Commit Graph

268 Commits

Author SHA1 Message Date
Derrick Stolee
483a6d9b5d maintenance: use 'git config --fixed-value'
When a repository's leading directories contain regex metacharacters,
the config calls for 'git maintenance register' and 'git maintenance
unregister' are not careful enough. Use the new --fixed-value option
to direct the config machinery to use exact string matches. This is a
more robust option than escaping these arguments in a piecemeal fashion.

For the test, require that we are not running on Windows since the '+'
and '*' characters are not allowed on that filesystem.

Reported-by: Emily Shaffer <emilyshaffer@google.com>
Reported-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-11-25 15:04:55 -08:00
Derrick Stolee
31345d5545 maintenance: extract platform-specific scheduling
The existing schedule mechanism using 'cron' is supported by POSIX
platforms, but not Windows. It also works slightly differently on
macOS to significant detriment of the user experience. To allow for
new implementations on these platforms, extract a method that
performs the platform-specific scheduling mechanism. This will be
swapped at compile time with new implementations on specialized
platforms.

As we add this generality, rename GIT_TEST_CRONTAB to
GIT_TEST_MAINT_SCHEDULER. Further, this variable is now parsed as
"<scheduler>:<command>" so we can test platform-specific scheduling
logic even when not on the correct platform. By specifying the
<scheduler> in this string, we will be able to test all three sets of
Git logic from a Linux machine.

Co-authored-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-11-24 13:02:29 -08:00
Ævar Arnfjörð Bjarmason
793c1464d3 gc: rename keep_base_pack variable for --keep-largest-pack
As noted in an earlier change the keep_base_pack variable name is a
relic from an earlier on-list version of ae4e89e549 ("gc: add
--keep-largest-pack option", 2018-04-15) before it was renamed to
--keep-largest-pack.

Let's change the variable name to avoid that confusion, it's easier to
read the code if there's a 1=1 mapping between the variable name and
option name.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-11-21 11:39:59 -08:00
René Scharfe
a1c74791d5 gc: fix cast in compare_tasks_by_selection()
compare_tasks_by_selection() is used with QSORT and gets passed pointers
to the elements of "static struct maintenance_task tasks[]".  It casts
the *addresses* of these passed pointers to element pointers, though,
and thus effectively compares some unrelated values from the stack.  Fix
the casts to actually compare array elements.

Detected by USan (make SANITIZE=undefined test).

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-11-18 14:15:58 -08:00
Junio C Hamano
7660da1618 Merge branch 'ds/maintenance-part-3'
Parts of "git maintenance" to ease writing crontab entries (and
other scheduling system configuration) for it.

* ds/maintenance-part-3:
  maintenance: add troubleshooting guide to docs
  maintenance: use 'incremental' strategy by default
  maintenance: create maintenance.strategy config
  maintenance: add start/stop subcommands
  maintenance: add [un]register subcommands
  for-each-repo: run subcommands on configured repos
  maintenance: add --schedule option and config
  maintenance: optionally skip --auto process
2020-11-18 13:32:53 -08:00
Junio C Hamano
902f358555 Merge branch 'rs/clear-commit-marks-in-repo'
Code clean-up.

* rs/clear-commit-marks-in-repo:
  bisect: clear flags in passed repository
  object: allow clear_commit_marks_all to handle any repo
2020-11-11 13:18:37 -08:00
Junio C Hamano
0be2d65132 Merge branch 'ds/maintenance-commit-graph-auto-fix'
Test-coverage enhancement of running commit-graph task "git
maintenance" as needed led to discovery and fix of a bug.

* ds/maintenance-commit-graph-auto-fix:
  maintenance: core.commitGraph=false prevents writes
  maintenance: test commit-graph auto condition
2020-11-02 13:17:39 -08:00
René Scharfe
cd8888452c object: allow clear_commit_marks_all to handle any repo
Allow callers to specify the repository to use.  Rename the function to
repo_clear_commit_marks to document its new scope.  No functional change
intended.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-31 10:46:34 -07:00
Derrick Stolee
61f7a383d3 maintenance: use 'incremental' strategy by default
The 'git maintenance (register|start)' subcommands add the current
repository to the global Git config so maintenance will operate on that
repository. It does not specify what maintenance should occur or how
often.

To make it simple for users to start background maintenance with a
recommended schedlue, update the 'maintenance.strategy' config option in
both the 'register' and 'start' subcommands. This allows users to
customize beyond the defaults using individual
'maintenance.<task>.schedule' options, but also the user can opt-out of
this strategy using 'maintenance.strategy=none'.

Helped-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-16 08:36:42 -07:00
Derrick Stolee
a4cb1a2339 maintenance: create maintenance.strategy config
To provide an on-ramp for users to use background maintenance without
several 'git config' commands, create a 'maintenance.strategy' config
option. Currently, the only important value is 'incremental' which
assigns the following schedule:

* gc: never
* prefetch: hourly
* commit-graph: hourly
* loose-objects: daily
* incremental-repack: daily

These tasks are chosen to minimize disruptions to foreground Git
commands and use few compute resources.

The 'maintenance.strategy' is intended as a baseline that can be
customzied further by manually assigning 'maintenance.<task>.enabled'
and 'maintenance.<task>.schedule' config options, which will override
any recommendation from 'maintenance.strategy'. This operates similarly
to config options like 'feature.experimental' which operate as "meta"
config options that change default config values.

This presents a way forward for updating the 'incremental' strategy in
the future or adding new strategies. For example, a potential strategy
could be to include a 'full' strategy that runs the 'gc' task weekly
and no other tasks by default.

Helped-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-16 08:36:42 -07:00
Derrick Stolee
d334107c5d maintenance: core.commitGraph=false prevents writes
Recently, a user had an issue due to combining
fetch.writeCommitGraph=true with core.commitGraph=false. The root bug
has been resolved by preventing commit-graph writes when
core.commitGraph is disabled. This happens inside the 'git commit-graph
write' command, but we can be more aware of this situation and prevent
that process from ever starting in the 'commit-graph' maintenance task.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-12 12:13:21 -07:00
Derrick Stolee
8f801804be maintenance: test commit-graph auto condition
The auto condition for the commit-graph maintenance task walks refs
looking for commits that are not in the commit-graph file. This was
added in 4ddc79b2 (maintenance: add auto condition for commit-graph
task, 2020-09-17) but was left untested.

The initial goal of this change was to demonstrate the feature works
properly by adding tests. However, there was an off-by-one error that
caused the basic tests around maintenance.commit-graph.auto=1 to fail
when it should work.

The subtlety is that if a ref tip is not in the commit-graph, then we
were not adding that to the total count. In the test, we see that we
have only added one commit since our last commit-graph write, so the
auto condition would say there is nothing to do.

The fix is simple: add the check for the commit-graph position to see
that the tip is not in the commit-graph file before starting our walk.
Since this happens before adding to the DFS stack, we do not need to
clear our (currently empty) commit list.

This does add some extra complexity for the test, because we also want
to verify that the walk along the parents actually does some work. This
means we need to add at least two commits in a row without writing the
commit-graph. However, we also need to make sure no additional refs are
pointing to the middle of this list or else the for_each_ref() in
should_write_commit_graph() might visit these commits as tips instead of
doing a DFS walk. Hence, the last two commits are added with "git
commit" instead of "test_commit".

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-08 10:24:40 -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
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
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
a13e3d0ec8 maintenance: auto-size incremental-repack batch
When repacking during the 'incremental-repack' task, we use the
--batch-size option in 'git multi-pack-index repack'. The initial setting
used --batch-size=0 to repack everything into a single pack-file. This is
not sustainable for a large repository. The amount of work required is
also likely to use too many system resources for a background job.

Update the 'incremental-repack' task by dynamically computing a
--batch-size option based on the current pack-file structure.

The dynamic default size is computed with this idea in mind for a client
repository that was cloned from a very large remote: there is likely one
"big" pack-file that was created at clone time. Thus, do not try
repacking it as it is likely packed efficiently by the server.

Instead, we select the second-largest pack-file, and create a batch size
that is one larger than that pack-file. If there are three or more
pack-files, then this guarantees that at least two will be combined into
a new pack-file.

Of course, this means that the second-largest pack-file size is likely
to grow over time and may eventually surpass the initially-cloned
pack-file. Recall that the pack-file batch is selected in a greedy
manner: the packs are considered from oldest to newest and are selected
if they have size smaller than the batch size until the total selected
size is larger than the batch size. Thus, that oldest "clone" pack will
be first to repack after the new data creates a pack larger than that.

We also want to place some limits on how large these pack-files become,
in order to bound the amount of time spent repacking. A maximum
batch-size of two gigabytes means that large repositories will never be
packed into a single pack-file using this job, but also that repack is
rather expensive. This is a trade-off that is valuable to have if the
maintenance is being run automatically or in the background. Users who
truly want to optimize for space and performance (and are willing to pay
the upfront cost of a full repack) can use the 'gc' task to do so.

Create a test for this two gigabyte limit by creating an EXPENSIVE test
that generates two pack-files of roughly 2.5 gigabytes in size, then
performs an incremental repack. Check that the --batch-size argument in
the subcommand uses the hard-coded maximum.

Helped-by: Chris Torek <chris.torek@gmail.com>
Reported-by: Son Luong Ngoc <sluongng@gmail.com>
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
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
Derrick Stolee
25914c4fde maintenance: add trace2 regions for task execution
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-17 11:30:05 -07:00
Derrick Stolee
4ddc79b2da maintenance: add auto condition for commit-graph task
Instead of writing a new commit-graph in every 'git maintenance run
--auto' process (when maintenance.commit-graph.enalbed is configured to
be true), only write when there are "enough" commits not in a
commit-graph file.

This count is controlled by the maintenance.commit-graph.auto config
option.

To compute the count, use a depth-first search starting at each ref, and
leaving markers using the SEEN flag. If this count reaches the limit,
then terminate early and start the task. Otherwise, this operation will
peel every ref and parse the commit it points to. If these are all in
the commit-graph, then this is typically a very fast operation. Users
with many refs might feel a slow-down, and hence could consider updating
their limit to be very small. A negative value will force the step to
run every time.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-17 11:30:05 -07:00
Derrick Stolee
916d0626c2 maintenance: use pointers to check --auto
The 'git maintenance run' command has an '--auto' option. This is used
by other Git commands such as 'git commit' or 'git fetch' to check if
maintenance should be run after adding data to the repository.

Previously, this --auto option was only used to add the argument to the
'git gc' command as part of the 'gc' task. We will be expanding the
other tasks to perform a check to see if they should do work as part of
the --auto flag, when they are enabled by config.

First, update the 'gc' task to perform the auto check inside the
maintenance process. This prevents running an extra 'git gc --auto'
command when not needed. It also shows a model for other tasks.

Second, use the 'auto_condition' function pointer as a signal for
whether we enable the maintenance task under '--auto'. For instance, we
do not want to enable the 'fetch' task in '--auto' mode, so that
function pointer will remain NULL.

Now that we are not automatically calling 'git gc', a test in
t5514-fetch-multiple.sh must be changed to watch for 'git maintenance'
instead.

We continue to pass the '--auto' option to the 'git gc' command when
necessary, because of the gc.autoDetach config option changes behavior.
Likely, we will want to absorb the daemonizing behavior implied by
gc.autoDetach as a maintenance.autoDetach config option.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-17 11:30:05 -07:00
Derrick Stolee
65d655b52d maintenance: create maintenance.<task>.enabled config
Currently, a normal run of "git maintenance run" will only run the 'gc'
task, as it is the only one enabled. This is mostly for backwards-
compatible reasons since "git maintenance run --auto" commands replaced
previous "git gc --auto" commands after some Git processes. Users could
manually run specific maintenance tasks by calling "git maintenance run
--task=<task>" directly.

Allow users to customize which steps are run automatically using config.
The 'maintenance.<task>.enabled' option then can turn on these other
tasks (or turn off the 'gc' task).

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-17 11:30:05 -07:00
Derrick Stolee
d7514f6ed5 maintenance: take a lock on the objects directory
Performing maintenance on a Git repository involves writing data to the
.git directory, which is not safe to do with multiple writers attempting
the same operation. Ensure that only one 'git maintenance' process is
running at a time by holding a file-based lock. Simply the presence of
the .git/maintenance.lock file will prevent future maintenance. This
lock is never committed, since it does not represent meaningful data.
Instead, it is only a placeholder.

If the lock file already exists, then no maintenance tasks are
attempted. This will become very important later when we implement the
'prefetch' task, as this is our stop-gap from creating a recursive process
loop between 'git fetch' and 'git maintenance run --auto'.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-17 11:30:05 -07:00
Derrick Stolee
090511bc0b maintenance: add --task option
A user may want to only run certain maintenance tasks in a certain
order. Add the --task=<task> option, which allows a user to specify an
ordered list of tasks to run. These cannot be run multiple times,
however.

Here is where our array of maintenance_task pointers becomes critical.
We can sort the array of pointers based on the task order, but we do not
want to move the struct data itself in order to preserve the hashmap
references. We use the hashmap to match the --task=<task> arguments into
the task struct data.

Keep in mind that the 'enabled' member of the maintenance_task struct is
a placeholder for a future 'maintenance.<task>.enabled' config option.
Thus, we use the 'enabled' member to specify which tasks are run when
the user does not specify any --task=<task> arguments. The 'enabled'
member should be ignored if --task=<task> appears.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-17 11:30:05 -07:00
Derrick Stolee
663b2b1b90 maintenance: add commit-graph task
The first new task in the 'git maintenance' builtin is the
'commit-graph' task. This updates the commit-graph file
incrementally with the command

	git commit-graph write --reachable --split

By writing an incremental commit-graph file using the "--split"
option we minimize the disruption from this operation. The default
behavior is to merge layers until the new "top" layer is less than
half the size of the layer below. This provides quick writes most
of the time, with the longer writes following a power law
distribution.

Most importantly, concurrent Git processes only look at the
commit-graph-chain file for a very short amount of time, so they
will verly likely not be holding a handle to the file when we try
to replace it. (This only matters on Windows.)

If a concurrent process reads the old commit-graph-chain file, but
our job expires some of the .graph files before they can be read,
then those processes will see a warning message (but not fail).
This could be avoided by a future update to use the --expire-time
argument when writing the commit-graph.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-17 11:30:05 -07:00
Derrick Stolee
3103e9848f maintenance: initialize task array
In anticipation of implementing multiple maintenance tasks inside the
'maintenance' builtin, use a list of structs to describe the work to be
done.

The struct maintenance_task stores the name of the task (as given by a
future command-line argument) along with a function pointer to its
implementation and a boolean for whether the step is enabled.

A list these structs are initialized with the full list of implemented
tasks along with a default order. For now, this list only contains the
"gc" task. This task is also the only task enabled by default.

The run subcommand will return a nonzero exit code if any task fails.
However, it will attempt all tasks in its loop before returning with the
failure. Also each failed task will print an error message.

Helped-by: Taylor Blau <me@ttaylorr.com>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-17 11:30:05 -07:00
Derrick Stolee
3ddaad0e06 maintenance: add --quiet option
Maintenance activities are commonly used as steps in larger scripts.
Providing a '--quiet' option allows those scripts to be less noisy when
run on a terminal window. Turn this mode on by default when stderr is
not a terminal.

Pipe the option to the 'git gc' child process.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-17 11:30:05 -07:00
Derrick Stolee
2057d75038 maintenance: create basic maintenance runner
The 'gc' builtin is our current entrypoint for automatically maintaining
a repository. This one tool does many operations, such as repacking the
repository, packing refs, and rewriting the commit-graph file. The name
implies it performs "garbage collection" which means several different
things, and some users may not want to use this operation that rewrites
the entire object database.

Create a new 'maintenance' builtin that will become a more general-
purpose command. To start, it will only support the 'run' subcommand,
but will later expand to add subcommands for scheduling maintenance in
the background.

For now, the 'maintenance' builtin is a thin shim over the 'gc' builtin.
In fact, the only option is the '--auto' toggle, which is handed
directly to the 'gc' builtin. The current change is isolated to this
simple operation to prevent more interesting logic from being lost in
all of the boilerplate of adding a new builtin.

Use existing builtin/gc.c file because we want to share code between the
two builtins. It is possible that we will have 'maintenance' replace the
'gc' builtin entirely at some point, leaving 'git gc' as an alias for
some specific arguments to 'git maintenance run'.

Create a new test_subcommand helper that allows us to test if a certain
subcommand was run. It requires storing the GIT_TRACE2_EVENT logs in a
file. A negation mode is available that will be used in later tests.

Helped-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-17 11:30:04 -07:00
Jeff King
d70a9eb611 strvec: rename struct fields
The "argc" and "argv" names made sense when the struct was argv_array,
but now they're just confusing. Let's rename them to "nr" (which we use
for counts elsewhere) and "v" (which is rather terse, but reads well
when combined with typical variable names like "args.v").

Note that we have to update all of the callers immediately. Playing
tricks with the preprocessor is hard here, because we wouldn't want to
rewrite unrelated tokens.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-07-30 19:18:06 -07:00
Jeff King
f6d8942b1f strvec: fix indentation in renamed calls
Code which split an argv_array call across multiple lines, like:

  argv_array_pushl(&args, "one argument",
                   "another argument", "and more",
		   NULL);

was recently mechanically renamed to use strvec, which results in
mis-matched indentation like:

  strvec_pushl(&args, "one argument",
                   "another argument", "and more",
		   NULL);

Let's fix these up to align the arguments with the opening paren. I did
this manually by sifting through the results of:

  git jump grep 'strvec_.*,$'

and liberally applying my editor's auto-format. Most of the changes are
of the form shown above, though I also normalized a few that had
originally used a single-tab indentation (rather than our usual style of
aligning with the open paren). I also rewrapped a couple of obvious
cases (e.g., where previously too-long lines became short enough to fit
on one), but I wasn't aggressive about it. In cases broken to three or
more lines, the grouping of arguments is sometimes meaningful, and it
wasn't worth my time or reviewer time to ponder each case individually.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-07-28 15:02:18 -07:00
Jeff King
22f9b7f3f5 strvec: convert builtin/ callers away from argv_array name
We eventually want to drop the argv_array name and just use strvec
consistently. There's no particular reason we have to do it all at once,
or care about interactions between converted and unconverted bits.
Because of our preprocessor compat layer, the names are interchangeable
to the compiler (so even a definition and declaration using different
names is OK).

This patch converts all of the files in builtin/ to keep the diff to a
manageable size.

The conversion was done purely mechanically with:

  git ls-files '*.c' '*.h' |
  xargs perl -i -pe '
    s/ARGV_ARRAY/STRVEC/g;
    s/argv_array/strvec/g;
  '

and then selectively staging files with "git add builtin/". We'll deal
with any indentation/style fallouts separately.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-07-28 15:02:18 -07:00
Jeff King
dbbcd44fb4 strvec: rename files from argv-array to strvec
This requires updating #include lines across the code-base, but that's
all fairly mechanical, and was done with:

  git ls-files '*.c' '*.h' |
  xargs perl -i -pe 's/argv-array.h/strvec.h/'

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-07-28 15:02:17 -07:00
Taylor Blau
0bd52e27e3 commit-graph.h: store an odb in 'struct write_commit_graph_context'
There are lots of places in 'commit-graph.h' where a function either has
(or almost has) a full 'struct object_directory *', accesses '->path',
and then throws away the rest of the struct.

This can cause headaches when comparing the locations of object
directories across alternates (e.g., in the case of deciding if two
commit-graph layers can be merged). These paths are normalized with
'normalize_path_copy()' which mitigates some comparison issues, but not
all [1].

Replace usage of 'char *object_dir' with 'odb->path' by storing a
'struct object_directory *' in the 'write_commit_graph_context'
structure. This is an intermediate step towards getting rid of all path
normalization in 'commit-graph.c'.

Resolving a user-provided '--object-dir' argument now requires that we
compare it to the known alternates for equality.  Prior to this patch,
an unknown '--object-dir' argument would silently exit with status zero.

This can clearly lead to unintended behavior, such as verifying
commit-graphs that aren't in a repository's own object store (or one of
its alternates), or causing a typo to mask a legitimate commit-graph
verification failure. Make this error non-silent by 'die()'-ing when the
given '--object-dir' does not match any known alternate object store.

[1]: In my testing, for example, I can get one side of the commit-graph
code to fill object_dir with "./objects" and the other with just
"objects".

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-04 11:36:37 -08:00
Elijah Newren
15beaaa3d1 Fix spelling errors in code comments
Reported-by: Jens Schleusener <Jens.Schleusener@fossies.org>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-11-10 16:00:54 +09:00
Junio C Hamano
b9ac6c59b8 Merge branch 'cc/multi-promisor'
Teach the lazy clone machinery that there can be more than one
promisor remote and consult them in order when downloading missing
objects on demand.

* cc/multi-promisor:
  Move core_partial_clone_filter_default to promisor-remote.c
  Move repository_format_partial_clone to promisor-remote.c
  Remove fetch-object.{c,h} in favor of promisor-remote.{c,h}
  remote: add promisor and partial clone config to the doc
  partial-clone: add multiple remotes in the doc
  t0410: test fetching from many promisor remotes
  builtin/fetch: remove unique promisor remote limitation
  promisor-remote: parse remote.*.partialclonefilter
  Use promisor_remote_get_direct() and has_promisor_remote()
  promisor-remote: use repository_format_partial_clone
  promisor-remote: add promisor_remote_reinit()
  promisor-remote: implement promisor_remote_get_direct()
  Add initial support for many promisor remotes
  fetch-object: make functions return an error code
  t0410: remove pipes after git commands
2019-09-18 11:50:09 -07:00
Junio C Hamano
f4f8dfe127 Merge branch 'ds/feature-macros'
A mechanism to affect the default setting for a (related) group of
configuration variables is introduced.

* ds/feature-macros:
  repo-settings: create feature.experimental setting
  repo-settings: create feature.manyFiles setting
  repo-settings: parse core.untrackedCache
  commit-graph: turn on commit-graph by default
  t6501: use 'git gc' in quiet mode
  repo-settings: consolidate some config settings
2019-09-09 12:26:36 -07:00
Derrick Stolee
7211b9e753 repo-settings: consolidate some config settings
There are a few important config settings that are not loaded
during git_default_config. These are instead loaded on-demand.

Centralize these config options to a single scan, and store
all of the values in a repo_settings struct. The values for
each setting are initialized as negative to indicate "unset".

This centralization will be particularly important in a later
change to introduce "meta" config settings that change the
defaults for these config settings.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-08-13 13:33:54 -07:00
SZEDER Gábor
39d8831856 commit-graph: turn a group of write-related macro flags into an enum
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Acked-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-08-05 14:31:24 -07:00
Junio C Hamano
92b1ea66b9 Merge branch 'ds/commit-graph-incremental'
The commits in a repository can be described by multiple
commit-graph files now, which allows the commit-graph files to be
updated incrementally.

* ds/commit-graph-incremental:
  commit-graph: test verify across alternates
  commit-graph: normalize commit-graph filenames
  commit-graph: test --split across alternate without --split
  commit-graph: test octopus merges with --split
  commit-graph: clean up chains after flattened write
  commit-graph: verify chains with --shallow mode
  commit-graph: create options for split files
  commit-graph: expire commit-graph files
  commit-graph: allow cross-alternate chains
  commit-graph: merge commit-graph chains
  commit-graph: add --split option to builtin
  commit-graph: write commit-graph chains
  commit-graph: rearrange chunk count logic
  commit-graph: add base graphs chunk
  commit-graph: load commit-graph chains
  commit-graph: rename commit_compare to oid_compare
  commit-graph: prepare for commit-graph chains
  commit-graph: document commit-graph chains
2019-07-19 11:30:20 -07:00
Junio C Hamano
5cb7c73589 Merge branch 'ds/close-object-store'
The commit-graph file is now part of the "files that the runtime
may keep open file descriptors on, all of which would need to be
closed when done with the object store", and the file descriptor to
an existing commit-graph file now is closed before "gc" finalizes a
new instance to replace it.

* ds/close-object-store:
  packfile: rename close_all_packs to close_object_store
  packfile: close commit-graph in close_all_packs
  commit-graph: use raw_object_store when closing
2019-07-09 15:25:37 -07:00
Junio C Hamano
e1168940ce Merge branch 'ds/commit-graph-write-refactor'
Renamed from commit-graph-format-v2 and changed scope.

* ds/commit-graph-write-refactor:
  commit-graph: extract write_commit_graph_file()
  commit-graph: extract copy_oids_to_commits()
  commit-graph: extract count_distinct_commits()
  commit-graph: extract fill_oids_from_all_packs()
  commit-graph: extract fill_oids_from_commit_hex()
  commit-graph: extract fill_oids_from_packs()
  commit-graph: create write_commit_graph_context
  commit-graph: remove Future Work section
  commit-graph: collapse parameters into flags
  commit-graph: return with errors during write
  commit-graph: fix the_repository reference
2019-07-09 15:25:36 -07:00
Christian Couder
b14ed5adaf Use promisor_remote_get_direct() and has_promisor_remote()
Instead of using the repository_format_partial_clone global
and fetch_objects() directly, let's use has_promisor_remote()
and promisor_remote_get_direct().

This way all the configured promisor remotes will be taken
into account, not only the one specified by
extensions.partialClone.

Also when cloning or fetching using a partial clone filter,
remote.origin.promisor will be set to "true" instead of
setting extensions.partialClone to "origin". This makes it
possible to use many promisor remote just by fetching from
them.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-25 14:05:37 -07:00
Derrick Stolee
c2bc6e6ab0 commit-graph: create options for split files
The split commit-graph feature is now fully implemented, but needs
some more run-time configurability. Allow direct callers to 'git
commit-graph write --split' to specify the values used in the
merge strategy and the expire time.

Update the documentation to specify these values.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-19 20:46:26 -07:00
Derrick Stolee
2d511cfc0b packfile: rename close_all_packs to close_object_store
The close_all_packs() method is now responsible for more than just pack-files.
It also closes the commit-graph and the multi-pack-index. Rename the function
to be more descriptive of its larger role. The name also fits because the
input parameter is a raw_object_store.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-12 11:33:54 -07:00
Derrick Stolee
5af8039452 commit-graph: collapse parameters into flags
The write_commit_graph() and write_commit_graph_reachable() methods
currently take two boolean parameters: 'append' and 'report_progress'.
As we update these methods, adding more parameters this way becomes
cluttered and hard to maintain.

Collapse these parameters into a 'flags' parameter, and adjust the
callers to provide flags as necessary.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-12 11:20:53 -07:00
Derrick Stolee
e103f7276f commit-graph: return with errors during write
The write_commit_graph() method uses die() to report failure and
exit when confronted with an unexpected condition. This use of
die() in a library function is incorrect and is now replaced by
error() statements and an int return type. Return zero on success
and a negative value on failure.

Now that we use 'goto cleanup' to jump to the terminal condition
on an error, we have new paths that could lead to uninitialized
values. New initializers are added to correct for this.

The builtins 'commit-graph', 'gc', and 'commit' call these methods,
so update them to check the return value. Test that 'git commit-graph
write' returns a proper error code when hitting a failure condition
in write_commit_graph().

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-12 11:20:53 -07:00
Ævar Arnfjörð Bjarmason
bf3d70fe93 gc: handle & check gc.reflogExpire config
Don't redundantly run "git reflog expire --all" when gc.reflogExpire
and gc.reflogExpireUnreachable are set to "never", and die immediately
if those configuration valuer are bad.

As an earlier "assert lack of early exit" change to the tests for "git
reflog expire" shows, an early check of gc.reflogExpire{Unreachable,}
isn't wanted in general for "git reflog expire", but it makes sense
for "gc" because:

 1) Similarly to 8ab5aa4bd8 ("parseopt: handle malformed --expire
    arguments more nicely", 2018-04-21) we'll now die early if the
    config variables are set to invalid values.

    We run "pack-refs" before "reflog expire", which can take a while,
    only to then die on an invalid gc.reflogExpire{Unreachable,}
    configuration.

 2) Not invoking the command at all means it won't show up in trace
    output, which makes what's going on more obvious when the two are
    set to "never".

 3) As a later change documents we lock the refs when looping over the
    refs to expire, even in cases where we end up doing nothing due to
    this config.

    For the reasons noted in the earlier "assert lack of early exit"
    change I don't think it's worth it to bend over backwards in "git
    reflog expire" itself to carefully detect if we'll really do
    nothing given the combination of all its possible options and skip
    that locking, but that's easy to detect here in "gc" where we'll
    only run "reflog expire" in a relatively simple mode.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-04-01 12:51:51 +09:00
Ævar Arnfjörð Bjarmason
cd8eb3a094 gc: refactor a "call me once" pattern
Change an idiom we're using to ensure that gc_before_repack() only
does work once (see 62aad1849f ("gc --auto: do not lock refs in the
background", 2014-05-25)) to be more obvious.

Nothing except this function cares about the "pack_refs" and
"prune_reflogs" variables, so let's not leave the reader wondering if
they're being zero'd out for later use somewhere else.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-03-18 15:09:40 +09:00
Ævar Arnfjörð Bjarmason
e5cdbd5f70 gc: convert to using the_hash_algo
There's been a lot of changing of the hardcoded "40" values to
the_hash_algo->hexsz, but we've so far missed this one where we
hardcoded 38 for the loose object file length.

This is because a SHA-1 like abcde[...] gets turned into
objects/ab/cde[...]. There's no reason to suppose the same won't be
the case for SHA-256, and reading between the lines in
hash-function-transition.txt the format is planned to be the same.

In the future we may want to further modify this code for the hash
function transition. There's a potential pathological case here where
we'll only consider the loose objects for the currently active hash,
but objects for that hash will share a directory storage with the
other hash.

Thus we could theoretically have e.g. 1k SHA-1 loose objects, and 1
million SHA-256 objects. Then not notice that we need to pack them
because we're currently using SHA-1, even though our FS may be
straining under the stress of such humongous directories.

So assuming that "gc" eventually learns to pack up both SHA-1 and
SHA-256 objects regardless of what the current the_hash_algo is,
perhaps this check should be changed to consider all files in
objects/17/ matching [0-9a-f] 38 or 62 characters in length (i.e. both
SHA-1 and SHA-256).

But none of that is something we need to worry about now, and
supporting both 38 and 62 characters depending on "the_hash_algo"
removes another case of SHA-1 hardcoding.

As noted in [1] I'm making no effort to somehow remove the hardcoding
for "2" as in "use the first two hexdigits for the directory
name". There's no indication that that'll ever change, and somehow
generalizing it here would be a drop in the ocean, so there's no point
in doing that. It also couldn't be done without coming up with some
generalized version of the magical "objects/17" directory. See [2] for
a discussion of that directory.

1. https://public-inbox.org/git/874l84ber7.fsf@evledraar.gmail.com/

2. https://public-inbox.org/git/87k1mta9x5.fsf@evledraar.gmail.com/

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-03-18 15:09:39 +09:00
Ævar Arnfjörð Bjarmason
8bf14444c3 gc: remove redundant check for gc_auto_threshold
Checking gc_auto_threshold in too_many_loose_objects() was added in
17815501a8 ("git-gc --auto: run "repack -A -d -l" as necessary.",
2007-09-17) when need_to_gc() itself was also reliant on
gc_auto_pack_limit before its early return:

    gc_auto_threshold <= 0 && gc_auto_pack_limit <= 0

When that check was simplified to just checking "gc_auto_threshold <=
0" in b14d255ba8 ("builtin-gc.c: allow disabling all auto-gc'ing by
assigning 0 to gc.auto", 2008-03-19) this unreachable code should have
been removed. We only call too_many_loose_objects() from within
need_to_gc() itself, which will return if this condition holds, and in
cmd_gc() which will return before ever getting to "auto_gc &&
too_many_loose_objects()" if "auto_gc && !need_to_gc()" is true
earlier in the function.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-03-14 13:55:28 +09:00
Junio C Hamano
5104f8f1ac Merge branch 'js/gc-repack-close-before-remove'
"git gc" and "git repack" did not close the open packfiles that
they found unneeded before removing them, which didn't work on a
platform incapable of removing an open file.  This has been
corrected.

* js/gc-repack-close-before-remove:
  gc/repack: release packs when needed
2019-01-18 13:49:57 -08:00
Johannes Schindelin
5bdece0d70 gc/repack: release packs when needed
On Windows, files cannot be removed nor renamed if there are still
handles held by a process. To remedy that, we introduced the
close_all_packs() function.

Earlier, we made sure that the packs are released just before `git gc`
is spawned, in case that gc wants to remove no-longer needed packs.

But this developer forgot that gc itself also needs to let go of packs,
e.g. when consolidating all packs via the --aggressive option.

Likewise, `git repack -d` wants to delete obsolete packs and therefore
needs to close all pack handles, too.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-01-11 09:22:39 -08:00
Nguyễn Thái Ngọc Duy
ec36c42a63 Indent code with TABs
We indent with TABs and sometimes for fine alignment, TABs followed by
spaces, but never all spaces (unless the indentation is less than 8
columns). Indenting with spaces slips through in some places. Fix
them.

Imported code and compat/ are left alone on purpose. The former should
remain as close as upstream as possible. The latter pretty much has
separate maintainers, it's up to them to decide.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-12-09 12:37:32 +09:00
Junio C Hamano
993fa56258 Merge branch 'jn/gc-auto'
"gc --auto" ended up calling exit(-1) upon error, which has been
corrected to use exit(1).  Also the error reporting behaviour when
daemonized has been updated to exit with zero status when stopping
due to a previously discovered error (which implies there is no
point running gc to improve the situation); we used to exit with
failure in such a case.

* jn/gc-auto:
  gc: do not return error for prior errors in daemonized mode
2018-10-16 16:16:02 +09:00
Junio C Hamano
99913dd118 Merge branch 'jn/gc-auto-prep'
Code clean-up.

* jn/gc-auto-prep:
  gc: exit with status 128 on failure
  gc: improve handling of errors reading gc.log
2018-10-16 16:16:02 +09:00
Junio C Hamano
36d767d02e Merge branch 'ab/commit-graph-progress'
Generation of (experimental) commit-graph files have so far been
fairly silent, even though it takes noticeable amount of time in a
meaningfully large repository.  The users will now see progress
output.

* ab/commit-graph-progress:
  gc: fix regression in 7b0f229222 impacting --quiet
  commit-graph verify: add progress output
  commit-graph write: add progress output
2018-10-16 16:15:58 +09:00
Ævar Arnfjörð Bjarmason
6b89a34c89 gc: fix regression in 7b0f229222 impacting --quiet
Fix a regression in my recent 7b0f229222 ("commit-graph write: add
progress output", 2018-09-17).  The newly added progress output for
"commit-graph write" didn't check the --quiet option.

Do so, and add a test asserting that this works as expected. Since the
TTY prequisite isn't available everywhere let's add a version of this
that both requires and doesn't require that. This test might be overly
specific and will break if new progress output is added, but I think
it'll serve as a good reminder to test the undertested progress
mode(s).

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Helped-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-09-20 12:25:05 -07:00
Ævar Arnfjörð Bjarmason
7b0f229222 commit-graph write: add progress output
Before this change the "commit-graph write" command didn't report any
progress. On my machine this command takes more than 10 seconds to
write the graph for linux.git, and around 1m30s on the
2015-04-03-1M-git.git[1] test repository (a test case for a large
monorepository).

Furthermore, since the gc.writeCommitGraph setting was added in
d5d5d7b641 ("gc: automatically write commit-graph files", 2018-06-27),
there was no indication at all from a "git gc" run that anything was
different. This why one of the progress bars being added here uses
start_progress() instead of start_delayed_progress(), so that it's
guaranteed to be seen. E.g. on my tiny 867 commit dotfiles.git
repository:

    $ git -c gc.writeCommitGraph=true gc
    Enumerating objects: 2821, done.
    [...]
    Computing commit graph generation numbers: 100% (867/867), done.

On larger repositories, such as linux.git the delayed progress bar(s)
will kick in, and we'll show what's going on instead of, as was
previously happening, printing nothing while we write the graph:

    $ git -c gc.writeCommitGraph=true gc
    [...]
    Annotating commits in commit graph: 1565573, done.
    Computing commit graph generation numbers: 100% (782484/782484), done.

Note that here we don't show "Finding commits for commit graph", this
is because under "git gc" we seed the search with the commit
references in the repository, and that set is too small to show any
progress, but would e.g. on a smaller repo such as git.git with
--stdin-commits:

    $ git rev-list --all | git -c gc.writeCommitGraph=true write --stdin-commits
    Finding commits for commit graph: 100% (162576/162576), done.
    Computing commit graph generation numbers: 100% (162576/162576), done.

With --stdin-packs we don't show any estimation of how much is left to
do. This is because we might be processing more than one pack. We
could be less lazy here and show progress, either by detecting that
we're only processing one pack, or by first looping over the packs to
discover how many commits they have. I don't see the point in doing
that work. So instead we get (on 2015-04-03-1M-git.git):

    $ echo pack-<HASH>.idx | git -c gc.writeCommitGraph=true --exec-path=$PWD commit-graph write --stdin-packs
    Finding commits for commit graph: 13064614, done.
    Annotating commits in commit graph: 3001341, done.
    Computing commit graph generation numbers: 100% (1000447/1000447), done.

No GC mode uses --stdin-packs. It's what they use at Microsoft to
manually compute the generation numbers for their collection of large
packs which are never coalesced.

The reason we need a "report_progress" variable passed down from "git
gc" is so that we don't report this output when we're running in the
process "git gc --auto" detaches from the terminal.

Since we write the commit graph from the "git gc" process itself (as
opposed to what we do with say the "git repack" phase), we'd end up
writing the output to .git/gc.log and reporting it to the user next
time as part of the "The last gc run reported the following[...]"
error, see 329e6e8794 ("gc: save log from daemonized gc --auto and
print it next time", 2015-09-19).

So we must keep track of whether or not we're running in that
demonized mode, and if so print no progress.

See [2] and subsequent replies for a discussion of an approach not
taken in compute_generation_numbers(). I.e. we're saying "Computing
commit graph generation numbers", even though on an established
history we're mostly skipping over all the work we did in the
past. This is similar to the white lie we tell in the "Writing
objects" phase (not all are objects being written).

Always showing progress is considered more important than
accuracy. I.e. on a repository like 2015-04-03-1M-git.git we'd hang
for 6 seconds with no output on the second "git gc" if no changes were
made to any objects in the interim if we'd take the approach in [2].

1. https://github.com/avar/2015-04-03-1M-git

2. <c6960252-c095-fb2b-e0bc-b1e6bb261614@gmail.com>
   (https://public-inbox.org/git/c6960252-c095-fb2b-e0bc-b1e6bb261614@gmail.com/)

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-09-17 10:12:30 -07:00
Derrick Stolee
454ea2e4d7 treewide: use get_all_packs
There are many places in the codebase that want to iterate over
all packfiles known to Git. The purposes are wide-ranging, and
those that can take advantage of the multi-pack-index already
do. So, use get_all_packs() instead of get_packed_git() to be
sure we are iterating over all packfiles.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-20 15:31:40 -07:00
Junio C Hamano
562413eb29 Merge branch 'kg/gc-auto-windows-workaround'
"git gc --auto" opens file descriptors for the packfiles before
spawning "git repack/prune", which would upset Windows that does
not want a process to work on a file that is open by another
process.  The issue has been worked around.

* kg/gc-auto-windows-workaround:
  gc --auto: release pack files before auto packing
2018-08-02 15:30:43 -07:00
Jonathan Nieder
3029970275 gc: do not return error for prior errors in daemonized mode
Some build machines started consistently failing to fetch updated
source using "repo sync", with error

  error: The last gc run reported the following. Please correct the root cause
  and remove /build/.repo/projects/tools/git.git/gc.log.
  Automatic cleanup will not be performed until the file is removed.

  warning: There are too many unreachable loose objects; run 'git prune' to remove them.

The cause takes some time to describe.

In v2.0.0-rc0~145^2 (gc: config option for running --auto in
background, 2014-02-08), "git gc --auto" learned to run in the
background instead of blocking the invoking command.  In this mode, it
closed stderr to avoid interleaving output with any subsequent
commands, causing warnings like the above to be swallowed; v2.6.3~24^2
(gc: save log from daemonized gc --auto and print it next time,
2015-09-19) addressed that by storing any diagnostic output in
.git/gc.log and allowing the next "git gc --auto" run to print it.

To avoid wasteful repeated fruitless gcs, when gc.log is present, the
subsequent "gc --auto" would die after printing its contents.  Most
git commands, such as "git fetch", ignore the exit status from "git gc
--auto" so all is well at this point: the user gets to see the error
message, and the fetch succeeds, without a wasteful additional attempt
at an automatic gc.

External tools like repo[1], though, do care about the exit status
from "git gc --auto".  In non-daemonized mode, the exit status is
straightforward: if there is an error, it is nonzero, but after a
warning like the above, the status is zero.  The daemonized mode, as a
side effect of the other properties provided, offers a very strange
exit code convention:

 - if no housekeeping was required, the exit status is 0

 - the first real run, after forking into the background, returns exit
   status 0 unconditionally.  The parent process has no way to know
   whether gc will succeed.

 - if there is any diagnostic output in gc.log, subsequent runs return
   a nonzero exit status to indicate that gc was not triggered.

There's nothing for the calling program to act on on the basis of that
error.  Use status 0 consistently instead, to indicate that we decided
not to run a gc (just like if no housekeeping was required).  This
way, repo and similar tools can get the benefit of the same behavior
as tools like "git fetch" that ignore the exit status from gc --auto.

Once the period of time described by gc.pruneExpire elapses, the
unreachable loose objects will be removed by "git gc --auto"
automatically.

[1] https://gerrit-review.googlesource.com/c/git-repo/+/10598/

Reported-by: Andrii Dehtiarov <adehtiarov@google.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-07-17 11:24:36 -07:00
Jonathan Nieder
fec2ed2187 gc: exit with status 128 on failure
A value of -1 returned from cmd_gc gets propagated to exit(),
resulting in an exit status of 255.  Use die instead for a clearer
error message and a controlled exit.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-07-17 11:19:45 -07:00
Jonathan Nieder
3c426eccc2 gc: improve handling of errors reading gc.log
A collection of minor error handling fixes:

- use an error message in lower case, following the usual style
- quote filenames in error messages to make them easier to read and to
  decrease translation load by matching other 'stat' error messages
- check for and report errors from 'read', too
- avoid being confused by a gc.log larger than INT_MAX bytes

Noticed by code inspection.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-07-17 11:18:07 -07:00
Kim Gybels
12e73a3ce4 gc --auto: release pack files before auto packing
Teach gc --auto to release pack files before auto packing the repository
to prevent failures when removing them.

Also teach the test 'fetching with auto-gc does not lock up' to complain
when it is no longer triggering an auto packing of the repository.

Fixes https://github.com/git-for-windows/git/issues/500

Signed-off-by: Kim Gybels <kgybels@infogroep.be>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-07-09 14:16:10 -07:00
Derrick Stolee
d5d5d7b641 gc: automatically write commit-graph files
The commit-graph file is a very helpful feature for speeding up git
operations. In order to make it more useful, make it possible to
write the commit-graph file during standard garbage collection
operations.

Add a 'gc.commitGraph' config setting that triggers writing a
commit-graph file after any non-trivial 'git gc' command. Defaults to
false while the commit-graph feature matures. We specifically do not
want to have this on by default until the commit-graph feature is fully
integrated with history-modifying features like shallow clones.

Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-06-27 10:29:10 -07:00
Junio C Hamano
2f76ebc93c Merge branch 'ma/lockfile-cleanup'
Code clean-up to adjust to a more recent lockfile API convention that
allows lockfile instances kept on the stack.

* ma/lockfile-cleanup:
  lock_file: move static locks into functions
  lock_file: make function-local locks non-static
  refs.c: do not die if locking fails in `delete_pseudoref()`
  refs.c: do not die if locking fails in `write_pseudoref()`
  t/helper/test-write-cache: clean up lock-handling
2018-05-30 14:04:05 +09:00
Junio C Hamano
30b015bffe Merge branch 'nd/repack-keep-pack'
"git gc" in a large repository takes a lot of time as it considers
to repack all objects into one pack by default.  The command has
been taught to pretend as if the largest existing packfile is
marked with ".keep" so that it is left untouched while objects in
other packs and loose ones are repacked.

* nd/repack-keep-pack:
  pack-objects: show some progress when counting kept objects
  gc --auto: exclude base pack if not enough mem to "repack -ad"
  gc: handle a corner case in gc.bigPackThreshold
  gc: add gc.bigPackThreshold config
  gc: add --keep-largest-pack option
  repack: add --keep-pack option
  t7700: have closing quote of a test at the beginning of line
2018-05-23 14:38:14 +09:00
Martin Ågren
b227586831 lock_file: make function-local locks non-static
Placing `struct lock_file`s on the stack used to be a bad idea, because
the temp- and lockfile-machinery would keep a pointer into the struct.
But after 076aa2cbd (tempfile: auto-allocate tempfiles on heap,
2017-09-05), we can safely have lockfiles on the stack. (This applies
even if a user returns early, leaving a locked lock behind.)

These `struct lock_file`s are local to their respective functions and we
can drop their staticness.

For good measure, I have inspected these sites and come to believe that
they always release the lock, with the possible exception of bailing out
using `die()` or `exit()` or by returning from a `cmd_foo()`.

As pointed out by Jeff King, it would be bad if someone held on to a
`struct lock_file *` for some reason. After some grepping, I agree with
his findings: no-one appears to be doing that.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-05-10 14:54:45 +09:00
Junio C Hamano
3915f9a4fa Merge branch 'jc/parseopt-expiry-errors'
"git gc --prune=nonsense" spent long time repacking and then
silently failed when underlying "git prune --expire=nonsense"
failed to parse its command line.  This has been corrected.

* jc/parseopt-expiry-errors:
  parseopt: handle malformed --expire arguments more nicely
  gc: do not upcase error message shown with die()
2018-05-08 15:59:33 +09:00
Junio C Hamano
8ab5aa4bd8 parseopt: handle malformed --expire arguments more nicely
A few commands that parse --expire=<time> command line option behave
sillily when given nonsense input.  For example

    $ git prune --no-expire
    Segmentation falut
    $ git prune --expire=npw; echo $?
    129

Both come from parse_opt_expiry_date_cb().

The former is because the function is not prepared to see arg==NULL
(for "--no-expire", it is a norm; "--expire" at the end of the
command line could be made to pass NULL, if it is told that the
argument is optional, but we don't so we do not have to worry about
that case).

The latter is because it does not check the value returned from the
underlying parse_expiry_date().

This seems to be a recent regression introduced while we attempted
to avoid spewing the entire usage message when given a correct
option but with an invalid value at 3bb0923f ("parse-options: do not
show usage upon invalid option value", 2018-03-22).  Before that, we
didn't fail silently but showed a full usage help (which arguably is
not all that better).

Also catch this error early when "git gc --prune=<expiration>" is
misspelled by doing a dummy parsing before the main body of "gc"
that is time consuming even begins.  Otherwise, we'd spend time to
pack objects and then later have "git prune" first notice the error.
Aborting "gc" in the middle that way is not harmful but is ugly and
can be avoided.

Helped-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-04-23 22:36:59 +09:00
Junio C Hamano
96913c9df6 gc: do not upcase error message shown with die()
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-04-23 22:36:14 +09:00
Nguyễn Thái Ngọc Duy
9806f5a7bf gc --auto: exclude base pack if not enough mem to "repack -ad"
pack-objects could be a big memory hog especially on large repos,
everybody knows that. The suggestion to stick a .keep file on the
giant base pack to avoid this problem is also known for a long time.

Recent patches add an option to do just this, but it has to be either
configured or activated manually. This patch lets `git gc --auto`
activate this mode automatically when it thinks `repack -ad` will use
a lot of memory and start affecting the system due to swapping or
flushing OS cache.

gc --auto decides to do this based on an estimation of pack-objects
memory usage, which is quite accurate at least for the heap part, and
whether that fits in half of system memory (the assumption here is for
desktop environment where there are many other applications running).

This mechanism only kicks in if gc.bigBasePackThreshold is not configured.
If it is, it is assumed that the user already knows what they want.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-04-16 13:52:29 +09:00
Nguyễn Thái Ngọc Duy
8fc6776247 gc: handle a corner case in gc.bigPackThreshold
This config allows us to keep <N> packs back if their size is larger
than a limit. But if this N >= gc.autoPackLimit, we may have a
problem. We are supposed to reduce the number of packs after a
threshold because it affects performance.

We could tell the user that they have incompatible gc.bigPackThreshold
and gc.autoPackLimit, but it's kinda hard when 'git gc --auto' runs in
background. Instead let's fall back to the next best stategy: try to
reduce the number of packs anyway, but keep the base pack out. This
reduces the number of packs to two and hopefully won't take up too
much resources to repack (the assumption still is the base pack takes
most resources to handle).

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-04-16 13:52:29 +09:00
Nguyễn Thái Ngọc Duy
55dfe13df9 gc: add gc.bigPackThreshold config
The --keep-largest-pack option is not very convenient to use because
you need to tell gc to do this explicitly (and probably on just a few
large repos).

Add a config key that enables this mode when packs larger than a limit
are found. Note that there's a slight behavior difference compared to
--keep-largest-pack: all packs larger than the threshold are kept, not
just the largest one.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-04-16 13:52:29 +09:00
Nguyễn Thái Ngọc Duy
ae4e89e549 gc: add --keep-largest-pack option
This adds a new repack mode that combines everything into a secondary
pack, leaving the largest pack alone.

This could help reduce memory pressure. On linux-2.6.git, valgrind
massif reports 1.6GB heap in "pack all" case, and 535MB in "pack
all except the base pack" case. We save roughly 1GB memory by
excluding the base pack.

This should also lower I/O because we don't have to rewrite a giant
pack every time (e.g. for linux-2.6.git that's a 1.4GB pack file)..

PS. The use of string_list here seems overkill, but we'll need it in
the next patch...

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-04-16 13:52:29 +09:00
Junio C Hamano
3a1ec60c43 Merge branch 'sb/packfiles-in-repository'
Refactoring of the internal global data structure continues.

* sb/packfiles-in-repository:
  packfile: keep prepare_packed_git() private
  packfile: allow find_pack_entry to handle arbitrary repositories
  packfile: add repository argument to find_pack_entry
  packfile: allow reprepare_packed_git to handle arbitrary repositories
  packfile: allow prepare_packed_git to handle arbitrary repositories
  packfile: allow prepare_packed_git_one to handle arbitrary repositories
  packfile: add repository argument to reprepare_packed_git
  packfile: add repository argument to prepare_packed_git
  packfile: add repository argument to prepare_packed_git_one
  packfile: allow install_packed_git to handle arbitrary repositories
  packfile: allow rearrange_packed_git to handle arbitrary repositories
  packfile: allow prepare_packed_git_mru to handle arbitrary repositories
2018-04-11 13:09:55 +09:00
Junio C Hamano
cf0b1793ea Merge branch 'sb/object-store'
Refactoring the internal global data structure to make it possible
to open multiple repositories, work with and then close them.

Rerolled by Duy on top of a separate preliminary clean-up topic.
The resulting structure of the topics looked very sensible.

* sb/object-store: (27 commits)
  sha1_file: allow sha1_loose_object_info to handle arbitrary repositories
  sha1_file: allow map_sha1_file to handle arbitrary repositories
  sha1_file: allow map_sha1_file_1 to handle arbitrary repositories
  sha1_file: allow open_sha1_file to handle arbitrary repositories
  sha1_file: allow stat_sha1_file to handle arbitrary repositories
  sha1_file: allow sha1_file_name to handle arbitrary repositories
  sha1_file: add repository argument to sha1_loose_object_info
  sha1_file: add repository argument to map_sha1_file
  sha1_file: add repository argument to map_sha1_file_1
  sha1_file: add repository argument to open_sha1_file
  sha1_file: add repository argument to stat_sha1_file
  sha1_file: add repository argument to sha1_file_name
  sha1_file: allow prepare_alt_odb to handle arbitrary repositories
  sha1_file: allow link_alt_odb_entries to handle arbitrary repositories
  sha1_file: add repository argument to prepare_alt_odb
  sha1_file: add repository argument to link_alt_odb_entries
  sha1_file: add repository argument to read_info_alternates
  sha1_file: add repository argument to link_alt_odb_entry
  sha1_file: add raw_object_store argument to alt_odb_usable
  pack: move approximate object count to object store
  ...
2018-04-11 13:09:55 +09:00
Nguyễn Thái Ngọc Duy
464416a2ea packfile: keep prepare_packed_git() private
The reason callers have to call this is to make sure either packed_git
or packed_git_mru pointers are initialized since we don't do that by
default. Sometimes it's hard to see this connection between where the
function is called and where packed_git pointer is used (sometimes in
separate functions).

Keep this dependency internal because now all access to packed_git and
packed_git_mru must go through get_xxx() wrappers.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-03-26 10:07:43 -07:00
Stefan Beller
a49d283435 packfile: add repository argument to reprepare_packed_git
See previous patch for explanation.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-03-26 10:07:43 -07:00
Stefan Beller
6fdb4e9f5a packfile: add repository argument to prepare_packed_git
Add a repository argument to allow prepare_packed_git callers to be
more specific about which repository to handle. See commit "sha1_file:
add repository argument to link_alt_odb_entry" for an explanation of
the #define trick.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-03-26 10:07:43 -07:00
Stefan Beller
a80d72db2a object-store: move packed_git and packed_git_mru to object store
In a process with multiple repositories open, packfile accessors
should be associated to a single repository and not shared globally.
Move packed_git and packed_git_mru into the_repository and adjust
callers to reflect this.

[nd: while at there, wrap access to these two fields in get_packed_git()
and get_packed_git_mru(). This allows us to lazily initialize these
fields without caller doing that explicitly]

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-03-26 10:05:46 -07:00
Junio C Hamano
7fb6aefd2a Merge branch 'nd/parseopt-completion'
Teach parse-options API an option to help the completion script,
and make use of the mechanism in command line completion.

* nd/parseopt-completion: (45 commits)
  completion: more subcommands in _git_notes()
  completion: complete --{reuse,reedit}-message= for all notes subcmds
  completion: simplify _git_notes
  completion: don't set PARSE_OPT_NOCOMPLETE on --rerere-autoupdate
  completion: use __gitcomp_builtin in _git_worktree
  completion: use __gitcomp_builtin in _git_tag
  completion: use __gitcomp_builtin in _git_status
  completion: use __gitcomp_builtin in _git_show_branch
  completion: use __gitcomp_builtin in _git_rm
  completion: use __gitcomp_builtin in _git_revert
  completion: use __gitcomp_builtin in _git_reset
  completion: use __gitcomp_builtin in _git_replace
  remote: force completing --mirror= instead of --mirror
  completion: use __gitcomp_builtin in _git_remote
  completion: use __gitcomp_builtin in _git_push
  completion: use __gitcomp_builtin in _git_pull
  completion: use __gitcomp_builtin in _git_notes
  completion: use __gitcomp_builtin in _git_name_rev
  completion: use __gitcomp_builtin in _git_mv
  completion: use __gitcomp_builtin in _git_merge_base
  ...
2018-03-14 12:01:07 -07:00
Nguyễn Thái Ngọc Duy
7e1eeaa431 completion: use __gitcomp_builtin in _git_gc
The new completable option is --quiet.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-02-09 10:24:51 -08:00
Jonathan Tan
0c16cd499d gc: do not repack promisor packfiles
Teach gc to stop traversal at promisor objects, and to leave promisor
packfiles alone. This has the effect of only repacking non-promisor
packfiles, and preserves the distinction between promisor packfiles and
non-promisor packfiles.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-12-08 09:52:42 -08:00
Junio C Hamano
abdf7d8e25 Merge branch 'aw/gc-lockfile-fscanf-fix'
"git gc" tries to avoid running two instances at the same time by
reading and writing pid/host from and to a lock file; it used to
use an incorrect fscanf() format when reading, which has been
corrected.

* aw/gc-lockfile-fscanf-fix:
  gc: call fscanf() with %<len>s, not %<len>c, when reading hostname
2017-09-25 15:24:09 +09:00
Junio C Hamano
afe2fab72c gc: call fscanf() with %<len>s, not %<len>c, when reading hostname
Earlier in this codepath, we (ab)used "%<len>c" to read the hostname
recorded in the lockfile into locking_host[HOST_NAME_MAX + 1] while
substituting <len> with the actual value of HOST_NAME_MAX.

This turns out to be incorrect, as it is an instruction to read
exactly the specified number of bytes.  Because we are trying to
read at most that many bytes, we should be using "%<len>s" instead.

Helped-by: A. Wilcox <awilfox@adelielinux.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-17 13:21:44 +09:00
Jeff King
076aa2cbda tempfile: auto-allocate tempfiles on heap
The previous commit taught the tempfile code to give up
ownership over tempfiles that have been renamed or deleted.
That makes it possible to use a stack variable like this:

  struct tempfile t;

  create_tempfile(&t, ...);
  ...
  if (!err)
          rename_tempfile(&t, ...);
  else
          delete_tempfile(&t);

But doing it this way has a high potential for creating
memory errors. The tempfile we pass to create_tempfile()
ends up on a global linked list, and it's not safe for it to
go out of scope until we've called one of those two
deactivation functions.

Imagine that we add an early return from the function that
forgets to call delete_tempfile(). With a static or heap
tempfile variable, the worst case is that the tempfile hangs
around until the program exits (and some functions like
setup_shallow_temporary rely on this intentionally, creating
a tempfile and then leaving it for later cleanup).

But with a stack variable as above, this is a serious memory
error: the variable goes out of scope and may be filled with
garbage by the time the tempfile code looks at it.  Let's
see if we can make it harder to get this wrong.

Since many callers need to allocate arbitrary numbers of
tempfiles, we can't rely on static storage as a general
solution. So we need to turn to the heap. We could just ask
all callers to pass us a heap variable, but that puts the
burden on them to call free() at the right time.

Instead, let's have the tempfile code handle the heap
allocation _and_ the deallocation (when the tempfile is
deactivated and removed from the list).

This changes the return value of all of the creation
functions. For the cleanup functions (delete and rename),
we'll add one extra bit of safety: instead of taking a
tempfile pointer, we'll take a pointer-to-pointer and set it
to NULL after freeing the object. This makes it safe to
double-call functions like delete_tempfile(), as the second
call treats the NULL input as a noop. Several callsites
follow this pattern.

The resulting patch does have a fair bit of noise, as each
caller needs to be converted to handle:

  1. Storing a pointer instead of the struct itself.

  2. Passing the pointer instead of taking the struct
     address.

  3. Handling a "struct tempfile *" return instead of a file
     descriptor.

We could play games to make this less noisy. For example, by
defining the tempfile like this:

  struct tempfile {
	struct heap_allocated_part_of_tempfile {
                int fd;
                ...etc
        } *actual_data;
  }

Callers would continue to have a "struct tempfile", and it
would be "active" only when the inner pointer was non-NULL.
But that just makes things more awkward in the long run.
There aren't that many callers, so we can simply bite
the bullet and adjust all of them. And the compiler makes it
easy for us to find them all.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-06 17:19:54 +09:00
Jonathan Tan
0abe14f6a5 pack: move {,re}prepare_packed_git and approximate_object_count
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-08-23 15:12:07 -07:00
Junio C Hamano
764046f6b0 Merge branch 'jk/gc-pre-detach-under-hook'
We run an early part of "git gc" that deals with refs before
daemonising (and not under lock) even when running a background
auto-gc, which caused multiple gc processes attempting to run the
early part at the same time.  This is now prevented by running the
early part also under the GC lock.

* jk/gc-pre-detach-under-hook:
  gc: run pre-detach operations under lock
2017-07-18 12:48:10 -07:00
Junio C Hamano
f056cde60e Merge branch 'rs/use-div-round-up'
Code cleanup.

* rs/use-div-round-up:
  use DIV_ROUND_UP
2017-07-12 15:18:23 -07:00
Jeff King
c45af94dbc gc: run pre-detach operations under lock
We normally try to avoid having two auto-gc operations run
at the same time, because it wastes resources. This was done
long ago in 64a99eb47 (gc: reject if another gc is running,
unless --force is given, 2013-08-08).

When we do a detached auto-gc, we run the ref-related
commands _before_ detaching, to avoid confusing lock
contention. This was done by 62aad1849 (gc --auto: do not
lock refs in the background, 2014-05-25).

These two features do not interact well. The pre-detach
operations are run before we check the gc.pid lock, meaning
that on a busy repository we may run many of them
concurrently. Ideally we'd take the lock before spawning any
operations, and hold it for the duration of the program.

This is tricky, though, with the way the pid-file interacts
with the daemonize() process.  Other processes will check
that the pid recorded in the pid-file still exists. But
detaching causes us to fork and continue running under a
new pid. So if we take the lock before detaching, the
pid-file will have a bogus pid in it. We'd have to go back
and update it with the new pid after detaching. We'd also
have to play some tricks with the tempfile subsystem to
tweak the "owner" field, so that the parent process does not
clean it up on exit, but the child process does.

Instead, we can do something a bit simpler: take the lock
only for the duration of the pre-detach work, then detach,
then take it again for the post-detach work. Technically,
this means that the post-detach lock could lose to another
process doing pre-detach work. But in the long run this
works out.

That second process would then follow-up by doing
post-detach work. Unless it was in turn blocked by a third
process doing pre-detach work, and so on. This could in
theory go on indefinitely, as the pre-detach work does not
repack, and so need_to_gc() will continue to trigger.  But
in each round we are racing between the pre- and post-detach
locks. Eventually, one of the post-detach locks will win the
race and complete the full gc. So in the worst case, we may
racily repeat the pre-detach work, but we would never do so
simultaneously (it would happen via a sequence of serialized
race-wins).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-07-12 09:41:04 -07:00
René Scharfe
42c78a216e use DIV_ROUND_UP
Convert code that divides and rounds up to use DIV_ROUND_UP to make the
intent clearer and reduce the number of magic constants.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-07-10 14:24:36 -07:00
Junio C Hamano
f31d23a399 Merge branch 'bw/config-h'
Fix configuration codepath to pay proper attention to commondir
that is used in multi-worktree situation, and isolate config API
into its own header file.

* bw/config-h:
  config: don't implicitly use gitdir or commondir
  config: respect commondir
  setup: teach discover_git_directory to respect the commondir
  config: don't include config.h by default
  config: remove git_config_iter
  config: create config.h
2017-06-24 14:28:41 -07:00
Brandon Williams
b2141fc1d2 config: don't include config.h by default
Stop including config.h by default in cache.h.  Instead only include
config.h in those files which require use of the config system.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-15 12:56:22 -07:00
Junio C Hamano
b15667bbdc Merge branch 'js/larger-timestamps'
Some platforms have ulong that is smaller than time_t, and our
historical use of ulong for timestamp would mean they cannot
represent some timestamp that the platform allows.  Invent a
separate and dedicated timestamp_t (so that we can distingiuish
timestamps and a vanilla ulongs, which along is already a good
move), and then declare uintmax_t is the type to be used as the
timestamp_t.

* js/larger-timestamps:
  archive-tar: fix a sparse 'constant too large' warning
  use uintmax_t for timestamps
  date.c: abort if the system time cannot handle one of our timestamps
  timestamp_t: a new data type for timestamps
  PRItime: introduce a new "printf format" for timestamps
  parse_timestamp(): specify explicitly where we parse timestamps
  t0006 & t5000: skip "far in the future" test when time_t is too limited
  t0006 & t5000: prepare for 64-bit timestamps
  ref-filter: avoid using `unsigned long` for catch-all data type
2017-05-16 11:51:59 +09:00
Johannes Schindelin
dddbad728c timestamp_t: a new data type for timestamps
Git's source code assumes that unsigned long is at least as precise as
time_t. Which is incorrect, and causes a lot of problems, in particular
where unsigned long is only 32-bit (notably on Windows, even in 64-bit
versions).

So let's just use a more appropriate data type instead. In preparation
for this, we introduce the new `timestamp_t` data type.

By necessity, this is a very, very large patch, as it has to replace all
timestamps' data type in one go.

As we will use a data type that is not necessarily identical to `time_t`,
we need to be very careful to use `time_t` whenever we interact with the
system functions, and `timestamp_t` everywhere else.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-04-27 13:07:39 +09:00
Junio C Hamano
5938454cbc Merge branch 'dt/xgethostname-nul-termination'
gethostname(2) may not NUL terminate the buffer if hostname does
not fit; unfortunately there is no easy way to see if our buffer
was too small, but at least this will make sure we will not end up
using garbage past the end of the buffer.

* dt/xgethostname-nul-termination:
  xgethostname: handle long hostnames
  use HOST_NAME_MAX to size buffers for gethostname(2)
2017-04-23 22:07:57 -07:00
David Turner
5781a9a270 xgethostname: handle long hostnames
If the full hostname doesn't fit in the buffer supplied to
gethostname, POSIX does not specify whether the buffer will be
null-terminated, so to be safe, we should do it ourselves.  Introduce
new function, xgethostname, which ensures that there is always a \0
at the end of the buffer.

Signed-off-by: David Turner <dturner@twosigma.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-04-18 19:58:04 -07:00
René Scharfe
da25bdb776 use HOST_NAME_MAX to size buffers for gethostname(2)
POSIX limits the length of host names to HOST_NAME_MAX.  Export the
fallback definition from daemon.c and use this constant to make all
buffers used with gethostname(2) big enough for any possible result
and a terminating NUL.

Inspired-by: David Turner <dturner@twosigma.com>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: David Turner <dturner@twosigma.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-04-18 19:57:41 -07:00
Jeff King
07af889136 gc: replace local buffer with git_path
We probe the "17/" loose object directory for auto-gc, and
use a local buffer to format the path. We can just use
git_path() for this. It handles paths of any length
(reducing our error handling). And because we feed the
result straight to a system call, we can just use the static
variant.

Note that git_path also knows the string "objects/" is
special, and will replace it with git_object_directory()
when necessary.

Another alternative would be to use sha1_file_name() for the
pretend object "170000...", but that ends up being more
hassle for no gain, as we have to truncate the final path
component.

Signed-off-by: Jeff King <peff@peff.net>
2017-03-30 14:59:50 -07:00
Junio C Hamano
94c9b5af70 Merge branch 'cc/split-index-config'
The experimental "split index" feature has gained a few
configuration variables to make it easier to use.

* cc/split-index-config: (22 commits)
  Documentation/git-update-index: explain splitIndex.*
  Documentation/config: add splitIndex.sharedIndexExpire
  read-cache: use freshen_shared_index() in read_index_from()
  read-cache: refactor read_index_from()
  t1700: test shared index file expiration
  read-cache: unlink old sharedindex files
  config: add git_config_get_expiry() from gc.c
  read-cache: touch shared index files when used
  sha1_file: make check_and_freshen_file() non static
  Documentation/config: add splitIndex.maxPercentChange
  t1700: add tests for splitIndex.maxPercentChange
  read-cache: regenerate shared index if necessary
  config: add git_config_get_max_percent_split_change()
  Documentation/git-update-index: talk about core.splitIndex config var
  Documentation/config: add information for core.splitIndex
  t1700: add tests for core.splitIndex
  update-index: warn in case of split-index incoherency
  read-cache: add and then use tweak_split_index()
  split-index: add {add,remove}_split_index() functions
  config: add git_config_get_split_index()
  ...
2017-03-17 13:50:23 -07:00
Christian Couder
77d67977ca config: add git_config_get_expiry() from gc.c
This function will be used in a following commit to get the expiration
time of the shared index files from the config, and it is generic
enough to be put in "config.c".

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-03-01 13:34:54 -08:00
David Turner
a831c06a2b gc: ignore old gc.log files
A server can end up in a state where there are lots of unreferenced
loose objects (say, because many users are doing a bunch of rebasing
and pushing their rebased branches).  Running "git gc --auto" in
this state would cause a gc.log file to be created, preventing
future auto gcs, causing pack files to pile up.  Since many git
operations are O(n) in the number of pack files, this would lead to
poor performance.

Git should never get itself into a state where it refuses to do any
maintenance, just because at some point some piece of the maintenance
didn't make progress.

Teach Git to ignore gc.log files which are older than (by default)
one day old, which can be tweaked via the gc.logExpiry configuration
variable.  That way, these pack files will get cleaned up, if
necessary, at least once per day.  And operators who find a need for
more-frequent gcs can adjust gc.logExpiry to meet their needs.

There is also some cleanup: a successful manual gc, or a
warning-free auto gc with an old log file, will remove any old
gc.log files.

It might still happen that manual intervention is required
(e.g. because the repo is corrupt), but at the very least it won't
be because Git is too dumb to try again.

Signed-off-by: David Turner <dturner@twosigma.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-02-13 15:19:11 -08:00
David Turner
bdf56de896 auto gc: don't write bitmaps for incremental repacks
When git gc --auto does an incremental repack of loose objects, we do
not expect to be able to write a bitmap; it is very likely that
objects in the new pack will have references to objects outside of the
pack.  So we shouldn't try to write a bitmap, because doing so will
likely issue a warning.

This warning was making its way into gc.log.  When the gc.log was
present, future auto gc runs would refuse to run.

Patch by Jeff King.
Bug report, test, and commit message by David Turner.

Signed-off-by: David Turner <dturner@twosigma.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-12-29 13:45:35 -08:00
Junio C Hamano
eb293ac8d6 Merge branch 'jk/reduce-gc-aggressive-depth' into maint
"git gc --aggressive" used to limit the delta-chain length to 250,
which is way too deep for gaining additional space savings and is
detrimental for runtime performance.  The limit has been reduced to
50.

* jk/reduce-gc-aggressive-depth:
  gc: default aggressive depth to 50
2016-09-29 16:49:42 -07:00
Junio C Hamano
0952ca8a95 Merge branch 'jk/reduce-gc-aggressive-depth'
"git gc --aggressive" used to limit the delta-chain length to 250,
which is way too deep for gaining additional space savings and is
detrimental for runtime performance.  The limit has been reduced to
50.

* jk/reduce-gc-aggressive-depth:
  gc: default aggressive depth to 50
2016-09-21 15:15:30 -07:00
Jeff King
07e7dbf0db gc: default aggressive depth to 50
This commit message is long and has lots of background and
numbers. The summary is: the current default of 250 doesn't
save much space, and costs CPU. It's not a good tradeoff.
Read on for details.

The "--aggressive" flag to git-gc does three things:

  1. use "-f" to throw out existing deltas and recompute from
     scratch

  2. use "--window=250" to look harder for deltas

  3. use "--depth=250" to make longer delta chains

Items (1) and (2) are good matches for an "aggressive"
repack. They ask the repack to do more computation work in
the hopes of getting a better pack. You pay the costs during
the repack, and other operations see only the benefit.

Item (3) is not so clear. Allowing longer chains means fewer
restrictions on the deltas, which means potentially finding
better ones and saving some space. But it also means that
operations which access the deltas have to follow longer
chains, which affects their performance. So it's a tradeoff,
and it's not clear that the tradeoff is even a good one.

The existing "250" numbers for "--aggressive" come
originally from this thread:

  http://public-inbox.org/git/alpine.LFD.0.9999.0712060803430.13796@woody.linux-foundation.org/

where Linus says:

  So when I said "--depth=250 --window=250", I chose those
  numbers more as an example of extremely aggressive
  packing, and I'm not at all sure that the end result is
  necessarily wonderfully usable. It's going to save disk
  space (and network bandwidth - the delta's will be re-used
  for the network protocol too!), but there are definitely
  downsides too, and using long delta chains may
  simply not be worth it in practice.

There are some numbers in that thread, but they're mostly
focused on the improved window size, and measure the
improvement from --depth=250 and --window=250 together.
E.g.:

  http://public-inbox.org/git/9e4733910712062006l651571f3w7f76ce64c6650dff@mail.gmail.com/

talks about the improved run-time of "git-blame", which
comes from the reduced pack size. But most of that reduction
is coming from --window=250, whereas most of the extra costs
come from --depth=250. There's a link in that thread showing
that increasing the depth beyond 50 doesn't seem to help
much with the size:

  https://vcscompare.blogspot.com/2008/06/git-repack-parameters.html

but again, no discussion of the timing impact.

In an earlier thread from Ted Ts'o which discussed setting
the non-aggressive default (from 10 to 50):

  http://public-inbox.org/git/20070509134958.GA21489%40thunk.org/

we have more numbers, with the conclusion that going past 50
does not help size much, and hurts the speed of normal
operations.

So from that, we might guess that 50 is actually a sweet
spot, even for aggressive, if we interpret aggressive to
"spend time now to make a better pack". It is not clear that
"--depth=250" is actually a better pack. It may be slightly
_smaller_, but it carries a run-time penalty.

Here are some more recent timings I did to verify that. They
show three things:

  - the size of the resulting pack (so disk saved to store,
    bandwidth saved on clones/fetches)

  - the cost of "rev-list --objects --all", which shows the
    effect of the delta chains on trees (commits typically
    don't delta, and the command doesn't touch the blobs at
    all)

  - the cost of "log -Sfoo", which will additionally access
    each blob

All cases were repacked with "git repack -adf --depth=$d
--window=250" (so basically, what would happen if we tweaked
the "gc --aggressive" default depth).

The timings are all wall-clock best-of-3. The machine itself
has plenty of RAM compared to the repositories (which is
probably typical of most workstations these days), so we're
really measuring CPU usage, as the whole thing will be in
disk cache after the first run.

The core.deltaBaseCacheLimit is at its default of 96MiB.
It's possible that tweaking it would have some impact on the
tests, as some of them (especially "log -S" on a large repo)
are likely to overflow that. But bumping that carries a
run-time memory cost, so for these tests, I focused on what
we could do just with the on-disk pack tradeoffs.

Each test is done for four depths: 250 (the current value),
50 (the current default that tested well previously), 100
(to show something on the larger side, which previous tests
showed was not a good tradeoff), and 10 (the very old
default, which previous tests showed was worse than 50).

Here are the numbers for linux.git:

   depth |  size |  %    | rev-list |  %     | log -Sfoo |   %
  -------+-------+-------+----------+--------+-----------+-------
    250  | 967MB |  n/a  | 48.159s  |   n/a  | 378.088   |   n/a
    100  | 971MB | +0.4% | 41.471s  | -13.9% | 342.060   |  -9.5%
     50  | 979MB | +1.2% | 37.778s  | -21.6% | 311.040s  | -17.7%
     10  | 1.1GB | +6.6% | 32.518s  | -32.5% | 279.890s  | -25.9%

and for git.git:

   depth |  size |  %    | rev-list |  %     | log -Sfoo |   %
  -------+-------+-------+----------+--------+-----------+-------
    250  |  48MB |  n/a  |  2.215s  |   n/a  |  20.922s  |   n/a
    100  |  49MB | +0.5% |  2.140s  |  -3.4% |  17.736s  | -15.2%
     50  |  49MB | +1.7% |  2.099s  |  -5.2% |  15.418s  | -26.3%
     10  |  53MB | +9.3% |  2.001s  |  -9.7% |  12.677s  | -39.4%

You can see that that the CPU savings for regular operations improves as we
decrease the depth. The savings are less for "rev-list" on a smaller repository
than they are for blob-accessing operations, or even rev-list on a larger
repository. This may mean that a larger delta cache would help (though setting
core.deltaBaseCacheLimit by itself doesn't).

But we can also see that the space savings are not that great as the depth goes
higher. Saving 5-10% between 10 and 50 is probably worth the CPU tradeoff.
Saving 1% to go from 50 to 100, or another 0.5% to go from 100 to 250 is
probably not.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-11 11:53:19 -07:00
Junio C Hamano
87be95b6f9 Merge branch 'ew/gc-auto-pack-limit-fix' into maint
"gc.autoPackLimit" when set to 1 should not trigger a repacking
when there is only one pack, but the code counted poorly and did
so.

* ew/gc-auto-pack-limit-fix:
  gc: fix off-by-one error with gc.autoPackLimit
2016-07-28 11:25:56 -07:00
Junio C Hamano
97865e83c7 Merge branch 'ew/gc-auto-pack-limit-fix'
"gc.autoPackLimit" when set to 1 should not trigger a repacking
when there is only one pack, but the code counted poorly and did
so.

* ew/gc-auto-pack-limit-fix:
  gc: fix off-by-one error with gc.autoPackLimit
2016-07-13 11:24:12 -07:00
Eric Wong
5f4e3bf536 gc: fix off-by-one error with gc.autoPackLimit
This matches the documentation and allows gc.autoPackLimit=1
to maintain a single pack without attempting a repack on every
"git gc --auto" invocation.

Signed-off-by: Eric Wong <e@80x24.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-27 08:28:47 -07:00
Jeff King
45014beac0 Merge branch 'dk/gc-idx-wo-pack'
Having a leftover .idx file without corresponding .pack file in
the repository hurts performance; "git gc" learned to prune them.

* dk/gc-idx-wo-pack:
  gc: remove garbage .idx files from pack dir
  t5304: test cleaning pack garbage
  prepare_packed_git(): refactor garbage reporting in pack directory
2015-11-20 06:55:34 -05:00
Doug Kelly
478f34d2b6 gc: remove garbage .idx files from pack dir
Add a custom report_garbage handler to collect and remove
garbage .idx files from the pack directory.

Signed-off-by: Doug Kelly <dougk.ff7@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-11-04 11:30:22 -08:00
Junio C Hamano
808d119263 Merge branch 'js/misc-fixes'
Various compilation fixes and squelching of warnings.

* js/misc-fixes:
  Correct fscanf formatting string for I64u values
  Silence GCC's "cast of pointer to integer of a different size" warning
  Squelch warning about an integer overflow
2015-10-30 13:07:00 -07:00
Junio C Hamano
fa46579555 Merge branch 'jk/repository-extension'
Prepare for Git on-disk repository representation to undergo
backward incompatible changes by introducing a new repository
format version "1", with an extension mechanism.

* jk/repository-extension:
  introduce "preciousObjects" repository extension
  introduce "extensions" form of core.repositoryformatversion
2015-10-26 15:55:25 -07:00
Waldek Maleska
fdcdb77855 Correct fscanf formatting string for I64u values
This fix is probably purely cosmetic because PRIuMAX is likely identical
to SCNuMAX. Nevertheless, when using a function of the scanf() family,
the correct interpolation to use is the latter, not the former.

Signed-off-by: Waldek Maleska <w.maleska@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-10-26 13:24:03 -07:00
Junio C Hamano
78891795df Merge branch 'jk/war-on-sprintf'
Many allocations that is manually counted (correctly) that are
followed by strcpy/sprintf have been replaced with a less error
prone constructs such as xstrfmt.

Macintosh-specific breakage was noticed and corrected in this
reroll.

* jk/war-on-sprintf: (70 commits)
  name-rev: use strip_suffix to avoid magic numbers
  use strbuf_complete to conditionally append slash
  fsck: use for_each_loose_file_in_objdir
  Makefile: drop D_INO_IN_DIRENT build knob
  fsck: drop inode-sorting code
  convert strncpy to memcpy
  notes: document length of fanout path with a constant
  color: add color_set helper for copying raw colors
  prefer memcpy to strcpy
  help: clean up kfmclient munging
  receive-pack: simplify keep_arg computation
  avoid sprintf and strcpy with flex arrays
  use alloc_ref rather than hand-allocating "struct ref"
  color: add overflow checks for parsing colors
  drop strcpy in favor of raw sha1_to_hex
  use sha1_to_hex_r() instead of strcpy
  daemon: use cld->env_array when re-spawning
  stat_tracking_info: convert to argv_array
  http-push: use an argv_array for setup_revisions
  fetch-pack: use argv_array for index-pack / unpack-objects
  ...
2015-10-20 15:24:01 -07:00
Junio C Hamano
076c827858 Merge branch 'nd/gc-auto-background-fix'
When "git gc --auto" is backgrounded, its diagnosis message is
lost.  Save it to a file in $GIT_DIR and show it next time the "gc
--auto" is run.

* nd/gc-auto-background-fix:
  gc: save log from daemonized gc --auto and print it next time
2015-10-15 15:43:33 -07:00
Jeff King
5096d4909f convert trivial sprintf / strcpy calls to xsnprintf
We sometimes sprintf into fixed-size buffers when we know
that the buffer is large enough to fit the input (either
because it's a constant, or because it's numeric input that
is bounded in size). Likewise with strcpy of constant
strings.

However, these sites make it hard to audit sprintf and
strcpy calls for buffer overflows, as a reader has to
cross-reference the size of the array with the input. Let's
use xsnprintf instead, which communicates to a reader that
we don't expect this to overflow (and catches the mistake in
case we do).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-09-25 10:18:18 -07:00
Nguyễn Thái Ngọc Duy
329e6e8794 gc: save log from daemonized gc --auto and print it next time
While commit 9f673f9 (gc: config option for running --auto in
background - 2014-02-08) helps reduce some complaints about 'gc
--auto' hogging the terminal, it creates another set of problems.

The latest in this set is, as the result of daemonizing, stderr is
closed and all warnings are lost. This warning at the end of cmd_gc()
is particularly important because it tells the user how to avoid "gc
--auto" running repeatedly. Because stderr is closed, the user does
not know, naturally they complain about 'gc --auto' wasting CPU.

Daemonized gc now saves stderr to $GIT_DIR/gc.log. Following gc --auto
will not run and gc.log printed out until the user removes gc.log.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-09-21 09:43:30 -07:00
Junio C Hamano
db86e61cbb Merge branch 'mh/tempfile'
The "lockfile" API has been rebuilt on top of a new "tempfile" API.

* mh/tempfile:
  credential-cache--daemon: use tempfile module
  credential-cache--daemon: delete socket from main()
  gc: use tempfile module to handle gc.pid file
  lock_repo_for_gc(): compute the path to "gc.pid" only once
  diff: use tempfile module
  setup_temporary_shallow(): use tempfile module
  write_shared_index(): use tempfile module
  register_tempfile(): new function to handle an existing temporary file
  tempfile: add several functions for creating temporary files
  prepare_tempfile_object(): new function, extracted from create_tempfile()
  tempfile: a new module for handling temporary files
  commit_lock_file(): use get_locked_file_path()
  lockfile: add accessor get_lock_file_path()
  lockfile: add accessors get_lock_file_fd() and get_lock_file_fp()
  create_bundle(): duplicate file descriptor to avoid closing it twice
  lockfile: move documentation to lockfile.h and lockfile.c
2015-08-25 14:57:09 -07:00
Michael Haggerty
ebebeaea0a gc: use tempfile module to handle gc.pid file
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-12 14:50:11 -07:00
Michael Haggerty
00539cef39 lock_repo_for_gc(): compute the path to "gc.pid" only once
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-12 14:50:11 -07:00
Junio C Hamano
c1e5ca90db Merge branch 'es/worktree-add'
Remove remaining cruft from  "git checkout --to", which
transitioned to "git worktree add".

* es/worktree-add:
  config: rename "gc.pruneWorktreesExpire" to "gc.worktreePruneExpire"
  Documentation/git-worktree: wordsmith worktree-related manpages
  Documentation/config: fix stale "git prune --worktree" reference
  Documentation/git-worktree: fix incorrect reference to file "locked"
  Documentation/git-worktree: consistently use term "linked working tree"
2015-08-12 14:09:55 -07:00
Eric Sunshine
114ff8881a config: rename "gc.pruneWorktreesExpire" to "gc.worktreePruneExpire"
As of df0b6cf (worktree: new place for "git prune --worktrees",
2015-06-29), linked worktree pruning functionality moved from
"git prune --worktrees" to "git worktree prune". Rename the
associated configuration variable accordingly.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-07-20 11:09:06 -07:00
Junio C Hamano
7783eb2e59 Merge branch 'nd/multiple-work-trees'
"git checkout [<tree-ish>] <paths>" spent unnecessary cycles
checking if the current branch was checked out elsewhere, when we
know we are not switching the branches ourselves.

* nd/multiple-work-trees:
  worktree: new place for "git prune --worktrees"
  checkout: don't check worktrees when not necessary
2015-07-13 14:02:02 -07:00
Nguyễn Thái Ngọc Duy
df0b6cfbda worktree: new place for "git prune --worktrees"
Commit 23af91d (prune: strategies for linked checkouts - 2014-11-30)
adds "--worktrees" to "git prune" without realizing that "git prune" is
for object database only. This patch moves the same functionality to a
new command "git worktree".

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
2015-06-29 08:48:44 -07:00
Jeff King
067fbd4105 introduce "preciousObjects" repository extension
If this extension is used in a repository, then no
operations should run which may drop objects from the object
storage. This can be useful if you are sharing that storage
with other repositories whose refs you cannot see.

For instance, if you do:

  $ git clone -s parent child
  $ git -C parent config extensions.preciousObjects true
  $ git -C parent config core.repositoryformatversion 1

you now have additional safety when running git in the
parent repository. Prunes and repacks will bail with an
error, and `git gc` will skip those operations (it will
continue to pack refs and do other non-object operations).
Older versions of git, when run in the repository, will
fail on every operation.

Note that we do not set the preciousObjects extension by
default when doing a "clone -s", as doing so breaks
backwards compatibility. It is a decision the user should
make explicitly.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-06-24 17:09:35 -07:00
Junio C Hamano
68a2e6a2c8 Merge branch 'nd/multiple-work-trees'
A replacement for contrib/workdir/git-new-workdir that does not
rely on symbolic links and make sharing of objects and refs safer
by making the borrowee and borrowers aware of each other.

* nd/multiple-work-trees: (41 commits)
  prune --worktrees: fix expire vs worktree existence condition
  t1501: fix test with split index
  t2026: fix broken &&-chain
  t2026 needs procondition SANITY
  git-checkout.txt: a note about multiple checkout support for submodules
  checkout: add --ignore-other-wortrees
  checkout: pass whole struct to parse_branchname_arg instead of individual flags
  git-common-dir: make "modules/" per-working-directory directory
  checkout: do not fail if target is an empty directory
  t2025: add a test to make sure grafts is working from a linked checkout
  checkout: don't require a work tree when checking out into a new one
  git_path(): keep "info/sparse-checkout" per work-tree
  count-objects: report unused files in $GIT_DIR/worktrees/...
  gc: support prune --worktrees
  gc: factor out gc.pruneexpire parsing code
  gc: style change -- no SP before closing parenthesis
  checkout: clean up half-prepared directories in --to mode
  checkout: reject if the branch is already checked out elsewhere
  prune: strategies for linked checkouts
  checkout: support checking out into a new working directory
  ...
2015-05-11 14:23:39 -07:00
Alex Henrie
9c9b4f2f8b standardize usage info string format
This patch puts the usage info strings that were not already in docopt-
like format into docopt-like format, which will be a litle easier for
end users and a lot easier for translators. Changes include:

- Placing angle brackets around fill-in-the-blank parameters
- Putting dashes in multiword parameter names
- Adding spaces to [-f|--foobar] to make [-f | --foobar]
- Replacing <foobar>* with [<foobar>...]

Signed-off-by: Alex Henrie <alexhenrie24@gmail.com>
Reviewed-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-01-14 09:32:04 -08:00
Nguyễn Thái Ngọc Duy
e3df33bb1b gc: support prune --worktrees
Helped-by: Marc Branchaud <marcnarc@xiplink.com>
Signed-off-by: Marc Branchaud <marcnarc@xiplink.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-12-01 11:00:18 -08:00
Nguyễn Thái Ngọc Duy
09dbb90b09 gc: factor out gc.pruneexpire parsing code
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-12-01 11:00:17 -08:00
Nguyễn Thái Ngọc Duy
2cfe2a7878 gc: style change -- no SP before closing parenthesis
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-12-01 11:00:17 -08:00
Michael Haggerty
697cc8efd9 lockfile.h: extract new header file for the functions in lockfile.c
Move the interface declaration for the functions in lockfile.c from
cache.h to a new file, lockfile.h. Add #includes where necessary (and
remove some redundant includes of cache.h by files that already
include builtin.h).

Move the documentation of the lock_file state diagram from lockfile.c
to the new header file.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-10-01 13:56:14 -07:00
Tanay Abhra
5801d3b416 builtin/gc.c: replace git_config() with git_config_get_*() family
Use `git_config_get_*()` family instead of `git_config()` to take advantage of
the config-set API which provides a cleaner control flow.

Signed-off-by: Tanay Abhra <tanayabh@gmail.com>
Reviewed-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-08-07 13:33:28 -07:00
Junio C Hamano
1a81f6ceea Merge branch 'nd/daemonize-gc'
"git gc --auto" was recently changed to run in the background to
give control back early to the end-user sitting in front of the
terminal, but it forgot that housekeeping involving reflogs should
be done without other processes competing for accesses to the refs.

* nd/daemonize-gc:
  gc --auto: do not lock refs in the background
2014-06-16 12:18:12 -07:00
Nguyễn Thái Ngọc Duy
62aad1849f gc --auto: do not lock refs in the background
9f673f9 (gc: config option for running --auto in background -
2014-02-08) puts "gc --auto" in background to reduce user's wait
time. Part of the garbage collecting is pack-refs and pruning
reflogs. These require locking some refs and may abort other processes
trying to lock the same ref. If gc --auto is fired in the middle of a
script, gc's holding locks in the background could fail the script,
which could never happen before 9f673f9.

Keep running pack-refs and "reflog --prune" in foreground to stop
parallel ref updates. The remaining background operations (repack,
prune and rerere) should not impact running git processes.

Reported-by: Adam Borowski <kilobyte@angband.pl>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-05-27 12:33:53 -07:00
Junio C Hamano
8815d8aa7c Merge branch 'nd/gc-aggressive'
Allow tweaking the maximum length of the delta-chain produced by
"gc --aggressive".

* nd/gc-aggressive:
  environment.c: fix constness for odb_pack_keep()
  gc --aggressive: make --depth configurable
2014-04-03 12:38:47 -07:00
Nguyễn Thái Ngọc Duy
125f81461d gc --aggressive: make --depth configurable
When 1c192f3 (gc --aggressive: make it really aggressive - 2007-12-06)
made --depth=250 the default value, it didn't really explain the
reason behind, especially the pros and cons of --depth=250.

An old mail from Linus below explains it at length. Long story short,
--depth=250 is a disk saver and a performance killer. Not everybody
agrees on that aggressiveness. Let the user configure it.

    From: Linus Torvalds <torvalds@linux-foundation.org>
    Subject: Re: [PATCH] gc --aggressive: make it really aggressive
    Date: Thu, 6 Dec 2007 08:19:24 -0800 (PST)
    Message-ID: <alpine.LFD.0.9999.0712060803430.13796@woody.linux-foundation.org>
    Gmane-URL: http://article.gmane.org/gmane.comp.gcc.devel/94637

    On Thu, 6 Dec 2007, Harvey Harrison wrote:
    >
    > 7:41:25elapsed 86%CPU

    Heh. And this is why you want to do it exactly *once*, and then just
    export the end result for others ;)

    > -r--r--r-- 1 hharrison hharrison 324094684 2007-12-06 07:26 pack-1d46...pack

    But yeah, especially if you allow longer delta chains, the end result can
    be much smaller (and what makes the one-time repack more expensive is the
    window size, not the delta chain - you could make the delta chains longer
    with no cost overhead at packing time)

    HOWEVER.

    The longer delta chains do make it potentially much more expensive to then
    use old history. So there's a trade-off. And quite frankly, a delta depth
    of 250 is likely going to cause overflows in the delta cache (which is
    only 256 entries in size *and* it's a hash, so it's going to start having
    hash conflicts long before hitting the 250 depth limit).

    So when I said "--depth=250 --window=250", I chose those numbers more as
    an example of extremely aggressive packing, and I'm not at all sure that
    the end result is necessarily wonderfully usable. It's going to save disk
    space (and network bandwidth - the delta's will be re-used for the network
    protocol too!), but there are definitely downsides too, and using long
    delta chains may simply not be worth it in practice.

    (And some of it might just want to have git tuning, ie if people think
    that long deltas are worth it, we could easily just expand on the delta
    hash, at the cost of some more memory used!)

    That said, the good news is that working with *new* history will not be
    affected negatively, and if you want to be _really_ sneaky, there are ways
    to say "create a pack that contains the history up to a version one year
    ago, and be very aggressive about those old versions that we still want to
    have around, but do a separate pack for newer stuff using less aggressive
    parameters"

    So this is something that can be tweaked, although we don't really have
    any really nice interfaces for stuff like that (ie the git delta cache
    size is hardcoded in the sources and cannot be set in the config file, and
    the "pack old history more aggressively" involves some manual scripting
    and knowing how "git pack-objects" works rather than any nice simple
    command line switch).

    So the thing to take away from this is:
     - git is certainly flexible as hell
     - .. but to get the full power you may need to tweak things
     - .. happily you really only need to have one person to do the tweaking,
       and the tweaked end results will be available to others that do not
       need to know/care.

    And whether the difference between 320MB and 500MB is worth any really
    involved tweaking (considering the potential downsides), I really don't
    know. Only testing will tell.

			    Linus

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-03-31 10:26:24 -07:00
Junio C Hamano
9abf65d23c Merge branch 'bp/commit-p-editor'
When it is not necessary to edit a commit log message (e.g. "git
commit -m" is given a message without specifying "-e"), we used to
disable the spawning of the editor by overriding GIT_EDITOR, but
this means all the uses of the editor, other than to edit the
commit log message, are also affected.

* bp/commit-p-editor:
  run-command: mark run_hook_with_custom_index as deprecated
  merge hook tests: fix and update tests
  merge: fix GIT_EDITOR override for commit hook
  commit: fix patch hunk editing with "commit -p -m"
  test patch hunk editing with "commit -p -m"
  merge hook tests: use 'test_must_fail' instead of '!'
  merge hook tests: fix missing '&&' in test
2014-03-28 13:51:11 -07:00
Benoit Pierre
15048f8a9a commit: fix patch hunk editing with "commit -p -m"
Don't change git environment: move the GIT_EDITOR=":" override to the
hook command subprocess, like it's already done for GIT_INDEX_FILE.

Signed-off-by: Benoit Pierre <benoit.pierre@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-03-18 11:25:12 -07:00
Junio C Hamano
4c4ac4db2c Merge branch 'nd/daemonize-gc'
Allow running "gc --auto" in the background.

* nd/daemonize-gc:
  gc: config option for running --auto in background
  daemon: move daemonize() to libgit.a
2014-03-05 15:06:39 -08:00
Junio C Hamano
043478308f Merge branch 'ep/varscope'
Shrink lifetime of variables by moving their definitions to an
inner scope where appropriate.

* ep/varscope:
  builtin/gc.c: reduce scope of variables
  builtin/fetch.c: reduce scope of variable
  builtin/commit.c: reduce scope of variables
  builtin/clean.c: reduce scope of variable
  builtin/blame.c: reduce scope of variables
  builtin/apply.c: reduce scope of variables
  bisect.c: reduce scope of variable
2014-02-27 14:01:30 -08:00
Nguyễn Thái Ngọc Duy
9f673f9477 gc: config option for running --auto in background
`gc --auto` takes time and can block the user temporarily (but not any
less annoyingly). Make it run in background on systems that support
it. The only thing lost with running in background is printouts. But
gc output is not really interesting. You can keep it in foreground by
changing gc.autodetach.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-02-10 10:46:37 -08:00
Elia Pinto
4f1c0b21e9 builtin/gc.c: reduce scope of variables
Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-01-31 10:44:05 -08:00
Junio C Hamano
92251b1b5b Merge branch 'nd/shallow-clone'
Fetching from a shallow-cloned repository used to be forbidden,
primarily because the codepaths involved were not carefully vetted
and we did not bother supporting such usage. This attempts to allow
object transfer out of a shallow-cloned repository in a controlled
way (i.e. the receiver become a shallow repository with truncated
history).

* nd/shallow-clone: (31 commits)
  t5537: fix incorrect expectation in test case 10
  shallow: remove unused code
  send-pack.c: mark a file-local function static
  git-clone.txt: remove shallow clone limitations
  prune: clean .git/shallow after pruning objects
  clone: use git protocol for cloning shallow repo locally
  send-pack: support pushing from a shallow clone via http
  receive-pack: support pushing to a shallow clone via http
  smart-http: support shallow fetch/clone
  remote-curl: pass ref SHA-1 to fetch-pack as well
  send-pack: support pushing to a shallow clone
  receive-pack: allow pushes that update .git/shallow
  connected.c: add new variant that runs with --shallow-file
  add GIT_SHALLOW_FILE to propagate --shallow-file to subprocesses
  receive/send-pack: support pushing from a shallow clone
  receive-pack: reorder some code in unpack()
  fetch: add --update-shallow to accept refs that update .git/shallow
  upload-pack: make sure deepening preserves shallow roots
  fetch: support fetching from a shallow repository
  clone: support remote shallow repository
  ...
2014-01-17 12:21:20 -08:00
Kyle J. McKay
ed7eda8b38 gc: notice gc processes run by other users
Since 64a99eb4 git gc refuses to run without the --force option if
another gc process on the same repository is already running.

However, if the repository is shared and user A runs git gc on the
repository and while that gc is still running user B runs git gc on
the same repository the gc process run by user A will not be noticed
and the gc run by user B will go ahead and run.

The problem is that the kill(pid, 0) test fails with an EPERM error
since user B is not allowed to signal processes owned by user A
(unless user B is root).

Update the test to recognize an EPERM error as meaning the process
exists and another gc should not be run (unless --force is given).

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-01-02 16:15:29 -08:00
Nguyễn Thái Ngọc Duy
eab3296c7e prune: clean .git/shallow after pruning objects
This patch teaches "prune" to remove shallow roots that are no longer
reachable from any refs (e.g. when the relevant refs are removed).

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-12-10 16:14:19 -08:00