privateJeff King3-7/+11
The "refs" pointer in a struct repository starts life as NULL, but then is lazily initialized when it is accessed via get_main_ref_store(). However, it's easy for calling code to forget this and access it directly, leading to code which works _some_ of the time, but fails if it is called before anybody else accesses the refs. This was the cause of the bug fixed by 5ff4b920eb (sha1-name: do not assume that the ref store is initialized, 2020-04-09). In order to prevent similar bugs, let's more clearly mark the "refs" field as private. In addition to helping future code, the name change will help us audit any existing direct uses. Besides get_main_ref_store() itself, it turns out there is only one. But we know it's OK as it is on the line directly after the fix from 5ff4b920eb, which will have initialized the pointer. However it's still a good idea for it to model the proper use of the accessing function, so we'll convert it. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-09builtin/receive-pack: use constant-time comparison for HMAC valuebrian m. carlson1-1/+20
When we're comparing a push cert nonce, we currently do so using strcmp. Most implementations of strcmp short-circuit and exit as soon as they know whether two values are equal. This, however, is a problem when we're comparing the output of HMAC, as it leaks information in the time taken about how much of the two values match if they do indeed differ. In our case, the nonce is used to prevent replay attacks against our server via the embedded timestamp and replay attacks using requests from a different server via the HMAC. Push certs, which contain the nonces, are signed, so an attacker cannot tamper with the nonces without breaking validation of the signature. They can, of course, create their own signatures with invalid nonces, but they can also create their own signatures with valid nonces, so there's nothing to be gained. Thus, there is no security problem. Even though it doesn't appear that there are any negative consequences from the current technique, for safety and to encourage good practices, let's use a constant time comparison function for nonce verification. POSIX does not provide one, but they are easy to write. The technique we use here is also used in NaCl and the Go standard library and relies on the fact that bitwise or and xor are constant time on all known architectures. We need not be concerned about exiting early if the actual and expected lengths differ, since the standard cryptographic assumption is that everyone, including an attacker, knows the format of and algorithm used in our nonces (and in any event, they have the source code and can determine it easily). As a result, we assume everyone knows how long our nonces should be. This philosophy is also taken by the Go standard library and other cryptographic libraries when performing constant time comparisons on HMAC values. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-09sha1-name: do not assume that the ref store is initializedJunio C Hamano2-1/+5
c931ba4e (sha1-name.c: remove the_repo from handle_one_ref(), 2019-04-16) replaced the use of for_each_ref() helper, which works with the main ref store of the default repository instance, with refs_for_each_ref(), which can work on any ref store instance, by assuming that the repository instance the function is given has its ref store already initialized. But it is possible that nobody has initialized it, in which case, the code ends up dereferencing a NULL pointer. Reported-by: Érico Rolim <erico.erc@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-09bloom: ignore renames when computing changed pathsDerrick Stolee1-0/+1
The changed-path Bloom filters record an entry in the filter for every path that was changed. This includes every add and delete, regardless of whether a rename was detected. Detecting renames causes significant performance issues, but also will trigger downloading missing blobs in partial clone. The simple fix is to disable rename detection when computing a changed-path Bloom filter. This should already be disabled by default, but it is good to explicitly enforce the intended behavior. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-09config.txt: move closing "----" to cover entire listingMartin Ågren1-5/+5
Commit 1925fe0c8a ("Documentation: wrap config listings in "----"", 2019-09-07) wrapped this fairly large block of example config directives in "----". The closing "----" ended up a few lines too early though. Make sure to include the trailing "IncludeIf.onbranch:..." example, too. Signed-off-by: Martin Ågren <martin.agren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-08stash -p: (partially) fix bug concerning split hunksJohannes Schindelin2-2/+2
When trying to stash part of the worktree changes by splitting a hunk and then only partially accepting the split bits and pieces, the user is presented with a rather cryptic error: error: patch failed: <file>:<line> error: test: patch does not apply Cannot remove worktree changes and the command would fail to stash the desired parts of the worktree changes (even if the `stash` ref was actually updated correctly). We even have a test case demonstrating that failure, carrying it for four years already. The explanation: when splitting a hunk, the changed lines are no longer separated by more than 3 lines (which is the amount of context lines Git's diffs use by default), but less than that. So when staging only part of the diff hunk for stashing, the resulting diff that we want to apply to the worktree in reverse will contain those changes to be dropped surrounded by three context lines, but since the diff is relative to HEAD rather than to the worktree, these context lines will not match. Example time. Let's assume that the file README contains these lines: We the people and the worktree added some lines so that it contains these lines instead: We are the kind people and the user tries to stash the line containing "are", then the command will internally stage this line to a temporary index file and try to revert the diff between HEAD and that index file. The diff hunk that `git stash` tries to revert will look somewhat like this: @@ -1776,3 +1776,4 We +are the people It is obvious, now, that the trailing context lines overlap with the part of the original diff hunk that the user did *not* want to stash. Keeping in mind that context lines in diffs serve the primary purpose of finding the exact location when the diff does not apply precisely (but when the exact line number in the file to be patched differs from the line number indicated in the diff), we work around this by reducing the amount of context lines: the diff was just generated. Note: this is not a *full* fix for the issue. Just as demonstrated in t3701's 'add -p works with pathological context lines' test case, there are ambiguities in the diff format. It is very rare in practice, of course, to encounter such repeated lines. The full solution for such cases would be to replace the approach of generating a diff from the stash and then applying it in reverse by emulating `git revert` (i.e. doing a 3-way merge). However, in `git stash -p` it would not apply to `HEAD` but instead to the worktree, which makes this non-trivial to implement as long as we also maintain a scripted version of `add -i`. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-08t3904: fix incorrect demonstration of a bugJohannes Schindelin1-2/+2
In 7e9e048661 (stash -p: demonstrate failure of split with mixed y/n, 2015-04-16), a regression test for a known breakage that was added to the test script `t3904-stash-patch.sh` that demonstrated that splitting a hunk and trying to stash only part of that split hunk fails (but shouldn't). As expected, it still fails, but for the wrong reason: once the bug is fixed, we would expect stderr to show nothing, yet the regression test expects stderr to show something. Let's fix that by telling that regression test case to expect nothing to be printed to stderr. While at it, also drop the obvious left-over from debugging where the regression test did not mind `git stash -p` to return a non-zero exit status. Of course, the regression test still fails, but this time for the correct reason. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-08mingw: do not treat `COM0` as a reserved file nameJohannes Schindelin2-3/+7
In 4dc42c6c186 (mingw: refuse paths containing reserved names, 2019-12-21), we started disallowing file names that are reserved, e.g. `NUL`, `CONOUT$`, etc. This included `COM<n>` where `<n>` is a digit. Unfortunately, this includes `COM0` but only `COM1`, ..., `COM9` are reserved, according to the official documentation, `COM0` is mentioned in the "NT Namespaces" section but it is explicitly _omitted_ from the list of reserved names: https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file#naming-conventions Tests corroborate this: it is totally possible to write a file called `com0.c` on Windows 10, but not `com1.c`. So let's tighten the code to disallow only the reserved `COM<n>` file names, but to allow `COM0` again. This fixes https://github.com/git-for-windows/git/issues/2470. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-08mingw: use modern strftime implementation if possibleMatthias Aßhauer1-1/+10
Microsoft introduced a new "Universal C Runtime Library" (UCRT) with Visual Studio 2015. The UCRT comes with a new strftime() implementation that supports more date formats. We link git against the older "Microsoft Visual C Runtime Library" (MSVCRT), so to use the UCRT strftime() we need to load it from ucrtbase.dll using DECLARE_PROC_ADDR()/INIT_PROC_ADDR(). Most supported Windows systems should have recieved the UCRT via Windows update, but in some cases only MSVCRT might be available. In that case we fall back to using that implementation. With this change, it is possible to use e.g. the `%g` and `%V` date format specifiers, e.g. git show -s --format=%cd --date=format:‘%g.%V’ HEAD Without this change, the user would see this error message on Windows: fatal: invalid strftime format: '‘%g.%V’' This fixes https://github.com/git-for-windows/git/issues/2495 Signed-off-by: Matthias Aßhauer <mha1993@live.de> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-08subtree: fix build with AsciiDoctor 2Johannes Schindelin1-2/+4
This is a (late) companion for f6461b82b93 (Documentation: fix build with Asciidoctor 2, 2019-09-15). Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-07format-patch: teach --no-encode-email-headersEmma Brooks9-3/+85
When commit subjects or authors have non-ASCII characters, git format-patch Q-encodes them so they can be safely sent over email. However, if the patch transfer method is something other than email (web review tools, sneakernet), this only serves to make the patch metadata harder to read without first applying it (unless you can decode RFC 2047 in your head). git am as well as some email software supports non-Q-encoded mail as described in RFC 6531. Add --[no-]encode-email-headers and format.encodeEmailHeaders to let the user control this behavior. Signed-off-by: Emma Brooks <me@pluvano.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-07ci: fix the `jobname` of the `GETTEXT_POISON` jobJohannes Schindelin2-2/+2
In 6cdccfce1e0f (i18n: make GETTEXT_POISON a runtime option, 2018-11-08), the `jobname` was adjusted to have the `GIT_TEST_` prefix, but that prefix makes no sense in this context. Co-authored-by: Đoàn Trần Công Danh <congdanhqx@gmail.com> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-07ci/lib: set TERM environment variable if not existĐoàn Trần Công Danh1-0/+3
GitHub Action doesn't set TERM environment variable, which is required by "tput". Fallback to dumb if it's not set. Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-07ci/lib: allow running in GitHub ActionsJohannes Schindelin1-1/+19
For each CI system we support, we need a specific arm in that if/else construct in ci/lib.sh. Let's add one for GitHub Actions. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-07ci/lib: if CI type is unknown, show the environment variablesJohannes Schindelin1-0/+1
This should help with adding new CI-specific if-else arms. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-07Merge branch 'dd/ci-musl-libc' into HEADJunio C Hamano7-46/+111
* dd/ci-musl-libc: travis: build and test on Linux with musl libc and busybox ci/linux32: libify install-dependencies step ci: refactor docker runner script ci/linux32: parameterise command to switch arch ci/lib-docker: preserve required environment variables ci: make MAKEFLAGS available inside the Docker container in the Linux32 job
2020-04-07Merge branch 'dd/test-with-busybox' into HEADJunio C Hamano8-21/+25
* dd/test-with-busybox: t5703: feed raw data into test-tool unpack-sideband t4124: tweak test so that non-compliant diff(1) can also be used t7063: drop non-POSIX argument "-ls" from find(1) t5616: use rev-parse instead to get HEAD's object_id t5003: skip conversion test if unzip -a is unavailable t5003: drop the subshell in test_lazy_prereq test-lib-functions: test_cmp: eval $GIT_TEST_CMP t4061: use POSIX compliant regex(7)
2020-04-07sequencer: make read_oneliner() externDenton Liu2-13/+15
The function read_oneliner() is a generally useful util function. Instead of hiding it as a static function within sequencer.c, extern it so that it can be reused by others. This patch is best viewed with --color-moved. Signed-off-by: Denton Liu <liu.denton@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-07sequencer: configurably warn on non-existent filesDenton Liu1-1/+3
In the future, we plan on externing read_oneliner(). Future users of read_oneliner() will want the ability to output warnings in the event that the `path` doesn't exist. Introduce the `READ_ONELINER_WARN_MISSING` flag which, if active, would issue a warning when a file doesn't exist by always executing warning_errno() in the case where strbuf_read_file() fails. Signed-off-by: Denton Liu <liu.denton@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-07sequencer: make read_oneliner() accept flagsDenton Liu1-7/+14
In a future commit, we will need read_oneliner() to accept flags other than just `skip_if_empty`. Instead of having an argument for each flag, teach read_oneliner() to accept the bitfield `flags` instead. For now, only recognize the `READ_ONELINER_SKIP_IF_EMPTY` flag. More flags will be added in a future commit. The result of this is that parallel topics which introduce invocations of read_oneliner() will still be compatible with this new function signature since, instead of passing 1 or 0 for `skip_if_empty`, they'll be passing 1 or 0 to `flags`, which gives equivalent behavior. Mechanically fix up invocations of read_oneliner() with the following spatch @@ expression a, b; @@ read_oneliner(a, b, - 1 + READ_ONELINER_SKIP_IF_EMPTY ) and manually break up long lines in the result. Signed-off-by: Denton Liu <liu.denton@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-07sequencer: make file exists check more efficientDenton Liu1-4/+2
We currently check whether a file exists and return early before reading the file. Instead of accessing the file twice, always read the file and check `errno` to see if the file doesn't exist. Signed-off-by: Denton Liu <liu.denton@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-07diff: restrict when prefetching occursJonathan Tan5-28/+181
Commit 7fbbcb21b1 ("diff: batch fetching of missing blobs", 2019-04-08) optimized "diff" by prefetching blobs in a partial clone, but there are some cases wherein blobs do not need to be prefetched. In these cases, any command that uses the diff machinery will unnecessarily fetch blobs. diffcore_std() may read blobs when it calls the following functions: (1) diffcore_skip_stat_unmatch() (controlled by the config variable diff.autorefreshindex) (2) diffcore_break() and diffcore_merge_broken() (for break-rewrite detection) (3) diffcore_rename() (for rename detection) (4) diffcore_pickaxe() (for detecting addition/deletion of specified string) Instead of always prefetching blobs, teach diffcore_skip_stat_unmatch(), diffcore_break(), and diffcore_rename() to prefetch blobs upon the first read of a missing object. This covers (1), (2), and (3): to cover the rest, teach diffcore_std() to prefetch if the output type is one that includes blob data (and hence blob data will be required later anyway), or if it knows that (4) will be run. Helped-by: Jeff King <peff@peff.net> Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-07diff: refactor object readJonathan Tan1-8/+21
Refactor the object reads in diff_populate_filespec() to have the first object read not be in an if/else branch, because in a future patch, a retry will be added to that first object read. Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-07diff: make diff_populate_filespec_options structJonathan Tan5-32/+54
The behavior of diff_populate_filespec() currently can be customized through a bitflag, but a subsequent patch requires it to support a non-boolean option. Replace the bitflag with an options struct. Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-07sequencer: honor GIT_REFLOG_ACTIONElijah Newren2-10/+16
There is a lot of code to honor GIT_REFLOG_ACTION throughout git, including some in sequencer.c; unfortunately, reflog_message() and its callers ignored it. Instruct reflog_message() to check the existing environment variable, and use it when present as an override to action_name(). Also restructure pick_commits() to only temporarily modify GIT_REFLOG_ACTION for a short duration and then restore the old value, so that when we do this setting within a loop we do not keep adding " (pick)" substrings and end up with a reflog message of the form rebase (pick) (pick) (pick) (finish): returning to refs/heads/master Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-06travis: build and test on Linux with musl libc and busyboxĐoàn Trần Công Danh5-0/+24
Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-06ci/linux32: libify install-dependencies stepĐoàn Trần Công Danh2-6/+15
In a later patch, we will add new Travis Job for linux-musl. Most of other code in this file could be reuse for that job. Move the code to install dependencies to a common script. Should we add new CI system that can run directly in container, we can reuse this script for installation step. Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-06ci: refactor docker runner scriptĐoàn Trần Công Danh4-12/+22
We will support alpine check in docker later in this series. While we're at it, tell people to run as root in podman, if podman is used as drop-in replacement for docker, because podman will map host-user to container's root, therefore, mapping their permission. Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-06ci/linux32: parameterise command to switch archĐoàn Trần Công Danh2-2/+13
In a later patch, the remaining of this command will be re-used for the CI job for linux with musl libc. Allow customisation of the emulator, now. Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-06ci/lib-docker: preserve required environment variablesĐoàn Trần Công Danh1-3/+10
We're using "su -m" to preserve environment variables in the shell run by "su". But, that options will be ignored while "-l" (aka "--login") is specified in util-linux and busybox's su. In a later patch this script will be reused for checking Git for Linux with musl libc on Alpine Linux, Alpine Linux uses "su" from busybox. Since we don't have interest in all environment variables, pass only those necessary variables to the inner script. Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-06doc: --recurse-submodules mostly applies to active submodulesDamien Robert6-7/+9
The documentation refers to "initialized" or "populated" submodules, to explain which submodules are affected by '--recurse-submodules', but the real terminology here is 'active' submodules. Update the documentation accordingly. Some terminology: - Active is defined in gitsubmodules(7), it only involves the configuration variables 'submodule.active', 'submodule.<name>.active' and 'submodule.<name>.url'. The function submodule.c::is_submodule_active checks that a submodule is active. - Populated means that the submodule's working tree is present (and the gitfile correctly points to the submodule repository), i.e. either the superproject was cloned with ` --recurse-submodules`, or the user ran `git submodule update --init`, or `git submodule init [<path>]` and `git submodule update [<path>]` separately which populated the submodule working tree. This does not involve the 3 configuration variables above. - Initialized (at least in the context of the man pages involved in this patch) means both "populated" and "active" as defined above, i.e. what `git submodule update --init` does. The --recurse-submodules option mostly affects active submodules. An exception is `git fetch` where the option affects populated submodules. As a consequence, in `git pull --recurse-submodules` the fetch affects populated submodules, but the resulting working tree update only affects active submodules. In the documentation of `git-pull`, let's distinguish between the fetching part which affects populated submodules, and the updating of worktrees, which only affects active submodules. Signed-off-by: Damien Robert <damien.olivier.robert+git@gmail.com> Helped-by: Philippe Blain <levraiphilippeblain@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-06doc: be more precise on (fetch|push).recurseSubmodulesDamien Robert4-8/+13
The default value also depends on the value of submodule.recurse. Use this opportunity to correct some grammar mistakes in Documentation/config/fetch.txt signaled by Robert P. J. Day. Also mention `fetch.recurseSubmodules` in fetch-options.txt. In git-push.txt, `push.recurseSubmodules` is implicitly mentioned (by explaining how to disable it), so no need to add it there. Lastly add a link to `git-fetch` in `git-pull.txt` to explain the meaning of `--recurse-submodules` there. Signed-off-by: Damien Robert <damien.olivier.robert+git@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-06doc: explain how to deactivate submodule.recurse completelyDamien Robert1-0/+7
Signed-off-by: Damien Robert <damien.olivier.robert+git@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-06doc: document --recurse-submodules for reset and restoreDamien Robert5-3/+20
Also unify the formulation about --no-recurse-submodules for checkout and switch, which we reuse for restore. And correct the formulation about submodules' HEAD in read-tree, which we reuse in reset. Signed-off-by: Damien Robert <damien.olivier.robert+git@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-06doc: list all commands affected by submodule.recurseDamien Robert2-3/+5
Note that `ls-files` is not affected, even though it has a `--recurse-submodules` option, so list it as an exception too. Signed-off-by: Damien Robert <damien.olivier.robert+git@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-06fast-import: replace custom hash with hashmap.cJeff King2-25/+59
We use a custom hash in fast-import to store the set of objects we've imported so far. It has a fixed set of 2^16 buckets and chains any collisions with a linked list. As the number of objects grows larger than that, the load factor increases and we degrade to O(n) lookups and O(n^2) insertions. We can scale better by using our hashmap.c implementation, which will resize the bucket count as we grow. This does incur an extra memory cost of 8 bytes per object, as hashmap stores the integer hash value for each entry in its hashmap_entry struct (which we really don't care about here, because we're just reusing the embedded object hash). But I think the numbers below justify this (and our per-object memory cost is already much higher). I also looked at using khash, but it seemed to perform slightly worse than hashmap at all sizes, and worse even than the existing code for small sizes. It's also awkward to use here, because we want to look up a "struct object_entry" from a "struct object_id", and it doesn't handle mismatched keys as well. Making a mapping of object_id to object_entry would be more natural, but that would require pulling the embedded oid out of the object_entry or incurring an extra 32 bytes per object. In a synthetic test creating as many cheap, tiny objects as possible perl -e ' my $bits = shift; my $nr = 2**$bits; for (my $i = 0; $i < $nr; $i++) { print "blob\n"; print "data 4\n"; print pack("N", $i); } ' $bits | git fast-import I got these results: nr_objects master khash hashmap 2^20 0m4.317s 0m5.109s 0m3.890s 2^21 0m10.204s 0m9.702s 0m7.933s 2^22 0m27.159s 0m17.911s 0m16.751s 2^23 1m19.038s 0m35.080s 0m31.963s 2^24 4m18.766s 1m10.233s 1m6.793s which points to hashmap as the winner. We didn't have any perf tests for fast-export or fast-import, so I added one as a more real-world case. It uses an export without blobs since that's significantly cheaper than a full one, but still is an interesting case people might use (e.g., for rewriting history). It will emphasize this change in some ways (as a percentage we spend more time making objects and less shuffling blob bytes around) and less in others (the total object count is lower). Here are the results for linux.git: Test HEAD^ HEAD ---------------------------------------------------------------------------- 9300.1: export (no-blobs) 67.64(66.96+0.67) 67.81(67.06+0.75) +0.3% 9300.2: import (no-blobs) 284.04(283.34+0.69) 198.09(196.01+0.92) -30.3% It only has ~5.2M commits and trees, so this is a larger effect than I expected (the 2^23 case above only improved by 50s or so, but here we gained almost 90s). This is probably due to actually performing more object lookups in a real import with trees and commits, as opposed to just dumping a bunch of blobs into a pack. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-06commit-graph: add GIT_TEST_COMMIT_GRAPH_CHANGED_PATHS test flagGarima Singh6-1/+12
Add GIT_TEST_COMMIT_GRAPH_CHANGED_PATHS test flag to the test setup suite in order to toggle writing Bloom filters when running any of the git tests. If set to true, we will compute and write Bloom filters every time a test calls `git commit-graph write`, as if the `--changed-paths` option was passed in. The test suite passes when GIT_TEST_COMMIT_GRAPH and GIT_TEST_COMMIT_GRAPH_CHANGED_PATHS are enabled. Helped-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Garima Singh <garima.singh@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-06t4216: add end to end tests for git log with Bloom filtersGarima Singh2-0/+159
These tests exercises writing commit graph with Bloom filters and exercises 'git log -- path' with all the applicable options. They check that the output is the same with and without Bloom filters, confirm Bloom filters were used by checking if trace2 statistics were logged correctly. Also confirms cases where Bloom filters are not used: 1. Multiple path specs, 2. --walk-reflogs (see patch titled 'revision.c: use Bloom filters...' for details, 3. If the latest commit graph does not have Bloom filters Signed-off-by: Garima Singh <garima.singh@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-06revision.c: add trace2 stats around Bloom filter usageGarima Singh1-0/+41
Add trace2 statistics around Bloom filter usage and behavior for 'git log -- path' commands that are hoping to benefit from the presence of computed changed paths Bloom filters. These statistics are great for performance analysis work and for formal testing, which we will see in the commit following this one. Helped-by: Derrick Stolee <dstolee@microsoft.com Helped-by: SZEDER Gábor <szeder.dev@gmail.com> Helped-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Garima Singh <garima.singh@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-06revision.c: use Bloom filters to speed up path based revision walksGarima Singh4-2/+118
Revision walk will now use Bloom filters for commits to speed up revision walks for a particular path (for computing history for that path), if they are present in the commit-graph file. We load the Bloom filters during the prepare_revision_walk step, currently only when dealing with a single pathspec. Extending it to work with multiple pathspecs can be explored and built on top of this series in the future. While comparing trees in rev_compare_trees(), if the Bloom filter says that the file is not different between the two trees, we don't need to compute the expensive diff. This is where we get our performance gains. The other response of the Bloom filter is '`:maybe', in which case we fall back to the full diff calculation to determine if the path was changed in the commit. We do not try to use Bloom filters when the '--walk-reflogs' option is specified. The '--walk-reflogs' option does not walk the commit ancestry chain like the rest of the options. Incorporating the performance gains when walking reflog entries would add more complexity, and can be explored in a later series. Performance Gains: We tested the performance of `git log -- <path>` on the git repo, the linux and some internal large repos, with a variety of paths of varying depths. On the git and linux repos: - we observed a 2x to 5x speed up. On a large internal repo with files seated 6-10 levels deep in the tree: - we observed 10x to 20x speed ups, with some paths going up to 28 times faster. Helped-by: Derrick Stolee <dstolee@microsoft.com Helped-by: SZEDER Gábor <szeder.dev@gmail.com> Helped-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Garima Singh <garima.singh@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-06commit-graph: add --changed-paths option to write subcommandGarima Singh2-2/+12
Add --changed-paths option to git commit-graph write. This option will allow users to compute information about the paths that have changed between a commit and its first parent, and write it into the commit graph file. If the option is passed to the write subcommand we set the COMMIT_GRAPH_WRITE_BLOOM_FILTERS flag and pass it down to the commit-graph logic. Helped-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Garima Singh <garima.singh@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-06commit-graph: reuse existing Bloom filters during writeGarima Singh4-6/+55
Add logic to a) parse Bloom filter information from the commit graph file and, b) re-use existing Bloom filters. See Documentation/technical/commit-graph-format for the format in which the Bloom filter information is written to the commit graph file. To read Bloom filter for a given commit with lexicographic position 'i' we need to: 1. Read BIDX[i] which essentially gives us the starting index in BDAT for filter of commit i+1. It is essentially the index past the end of the filter of commit i. It is called end_index in the code. 2. For i>0, read BIDX[i-1] which will give us the starting index in BDAT for filter of commit i. It is called the start_index in the code. For the first commit, where i = 0, Bloom filter data starts at the beginning, just past the header in the BDAT chunk. Hence, start_index will be 0. 3. The length of the filter will be end_index - start_index, because BIDX[i] gives the cumulative 8-byte words including the ith commit's filter. We toggle whether Bloom filters should be recomputed based on the compute_if_not_present flag. Helped-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Garima Singh <garima.singh@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-06commit-graph: write Bloom filters to commit graph fileGarima Singh3-1/+147
Update the technical documentation for commit-graph-format with the formats for the Bloom filter index (BIDX) and Bloom filter data (BDAT) chunks. Write the computed Bloom filters information to the commit graph file using this format. Helped-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Garima Singh <garima.singh@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-05pull doc: correct outdated description of an examplePhilippe Blain1-3/+3
Since f269048754 (fetch: opportunistically update tracking refs, 2013-05-11), the underlying `git fetch` in `git pull <remote> <branch>` updates the configured remote-tracking branch for <branch>. However, an example in the 'Examples' section of the `git pull` documentation still states that this is not the case. Correct the description of this example. Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-05pull doc: refer to a specific section in 'fetch' docPhilippe Blain1-1/+2
The documentation for the `<refspec>` parameter in the `git fetch` documentation refers to the section "CONFIGURED REMOTE-TRACKING BRANCHES" in this same documentation page. In the `git pull` documentation, let's also refer specifically to this section instead of just linking to the `git fetch` documentation. Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>