"git repack" learned "--max-cruft-size" to prevent cruft packs from
growing without bounds.
* tb/repack-max-cruft-size:
repack: free existing_cruft array after use
builtin/repack.c: avoid making cruft packs preferred
builtin/repack.c: implement support for `--max-cruft-size`
builtin/repack.c: parse `--max-pack-size` with OPT_MAGNITUDE
t7700: split cruft-related tests to t7704
The documentation for geometric repacking mentions a "--unpacked" option
that supposedly changes how loose objects are rolled up. This option has
never existed, and the implied behaviour, namely to include all unpacked
objects into the resulting packfile, is in fact the default behaviour.
Correct the documentation to not mention this option.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The `-g` switch is a shorthand for `--geometric=` and allows the user to
specify the geometric. The documentation is wrong though and indicates
that the syntax for the shorthand is `-g=<factor>`. In fact though, the
option must be specified without the equals sign via `-g<factor>`.
Fix the syntax accordingly.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Cruft packs are an alternative mechanism for storing a collection of
unreachable objects whose mtimes are recent enough to avoid being
pruned out of the repository.
When cruft packs were first introduced back in b757353676
(builtin/pack-objects.c: --cruft without expiration, 2022-05-20) and
a7d493833f (builtin/pack-objects.c: --cruft with expiration,
2022-05-20), the recommended workflow consisted of:
- Repacking periodically, either by packing anything loose in the
repository (via `git repack -d`) or producing a geometric sequence
of packs (via `git repack --geometric=<d> -d`).
- Every so often, splitting the repository into two packs, one cruft
to store the unreachable objects, and another non-cruft pack to
store the reachable objects.
Repositories may (out of band with the above) choose periodically to
prune out some unreachable objects which have aged out of the grace
period by generating a pack with `--cruft-expiration=<approxidate>`.
This allowed repositories to maintain relatively few packs on average,
and quarantine unreachable objects together in a cruft pack, avoiding
the pitfalls of holding unreachable objects as loose while they age out
(for more, see some of the details in 3d89a8c118
(Documentation/technical: add cruft-packs.txt, 2022-05-20)).
This all works, but can be costly from an I/O-perspective when
frequently repacking a repository that has many unreachable objects.
This problem is exacerbated when those unreachable objects are rarely
(if every) pruned.
Since there is at most one cruft pack in the above scheme, each time we
update the cruft pack it must be rewritten from scratch. Because much of
the pack is reused, this is a relatively inexpensive operation from a
CPU-perspective, but is very costly in terms of I/O since we end up
rewriting basically the same pack (plus any new unreachable objects that
have entered the repository since the last time a cruft pack was
generated).
At the time, we decided against implementing more robust support for
multiple cruft packs. This patch implements that support which we were
lacking.
Introduce a new option `--max-cruft-size` which allows repositories to
accumulate cruft packs up to a given size, after which point a new
generation of cruft packs can accumulate until it reaches the maximum
size, and so on. To generate a new cruft pack, the process works like
so:
- Sort a list of any existing cruft packs in ascending order of pack
size.
- Starting from the beginning of the list, group cruft packs together
while the accumulated size is smaller than the maximum specified
pack size.
- Combine the objects in these cruft packs together into a new cruft
pack, along with any other unreachable objects which have since
entered the repository.
Once a cruft pack grows beyond the size specified via `--max-cruft-size`
the pack is effectively frozen. This limits the I/O churn up to a
quadratic function of the value specified by the `--max-cruft-size`
option, instead of behaving quadratically in the number of total
unreachable objects.
When pruning unreachable objects, we bypass the new code paths which
combine small cruft packs together, and instead start from scratch,
passing in the appropriate `--max-pack-size` down to `pack-objects`,
putting it in charge of keeping the resulting set of cruft packs sized
correctly.
This may seem like further I/O churn, but in practice it isn't so bad.
We could prune old cruft packs for whom all or most objects are removed,
and then generate a new cruft pack with just the remaining set of
objects. But this additional complexity buys us relatively little,
because most objects end up being pruned anyway, so the I/O churn is
well contained.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A previous commit has implemented `git repack --filter=<filter-spec>` to
allow users to filter out some objects from the main pack and move them
into a new different pack.
It would be nice if this new different pack could be created in a
different directory than the regular pack. This would make it possible
to move large blobs into a pack on a different kind of storage, for
example cheaper storage.
Even in a different directory, this pack can be accessible if, for
example, the Git alternates mechanism is used to point to it. In fact
not using the Git alternates mechanism can corrupt a repo as the
generated pack containing the filtered objects might not be accessible
from the repo any more. So setting up the Git alternates mechanism
should be done before using this feature if the user wants the repo to
be fully usable while this feature is used.
In some cases, like when a repo has just been cloned or when there is no
other activity in the repo, it's Ok to setup the Git alternates
mechanism afterwards though. It's also Ok to just inspect the generated
packfile containing the filtered objects and then just move it into the
'.git/objects/pack/' directory manually. That's why it's not necessary
for this command to check that the Git alternates mechanism has been
already setup.
While at it, as an example to show that `--filter` and `--filter-to`
work well with other options, let's also add a test to check that these
options work well with `--max-pack-size`.
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This new option puts the objects specified by `<filter-spec>` into a
separate packfile.
This could be useful if, for example, some blobs take up a lot of
precious space on fast storage while they are rarely accessed. It could
make sense to move them into a separate cheaper, though slower, storage.
It's possible to find which new packfile contains the filtered out
objects using one of the following:
- `git verify-pack -v ...`,
- `test-tool find-pack ...`, which a previous commit added,
- `--filter-to=<dir>`, which a following commit will add to specify
where the pack containing the filtered out objects will be.
This feature is implemented by running `git pack-objects` twice in a
row. The first command is run with `--filter=<filter-spec>`, using the
specified filter. It packs objects while omitting the objects specified
by the filter. Then another `git pack-objects` command is launched using
`--stdin-packs`. We pass it all the previously existing packs into its
stdin, so that it will pack all the objects in the previously existing
packs. But we also pass into its stdin, the pack created by the previous
`git pack-objects --filter=<filter-spec>` command as well as the kept
packs, all prefixed with '^', so that the objects in these packs will be
omitted from the resulting pack. The result is that only the objects
filtered out by the first `git pack-objects` command are in the pack
resulting from the second `git pack-objects` command.
As the interactions with kept packs are a bit tricky, a few related
tests are added.
Helped-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: John Cai <johncai86@gmail.com>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When pruning objects with `--cruft`, `git repack` offers some
flexibility when selecting the set of which objects are pruned via the
`--cruft-expiration` option.
This is useful for expiring objects which are older than the grace
period, making races where to-be-pruned objects become reachable and
then ancestors of freshly pushed objects, leaving the repository in a
corrupt state after pruning substantially less likely [1].
But in practice, such races are impossible to avoid entirely, no matter
how long the grace period is. To prevent this race, it is often
advisable to temporarily put a repository into a read-only state. But in
practice, this is not always practical, and so some middle ground would
be nice.
This patch introduces a new option, `--expire-to`, which teaches `git
repack` to write an additional cruft pack containing just the objects
which were pruned from the repository. The caller can specify a
directory outside of the current repository as the destination for this
second cruft pack.
This makes it possible to prune objects from a repository, while still
holding onto a supplemental copy of them outside of the original
repository. Having this copy on-disk makes it substantially easier to
recover objects when the aforementioned race is encountered.
`--expire-to` is implemented in a somewhat convoluted manner, which is
to take advantage of the fact that the first time `write_cruft_pack()`
is called, it adds the name of the cruft pack to the `names` string
list. That means the second time we call `write_cruft_pack()`, objects
in the previously-written cruft pack will be excluded.
As long as the caller ensures that no objects are expired during the
second pass, this is sufficient to generate a cruft pack containing all
objects which don't appear in any of the new packs written by `git
repack`, including the cruft pack. In other words, all of the objects
which are about to be pruned from the repository.
It is important to note that the destination in `--expire-to` does not
necessarily need to be a Git repository (though it can be) Notably, the
expired packs do not contain all ancestors of expired objects. So if the
source repository contains something like:
<unreachable>
/
C1 --- C2
\
refs/heads/master
where C2 is unreachable, but has a parent (C1) which is reachable, and
C2 would be pruned, then the expiry pack will contain only C2, not C1.
[1]: https://lore.kernel.org/git/20190319001829.GL29661@sigill.intra.peff.net/
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Expose a way to split the contents of a repository into a main and cruft
pack when doing an all-into-one repack with `git repack --cruft -d`, and
a complementary configuration variable.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
While testing some ideas in 'git repack', I ran it with '--quiet' and
discovered that some progress output was still shown. Specifically, the
output for writing the multi-pack-index showed the progress.
The 'show_progress' variable in cmd_repack() is initialized with
isatty(2) and is not modified at all by the '--quiet' flag. The
'--quiet' flag modifies the po_args.quiet option which is translated
into a '--quiet' flag for the 'git pack-objects' child process. However,
'show_progress' is used to directly send progress information to the
multi-pack-index writing logic which does not use a child process.
The fix here is to modify 'show_progress' to be false if po_opts.quiet
is true, and isatty(2) otherwise. This new expectation simplifies a
later condition that checks both.
Update the documentation to make it clear that '-q' will disable all
progress in addition to ensuring the 'git pack-objects' child process
will receive the flag.
Use 'test_terminal' to check that this works to get around the isatty(2)
check.
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When repacking into a geometric series and writing a multi-pack bitmap,
it is beneficial to have the largest resulting pack be the preferred
object source in the bitmap's MIDX, since selecting the large packs can
lead to fewer broken delta chains and better compression.
Teach 'git repack' to identify this pack and pass it to the MIDX write
machinery in order to mark it as preferred.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Teach `git repack` a new `--write-midx` option for callers that wish to
persist a multi-pack index in their repository while repacking.
There are two existing alternatives to this new flag, but they don't
cover our particular use-case. These alternatives are:
- Call 'git multi-pack-index write' after running 'git repack', or
- Set 'GIT_TEST_MULTI_PACK_INDEX=1' in your environment when running
'git repack'.
The former works, but introduces a gap in bitmap coverage between
repacking and writing a new MIDX (since the repack may have deleted a
pack included in the existing MIDX, invalidating it altogether).
Setting the 'GIT_TEST_' environment variable is obviously unsupported.
In fact, even if it were supported officially, it still wouldn't work,
because it generates the MIDX *after* redundant packs have been dropped,
leading to the same issue as above.
Introduce a new option which eliminates this race by teaching `git
repack` to generate the MIDX at the critical point: after the new packs
have been written and moved into place, but before the redundant packs
have been removed.
This option is compatible with `git repack`'s '--bitmap' option (it
changes the interpretation to be: "write a bitmap corresponding to the
MIDX after one has been generated").
There is a little bit of additional noise in the patch below to avoid
repeating ourselves when selecting which packs to delete. Instead of a
single loop as before (where we iterate over 'existing_packs', decide if
a pack is worth deleting, and if so, delete it), we have two loops (the
first where we decide which ones are worth deleting, and the second
where we actually do the deleting). This makes it so we have a single
check we can make consistently when (1) telling the MIDX which packs we
want to exclude, and (2) actually unlinking the redundant packs.
There is also a tiny change to short-circuit the body of
write_midx_included_packs() when no packs remain in the case of an empty
repository. The MIDX code does not handle this, so avoid trying to
generate a MIDX covering zero packs in the first place.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This option is almost never a good idea, as the resulting repository is
larger and slower (see the new explanations in the docs).
I outlined the potential problems. We could go further and make the
option harder to find (or at least, make the command-line option
descriptions a much more terse "you probably don't want this; see
pack.packsizeLimit for details"). But this seems like a minimal change
that may prevent people from thinking it's more useful than it is.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Drop the ")" at the end of this paragraph. There's a parenthetical
remark in this paragraph, but it's been closed on the line above.
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git repack" so far has been only capable of repacking everything
under the sun into a single pack (or split by size). A cleverer
strategy to reduce the cost of repacking a repository has been
introduced.
* tb/geometric-repack:
builtin/pack-objects.c: ignore missing links with --stdin-packs
builtin/repack.c: reword comment around pack-objects flags
builtin/repack.c: be more conservative with unsigned overflows
builtin/repack.c: assign pack split later
t7703: test --geometric repack with loose objects
builtin/repack.c: do not repack single packs with --geometric
builtin/repack.c: add '--geometric' option
packfile: add kept-pack cache for find_kept_pack_entry()
builtin/pack-objects.c: rewrite honor-pack-keep logic
p5303: measure time to repack with keep
p5303: add missing &&-chains
builtin/pack-objects.c: add '--stdin-packs' option
revision: learn '--no-kept-objects'
packfile: introduce 'find_kept_pack_entry()'
Often it is useful to both:
- have relatively few packfiles in a repository, and
- avoid having so few packfiles in a repository that we repack its
entire contents regularly
This patch implements a '--geometric=<n>' option in 'git repack'. This
allows the caller to specify that they would like each pack to be at
least a factor times as large as the previous largest pack (by object
count).
Concretely, say that a repository has 'n' packfiles, labeled P1, P2,
..., up to Pn. Each packfile has an object count equal to 'objects(Pn)'.
With a geometric factor of 'r', it should be that:
objects(Pi) > r*objects(P(i-1))
for all i in [1, n], where the packs are sorted by
objects(P1) <= objects(P2) <= ... <= objects(Pn).
Since finding a true optimal repacking is NP-hard, we approximate it
along two directions:
1. We assume that there is a cutoff of packs _before starting the
repack_ where everything to the right of that cut-off already forms
a geometric progression (or no cutoff exists and everything must be
repacked).
2. We assume that everything smaller than the cutoff count must be
repacked. This forms our base assumption, but it can also cause
even the "heavy" packs to get repacked, for e.g., if we have 6
packs containing the following number of objects:
1, 1, 1, 2, 4, 32
then we would place the cutoff between '1, 1' and '1, 2, 4, 32',
rolling up the first two packs into a pack with 2 objects. That
breaks our progression and leaves us:
2, 1, 2, 4, 32
^
(where the '^' indicates the position of our split). To restore a
progression, we move the split forward (towards larger packs)
joining each pack into our new pack until a geometric progression
is restored. Here, that looks like:
2, 1, 2, 4, 32 ~> 3, 2, 4, 32 ~> 5, 4, 32 ~> ... ~> 9, 32
^ ^ ^ ^
This has the advantage of not repacking the heavy-side of packs too
often while also only creating one new pack at a time. Another wrinkle
is that we assume that loose, indexed, and reflog'd objects are
insignificant, and lump them into any new pack that we create. This can
lead to non-idempotent results.
Suggested-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Knowing about the core.bigFileThreshold configuration variable is
helpful when examining pack file size differences between repositories.
Add a reference to it to the manpages a user is likely to read in this
situation.
Capitalize CONFIGURATION for consistency with other pages having such a
section.
Signed-off-by: Christian Walther <cwalther@gmx.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Inspired by 21416f0a07 ("restore: fix typo in docs", 2019-08-03), I ran
"git grep -E '(\b[a-zA-Z]+) \1\b' -- Documentation/" to find other cases
where words were duplicated, e.g. "the the", and in most cases removed
one of the repeated words.
There were many false positives by this grep command, including
deliberate repeated words like "really really" or valid uses of "that
that" which I left alone, of course.
I also did not correct any of the legitimate, accidentally repeated
words in old RelNotes.
Signed-off-by: Mark Rushakoff <mark.rushakoff@gmail.com>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Lift code from GitHub to restrict delta computation so that an
object that exists in one fork is not made into a delta against
another object that does not appear in the same forked repository.
* cc/delta-islands:
pack-objects: move 'layer' into 'struct packing_data'
pack-objects: move tree_depth into 'struct packing_data'
t5320: tests for delta islands
repack: add delta-islands support
pack-objects: add delta-islands support
pack-objects: refactor code into compute_layer_order()
Add delta-islands.{c,h}
Implement simple support for --delta-islands option and
repack.useDeltaIslands config variable in git repack.
This allows users to setup delta islands in their config and
get the benefit of less disk usage while cloning and fetching
is still quite fast and not much more CPU intensive.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Currently, repack does not touch promisor packfiles at all, potentially
causing the performance of repositories that have many such packfiles to
drop. Therefore, repack all promisor objects if invoked with -a or -A.
This is done by an additional invocation of pack-objects on all promisor
objects individually given, which takes care of deduplication and allows
the resulting packfiles to respect flags such as --max-pack-size.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git pack-objects" needs to allocate tons of "struct object_entry"
while doing its work, and shrinking its size helps the performance
quite a bit.
* nd/pack-objects-pack-struct:
ci: exercise the whole test suite with uncommon code in pack-objects
pack-objects: reorder members to shrink struct object_entry
pack-objects: shrink delta_size field in struct object_entry
pack-objects: shrink size field in struct object_entry
pack-objects: clarify the use of object_entry::size
pack-objects: don't check size when the object is bad
pack-objects: shrink z_delta_size field in struct object_entry
pack-objects: refer to delta objects by index instead of pointer
pack-objects: move in_pack out of struct object_entry
pack-objects: move in_pack_pos out of struct object_entry
pack-objects: use bitfield for object_entry::depth
pack-objects: use bitfield for object_entry::dfs_state
pack-objects: turn type and in_pack_type to bitfields
pack-objects: a bit of document about struct object_entry
read-cache.c: make $GIT_TEST_SPLIT_INDEX boolean
We allow to keep existing packs by having companion .keep files. This
is helpful when a pack is permanently kept. In the next patch, git-gc
just wants to keep a pack temporarily, for one pack-objects
run. git-gc can use --keep-pack for this use case.
A note about why the pack_keep field cannot be reused and
pack_keep_in_core has to be added. This is about the case when
--keep-pack is specified together with either --keep-unreachable or
--unpack-unreachable, but --honor-pack-keep is NOT specified.
In this case, we want to exclude objects from the packs specified on
command line, not from ones with .keep files. If only one bit flag is
used, we have to clear pack_keep on pack files with the .keep file.
But we can't make any assumption about unreachable objects in .keep
packs. If "pack_keep" field is false for .keep packs, we could
potentially pull lots of unreachable objects into the new pack, or
unpack them loose. The safer approach is ignore all packs with either
.keep file or --keep-pack.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Because of struct packing from now on we can only handle max depth
4095 (or even lower when new booleans are added in this struct). This
should be ok since long delta chain will cause significant slow down
anyway.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We already do so for --window=<n> and --depth=<n>; this will help
when the user wants to force --threads=1 for reproducible testing
without getting affected by racing multiple threads.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
More mark-up updates to typeset strings that are expected to
literally typed by the end user in fixed-width font.
* mm/doc-tt:
doc: typeset HEAD and variants as literal
CodingGuidelines: formatting HEAD in documentation
doc: typeset long options with argument as literal
doc: typeset '--' as literal
doc: typeset long command-line options as literal
doc: typeset short command-line options as literal
Documentation/git-mv.txt: fix whitespace indentation
It was common in our documentation to surround short option names with
forward quotes, which renders as italic in HTML. Instead, use backquotes
which renders as monospace. This is one more step toward conformance to
Documentation/CodingGuidelines.
This was obtained with:
perl -pi -e "s/'(-[a-z])'/\`\$1\`/g" *.txt
Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If you use "repack -adk" currently, we will pack all objects
that are already packed into the new pack, and then drop the
old packs. However, loose unreachable objects will be left
as-is. In theory these are meant to expire eventually with
"git prune". But if you are using "repack -k", you probably
want to keep things forever and therefore do not run "git
prune" at all. Meaning those loose objects may build up over
time and end up fooling any object-count heuristics (such as
the one done by "gc --auto", though since git-gc does not
support "repack -k", this really applies to whatever custom
scripts people might have driving "repack -k").
With this patch, we instead stuff any loose unreachable
objects into the pack along with the already-packed
unreachable objects. This may seem wasteful, but it is
really no more so than using "repack -k" in the first place.
We are at a slight disadvantage, in that we have no useful
ordering for the result, or names to hand to the delta code.
However, this is again no worse than what "repack -k" is
already doing for the packed objects. The packing of these
objects doesn't matter much because they should not be
accessed frequently (unless they actually _do_ become
referenced, but then they would get moved to a different
part of the packfile during the next repack).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The usual way to do a full repack (and what is done by
git-gc) is to run "repack -Ad --unpack-unreachable=<when>",
which will loosen any unreachable objects newer than
"<when>", and drop any older ones.
This is a safer alternative to "repack -ad", because
"<when>" becomes a grace period during which we will not
drop any new objects that are about to be referenced.
However, it isn't perfectly safe. It's always possible that
a process is about to reference an old object. Even if that
process were to take care to update the timestamp on the
object, there is no atomicity with a simultaneously running
"repack" process.
So while unlikely, there is a small race wherein we may drop
an object that is in the process of being referenced. If you
do automated repacking on a large number of active
repositories, you may hit it eventually, and the result is a
corrupted repository.
It would be nice to fix that race in the long run, but it's
complicated. In the meantime, there is a much simpler
strategy for automated repository maintenance: do not drop
objects at all. We already have a "--keep-unreachable"
option in pack-objects; we just need to plumb it through
from git-repack.
Note that this _isn't_ plumbed through from git-gc, so at
this point it's strictly a tool for people doing their own
advanced repository maintenance strategy.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This was added back in 7e52f56 (gc: do not explode objects
which will be immediately pruned, 2012-04-07), but not
documented at the time, since it was an internal detail
between git-gc and git-repack. However, as people with
complicated setups may want to effectively reimplement the
steps of git-gc themselves, it is nice for us to document
these interfaces.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It can be tempting for a server admin to want a stable set of
long-lived packs for dumb clients; but also want to enable bitmaps
to serve smart clients more quickly.
Unfortunately, such a configuration is impossible; so at least warn
users of this incompatibility since commit 21134714 (pack-objects:
turn off bitmaps when we split packs, 2014-10-16).
Tested the warning by inspecting the output of:
make -C t t5310-pack-bitmaps.sh GIT_TEST_OPTS=-v
Signed-off-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The git-over-rsync protocol is inefficient and broken, and
has been for a long time. It transfers way more objects than
it needs (grabbing all of the remote's "objects/",
regardless of which objects we need). It does its own ad-hoc
parsing of loose and packed refs from the remote, but
doesn't properly override packed refs with loose ones,
leading to garbage results (e.g., expecting the other side
to have an object pointed to by a stale packed-refs entry,
or complaining that the other side has two copies of the
refs[1]).
This latter breakage means that nobody could have
successfully pulled from a moderately active repository
since cd547b4 (fetch/push: readd rsync support, 2007-10-01).
We never made an official deprecation notice in the release
notes for git's rsync protocol, but the tutorial has marked
it as such since 914328a (Update tutorial., 2005-08-30).
And on the mailing list as far back as Oct 2005, we can find
Junio mentioning it as having "been deprecated for quite
some time."[2,3,4]. So it was old news then; cogito had
deprecated the transport in July of 2005[5] (though it did
come back briefly when Linus broke git-http-pull!).
Of course some people professed their love of rsync through
2006, but Linus clarified in his usual gentle manner[6]:
> Thanks! This is why I still use rsync, even though
> everybody and their mother tells me "Linus says rsync is
> deprecated."
No. You're using rsync because you're actively doing
something _wrong_.
The deprecation sentiment was reinforced in 2008, with a
mention that cloning via rsync is broken (with no fix)[7].
Even the commit porting rsync over to C from shell (cd547b4)
lists it as deprecated! So between the 10 years of informal
warnings, and the fact that it has been severely broken
since 2007, it's probably safe to simply remove it without
further deprecation warnings.
[1] http://article.gmane.org/gmane.comp.version-control.git/285101
[2] http://article.gmane.org/gmane.comp.version-control.git/10093
[3] http://article.gmane.org/gmane.comp.version-control.git/17734
[4] http://article.gmane.org/gmane.comp.version-control.git/18911
[5] http://article.gmane.org/gmane.comp.version-control.git/5617
[6] http://article.gmane.org/gmane.comp.version-control.git/19354
[7] http://article.gmane.org/gmane.comp.version-control.git/103635
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This should improve readability. Compare "thislongname" and
"thisLongName". The following keys are left in unchanged. We can
decide what to do with them later.
- am.keepcr
- core.autocrlf .safecrlf .trustctime
- diff.dirstat .noprefix
- gitcvs.usecrlfattr
- gui.blamehistoryctx .trustmtime
- pull.twohead
- receive.autogc
- sendemail.signedoffbycc .smtpsslcertpath .suppresscc
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The git-repack command always passes `--honor-pack-keep`
to pack-objects. This has traditionally been a good thing,
as we do not want to duplicate those objects in a new pack,
and we are not going to delete the old pack.
However, when bitmaps are in use, it is important for a full
repack to include all reachable objects, even if they may be
duplicated in a .keep pack. Otherwise, we cannot generate
the bitmaps, as the on-disk format requires the set of
objects in the pack to be fully closed.
Even if the repository does not generally have .keep files,
a simultaneous push could cause a race condition in which a
.keep file exists at the moment of a repack. The repack may
try to include those objects in one of two situations:
1. The pushed .keep pack contains objects that were
already in the repository (e.g., blobs due to a revert of
an old commit).
2. Receive-pack updates the refs, making the objects
reachable, but before it removes the .keep file, the
repack runs.
In either case, we may prefer to duplicate some objects in
the new, full pack, and let the next repack (after the .keep
file is cleaned up) take care of removing them.
This patch introduces both a command-line and config option
to disable the `--honor-pack-keep` option. By default, it
is triggered when pack.writeBitmaps (or `--write-bitmap-index`
is turned on), but specifying it explicitly can override the
behavior (e.g., in cases where you prefer .keep files to
bitmaps, but only when they are present).
Note that this option just disables the pack-objects
behavior. We still leave packs with a .keep in place, as we
do not necessarily know that we have duplicated all of their
objects.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Borrow the bitmap index into packfiles from JGit to speed up
enumeration of objects involved in a commit range without having to
fully traverse the history.
* jk/pack-bitmap: (26 commits)
ewah: unconditionally ntohll ewah data
ewah: support platforms that require aligned reads
read-cache: use get_be32 instead of hand-rolled ntoh_l
block-sha1: factor out get_be and put_be wrappers
do not discard revindex when re-preparing packfiles
pack-bitmap: implement optional name_hash cache
t/perf: add tests for pack bitmaps
t: add basic bitmap functionality tests
count-objects: recognize .bitmap in garbage-checking
repack: consider bitmaps when performing repacks
repack: handle optional files created by pack-objects
repack: turn exts array into array-of-struct
repack: stop using magic number for ARRAY_SIZE(exts)
pack-objects: implement bitmap writing
rev-list: add bitmap mode to speed up object lists
pack-objects: use bitmaps when packing objects
pack-objects: split add_object_entry
pack-bitmap: add support for bitmap indexes
documentation: add documentation for the bitmap format
ewah: compressed bitmap implementation
...
Since `pack-objects` will write a `.bitmap` file next to the `.pack` and
`.idx` files, this commit teaches `git-repack` to consider the new
bitmap indexes (if they exist) when performing repack operations.
This implies moving old bitmap indexes out of the way if we are
repacking a repository that already has them, and moving the newly
generated bitmap indexes into the `objects/pack` directory, next to
their corresponding packfiles.
Since `git repack` is now capable of handling these `.bitmap` files,
a normal `git gc` run on a repository that has `pack.writebitmaps` set
to true in its config file will generate bitmap indexes as part of the
garbage collection process.
Alternatively, `git repack` can be called with the `-b` switch to
explicitly generate bitmap indexes if you are experimenting
and don't want them on all the time.
Signed-off-by: Vicent Marti <tanoku@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This updates the documentation regarding the changes introduced
by a1bbc6c01 (2013-09-15, repack: rewrite the shell script in C).
Signed-off-by: Stefan Beller <stefanbeller@googlemail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The default output from "fsck" is often overwhelmed by informational
message on dangling objects, especially if you do not repack often, and a
real error can easily be buried.
Add "--no-dangling" option to omit them, and update the user manual to
demonstrate its use.
Based on a patch by Clemens Buchacher, but reverted the part to change
the default to --no-dangling, which is unsuitable for the first patch.
The usual three-step procedure to break the backward compatibility over
time needs to happen on top of this, if we were to go in that direction.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The SYNOPSIS sections of most commands that span several lines already
use [verse] to retain line breaks. Most commands that don't span
several lines seem not to use [verse]. In the HTML output, [verse]
does not only preserve line breaks, but also makes the section
indented, which causes a slight inconsistency between commands that
use [verse] and those that don't. Use [verse] in all SYNOPSIS sections
for consistency.
Also remove the blank lines from git-fetch.txt and git-rebase.txt to
align with the other man pages. In the case of git-rebase.txt, which
already uses [verse], the blank line makes the [verse] not apply to
the last line, so removing the blank line also makes the formatting
within the document more consistent.
While at it, add single quotes to 'git cvsimport' for consistency with
other commands.
Signed-off-by: Martin von Zweigbergk <martin.von.zweigbergk@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The point of these sections is generally to:
1. Give credit where it is due.
2. Give the reader an idea of where to ask questions or
file bug reports.
But they don't do a good job of either case. For (1), they
are out of date and incomplete. A much more accurate answer
can be gotten through shortlog or blame. For (2), the
correct contact point is generally git@vger, and even if you
wanted to cc the contact point, the out-of-date and
incomplete fields mean you're likely sending to somebody
useless.
So let's drop the fields entirely from all manpages except
git(1) itself. We already point people to the mailing list
for bug reports there, and we can update the Authors section
to give credit to the major contributors and point to
shortlog and blame for more information.
Each page has a "This is part of git" footer, so people can
follow that to the main git manpage.
In 479b56ba ('make "repack -f" imply "pack-objects --no-reuse-object"'),
git repack -f was changed to include recompressing all objects on the
zlib level on the assumption that if the user wants to spend that much
time already, some more time won't hurt (and recompressing is useful if
the user changed the zlib compression level).
However, "some more time" can be quite long with very big repositories,
so some users are going to appreciate being able to choose. If we are
going to give them the choice, --no-reuse-object will probably be
interesting a lot less frequently than --no-reuse-delta. Hence, this
reverts -f to the old behaviour (--no-reuse-delta) and adds a new -F
option that replaces the current -f.
Measurements taken using this patch on a current clone of git.git
indicate a 17% decrease in time being made available to users:
git repack -Adf 34.84s user 0.56s system 145% cpu 24.388 total
git repack -AdF 38.79s user 0.56s system 133% cpu 29.394 total
Signed-off-by: Jan Krüger <jk@jk.gs>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
