The existing mechanism for scheduling background maintenance is done
through cron. On Linux systems managed by systemd, systemd provides an
alternative to schedule recurring tasks: systemd timers.
The main motivations to implement systemd timers in addition to cron
are:
* cron is optional and Linux systems running systemd might not have it
installed.
* The execution of `crontab -l` can tell us if cron is installed but not
if the daemon is actually running.
* With systemd, each service is run in its own cgroup and its logs are
tagged by the service inside journald. With cron, all scheduled tasks
are running in the cron daemon cgroup and all the logs of the
user-scheduled tasks are pretended to belong to the system cron
service.
Concretely, a user that doesn’t have access to the system logs won’t
have access to the log of their own tasks scheduled by cron whereas
they will have access to the log of their own tasks scheduled by
systemd timer.
Although `cron` attempts to send email, that email may go unseen by
the user because these days, local mailboxes are not heavily used
anymore.
In order to schedule git maintenance, we need two unit template files:
* ~/.config/systemd/user/git-maintenance@.service
to define the command to be started by systemd and
* ~/.config/systemd/user/git-maintenance@.timer
to define the schedule at which the command should be run.
Those units are templates that are parameterized by the frequency.
Based on those templates, 3 timers are started:
* git-maintenance@hourly.timer
* git-maintenance@daily.timer
* git-maintenance@weekly.timer
The command launched by those three timers are the same as with the
other scheduling methods:
/path/to/git for-each-repo --exec-path=/path/to
--config=maintenance.repo maintenance run --schedule=%i
with the full path for git to ensure that the version of git launched
for the scheduled maintenance is the same as the one used to run
`maintenance start`.
The timer unit contains `Persistent=true` so that, if the computer is
powered down when a maintenance task should run, the task will be run
when the computer is back powered on.
Signed-off-by: Lénaïc Huard <lenaic@lhuard.fr>
Acked-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Depending on the system, different schedulers can be used to schedule
the hourly, daily and weekly executions of `git maintenance run`:
* `launchctl` for MacOS,
* `schtasks` for Windows and
* `crontab` for everything else.
`git maintenance run` now has an option to let the end-user explicitly
choose which scheduler he wants to use:
`--scheduler=auto|crontab|launchctl|schtasks`.
When `git maintenance start --scheduler=XXX` is run, it not only
registers `git maintenance run` tasks in the scheduler XXX, it also
removes the `git maintenance run` tasks from all the other schedulers to
ensure we cannot have two schedulers launching concurrent identical
tasks.
The default value is `auto` which chooses a suitable scheduler for the
system.
`git maintenance stop` doesn't have any `--scheduler` parameter because
this command will try to remove the `git maintenance run` tasks from all
the available schedulers.
Signed-off-by: Lénaïc Huard <lenaic@lhuard.fr>
Acked-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Remove the trailing dot from the warning we emit about gc.log. It's
common for various terminal UX's to allow the user to select "words",
and by including the trailing dot a user wanting to select the path to
gc.log will need to manually remove the trailing dot.
Such a user would also probably need to adjust the path if it e.g. had
spaces in it, but this should address this very common case.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Suggested-by: Jan Judas <snugar.i@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
On macOS, we use launchctl to manage the background maintenance
schedule. This uses a set of .plist files to describe the schedule, but
these files are also registered with 'launchctl bootstrap'. If multiple
'git maintenance start' commands run concurrently, then they can collide
replacing these schedule files and registering them with launchctl.
To avoid extra launchctl commands, do a check for the .plist files on
disk and check if they are registered using 'launchctl list <name>'.
This command will return with exit code 0 if it exists, or exit code 113
if it does not.
We can test this behavior using the GIT_TEST_MAINT_SCHEDULER environment
variable.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When two `git maintenance` processes try to write the `.plist` file, we
need to help them with serializing their efforts.
The 150ms time-out value was determined from thin air.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It is not immediately clear what `expand_user_path()` means, so let's
rename it to `interpolate_path()`. This also opens the path for
interpolating more than just a home directory.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fixes two memory leaks when running `git maintenance start` or `git
maintenance stop` in `update_background_schedule`:
$ valgrind --leak-check=full ~/git/bin/git maintenance start
==76584== Memcheck, a memory error detector
==76584== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==76584== Using Valgrind-3.16.1 and LibVEX; rerun with -h for copyright info
==76584== Command: /home/lenaic/git/bin/git maintenance start
==76584==
==76584==
==76584== HEAP SUMMARY:
==76584== in use at exit: 34,880 bytes in 252 blocks
==76584== total heap usage: 820 allocs, 568 frees, 146,414 bytes allocated
==76584==
==76584== 65 bytes in 1 blocks are definitely lost in loss record 17 of 39
==76584== at 0x483E6AF: malloc (vg_replace_malloc.c:306)
==76584== by 0x3DC39C: xrealloc (wrapper.c:126)
==76584== by 0x3992CC: strbuf_grow (strbuf.c:98)
==76584== by 0x39A473: strbuf_vaddf (strbuf.c:392)
==76584== by 0x39BC54: xstrvfmt (strbuf.c:979)
==76584== by 0x39BD2C: xstrfmt (strbuf.c:989)
==76584== by 0x18451B: update_background_schedule (gc.c:1977)
==76584== by 0x1846F6: maintenance_start (gc.c:2011)
==76584== by 0x1847B4: cmd_maintenance (gc.c:2030)
==76584== by 0x127A2E: run_builtin (git.c:453)
==76584== by 0x127E81: handle_builtin (git.c:704)
==76584== by 0x128142: run_argv (git.c:771)
==76584==
==76584== 240 bytes in 1 blocks are definitely lost in loss record 29 of 39
==76584== at 0x4840D7B: realloc (vg_replace_malloc.c:834)
==76584== by 0x491CE5D: getdelim (in /usr/lib/libc-2.33.so)
==76584== by 0x39ADD7: strbuf_getwholeline (strbuf.c:635)
==76584== by 0x39AF31: strbuf_getdelim (strbuf.c:706)
==76584== by 0x39B064: strbuf_getline_lf (strbuf.c:727)
==76584== by 0x184273: crontab_update_schedule (gc.c:1919)
==76584== by 0x184678: update_background_schedule (gc.c:1997)
==76584== by 0x1846F6: maintenance_start (gc.c:2011)
==76584== by 0x1847B4: cmd_maintenance (gc.c:2030)
==76584== by 0x127A2E: run_builtin (git.c:453)
==76584== by 0x127E81: handle_builtin (git.c:704)
==76584== by 0x128142: run_argv (git.c:771)
==76584==
==76584== LEAK SUMMARY:
==76584== definitely lost: 305 bytes in 2 blocks
==76584== indirectly lost: 0 bytes in 0 blocks
==76584== possibly lost: 0 bytes in 0 blocks
==76584== still reachable: 34,575 bytes in 250 blocks
==76584== suppressed: 0 bytes in 0 blocks
==76584== Reachable blocks (those to which a pointer was found) are not shown.
==76584== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==76584==
==76584== For lists of detected and suppressed errors, rerun with: -s
==76584== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 0 from 0)
Signed-off-by: Lénaïc Huard <lenaic@lhuard.fr>
Acked-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If a remote has the skipFetchAll setting enabled, then that remote is
not intended for frequent fetching. It makes sense to not fetch that
data during the 'prefetch' maintenance task. Skip that remote in the
iteration without error. The skip_default_update member is initialized
in remote.c:handle_config() as part of initializing the 'struct remote'.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The 'prefetch' maintenance task previously forced the following refspec
for each remote:
+refs/heads/*:refs/prefetch/<remote>/*
If a user has specified a more strict refspec for the remote, then this
prefetch task downloads more objects than necessary.
The previous change introduced the '--prefetch' option to 'git fetch'
which manipulates the remote's refspec to place all resulting refs into
refs/prefetch/, with further partitioning based on the destinations of
those refspecs.
Update the documentation to be more generic about the destination refs.
Do not mention custom refspecs explicitly, as that does not need to be
highlighted in this documentation. The important part of placing refs in
refs/prefetch/ remains.
Reported-by: Tom Saeger <tom.saeger@oracle.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The previous logic filled a string list with the names of each remote,
but instead we could simply run the appropriate 'git fetch' data
directly in the remote iterator. Do this for reduced code size, but also
because it sets up an upcoming change to use the remote's refspec. This
data is accessible from the 'struct remote' data that is now accessible
in fetch_remote().
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The periodic maintenance tasks configured by `git maintenance start`
invoke `git for-each-repo` to run `git maintenance run` on each path
specified by the multi-value global configuration variable
`maintenance.repo`. Because `git for-each-repo` will likely be run
outside of the repositories which require periodic maintenance, it is
mandatory that the repository paths specified by `maintenance.repo` are
absolute.
Unfortunately, however, `git maintenance register` does nothing to
ensure that the paths it assigns to `maintenance.repo` are indeed
absolute, and may in fact -- especially in the case of a bare repository
-- assign a relative path to `maintenance.repo` instead. Fix this
problem by converting all paths to absolute before assigning them to
`maintenance.repo`.
While at it, also fix `git maintenance unregister` to convert paths to
absolute, as well, in order to ensure that it can correctly remove from
`maintenance.repo` a path assigned via `git maintenance register`.
Reported-by: Clement Moyroud <clement.moyroud@gmail.com>
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When the 'maintenance.strategy' config option is set to 'incremental',
a default maintenance schedule is enabled. Add the 'pack-refs' task to
that strategy at the weekly cadence.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It is valuable to collect loose refs into a more compressed form. This
is typically the packed-refs file, although this could be the reftable
in the future. Having packed refs can be extremely valuable in repos
with many tags or remote branches that are not modified by the local
user, but still are necessary for other queries.
For instance, with many exploded refs, commands such as
git describe --tags --exact-match HEAD
can be very slow (multiple seconds). This command in particular is used
by terminal prompts to show when a detatched HEAD is pointing to an
existing tag, so having it be slow causes significant delays for users.
Add a new 'pack-refs' maintenance task. It runs 'git pack-refs --all
--prune' to move loose refs into a packed form. For now, that is the
packed-refs file, but could adjust to other file formats in the future.
This is the first of several sub-tasks of the 'gc' task that could be
extracted to their own tasks. In this process, we should not change the
behavior of the 'gc' task since that remains the default way to keep
repositories maintained. Creating a new task for one of these sub-tasks
only provides more customization options for those choosing to not use
the 'gc' task. It is certainly possible to have both the 'gc' and
'pack-refs' tasks enabled and run regularly. While they may repeat
effort, they do not conflict in a destructive way.
The 'auto_condition' function pointer is left NULL for now. We could
extend this in the future to have a condition check if pack-refs should
be run during 'git maintenance run --auto'.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Test clean-up plus UI improvement by hiding extra refs that
the prefetch task uses from "log --decorate" output.
* ds/maintenance-prefetch-cleanup:
t7900: clean up some broken refs
maintenance: set log.excludeDecoration durin prefetch
Abstract accesses to in-core revindex that allows enumerating
objects stored in a packfile in the order they appear in the pack,
in preparation for introducing an on-disk precomputed revindex.
* tb/pack-revindex-api: (21 commits)
for_each_object_in_pack(): clarify pack vs index ordering
pack-revindex.c: avoid direct revindex access in 'offset_to_pack_pos()'
pack-revindex: hide the definition of 'revindex_entry'
pack-revindex: remove unused 'find_revindex_position()'
pack-revindex: remove unused 'find_pack_revindex()'
builtin/gc.c: guess the size of the revindex
for_each_object_in_pack(): convert to new revindex API
unpack_entry(): convert to new revindex API
packed_object_info(): convert to new revindex API
retry_bad_packed_offset(): convert to new revindex API
get_delta_base_oid(): convert to new revindex API
rebuild_existing_bitmaps(): convert to new revindex API
try_partial_reuse(): convert to new revindex API
get_size_by_pos(): convert to new revindex API
show_objects_for_type(): convert to new revindex API
bitmap_position_packfile(): convert to new revindex API
check_object(): convert to new revindex API
write_reused_pack_verbatim(): convert to new revindex API
write_reused_pack_one(): convert to new revindex API
write_reuse_object(): convert to new revindex API
...
The peel_ref() interface is confusing and error-prone:
- it's typically used by ref iteration callbacks that have both a
refname and oid. But since they pass only the refname, we may load
the ref value from the filesystem again. This is inefficient, but
also means we are open to a race if somebody simultaneously updates
the ref. E.g., this:
int some_ref_cb(const char *refname, const struct object_id *oid, ...)
{
if (!peel_ref(refname, &peeled))
printf("%s peels to %s",
oid_to_hex(oid), oid_to_hex(&peeled);
}
could print nonsense. It is correct to say "refname peels to..."
(you may see the "before" value or the "after" value, either of
which is consistent), but mentioning both oids may be mixing
before/after values.
Worse, whether this is possible depends on whether the optimization
to read from the current iterator value kicks in. So it is actually
not possible with:
for_each_ref(some_ref_cb);
but it _is_ possible with:
head_ref(some_ref_cb);
which does not use the iterator mechanism (though in practice, HEAD
should never peel to anything, so this may not be triggerable).
- it must take a fully-qualified refname for the read_ref_full() code
path to work. Yet we routinely pass it partial refnames from
callbacks to for_each_tag_ref(), etc. This happens to work when
iterating because there we do not call read_ref_full() at all, and
only use the passed refname to check if it is the same as the
iterator. But the requirements for the function parameters are quite
unclear.
Instead of taking a refname, let's instead take an oid. That fixes both
problems. It's a little funny for a "ref" function not to involve refs
at all. The key thing is that it's optimizing under the hood based on
having access to the ref iterator. So let's change the name to make it
clear why you'd want this function versus just peel_object().
There are two other directions I considered but rejected:
- we could pass the peel information into the each_ref_fn callback.
However, we don't know if the caller actually wants it or not. For
packed-refs, providing it is essentially free. But for loose refs,
we actually have to peel the object, which would be wasteful in most
cases. We could likewise pass in a flag to the callback indicating
whether the peeled information is known, but that complicates those
callbacks, as they then have to decide whether to manually peel
themselves. Plus it requires changing the interface of every
callback, whether they care about peeling or not, and there are many
of them.
- we could make a function to return the peeled value of the current
iterated ref (computing it if necessary), and BUG() otherwise. I.e.:
int peel_current_iterated_ref(struct object_id *out);
Each of the current callers is an each_ref_fn callback, so they'd
mostly be happy. But:
- we use those callbacks with functions like head_ref(), which do
not use the iteration code. So we'd need to handle the fallback
case there, anyway.
- it's possible that a caller would want to call into generic code
that sometimes is used during iteration and sometimes not. This
encapsulates the logic to do the fast thing when possible, and
fallback when necessary.
The implementation is mostly obvious, but I want to call out a few
things in the patch:
- the test-tool coverage for peel_ref() is now meaningless, as it all
collapses to a single peel_object() call (arguably they were pretty
uninteresting before; the tricky part of that function is the
fast-path we see during iteration, but these calls didn't trigger
that). I've just dropped it entirely, though note that some other
tests relied on the tags we created; I've moved that creation to the
tests where it matters.
- we no longer need to take a ref_store parameter, since we'd never
look up a ref now. We do still rely on a global "current iterator"
variable which _could_ be kept per-ref-store. But in practice this
is only useful if there are multiple recursive iterations, at which
point the more appropriate solution is probably a stack of
iterators. No caller used the actual ref-store parameter anyway
(they all call the wrapper that passes the_repository).
- the original only kicked in the optimization when the "refname"
pointer matched (i.e., not string comparison). We do likewise with
the "oid" parameter here, but fall back to doing an actual oideq()
call. This in theory lets us kick in the optimization more often,
though in practice no current caller cares. It should never be
wrong, though (peeling is a property of an object, so two refs
pointing to the same object would peel identically).
- the original took care not to touch the peeled out-parameter unless
we found something to put in it. But no caller cares about this, and
anyway, it is enforced by peel_object() itself (and even in the
optimized iterator case, that's where we eventually end up). We can
shorten the code and avoid an extra copy by just passing the
out-parameter through the stack.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The 'prefetch' task fetches refs from all remotes and places them in the
refs/prefetch/<remote>/ refspace. As this task is intended to run in the
background, this allows users to keep their local data very close to the
remote servers' data while not updating the users' understanding of the
remote refs in refs/remotes/<remote>/.
However, this can clutter 'git log' decorations with copies of the refs
with the full name 'refs/prefetch/<remote>/<branch>'.
The log.excludeDecoration config option was added in a6be5e67 (log: add
log.excludeDecoration config option, 2020-05-16) for exactly this
purpose.
Ensure we set this only for users that would benefit from it by
assigning it at the beginning of the prefetch task. Other alternatives
would be during 'git maintenance register' or 'git maintenance start',
but those might assign the config even when the prefetch task is
disabled by existing config. Further, users could run 'git maintenance
run --task=prefetch' using their own scripting or scheduling. This
provides the best coverage to automatically update the config when
valuable.
It is improbable, but possible, that users might want to run the
prefetch task _and_ see these refs in their log decorations. This seems
incredibly unlikely to me, but users can always opt-in on a
command-by-command basis using --decorate-refs=refs/prefetch/.
Test that this works in a few cases. In particular, ensure that our
assignment of log.excludeDecoration=refs/prefetch/ is additive to other
existing exclusions. Further, ensure we do not add multiple copies in
multiple runs.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Follow-up on the "maintenance part-3" which introduced scheduled
maintenance tasks to support platforms whose native scheduling
methods are not 'cron'.
* ds/maintenance-part-4:
maintenance: use Windows scheduled tasks
maintenance: use launchctl on macOS
maintenance: include 'cron' details in docs
maintenance: extract platform-specific scheduling
'estimate_repack_memory()' takes into account the amount of memory
required to load the reverse index in memory by multiplying the assumed
number of objects by the size of the 'revindex_entry' struct.
Prepare for hiding the definition of 'struct revindex_entry' by removing
a 'sizeof()' of that type from outside of pack-revindex.c. Instead,
guess that one off_t and one uint32_t are required per object. Strictly
speaking, this is a worse guess than asking for 'sizeof(struct
revindex_entry)' directly, since the true size of this struct is 16
bytes with padding on the end of the struct in order to align the offset
field.
But, this is an approximation anyway, and it does remove a use of the
'struct revindex_entry' from outside of pack-revindex internals.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A `struct lock_file` is pretty much just a wrapper around a tempfile.
But it's easy enough to avoid relying on this. Use the wrappers that the
lock file API provides rather than peeking at the temp file or even into
*its* internals.
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Reviewed-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git's background maintenance uses cron by default, but this is not
available on Windows. Instead, integrate with Task Scheduler.
Tasks can be scheduled using the 'schtasks' command. There are several
command-line options that can allow for some advanced scheduling, but
unfortunately these seem to all require authenticating using a password.
Instead, use the "/xml" option to pass an XML file that contains the
configuration for the necessary schedule. These XML files are based on
some that I exported after constructing a schedule in the Task Scheduler
GUI. These options only run background maintenance when the user is
logged in, and more fields are populated with the current username and
SID at run-time by 'schtasks'.
Since the GIT_TEST_MAINT_SCHEDULER environment variable allows us to
specify 'schtasks' as the scheduler, we can test the Windows-specific
logic on other platforms. Thus, add a check that the XML file written
by Git is valid when xmllint exists on the system.
Since we use a temporary file for the XML files sent to 'schtasks', we
prefix the random characters with the frequency so it is easier to
examine the proper file during tests. Instead of an exact match on the
'args' file, we 'grep' for the arguments other than the filename.
There is a deficiency in the current design. Windows has two kinds of
applications: GUI applications that start by "winmain()" and console
applications that start by "main()". Console applications are attached
to a new Console window if they are not already associated with a GUI
application. This means that every hour the scheudled task launches a
command window for the scheduled tasks. Not only is this visually
obtrusive, but it also takes focus from whatever else the user is
doing!
A simple fix would be to insert a GUI application that acts as a shim
between the scheduled task and Git. This is currently possible in Git
for Windows by setting the <Command> tag equal to
C:\Program Files\Git\git-bash.exe
with options "--hide --no-needs-console --command=cmd\git.exe"
followed by the arguments currently used. Since git-bash.exe is not
included in Windows builds of core Git, I chose to leave out this
feature. My plan is to submit a small patch to Git for Windows that
converts the use of git.exe with this use of git-bash.exe in the
short term. In the long term, we can consider creating this GUI
shim application within core Git, perhaps in contrib/.
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>
The existing mechanism for scheduling background maintenance is done
through cron. The 'crontab -e' command allows updating the schedule
while cron itself runs those commands. While this is technically
supported by macOS, it has some significant deficiencies:
1. Every run of 'crontab -e' must request elevated privileges through
the user interface. When running 'git maintenance start' from the
Terminal app, it presents a dialog box saying "Terminal.app would
like to administer your computer. Administration can include
modifying passwords, networking, and system settings." This is more
alarming than what we are hoping to achieve. If this alert had some
information about how "git" is trying to run "crontab" then we would
have some reason to believe that this dialog might be fine. However,
it also doesn't help that some scenarios just leave Git waiting for
a response without presenting anything to the user. I experienced
this when executing the command from a Bash terminal view inside
Visual Studio Code.
2. While cron initializes a user environment enough for "git config
--global --show-origin" to show the correct config file information,
it does not set up the environment enough for Git Credential Manager
Core to load credentials during a 'prefetch' task. My prefetches
against private repositories required re-authenticating through UI
pop-ups in a way that should not be required.
The solution is to switch from cron to the Apple-recommended [1]
'launchd' tool.
[1] https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPSystemStartup/Chapters/ScheduledJobs.html
The basics of this tool is that we need to create XML-formatted
"plist" files inside "~/Library/LaunchAgents/" and then use the
'launchctl' tool to make launchd aware of them. The plist files
include all of the scheduling information, along with the command-line
arguments split across an array of <string> tags.
For example, here is my plist file for the weekly scheduled tasks:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0"><dict>
<key>Label</key><string>org.git-scm.git.weekly</string>
<key>ProgramArguments</key>
<array>
<string>/usr/local/libexec/git-core/git</string>
<string>--exec-path=/usr/local/libexec/git-core</string>
<string>for-each-repo</string>
<string>--config=maintenance.repo</string>
<string>maintenance</string>
<string>run</string>
<string>--schedule=weekly</string>
</array>
<key>StartCalendarInterval</key>
<array>
<dict>
<key>Day</key><integer>0</integer>
<key>Hour</key><integer>0</integer>
<key>Minute</key><integer>0</integer>
</dict>
</array>
</dict>
</plist>
The schedules for the daily and hourly tasks are more complicated
since we need to use an array for the StartCalendarInterval with
an entry for each of the six days other than the 0th day (to avoid
colliding with the weekly task), and each of the 23 hours other
than the 0th hour (to avoid colliding with the daily task).
The "Label" value is currently filled with "org.git-scm.git.X"
where X is the frequency. We need a different plist file for each
frequency.
The launchctl command needs to be aligned with a user id in order
to initialize the command environment. This must be done using
the 'launchctl bootstrap' subcommand. This subcommand is new as
of macOS 10.11, which was released in September 2015. Before that
release the 'launchctl load' subcommand was recommended. The best
source of information on this transition I have seen is available
at [2]. The current design does not preclude a future version that
detects the available fatures of 'launchctl' to use the older
commands. However, it is best to rely on the newest version since
Apple might completely remove the deprecated version on short
notice.
[2] https://babodee.wordpress.com/2016/04/09/launchctl-2-0-syntax/
To remove a schedule, we must run 'launchctl bootout' with a valid
plist file. We also need to 'bootout' a task before the 'bootstrap'
subcommand will succeed, if such a task already exists.
The need for a user id requires us to run 'id -u' which works on
POSIX systems but not Windows. Further, the need for fully-qualitifed
path names including $HOME behaves differently in the Git internals and
the external test suite. The $HOME variable starts with "C:\..." instead
of the "/c/..." that is provided by Git in these subcommands. The test
therefore has a prerequisite that we are not on Windows. The cross-
platform logic still allows us to test the macOS logic on a Linux
machine.
We can verify the commands that were run by 'git maintenance start'
and 'git maintenance stop' by injecting a script that writes the
command-line arguments into GIT_TEST_MAINT_SCHEDULER.
An earlier version of this patch accidentally had an opening
"<dict>" tag when it should have had a closing "</dict>" tag. This
was caught during manual testing with actual 'launchctl' commands,
but we do not want to update developers' tasks when running tests.
It appears that macOS includes the "xmllint" tool which can verify
the XML format. This is useful for any system that might contain
the tool, so use it whenever it is available.
We strive to make these tests work on all platforms, but Windows caused
some headaches. In particular, the value of getuid() called by the C
code is not guaranteed to be the same as `$(id -u)` invoked by a test.
This is because `git.exe` is a native Windows program, whereas the
utility programs run by the test script mostly utilize the MSYS2 runtime,
which emulates a POSIX-like environment. Since the purpose of the test
is to check that the input to the hook is well-formed, the actual user
ID is immaterial, thus we can work around the problem by making the the
test UID-agnostic. Another subtle issue is the $HOME environment
variable being a Windows-style path instead of a Unix-style path. We can
be more flexible here instead of expecting exact path matches.
Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
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>
On `git maintenance start`, we add a few entries to the user's cron
table. We wrap our entries using two magic markers, "# BEGIN GIT
MAINTENANCE SCHEDULE" and "# END GIT MAINTENANCE SCHEDULE". At a later
`git maintenance stop`, we will go through the table and remove these
lines. Or rather, we will remove the "BEGIN" marker, the "END" marker
and everything between them.
Alas, we have a bug in how we detect the "END" marker: we don't. As we
loop through all the lines of the crontab, if we are in the "old
region", i.e., the region we're aiming to remove, we make an early
`continue` and don't get as far as checking for the "END" marker. Thus,
once we've seen our "BEGIN", we remove everything until the end of the
file.
Rewrite the logic for identifying these markers. There are four cases
that are mutually exclusive: The current line starts a region or it ends
it, or it's firmly within the region, or it's outside of it (and should
be printed).
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Acked-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git maintenance run/start/stop" needed to be run in a repository
to hold the lockfile they use, but didn't make sure they are
actually in a repository, which has been corrected.
* rs/maintenance-run-outside-repo:
t7900: fix typo: "test_execpt_success"
maintenance: fix SEGFAULT when no repository
"git maintenance" command had trouble working in a directory whose
pathname contained an ERE metacharacter like '+'.
* ds/maintenance-part-3:
maintenance: use 'git config --fixed-value'
Fix an option name in "gc" documentation.
* ab/gc-keep-base-option:
gc: rename keep_base_pack variable for --keep-largest-pack
gc docs: change --keep-base-pack to --keep-largest-pack
The "git maintenance run" and "git maintenance start/stop" commands
holds a file-based lock at the .git/maintenance.lock and
.git/schedule.lock respectively. These locks are used to ensure only
one maintenance process is executed at the time as both operations
involves writing data into the git repository.
The path to the lock file is built using
"the_repository->objects->odb->path" that results in SEGFAULT when we
have no repository available as "the_repository->objects->odb" is
set to NULL.
Let's teach maintenance command to use RUN_SETUP option that will
provide the validation and fail when running outside of a repository.
Hence fixing the SEGFAULT for all three operations and making the
behaviour consistent across all subcommands.
Setting the RUN_SETUP also provides the same protection for all
subcommands given that the "register" and "unregister" also requires to
be executed inside a repository.
Furthermore let's remove the local validation implemented by the
"register" and "unregister" as this will not be required anymore with
the new option.
Signed-off-by: Rafael Silva <rafaeloliveira.cs@gmail.com>
Reviewed-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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>
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>
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>
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>
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
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
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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
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
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>
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
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
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>
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>
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>
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>
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>
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>
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>
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>
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>
"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
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>
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>
"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
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
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>
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>
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>
"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
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>
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>
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>
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>
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>
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
"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
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>
