Commit Graph

15012 Commits

Author SHA1 Message Date
Philippe Blain
7d15fdbe4c gitsubmodules doc: invoke 'ls-files' with '--recurse-submodules'
`git ls-files` was never taught to respect the `submodule.recurse`
configuration variable, and it is too late now to change that [1],
but still the command is mentioned in 'gitsubmodules(7)' as if it
does respect that config.

Adjust the call in 'gitsubmodules(7)' by calling 'ls-files' with the
'--recurse-submodules' option.

While at it, uniformize the capitalization in that file, and use
backticks instead of quotes for Git commands and configuration
variables.

[1] https://lore.kernel.org/git/pull.732.git.1599707259907.gitgitgadget@gmail.com/T/#u

Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-04 12:54:07 -07:00
Junio C Hamano
ab4691b67b Nineteenth batch
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-04 12:49:15 -07:00
Junio C Hamano
2fa8aacc72 Merge branch 'jk/shortlog-group-by-trailer'
"git shortlog" has been taught to group commits by the contents of
the trailer lines, like "Reviewed-by:", "Coauthored-by:", etc.

* jk/shortlog-group-by-trailer:
  shortlog: allow multiple groups to be specified
  shortlog: parse trailer idents
  shortlog: rename parse_stdin_ident()
  shortlog: de-duplicate trailer values
  shortlog: match commit trailers with --group
  trailer: add interface for iterating over commit trailers
  shortlog: add grouping option
  shortlog: change "author" variables to "ident"
2020-10-04 12:49:14 -07:00
Junio C Hamano
ea1f6118b7 Merge branch 'jc/fmt-merge-msg-suppress-destination'
Docfix.

* jc/fmt-merge-msg-suppress-destination:
  config/fmt-merge-msg.txt: drop space in quote
2020-10-04 12:49:13 -07:00
Junio C Hamano
d1b75045a0 Merge branch 'tb/upload-pack-filters'
Hotfix.

* tb/upload-pack-filters:
  config/uploadpack.txt: fix typo in `--filter=tree:<n>`
2020-10-04 12:49:12 -07:00
Junio C Hamano
9839cce4a7 Merge branch 'eg/mailinfo-doc-scissors'
The explanation of the "scissors line" has been clarified.

* eg/mailinfo-doc-scissors:
  Doc: show example scissors line
2020-10-04 12:49:09 -07:00
Srinidhi Kaushik
3b5bf96573 t, doc: update tests, reference for "--force-if-includes"
Update test cases for the new option, and document its usage
and update related references.

Update test cases for the new option, and document its usage
and update related references.

 - t/t5533-push-cas.sh:
   Update test cases for "compare-and-swap" when used along with
   "--force-if-includes" helps mitigate overwrites when remote
   refs are updated in the background; allows forced updates when
   changes from remote are integrated locally.

 - Documentation:
   Add reference for the new option, configuration setting
   ("push.useForceIfIncludes") and advise messages.

Signed-off-by: Srinidhi Kaushik <shrinidhi.kaushik@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-03 09:59:19 -07:00
Jacob Keller
7efba5fa39 format-patch: teach format.useAutoBase "whenAble" option
The format.useAutoBase configuration option exists to allow users to
enable '--base=auto' for format-patch by default.

This can sometimes lead to poor workflow, due to unexpected failures
when attempting to format an ancient patch:

    $ git format-patch -1 <an old commit>
    fatal: base commit shouldn't be in revision list

This can be very confusing, as it is not necessarily immediately obvious
that the user requested a --base (since this was in the configuration,
not on the command line).

We do want --base=auto to fail when it cannot provide a suitable base,
as it would be equally confusing if a formatted patch did not include
the base information when it was requested.

Teach format.useAutoBase a new mode, "whenAble". This mode will cause
format-patch to attempt to include a base commit when it can. However,
if no valid base commit can be found, then format-patch will continue
formatting the patch without a base commit.

In order to avoid making yet another branch name unusable with --base,
do not teach --base=whenAble or --base=whenable.

Instead, refactor the base_commit option to use a callback, and rely on
the global configuration variable auto_base.

This does mean that a user cannot request this optional base commit
generation from the command line. However, this is likely not too
valuable. If the user requests base information manually, they will be
immediately informed of the failure to acquire a suitable base commit.
This allows the user to make an informed choice about whether to
continue the format.

Add tests to cover the new mode of operation for --base.

Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-01 15:22:10 -07:00
Sean Barag
de9ed3ef37 clone: allow configurable default for -o/--origin
While the default remote name of "origin" can be changed at clone-time
with `git clone`'s `--origin` option, it was previously not possible
to specify a default value for the name of that remote.  Add support for
a new `clone.defaultRemoteName` config, with the newly-created remote
name resolved in priority order:

1. (Highest priority) A remote name passed directly to `git clone -o`
2. A `clone.defaultRemoteName=new_name` in config `git clone -c`
3. A `clone.defaultRemoteName` value set in `/path/to/template/config`,
   where `--template=/path/to/template` is provided
4. A `clone.defaultRemoteName` value set in a non-template config file
5. The default value of `origin`

Helped-by: Junio C Hamano <gitster@pobox.com>
Helped-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Helped-by: Derrick Stolee <stolee@gmail.com>
Helped-by: Andrei Rybak <rybak.a.v@gmail.com>
Signed-off-by: Sean Barag <sean@barag.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-30 22:09:13 -07:00
Jacob Keller
c0192df630 refspec: add support for negative refspecs
Both fetch and push support pattern refspecs which allow fetching or
pushing references that match a specific pattern. Because these patterns
are globs, they have somewhat limited ability to express more complex
situations.

For example, suppose you wish to fetch all branches from a remote except
for a specific one. To allow this, you must setup a set of refspecs
which match only the branches you want. Because refspecs are either
explicit name matches, or simple globs, many patterns cannot be
expressed.

Add support for a new type of refspec, referred to as "negative"
refspecs. These are prefixed with a '^' and mean "exclude any ref
matching this refspec". They can only have one "side" which always
refers to the source. During a fetch, this refers to the name of the ref
on the remote. During a push, this refers to the name of the ref on the
local side.

With negative refspecs, users can express more complex patterns. For
example:

 git fetch origin refs/heads/*:refs/remotes/origin/* ^refs/heads/dontwant

will fetch all branches on origin into remotes/origin, but will exclude
fetching the branch named dontwant.

Refspecs today are commutative, meaning that order doesn't expressly
matter. Rather than forcing an implied order, negative refspecs will
always be applied last. That is, in order to match, a ref must match at
least one positive refspec, and match none of the negative refspecs.
This is similar to how negative pathspecs work.

Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-30 14:52:00 -07:00
Junio C Hamano
306ee63a70 Eighteenth batch
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-29 14:01:22 -07:00
Junio C Hamano
e76ae33009 Merge branch 'jk/make-protocol-v2-the-default'
The transport protocol v2 has become the default again.

* jk/make-protocol-v2-the-default:
  protocol: re-enable v2 protocol by default
2020-09-29 14:01:20 -07:00
Junio C Hamano
288ed98bf7 Merge branch 'tb/bloom-improvements'
"git commit-graph write" learned to limit the number of bloom
filters that are computed from scratch with the --max-new-filters
option.

* tb/bloom-improvements:
  commit-graph: introduce 'commitGraph.maxNewFilters'
  builtin/commit-graph.c: introduce '--max-new-filters=<n>'
  commit-graph: rename 'split_commit_graph_opts'
  bloom: encode out-of-bounds filters as non-empty
  bloom/diff: properly short-circuit on max_changes
  bloom: use provided 'struct bloom_filter_settings'
  bloom: split 'get_bloom_filter()' in two
  commit-graph.c: store maximum changed paths
  commit-graph: respect 'commitGraph.readChangedPaths'
  t/helper/test-read-graph.c: prepare repo settings
  commit-graph: pass a 'struct repository *' in more places
  t4216: use an '&&'-chain
  commit-graph: introduce 'get_bloom_filter_settings()'
2020-09-29 14:01:20 -07:00
Junio C Hamano
c5a8f1efc0 Merge branch 'bc/faq-misc'
More FAQ entries.

* bc/faq-misc:
  docs: explain how to deal with files that are always modified
  docs: explain why reverts are not always applied on merge
  docs: explain why squash merges are broken with long-running branches
2020-09-29 14:01:20 -07:00
Evan Gates
287416dba6 Doc: show example scissors line
The text tries to say the code accepts many variations that look remotely
like scissors and perforation marks, but gives too little detail for users
to decide what is and what is not taken as a scissors line for themselves.
Instead of describing the heuristics more, just spell out what will always
be accepted, namely "-- >8 --", as it would not help users to give them
more choices and flexibility and be "creative" in their scissors line.

Signed-off-by: Evan Gates <evan.gates@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-28 16:09:04 -07:00
Martin Ågren
71ccaa0993 config/uploadpack.txt: fix typo in --filter=tree:<n>
That should be a ":", not a second "=". While at it, refer to the
placeholder "<n>" as "<n>", not "n" (see, e.g., the entry just before
this one).

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-27 14:23:20 -07:00
Martin Ågren
10a758479e config/fmt-merge-msg.txt: drop space in quote
We document how `merge.suppressDest` can be used to omit " into <branch
name>" from the title of the merge message. It is true that we omit the
space character before "into", but that lone double quote character
risks ending up on the wrong side of a line break, looking a bit out of
place. This currently happens with, e.g., 80-character terminals.

Drop that leading quoted space. The result should be just as clear about
how this option affects the formatted message.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-27 14:22:41 -07:00
Jeff King
63d24fa0b0 shortlog: allow multiple groups to be specified
Now that shortlog supports reading from trailers, it can be useful to
combine counts from multiple trailers, or between trailers and authors.
This can be done manually by post-processing the output from multiple
runs, but it's non-trivial to make sure that each name/commit pair is
counted only once.

This patch teaches shortlog to accept multiple --group options on the
command line, and pull data from all of them. That makes it possible to
run:

  git shortlog -ns --group=author --group=trailer:co-authored-by

to get a shortlog that counts authors and co-authors equally.

The implementation is mostly straightforward. The "group" enum becomes a
bitfield, and the trailer key becomes a list. I didn't bother
implementing the multi-group semantics for reading from stdin. It would
be possible to do, but the existing matching code makes it awkward, and
I doubt anybody cares.

The duplicate suppression we used for trailers now covers authors and
committers as well (though in non-trailer single-group mode we can skip
the hash insertion and lookup, since we only see one value per commit).

There is one subtlety: we now care about the case when no group bit is
set (in which case we default to showing the author). The caller in
builtin/log.c needs to be adapted to ask explicitly for authors, rather
than relying on shortlog_init(). It would be possible with some
gymnastics to make this keep working as-is, but it's not worth it for a
single caller.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-27 12:21:05 -07:00
Jeff King
56d5dde752 shortlog: parse trailer idents
Trailers don't necessarily contain name/email identity values, so
shortlog has so far treated them as opaque strings. However, since many
trailers do contain identities, it's useful to treat them as such when
they can be parsed. That lets "-e" work as usual, as well as mailmap.

When they can't be parsed, we'll continue with the old behavior of
treating them as a single string (there's no new test for that here,
since the existing tests cover a trailer like this).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-27 12:21:05 -07:00
Jeff King
f17b0b99bf shortlog: de-duplicate trailer values
The current documentation is vague about what happens with
--group=trailer:signed-off-by when we see a commit with:

  Signed-off-by: One
  Signed-off-by: Two
  Signed-off-by: One

We clearly should credit both "One" and "Two", but should "One" get
credited twice? The current code does so, but mostly because that was
the easiest thing to do. It's probably more useful to count each commit
at most once. This will become especially important when we allow
values from multiple sources in a future patch.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-27 12:21:05 -07:00
Jeff King
47beb37bc6 shortlog: match commit trailers with --group
If a project uses commit trailers, this patch lets you use
shortlog to see who is performing each action. For example,
running:

  git shortlog -ns --group=trailer:reviewed-by

in git.git shows who has reviewed. You can even use a custom
format to see things like who has helped whom:

  git shortlog --format="...helped %an (%ad)" \
               --group=trailer:helped-by

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-27 12:21:05 -07:00
Jeff King
92338c450b shortlog: add grouping option
In preparation for adding more grouping types, let's refactor the
committer/author grouping code and add a user-facing option that binds
them together. In particular:

  - the main option is now "--group", to make it clear
    that the various group types are mutually exclusive. The
    "--committer" option is an alias for "--group=committer".

  - we keep an enum rather than a binary flag, to prepare
    for more values

  - we prefer switch statements to ternary assignment, since
    other group types will need more custom code

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-27 12:21:05 -07:00
Junio C Hamano
9bc233ae1c Seventeenth batch
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-25 15:25:42 -07:00
Junio C Hamano
6c430a647c Merge branch 'jx/proc-receive-hook'
"git receive-pack" that accepts requests by "git push" learned to
outsource most of the ref updates to the new "proc-receive" hook.

* jx/proc-receive-hook:
  doc: add documentation for the proc-receive hook
  transport: parse report options for tracking refs
  t5411: test updates of remote-tracking branches
  receive-pack: new config receive.procReceiveRefs
  doc: add document for capability report-status-v2
  New capability "report-status-v2" for git-push
  receive-pack: feed report options to post-receive
  receive-pack: add new proc-receive hook
  t5411: add basic test cases for proc-receive hook
  transport: not report a non-head push as a branch
2020-09-25 15:25:39 -07:00
Junio C Hamano
48794acc50 Merge branch 'ds/maintenance-part-1'
A "git gc"'s big brother has been introduced to take care of more
repository maintenance tasks, not limited to the object database
cleaning.

* ds/maintenance-part-1:
  maintenance: add trace2 regions for task execution
  maintenance: add auto condition for commit-graph task
  maintenance: use pointers to check --auto
  maintenance: create maintenance.<task>.enabled config
  maintenance: take a lock on the objects directory
  maintenance: add --task option
  maintenance: add commit-graph task
  maintenance: initialize task array
  maintenance: replace run_auto_gc()
  maintenance: add --quiet option
  maintenance: create basic maintenance runner
2020-09-25 15:25:38 -07:00
Jeff King
eb049759fb protocol: re-enable v2 protocol by default
Protocol v2 became the default in v2.26.0 via 684ceae32d (fetch: default
to protocol version 2, 2019-12-23). More widespread use turned up a
regression in negotiation. That was fixed in v2.27.0 via 4fa3f00abb
(fetch-pack: in protocol v2, in_vain only after ACK, 2020-04-27), but we
also reverted the default to v0 as a precuation in 11c7f2a30b (Revert
"fetch: default to protocol version 2", 2020-04-22).

In v2.28.0, we re-enabled it for experimental users with 3697caf4b9
(config: let feature.experimental imply protocol.version=2, 2020-05-20)
and haven't heard any complaints. v2.28 has only been out for 2 months,
but I'd generally expect people turning on feature.experimental to also
stay pretty up-to-date. So we're not likely to collect much more data by
waiting. In addition, we have no further reports from people running
v2.26.0, and of course some people have been setting protocol.version
manually for ages.

Let's move forward with v2 as the default again. It's possible there are
still lurking bugs, but we won't know until it gets more widespread use.
And we can find and squash them just like any other bug at this point.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-25 11:40:42 -07:00
Derrick Stolee
2fec604f8d maintenance: add start/stop subcommands
Add new subcommands to 'git maintenance' that start or stop background
maintenance using 'cron', when available. This integration is as simple
as I could make it, barring some implementation complications.

The schedule is laid out as follows:

  0 1-23 * * *   $cmd maintenance run --schedule=hourly
  0 0    * * 1-6 $cmd maintenance run --schedule=daily
  0 0    * * 0   $cmd maintenance run --schedule=weekly

where $cmd is a properly-qualified 'git for-each-repo' execution:

$cmd=$path/git --exec-path=$path for-each-repo --config=maintenance.repo

where $path points to the location of the Git executable running 'git
maintenance start'. This is critical for systems with multiple versions
of Git. Specifically, macOS has a system version at '/usr/bin/git' while
the version that users can install resides at '/usr/local/bin/git'
(symlinked to '/usr/local/libexec/git-core/git'). This will also use
your locally-built version if you build and run this in your development
environment without installing first.

This conditional schedule avoids having cron launch multiple 'git
for-each-repo' commands in parallel. Such parallel commands would likely
lead to the 'hourly' and 'daily' tasks competing over the object
database lock. This could lead to to some tasks never being run! Since
the --schedule=<frequency> argument will run all tasks with _at least_
the given frequency, the daily runs will also run the hourly tasks.
Similarly, the weekly runs will also run the daily and hourly tasks.

The GIT_TEST_CRONTAB environment variable is not intended for users to
edit, but instead as a way to mock the 'crontab [-l]' command. This
variable is set in test-lib.sh to avoid a future test from accidentally
running anything with the cron integration from modifying the user's
schedule. We use GIT_TEST_CRONTAB='test-tool crontab <file>' in our
tests to check how the schedule is modified in 'git maintenance
(start|stop)' commands.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-25 10:59:44 -07:00
Derrick Stolee
0c18b70081 maintenance: add [un]register subcommands
In preparation for launching background maintenance from the 'git
maintenance' builtin, create register/unregister subcommands. These
commands update the new 'maintenance.repos' config option in the global
config so the background maintenance job knows which repositories to
maintain.

These commands allow users to add a repository to the background
maintenance list without disrupting the actual maintenance mechanism.

For example, a user can run 'git maintenance register' when no
background maintenance is running and it will not start the background
maintenance. A later update to start running background maintenance will
then pick up this repository automatically.

The opposite example is that a user can run 'git maintenance unregister'
to remove the current repository from background maintenance without
halting maintenance for other repositories.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-25 10:59:44 -07:00
Derrick Stolee
4950b2a2b5 for-each-repo: run subcommands on configured repos
It can be helpful to store a list of repositories in global or system
config and then iterate Git commands on that list. Create a new builtin
that makes this process simple for experts. We will use this builtin to
run scheduled maintenance on all configured repositories in a future
change.

The test is very simple, but does highlight that the "--" argument is
optional.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-25 10:59:44 -07:00
Derrick Stolee
b08ff1fee0 maintenance: add --schedule option and config
Maintenance currently triggers when certain data-size thresholds are
met, such as number of pack-files or loose objects. Users may want to
run certain maintenance tasks based on frequency instead. For example,
a user may want to perform a 'prefetch' task every hour, or 'gc' task
every day. To help these users, update the 'git maintenance run' command
to include a '--schedule=<frequency>' option. The allowed frequencies
are 'hourly', 'daily', and 'weekly'. These values are also allowed in a
new config value 'maintenance.<task>.schedule'.

The 'git maintenance run --schedule=<frequency>' checks the '*.schedule'
config value for each enabled task to see if the configured frequency is
at least as frequent as the frequency from the '--schedule' argument. We
use the following order, for full clarity:

	'hourly' > 'daily' > 'weekly'

Use new 'enum schedule_priority' to track these values numerically.

The following cron table would run the scheduled tasks with the correct
frequencies:

  0 1-23 * * *    git -C <repo> maintenance run --schedule=hourly
  0 0    * * 1-6  git -C <repo> maintenance run --schedule=daily
  0 0    * * 0    git -C <repo> maintenance run --schedule=weekly

This cron schedule will run --schedule=hourly every hour except at
midnight. This avoids a concurrent run with the --schedule=daily that
runs at midnight every day except the first day of the week. This avoids
a concurrent run with the --schedule=weekly that runs at midnight on
the first day of the week. Since --schedule=daily also runs the
'hourly' tasks and --schedule=weekly runs the 'hourly' and 'daily'
tasks, we will still see all tasks run with the proper frequencies.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-25 10:59:44 -07:00
Derrick Stolee
1942d48380 maintenance: optionally skip --auto process
Some commands run 'git maintenance run --auto --[no-]quiet' after doing
their normal work, as a way to keep repositories clean as they are used.
Currently, users who do not want this maintenance to occur would set the
'gc.auto' config option to 0 to avoid the 'gc' task from running.
However, this does not stop the extra process invocation. On Windows,
this extra process invocation can be more expensive than necessary.

Allow users to drop this extra process by setting 'maintenance.auto' to
'false'.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-25 10:59:44 -07:00
Derrick Stolee
e841a79a13 maintenance: add incremental-repack auto condition
The incremental-repack task updates the multi-pack-index by deleting pack-
files that have been replaced with new packs, then repacking a batch of
small pack-files into a larger pack-file. This incremental repack is faster
than rewriting all object data, but is slower than some other
maintenance activities.

The 'maintenance.incremental-repack.auto' config option specifies how many
pack-files should exist outside of the multi-pack-index before running
the step. These pack-files could be created by 'git fetch' commands or
by the loose-objects task. The default value is 10.

Setting the option to zero disables the task with the '--auto' option,
and a negative value makes the task run every time.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-25 10:53:05 -07:00
Derrick Stolee
52fe41ff1c maintenance: add incremental-repack task
The previous change cleaned up loose objects using the
'loose-objects' that can be run safely in the background. Add a
similar job that performs similar cleanups for pack-files.

One issue with running 'git repack' is that it is designed to
repack all pack-files into a single pack-file. While this is the
most space-efficient way to store object data, it is not time or
memory efficient. This becomes extremely important if the repo is
so large that a user struggles to store two copies of the pack on
their disk.

Instead, perform an "incremental" repack by collecting a few small
pack-files into a new pack-file. The multi-pack-index facilitates
this process ever since 'git multi-pack-index expire' was added in
19575c7 (multi-pack-index: implement 'expire' subcommand,
2019-06-10) and 'git multi-pack-index repack' was added in ce1e4a1
(midx: implement midx_repack(), 2019-06-10).

The 'incremental-repack' task runs the following steps:

1. 'git multi-pack-index write' creates a multi-pack-index file if
   one did not exist, and otherwise will update the multi-pack-index
   with any new pack-files that appeared since the last write. This
   is particularly relevant with the background fetch job.

   When the multi-pack-index sees two copies of the same object, it
   stores the offset data into the newer pack-file. This means that
   some old pack-files could become "unreferenced" which I will use
   to mean "a pack-file that is in the pack-file list of the
   multi-pack-index but none of the objects in the multi-pack-index
   reference a location inside that pack-file."

2. 'git multi-pack-index expire' deletes any unreferenced pack-files
   and updaes the multi-pack-index to drop those pack-files from the
   list. This is safe to do as concurrent Git processes will see the
   multi-pack-index and not open those packs when looking for object
   contents. (Similar to the 'loose-objects' job, there are some Git
   commands that open pack-files regardless of the multi-pack-index,
   but they are rarely used. Further, a user that self-selects to
   use background operations would likely refrain from using those
   commands.)

3. 'git multi-pack-index repack --bacth-size=<size>' collects a set
   of pack-files that are listed in the multi-pack-index and creates
   a new pack-file containing the objects whose offsets are listed
   by the multi-pack-index to be in those objects. The set of pack-
   files is selected greedily by sorting the pack-files by modified
   time and adding a pack-file to the set if its "expected size" is
   smaller than the batch size until the total expected size of the
   selected pack-files is at least the batch size. The "expected
   size" is calculated by taking the size of the pack-file divided
   by the number of objects in the pack-file and multiplied by the
   number of objects from the multi-pack-index with offset in that
   pack-file. The expected size approximates how much data from that
   pack-file will contribute to the resulting pack-file size. The
   intention is that the resulting pack-file will be close in size
   to the provided batch size.

   The next run of the incremental-repack task will delete these
   repacked pack-files during the 'expire' step.

   In this version, the batch size is set to "0" which ignores the
   size restrictions when selecting the pack-files. It instead
   selects all pack-files and repacks all packed objects into a
   single pack-file. This will be updated in the next change, but
   it requires doing some calculations that are better isolated to
   a separate change.

These steps are based on a similar background maintenance step in
Scalar (and VFS for Git) [1]. This was incredibly effective for
users of the Windows OS repository. After using the same VFS for Git
repository for over a year, some users had _thousands_ of pack-files
that combined to up to 250 GB of data. We noticed a few users were
running into the open file descriptor limits (due in part to a bug
in the multi-pack-index fixed by af96fe3 (midx: add packs to
packed_git linked list, 2019-04-29).

These pack-files were mostly small since they contained the commits
and trees that were pushed to the origin in a given hour. The GVFS
protocol includes a "prefetch" step that asks for pre-computed pack-
files containing commits and trees by timestamp. These pack-files
were grouped into "daily" pack-files once a day for up to 30 days.
If a user did not request prefetch packs for over 30 days, then they
would get the entire history of commits and trees in a new, large
pack-file. This led to a large number of pack-files that had poor
delta compression.

By running this pack-file maintenance step once per day, these repos
with thousands of packs spanning 200+ GB dropped to dozens of pack-
files spanning 30-50 GB. This was done all without removing objects
from the system and using a constant batch size of two gigabytes.
Once the work was done to reduce the pack-files to small sizes, the
batch size of two gigabytes means that not every run triggers a
repack operation, so the following run will not expire a pack-file.
This has kept these repos in a "clean" state.

[1] https://github.com/microsoft/scalar/blob/master/Scalar.Common/Maintenance/PackfileMaintenanceStep.cs

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-25 10:53:04 -07:00
Derrick Stolee
18e449f86b midx: enable core.multiPackIndex by default
The core.multiPackIndex setting has been around since c4d25228eb
(config: create core.multiPackIndex setting, 2018-07-12), but has been
disabled by default. If a user wishes to use the multi-pack-index
feature, then they must enable this config and run 'git multi-pack-index
write'.

The multi-pack-index feature is relatively stable now, so make the
config option true by default. For users that do not use a
multi-pack-index, the only extra cost will be a file lookup to see if a
multi-pack-index file exists (once per process, per object directory).

Also, this config option will be referenced by an upcoming
"incremental-repack" task in the maintenance builtin, so move the config
option into the repository settings struct. Note that if
GIT_TEST_MULTI_PACK_INDEX=1, then we want to ignore the config option
and treat core.multiPackIndex as enabled.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-25 10:53:04 -07:00
Derrick Stolee
3e220e6069 maintenance: create auto condition for loose-objects
The loose-objects task deletes loose objects that already exist in a
pack-file, then place the remaining loose objects into a new pack-file.
If this step runs all the time, then we risk creating pack-files with
very few objects with every 'git commit' process. To prevent
overwhelming the packs directory with small pack-files, place a minimum
number of objects to justify the task.

The 'maintenance.loose-objects.auto' config option specifies a minimum
number of loose objects to justify the task to run under the '--auto'
option. This defaults to 100 loose objects. Setting the value to zero
will prevent the step from running under '--auto' while a negative value
will force it to run every time.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-25 10:53:04 -07:00
Derrick Stolee
252cfb7cb8 maintenance: add loose-objects task
One goal of background maintenance jobs is to allow a user to
disable auto-gc (gc.auto=0) but keep their repository in a clean
state. Without any cleanup, loose objects will clutter the object
database and slow operations. In addition, the loose objects will
take up extra space because they are not stored with deltas against
similar objects.

Create a 'loose-objects' task for the 'git maintenance run' command.
This helps clean up loose objects without disrupting concurrent Git
commands using the following sequence of events:

1. Run 'git prune-packed' to delete any loose objects that exist
   in a pack-file. Concurrent commands will prefer the packed
   version of the object to the loose version. (Of course, there
   are exceptions for commands that specifically care about the
   location of an object. These are rare for a user to run on
   purpose, and we hope a user that has selected background
   maintenance will not be trying to do foreground maintenance.)

2. Run 'git pack-objects' on a batch of loose objects. These
   objects are grouped by scanning the loose object directories in
   lexicographic order until listing all loose objects -or-
   reaching 50,000 objects. This is more than enough if the loose
   objects are created only by a user doing normal development.
   We noticed users with _millions_ of loose objects because VFS
   for Git downloads blobs on-demand when a file read operation
   requires populating a virtual file.

This step is based on a similar step in Scalar [1] and VFS for Git.
[1] https://github.com/microsoft/scalar/blob/master/Scalar.Common/Maintenance/LooseObjectsStep.cs

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-25 10:53:04 -07:00
Derrick Stolee
28cb5e66dd maintenance: add prefetch task
When working with very large repositories, an incremental 'git fetch'
command can download a large amount of data. If there are many other
users pushing to a common repo, then this data can rival the initial
pack-file size of a 'git clone' of a medium-size repo.

Users may want to keep the data on their local repos as close as
possible to the data on the remote repos by fetching periodically in
the background. This can break up a large daily fetch into several
smaller hourly fetches.

The task is called "prefetch" because it is work done in advance
of a foreground fetch to make that 'git fetch' command much faster.

However, if we simply ran 'git fetch <remote>' in the background,
then the user running a foreground 'git fetch <remote>' would lose
some important feedback when a new branch appears or an existing
branch updates. This is especially true if a remote branch is
force-updated and this isn't noticed by the user because it occurred
in the background. Further, the functionality of 'git push
--force-with-lease' becomes suspect.

When running 'git fetch <remote> <options>' in the background, use
the following options for careful updating:

1. --no-tags prevents getting a new tag when a user wants to see
   the new tags appear in their foreground fetches.

2. --refmap= removes the configured refspec which usually updates
   refs/remotes/<remote>/* with the refs advertised by the remote.
   While this looks confusing, this was documented and tested by
   b40a50264a (fetch: document and test --refmap="", 2020-01-21),
   including this sentence in the documentation:

	Providing an empty `<refspec>` to the `--refmap` option
	causes Git to ignore the configured refspecs and rely
	entirely on the refspecs supplied as command-line arguments.

3. By adding a new refspec "+refs/heads/*:refs/prefetch/<remote>/*"
   we can ensure that we actually load the new values somewhere in
   our refspace while not updating refs/heads or refs/remotes. By
   storing these refs here, the commit-graph job will update the
   commit-graph with the commits from these hidden refs.

4. --prune will delete the refs/prefetch/<remote> refs that no
   longer appear on the remote.

5. --no-write-fetch-head prevents updating FETCH_HEAD.

We've been using this step as a critical background job in Scalar
[1] (and VFS for Git). This solved a pain point that was showing up
in user reports: fetching was a pain! Users do not like waiting to
download the data that was created while they were away from their
machines. After implementing background fetch, the foreground fetch
commands sped up significantly because they mostly just update refs
and download a small amount of new data. The effect is especially
dramatic when paried with --no-show-forced-udpates (through
fetch.showForcedUpdates=false).

[1] https://github.com/microsoft/scalar/blob/master/Scalar.Common/Maintenance/FetchStep.cs

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-25 10:53:04 -07:00
Junio C Hamano
e1cfff6765 Sixteenth batch
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-22 12:36:34 -07:00
Junio C Hamano
26a3728bed Merge branch 'al/ref-filter-merged-and-no-merged'
"git for-each-ref" and friends that list refs used to allow only
one --merged or --no-merged to filter them; they learned to take
combination of both kind of filtering.

* al/ref-filter-merged-and-no-merged:
  Doc: prefer more specific file name
  ref-filter: make internal reachable-filter API more precise
  ref-filter: allow merged and no-merged filters
  Doc: cover multiple contains/no-contains filters
  t3201: test multiple branch filter combinations
2020-09-22 12:36:31 -07:00
Junio C Hamano
4d515253af Merge branch 'cd/commit-graph-doc'
Doc update.

* cd/commit-graph-doc:
  commit-graph-format.txt: fix no-parent value
2020-09-22 12:36:30 -07:00
Junio C Hamano
4aff18a3f0 Merge branch 'ls/mergetool-meld-auto-merge'
The 'meld' backend of the "git mergetool" learned to give the
underlying 'meld' the '--auto-merge' option, which would help
reduce the amount of text that requires manual merging.

* ls/mergetool-meld-auto-merge:
  mergetool: allow auto-merge for meld to follow the vim-diff behavior
2020-09-22 12:36:29 -07:00
Junio C Hamano
c9a04f036f Merge branch 'hn/refs-trace-backend'
Developer support.

* hn/refs-trace-backend:
  refs: add GIT_TRACE_REFS debugging mechanism
2020-09-22 12:36:28 -07:00
Junio C Hamano
b7e65b51e5 Merge branch 'jt/threaded-index-pack'
"git index-pack" learned to resolve deltified objects with greater
parallelism.

* jt/threaded-index-pack:
  index-pack: make quantum of work smaller
  index-pack: make resolve_delta() assume base data
  index-pack: calculate {ref,ofs}_{first,last} early
  index-pack: remove redundant child field
  index-pack: unify threaded and unthreaded code
  index-pack: remove redundant parameter
  Documentation: deltaBaseCacheLimit is per-thread
2020-09-22 12:36:28 -07:00
Denton Liu
3d09c22869 builtin/diff-tree: learn --merge-base
The previous commit introduced ---merge-base a way to take the diff
between the working tree or index and the merge base between an arbitrary
commit and HEAD. It makes sense to extend this option to support the
case where two commits are given too and behave in a manner identical to
`git diff A...B`.

Introduce the --merge-base flag as an alternative to triple-dot
notation. Thus, we would be able to write the above as
`git diff --merge-base A B`.

Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-21 13:37:03 -07:00
Denton Liu
0f5a1d449b builtin/diff-index: learn --merge-base
There is currently no easy way to take the diff between the working tree
or index and the merge base between an arbitrary commit and HEAD. Even
diff's `...` notation doesn't allow this because it only works between
commits. However, the ability to do this would be desirable to a user
who would like to see all the changes they've made on a branch plus
uncommitted changes without taking into account changes made in the
upstream branch.

Teach diff-index and diff (with one commit) the --merge-base option
which allows a user to use the merge base of a commit and HEAD as the
"before" side.

Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-20 21:30:26 -07:00
brian m. carlson
087c61677c docs: explain how to deal with files that are always modified
Users frequently have problems where two filenames differ only in case,
causing one of those files to show up consistently as being modified.
Let's add a FAQ entry that explains how to deal with that.

In addition, let's explain another common case where files are
consistently modified, which is when files using a smudge or clean
filter have not been run through that filter.  Explain the way to fix
this as well.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-20 21:29:02 -07:00
brian m. carlson
409f066716 docs: explain why reverts are not always applied on merge
A common scenario is for a user to apply a change to one branch and
cherry-pick it into another, then later revert it in the first branch.
This results in the change being present when the two branches are
merged, which is confusing to many users.

We already have documentation for how this works in `git merge`, but it
is clear from the frequency with which this is asked that it's hard to
grasp.  We also don't explain to users that they are better off doing a
rebase in this case, which will do what they intended.  Let's add an
entry to the FAQ telling users what's happening and advising them to use
rebase here.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-20 21:29:02 -07:00
brian m. carlson
5065ce412e docs: explain why squash merges are broken with long-running branches
In many projects, squash merges are commonly used, primarily to keep a
tidy history in the face of developers who do not use logically
independent, bisectable commits.  As common as this is, this tends to
cause significant problems when squash merges are used to merge
long-running branches due to the lack of any new merge bases.  Even very
experienced developers may make this mistake, so let's add a FAQ entry
explaining why this is problematic and explaining that regular merge
commits should be used to merge two long-running branches.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-20 21:29:02 -07:00
René Scharfe
2947a7930d archive: add --add-file
Allow users to append non-tracked files.  This simplifies the generation
of source packages with a few extra files, e.g. containing version
information.  They get the same access times and user information as
tracked files.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-19 15:56:06 -07:00
Junio C Hamano
385c171a01 Fifteenth batch
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-18 17:58:06 -07:00