Too large files may lead to failure to allocate memory. If it happens
here, it could impact quite a few commands that involve
diff. Moreover, too large files are inefficient to compare anyway (and
most likely non-text), so mark them binary and skip looking at their
content.
Noticed-by: Dale R. Worley <worley@alum.mit.edu>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add support for configuring default sort ordering for git tags. Command
line option will override this configured value, using the exact same
syntax.
Cc: Jeff King <peff@peff.net>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
submodule.*.ignore and diff.ignoresubmodules are used to ignore all
submodule changes in "diff" output, but it can be confusing to
apply these configuration values to status and commit.
This is a backward-incompatible change, but should be so in a good
way (aka bugfix).
* jl/status-added-submodule-is-never-ignored:
commit -m: commit staged submodules regardless of ignore config
status/commit: show staged submodules regardless of ignore config
We currently have pack.writeBitmaps, which originally
operated at the pack-objects level. This should really have
been a repack.* option from day one. Let's give it the more
sensible name, but keep the old version as a deprecated
synonym.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The `core.deltabasecachelimit` used to default to 16 MiB , but this
proved to be too small, and has been bumped to 96 MiB.
* dk/raise-core-deltabasecachelimit:
Bump core.deltaBaseCacheLimit to 96m
Since the very beginning of Git, we gave the LESS environment a
default value "FRSX" when we spawn "less" as the pager. "S" (chop
long lines instead of wrapping) has been removed from this default
set of options, because it is more or less a personal taste thing,
as opposed to others that have good justifications (i.e. "R" is very
much justified because many kinds of output we produce are colored
and "FX" is justified because output we produce is often shorter
than a page).
Existing users who prefer not to see line-wrapped output may want to
set
$ git config core.pager "less -S"
to restore the traditional behaviour. It is expected that people
find output from the most subcommands easier to read with the new
default, except for "blame" which tends to produce really long
lines. To override the new default only for "git blame", you can do
this:
$ git config pager.blame "less -S"
* mm/pager-less-sans-S:
pager: remove 'S' from $LESS by default
Many people are on filesystems with horrible stat latency (not
limited to Windows but also NFS), which core.preloadindex was
designed to help. We discussed enabling it by default early in 2013
but didn't.
Per
http://thread.gmane.org/gmane.comp.version-control.git/219273/focus=219322
let's enable the setting by default, with the original choice of max
20 threads / min 500 paths per thread parameters.
Signed-off-by: Steve Hoelzer <shoelzer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add an option to format-patch for reading a signature from a file.
$ git format-patch -1 --signature-file=$HOME/.signature
The config variable `format.signaturefile` can also be used to make
this the default.
$ git config format.signaturefile $HOME/.signature
$ git format-patch -1
Signed-off-by: Jeremiah Mahler <jmmahler@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When core.commentChar is "auto", the comment char starts with '#' as
in default but if it's already in the prepared message, find another
char in a small subset. This should stop surprises because git strips
some lines unexpectedly.
Note that git is not smart enough to recognize '#' as the comment char
in custom templates and convert it if the final comment char is
different. It thinks '#' lines in custom templates as part of the
commit message. So don't use this with custom templates.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
By default, Git used to set $LESS to -FRSX if $LESS was not set by
the user. The FRX flags actually make sense for Git (F and X because
sometimes the output Git pipes to less is short, and R because Git
pipes colored output). The S flag (chop long lines), on the other
hand, is not related to Git and is a matter of user preference. Git
should not decide for the user to change LESS's default.
More specifically, the S flag harms users who review untrusted code
within a pager, since a patch looking like:
-old code;
+new good code; [... lots of tabs ...] malicious code;
would appear identical to:
-old code;
+new good code;
Users who prefer the old behavior can still set the $LESS environment
variable to -FRSX explicitly, or set core.pager to 'less -S'.
The documentation in config.txt is made a bit longer to keep both an
example setting the 'S' flag (needed to recover the old behavior)
and an example showing how to unset a flag set by Git.
Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The default of 16m causes serious thrashing for large delta chains
combined with large files.
Here are some benchmarks (pu variant of git blame):
time git blame -C src/xdisp.c >/dev/null
for a repository of Emacs repacked with git gc --aggressive (v1.9,
resulting in a window size of 250) located on an SSD drive. The file in
question has about 30000 lines, 1Mb of size, and a history with about
2500 commits.
16m (previous default):
real 3m33.936s
user 2m15.396s
sys 1m17.352s
32m:
real 3m1.319s
user 2m8.660s
sys 0m51.904s
64m:
real 2m20.636s
user 1m55.780s
sys 0m23.964s
96m:
real 2m5.668s
user 1m50.784s
sys 0m14.288s
128m:
real 2m4.337s
user 1m50.764s
sys 0m12.832s
192m:
real 2m3.567s
user 1m49.508s
sys 0m13.312s
Signed-off-by: David Kastrup <dak@gnu.org>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Eradicate mistaken use of "nor" (that is, essentially "nor" used
not in "neither A nor B" ;-)) from in-code comments, command output
strings, and documentations.
* jl/nor-or-nand-and:
code and test: fix misuses of "nor"
comments: fix misuses of "nor"
contrib: fix misuses of "nor"
Documentation: fix misuses of "nor"
Currently setting submodule.<name>.ignore and/or diff.ignoreSubmodules to
"all" suppresses all output of submodule changes for the diff family,
status and commit. For status and commit this is really confusing, as it
even when the user chooses to record a new commit for an ignored submodule
by adding it manually this change won't show up under the to-be-committed
changes. To add insult to injury, a later "git commit" will error out with
"nothing to commit" when only ignored submodules are staged.
Fix that by making wt_status always print staged submodule changes, no
matter what ignore settings are configured. The only exception is when the
user explicitly uses the "--ignore-submodules=all" command line option, in
that case the submodule output is still suppressed. This also makes "git
commit" work again when only modifications of ignored submodules are
staged, as that command uses the "commitable" member of the wt_status
struct to determine if staged changes are present. But this only happens
when the commit command uses the wt_status* functions to produce status
output for human consumption (when forking an editor or with --dry-run),
in all other cases (e.g. when run in a script with '-m') another code path
is taken which uses index_differs_from() to determine if any changes are
staged which still ignores submodules according to their configuration.
This will be fixed in a follow-up commit.
Change t7508 to reflect this new behavior and add three new tests to show
that a single staged submodule configured to be ignored will be committed
when the status output is generated and won't be if not. Also update the
documentation of the ignore config options accordingly.
Signed-off-by: Jens Lehmann <Jens.Lehmann@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Allow tweaking the maximum length of the delta-chain produced by
"gc --aggressive".
* nd/gc-aggressive:
environment.c: fix constness for odb_pack_keep()
gc --aggressive: make --depth configurable
When 1c192f3 (gc --aggressive: make it really aggressive - 2007-12-06)
made --depth=250 the default value, it didn't really explain the
reason behind, especially the pros and cons of --depth=250.
An old mail from Linus below explains it at length. Long story short,
--depth=250 is a disk saver and a performance killer. Not everybody
agrees on that aggressiveness. Let the user configure it.
From: Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH] gc --aggressive: make it really aggressive
Date: Thu, 6 Dec 2007 08:19:24 -0800 (PST)
Message-ID: <alpine.LFD.0.9999.0712060803430.13796@woody.linux-foundation.org>
Gmane-URL: http://article.gmane.org/gmane.comp.gcc.devel/94637
On Thu, 6 Dec 2007, Harvey Harrison wrote:
>
> 7:41:25elapsed 86%CPU
Heh. And this is why you want to do it exactly *once*, and then just
export the end result for others ;)
> -r--r--r-- 1 hharrison hharrison 324094684 2007-12-06 07:26 pack-1d46...pack
But yeah, especially if you allow longer delta chains, the end result can
be much smaller (and what makes the one-time repack more expensive is the
window size, not the delta chain - you could make the delta chains longer
with no cost overhead at packing time)
HOWEVER.
The longer delta chains do make it potentially much more expensive to then
use old history. So there's a trade-off. And quite frankly, a delta depth
of 250 is likely going to cause overflows in the delta cache (which is
only 256 entries in size *and* it's a hash, so it's going to start having
hash conflicts long before hitting the 250 depth limit).
So when I said "--depth=250 --window=250", I chose those numbers more as
an example of extremely aggressive packing, and I'm not at all sure that
the end result is necessarily wonderfully usable. It's going to save disk
space (and network bandwidth - the delta's will be re-used for the network
protocol too!), but there are definitely downsides too, and using long
delta chains may simply not be worth it in practice.
(And some of it might just want to have git tuning, ie if people think
that long deltas are worth it, we could easily just expand on the delta
hash, at the cost of some more memory used!)
That said, the good news is that working with *new* history will not be
affected negatively, and if you want to be _really_ sneaky, there are ways
to say "create a pack that contains the history up to a version one year
ago, and be very aggressive about those old versions that we still want to
have around, but do a separate pack for newer stuff using less aggressive
parameters"
So this is something that can be tweaked, although we don't really have
any really nice interfaces for stuff like that (ie the git delta cache
size is hardcoded in the sources and cannot be set in the config file, and
the "pack old history more aggressively" involves some manual scripting
and knowing how "git pack-objects" works rather than any nice simple
command line switch).
So the thing to take away from this is:
- git is certainly flexible as hell
- .. but to get the full power you may need to tweak things
- .. happily you really only need to have one person to do the tweaking,
and the tweaked end results will be available to others that do not
need to know/care.
And whether the difference between 320MB and 500MB is worth any really
involved tweaking (considering the potential downsides), I really don't
know. Only testing will tell.
Linus
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* sr/add--interactive-term-readkey:
git-add--interactive: warn if module for interactive.singlekey is missing
git-config: document interactive.singlekey requires Term::ReadKey
Allow loosening remote "git archive" invocation security check that
refuses to serve tree-ish not at the tip of any ref.
* sg/archive-restrict-remote:
add uploadarchive.allowUnreachable option
docs: clarify remote restrictions for git-upload-archive
* tg/index-v4-format:
read-cache: add index.version config variable
test-lib: allow setting the index format version
introduce GIT_INDEX_VERSION environment variable
Allow running "gc --auto" in the background.
* nd/daemonize-gc:
gc: config option for running --auto in background
daemon: move daemonize() to libgit.a
Most distributions don't require Term::ReadKey as dependency, leaving
the user to wonder why the setting doesn't work.
Signed-off-by: Simon Ruderich <simon@ruderich.org>
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>
In commit ee27ca4, we started restricting remote git-archive
invocations to only accessing reachable commits. This
matches what upload-pack allows, but does restrict some
useful cases (e.g., HEAD:foo). We loosened this in 0f544ee,
which allows `foo:bar` as long as `foo` is a ref tip.
However, that still doesn't allow many useful things, like:
1. Commits accessible from a ref, like `foo^:bar`, which
are reachable
2. Arbitrary sha1s, even if they are reachable.
We can do a full object-reachability check for these cases,
but it can be quite expensive if the client has sent us the
sha1 of a tree; we have to visit every sub-tree of every
commit in the worst case.
Let's instead give site admins an escape hatch, in case they
prefer the more liberal behavior. For many sites, the full
object database is public anyway (e.g., if you allow dumb
walker access), or the site admin may simply decide the
security/convenience tradeoff is not worth it.
This patch adds a new config option to disable the
restrictions added in ee27ca4. It defaults to off, meaning
there is no change in behavior by default.
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
...
"git pull" learned to pay attention to pull.ff configuration
variable.
* da/pull-ff-configuration:
pull: add --ff-only to the help text
pull: add pull.ff configuration
Introduce commit.gpgsign configuration variable to force every
commit to be GPG signed. The variable cannot be overriden from the
command line of some of the commands that create commits except for
"git commit" and "git commit-tree", but I am not convinced that it
is a good idea to sprinkle support for --no-gpg-sign everywhere,
which in turn means that this configuration variable may not be
such a good idea.
* nv/commit-gpgsign-config:
test the commit.gpgsign config option
commit-tree: add and document --no-gpg-sign
commit-tree: add the commit.gpgsign option to sign all commits
If you want to GPG sign all your commits, you have to add the -S option
all the time. The commit.gpgsign config option allows to sign all
commits automatically.
Signed-off-by: Nicolas Vigier <boklm@mars-attacks.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a config variable that allows setting the default index version when
initializing a new index file. Similar to the GIT_INDEX_VERSION
environment variable this only affects new index files.
Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
`gc --auto` takes time and can block the user temporarily (but not any
less annoyingly). Make it run in background on systems that support
it. The only thing lost with running in background is printouts. But
gc output is not really interesting. You can keep it in foreground by
changing gc.autodetach.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fetching from a shallow-cloned repository used to be forbidden,
primarily because the codepaths involved were not carefully vetted
and we did not bother supporting such usage. This attempts to allow
object transfer out of a shallow-cloned repository in a controlled
way (i.e. the receiver become a shallow repository with truncated
history).
* nd/shallow-clone: (31 commits)
t5537: fix incorrect expectation in test case 10
shallow: remove unused code
send-pack.c: mark a file-local function static
git-clone.txt: remove shallow clone limitations
prune: clean .git/shallow after pruning objects
clone: use git protocol for cloning shallow repo locally
send-pack: support pushing from a shallow clone via http
receive-pack: support pushing to a shallow clone via http
smart-http: support shallow fetch/clone
remote-curl: pass ref SHA-1 to fetch-pack as well
send-pack: support pushing to a shallow clone
receive-pack: allow pushes that update .git/shallow
connected.c: add new variant that runs with --shallow-file
add GIT_SHALLOW_FILE to propagate --shallow-file to subprocesses
receive/send-pack: support pushing from a shallow clone
receive-pack: reorder some code in unpack()
fetch: add --update-shallow to accept refs that update .git/shallow
upload-pack: make sure deepening preserves shallow roots
fetch: support fetching from a shallow repository
clone: support remote shallow repository
...
Add a `pull.ff` configuration option that is analogous
to the `merge.ff` option.
This allows us to control the fast-forward behavior for
pull-initiated merges only.
Signed-off-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Just like we give a reasonable default for "less" via the LESS
environment variable, specify a reasonable default for "lv" via the
"LV" environment variable when spawning the pager.
* jn/pager-lv-default-env:
pager: set LV=-c alongside LESS=FRSX
On systems with lv configured as the preferred pager (i.e.,
DEFAULT_PAGER=lv at build time, or PAGER=lv exported in the
environment) git commands that use color show control codes instead of
color in the pager:
$ git diff
^[[1mdiff --git a/.mailfilter b/.mailfilter^[[m
^[[1mindex aa4f0b2..17e113e 100644^[[m
^[[1m--- a/.mailfilter^[[m
^[[1m+++ b/.mailfilter^[[m
^[[36m@@ -1,11 +1,58 @@^[[m
"less" avoids this problem because git uses the LESS environment
variable to pass the -R option ('output ANSI color escapes in raw
form') by default. Use the LV environment variable to pass 'lv' the
-c option ('allow ANSI escape sequences for text decoration / color')
to fix it for lv, too.
Noticed when the default value for color.ui flipped to 'auto' in
v1.8.4-rc0~36^2~1 (2013-06-10).
Reported-by: Olaf Meeuwissen <olaf.meeuwissen@avasys.jp>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When we use pack bitmaps rather than walking the object
graph, we end up with the list of objects to include in the
packfile, but we do not know the path at which any tree or
blob objects would be found.
In a recently packed repository, this is fine. A fetch would
use the paths only as a heuristic in the delta compression
phase, and a fully packed repository should not need to do
much delta compression.
As time passes, though, we may acquire more objects on top
of our large bitmapped pack. If clients fetch frequently,
then they never even look at the bitmapped history, and all
works as usual. However, a client who has not fetched since
the last bitmap repack will have "have" tips in the
bitmapped history, but "want" newer objects.
The bitmaps themselves degrade gracefully in this
circumstance. We manually walk the more recent bits of
history, and then use bitmaps when we hit them.
But we would also like to perform delta compression between
the newer objects and the bitmapped objects (both to delta
against what we know the user already has, but also between
"new" and "old" objects that the user is fetching). The lack
of pathnames makes our delta heuristics much less effective.
This patch adds an optional cache of the 32-bit name_hash
values to the end of the bitmap file. If present, a reader
can use it to match bitmapped and non-bitmapped names during
delta compression.
Here are perf results for p5310:
Test origin/master HEAD^ HEAD
-------------------------------------------------------------------------------------------------
5310.2: repack to disk 36.81(37.82+1.43) 47.70(48.74+1.41) +29.6% 47.75(48.70+1.51) +29.7%
5310.3: simulated clone 30.78(29.70+2.14) 1.08(0.97+0.10) -96.5% 1.07(0.94+0.12) -96.5%
5310.4: simulated fetch 3.16(6.10+0.08) 3.54(10.65+0.06) +12.0% 1.70(3.07+0.06) -46.2%
5310.6: partial bitmap 36.76(43.19+1.81) 6.71(11.25+0.76) -81.7% 4.08(6.26+0.46) -88.9%
You can see that the time spent on an incremental fetch goes
down, as our delta heuristics are able to do their work.
And we save time on the partial bitmap clone for the same
reason.
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 commit extends more the functionality of `pack-objects` by allowing
it to write out a `.bitmap` index next to any written packs, together
with the `.idx` index that currently gets written.
If bitmap writing is enabled for a given repository (either by calling
`pack-objects` with the `--write-bitmap-index` flag or by having
`pack.writebitmaps` set to `true` in the config) and pack-objects is
writing a packfile that would normally be indexed (i.e. not piping to
stdout), we will attempt to write the corresponding bitmap index for the
packfile.
Bitmap index writing happens after the packfile and its index has been
successfully written to disk (`finish_tmp_packfile`). The process is
performed in several steps:
1. `bitmap_writer_set_checksum`: this call stores the partial
checksum for the packfile being written; the checksum will be
written in the resulting bitmap index to verify its integrity
2. `bitmap_writer_build_type_index`: this call uses the array of
`struct object_entry` that has just been sorted when writing out
the actual packfile index to disk to generate 4 type-index bitmaps
(one for each object type).
These bitmaps have their nth bit set if the given object is of
the bitmap's type. E.g. the nth bit of the Commits bitmap will be
1 if the nth object in the packfile index is a commit.
This is a very cheap operation because the bitmap writing code has
access to the metadata stored in the `struct object_entry` array,
and hence the real type for each object in the packfile.
3. `bitmap_writer_reuse_bitmaps`: if there exists an existing bitmap
index for one of the packfiles we're trying to repack, this call
will efficiently rebuild the existing bitmaps so they can be
reused on the new index. All the existing bitmaps will be stored
in a `reuse` hash table, and the commit selection phase will
prioritize these when selecting, as they can be written directly
to the new index without having to perform a revision walk to
fill the bitmap. This can greatly speed up the repack of a
repository that already has bitmaps.
4. `bitmap_writer_select_commits`: if bitmap writing is enabled for
a given `pack-objects` run, the sequence of commits generated
during the Counting Objects phase will be stored in an array.
We then use that array to build up the list of selected commits.
Writing a bitmap in the index for each object in the repository
would be cost-prohibitive, so we use a simple heuristic to pick
the commits that will be indexed with bitmaps.
The current heuristics are a simplified version of JGit's
original implementation. We select a higher density of commits
depending on their age: the 100 most recent commits are always
selected, after that we pick 1 commit of each 100, and the gap
increases as the commits grow older. On top of that, we make sure
that every single branch that has not been merged (all the tips
that would be required from a clone) gets their own bitmap, and
when selecting commits between a gap, we tend to prioritize the
commit with the most parents.
Do note that there is no right/wrong way to perform commit
selection; different selection algorithms will result in
different commits being selected, but there's no such thing as
"missing a commit". The bitmap walker algorithm implemented in
`prepare_bitmap_walk` is able to adapt to missing bitmaps by
performing manual walks that complete the bitmap: the ideal
selection algorithm, however, would select the commits that are
more likely to be used as roots for a walk in the future (e.g.
the tips of each branch, and so on) to ensure a bitmap for them
is always available.
5. `bitmap_writer_build`: this is the computationally expensive part
of bitmap generation. Based on the list of commits that were
selected in the previous step, we perform several incremental
walks to generate the bitmap for each commit.
The walks begin from the oldest commit, and are built up
incrementally for each branch. E.g. consider this dag where A, B,
C, D, E, F are the selected commits, and a, b, c, e are a chunk
of simplified history that will not receive bitmaps.
A---a---B--b--C--c--D
\
E--e--F
We start by building the bitmap for A, using A as the root for a
revision walk and marking all the objects that are reachable
until the walk is over. Once this bitmap is stored, we reuse the
bitmap walker to perform the walk for B, assuming that once we
reach A again, the walk will be terminated because A has already
been SEEN on the previous walk.
This process is repeated for C, and D, but when we try to
generate the bitmaps for E, we can reuse neither the current walk
nor the bitmap we have generated so far.
What we do now is resetting both the walk and clearing the
bitmap, and performing the walk from scratch using E as the
origin. This new walk, however, does not need to be completed.
Once we hit B, we can lookup the bitmap we have already stored
for that commit and OR it with the existing bitmap we've composed
so far, allowing us to limit the walk early.
After all the bitmaps have been generated, another iteration
through the list of commits is performed to find the best XOR
offsets for compression before writing them to disk. Because of
the incremental nature of these bitmaps, XORing one of them with
its predecesor results in a minimal "bitmap delta" most of the
time. We can write this delta to the on-disk bitmap index, and
then re-compose the original bitmaps by XORing them again when
loaded.
This is a phase very similar to pack-object's `find_delta` (using
bitmaps instead of objects, of course), except the heuristics
have been greatly simplified: we only check the 10 bitmaps before
any given one to find best compressing one. This gives good
results in practice, because there is locality in the ordering of
the objects (and therefore bitmaps) in the packfile.
6. `bitmap_writer_finish`: the last step in the process is
serializing to disk all the bitmap data that has been generated
in the two previous steps.
The bitmap is written to a tmp file and then moved atomically to
its final destination, using the same process as
`pack-write.c:write_idx_file`.
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>
In this patch, we use the bitmap API to perform the `Counting Objects`
phase in pack-objects, rather than a traditional walk through the object
graph. For a reasonably-packed large repo, the time to fetch and clone
is often dominated by the full-object revision walk during the Counting
Objects phase. Using bitmaps can reduce the CPU time required on the
server (and therefore start sending the actual pack data with less
delay).
For bitmaps to be used, the following must be true:
1. We must be packing to stdout (as a normal `pack-objects` from
`upload-pack` would do).
2. There must be a .bitmap index containing at least one of the
"have" objects that the client is asking for.
3. Bitmaps must be enabled (they are enabled by default, but can be
disabled by setting `pack.usebitmaps` to false, or by using
`--no-use-bitmap-index` on the command-line).
If any of these is not true, we fall back to doing a normal walk of the
object graph.
Here are some sample timings from a full pack of `torvalds/linux` (i.e.
something very similar to what would be generated for a clone of the
repository) that show the speedup produced by various
methods:
[existing graph traversal]
$ time git pack-objects --all --stdout --no-use-bitmap-index \
</dev/null >/dev/null
Counting objects: 3237103, done.
Compressing objects: 100% (508752/508752), done.
Total 3237103 (delta 2699584), reused 3237103 (delta 2699584)
real 0m44.111s
user 0m42.396s
sys 0m3.544s
[bitmaps only, without partial pack reuse; note that
pack reuse is automatic, so timing this required a
patch to disable it]
$ time git pack-objects --all --stdout </dev/null >/dev/null
Counting objects: 3237103, done.
Compressing objects: 100% (508752/508752), done.
Total 3237103 (delta 2699584), reused 3237103 (delta 2699584)
real 0m5.413s
user 0m5.604s
sys 0m1.804s
[bitmaps with pack reuse (what you get with this patch)]
$ time git pack-objects --all --stdout </dev/null >/dev/null
Reusing existing pack: 3237103, done.
Total 3237103 (delta 0), reused 0 (delta 0)
real 0m1.636s
user 0m1.460s
sys 0m0.172s
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>
The basic 8 steps to update .git/shallow does not fully apply here
because the user may choose to accept just a few refs (while fetch
always accepts all refs). The steps are modified a bit.
1-6. same as before. After calling assign_shallow_commits_to_refs at
step 6, each shallow commit has a bitmap that marks all refs that
require it.
7. mark all "ours" shallow commits that are reachable from any
refs. We will need to do the original step 7 on them later.
8. go over all shallow commit bitmaps, mark refs that require new
shallow commits.
9. setup a strict temporary shallow file to plug all the holes, even
if it may cut some of our history short. This file is used by all
hooks. The hooks could use --shallow-file=$GIT_DIR/shallow to
overcome this and reach everything in current repo.
10. go over the new refs one by one. For each ref, do the reachability
test if it needs a shallow commit on the list from step 7. Remove
it if it's reachable from our refs. Gather all required shallow
commits, run check_everything_connected() with the new ref, then
install them to .git/shallow.
This mode is disabled by default and can be turned on with
receive.shallowupdate
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The old behavior of "fetch --prune" was to prune whatever was being
fetched. In particular, "fetch --prune --tags" caused tags not only
to be fetched, but also to be pruned. This is inappropriate because
there is only one tags namespace that is shared among the local
repository and all remotes. Therefore, if the user defines a local
tag and then runs "git fetch --prune --tags", then the local tag is
deleted. Moreover, "--prune" and "--tags" can also be configured via
fetch.prune / remote.<name>.prune and remote.<name>.tagopt, making it
even less obvious that an invocation of "git fetch" could result in
tag lossage.
Since the command "git remote update" invokes "git fetch", it had the
same problem.
The command "git remote prune", on the other hand, disregarded the
setting of remote.<name>.tagopt, and so its behavior was inconsistent
with that of the other commands.
So the old behavior made it too easy to lose tags. To fix this
problem, change "fetch --prune" to prune references based only on
refspecs specified explicitly by the user, either on the command line
or via remote.<name>.fetch. Thus, tags are no longer made subject to
pruning by the --tags option or the remote.<name>.tagopt setting.
However, tags *are* still subject to pruning if they are fetched as
part of a refspec, and that is good. For example:
* On the command line,
git fetch --prune 'refs/tags/*:refs/tags/*'
causes tags, and only tags, to be fetched and pruned, and is
therefore a simple way for the user to get the equivalent of the old
behavior of "--prune --tag".
* For a remote that was configured with the "--mirror" option, the
configuration is set to include
[remote "name"]
fetch = +refs/*:refs/*
, which causes tags to be subject to pruning along with all other
references. This is the behavior that will typically be desired for
a mirror.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
