Commit Graph

9870 Commits

Author SHA1 Message Date
Jeff King
54590a0eda color: support "italic" attribute
We already support bold, underline, and similar attributes.
Let's add italic to the mix.  According to the Wikipedia
page on ANSI colors, this attribute is "not widely
supported", but it does seem to work on my xterm.

We don't have to bump the maximum color size because we were
already over-allocating it (but we do adjust the comment
appropriately).

Requested-by: Simon Courtois <scourtois@cubyx.fr>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-23 11:32:51 -07:00
Jeff King
5621068f3d color: allow "no-" for negating attributes
Using "no-bold" rather than "nobold" is easier to read and
more natural to type (to me, anyway, even though I was the
person who introduced "nobold" in the first place). It's
easy to allow both.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-23 11:32:51 -07:00
Jeff King
adb3356664 doc: refactor description of color format
This is a general cleanup of the description of colors in
git-config, mostly to address inaccuracies and confusion
that had grown over time:

  - you can have many attributes, not just one

  - the discussion flip-flopped between colors and
    attributes; now we discuss everything about colors, then
    everything about attributes

  - many concepts were lumped into the first paragraph,
    making it hard to read, and especially to find the
    actual lists of colors and attributes. I stopped short
    of breaking those out into their own lists, as it seemed
    like an excessive use of vertical screen real estate.

  - we introduced negated attributes, but then the next
    paragraph basically explains how each item starts off
    with no attributes. So why would one need negated
    attributes? We now explain.

  - minor typo, language, and typography fixes

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-23 11:32:51 -07:00
Jonathan Nieder
f79358279c doc: git-htmldocs.googlecode.com is no more
http://git-htmldocs.googlecode.com/git/git.html says

 There was no service found for the uri requested.

Link to the rendered documentation on Jekyll instead.

Reported-by: Andrea Stacchiotti <andreastacchiotti@gmail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-22 12:37:33 -07:00
Junio C Hamano
18a74a092b clone: do not let --depth imply --shallow-submodules
In v2.9.0, we prematurely flipped the default to force cloning
submodules shallowly, when the superproject is getting cloned
shallowly.  This is likely to fail when the upstream repositories
submodules are cloned from a repository that is not prepared to
serve histories that ends at a commit that is not at the tip of a
branch, and we know the world is not yet ready.

Use a safer default to clone the submodules fully, unless the user
tells us that she knows that the upstream repository of the
submodules are willing to cooperate with "--shallow-submodules"
option.

Noticed-by: Vadim Eisenberg <VADIME@il.ibm.com>
Helped-by: Jeff King <peff@peff.net>
Helped-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-20 11:35:28 -07:00
Junio C Hamano
ab7797dbe9 Start the post-2.9 cycle
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-20 11:06:49 -07:00
Junio C Hamano
8699b74ae1 Merge branch 'wd/userdiff-css'
Update the funcname definition to support css files.

* wd/userdiff-css:
  userdiff: add built-in pattern for CSS
2016-06-20 11:01:02 -07:00
Junio C Hamano
0196c75e14 Merge branch 'aq/upload-pack-use-parse-options'
"git upload-pack" command has been updated to use the parse-options
API.

* aq/upload-pack-use-parse-options:
  upload-pack.c: use parse-options API
2016-06-20 11:01:02 -07:00
Junio C Hamano
6d41eb685a Merge branch 'jg/dash-is-last-branch-in-worktree-add'
"git worktree add" learned that '-' can be used as a short-hand for
"@{-1}", the previous branch.

* jg/dash-is-last-branch-in-worktree-add:
  worktree: allow "-" short-hand for @{-1} in add command
2016-06-20 11:01:02 -07:00
Junio C Hamano
3807098cd6 Merge branch 'sb/submodule-recommend-shallowness'
An upstream project can make a recommendation to shallowly clone
some submodules in the .gitmodules file it ships.

* sb/submodule-recommend-shallowness:
  submodule update: learn `--[no-]recommend-shallow` option
  submodule-config: keep shallow recommendation around
2016-06-20 11:01:01 -07:00
Junio C Hamano
8d6a7e9a19 Merge branch 'ew/fast-import-unpack-limit'
"git fast-import" learned the same performance trick to avoid
creating too small a packfile as "git fetch" and "git push" have,
using *.unpackLimit configuration.

* ew/fast-import-unpack-limit:
  fast-import: invalidate pack_id references after loosening
  fast-import: implement unpack limit
2016-06-20 11:01:00 -07:00
Michael J Gruber
cc6ee97cb3 Documentation/technical: signed merge tag format
Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-17 12:10:48 -07:00
Michael J Gruber
eda2f11ee3 Documentation/technical: signed commit format
Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-17 12:10:30 -07:00
Michael J Gruber
5f1abfeb69 Documentation/technical: signed tag format
Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-17 11:40:58 -07:00
Michael J Gruber
76f9d8bac8 Documentation/technical: describe signature formats
We use different types of signature formats in different places.
Set up the infrastructure and overview to describe them systematically
in our technical documentation.

Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-17 11:39:05 -07:00
Dave Nicolson
bc91316781 Documentation: GPG capitalization
When "GPG" is used in a sentence it is now consistently capitalized.
When referring to the binary it is left as "gpg".

Signed-off-by: David Nicolson <david.nicolson@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-16 17:32:28 -07:00
Alfred Perlstein
19a7f24b6f git-svn: document the 'git svn propset' command
Add example usage to the git-svn documentation.

Reported-by: Joseph Pecoraro <pecoraro@apple.com>
Signed-off-by: Alfred Perlstein <alfred@freebsd.org>
Reviewed-by: Eric Wong <e@80x24.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-15 13:21:11 -07:00
Jeff King
e26a8c4721 repack: extend --keep-unreachable to loose objects
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>
2016-06-14 13:57:45 -07:00
Jeff King
905f27b86a repack: add --keep-unreachable option
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>
2016-06-14 13:57:42 -07:00
Jeff King
6a7bcb5471 repack: document --unpack-unreachable option
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>
2016-06-14 13:57:38 -07:00
Junio C Hamano
e1d09701a4 blame: dwim "blame --reverse OLD" as "blame --reverse OLD.."
Instead of always requiring both ends of a range, we could DWIM
"OLD", which could be a misspelt "OLD..", to be a range that ends at
the current commit.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-14 12:13:07 -07:00
Junio C Hamano
d993ce1ed2 blame: improve diagnosis for "--reverse NEW"
"git blame --reverse OLD..NEW -- PATH" tells us to start from the
contents in PATH at OLD and observe how each line is changed while
the history develops up to NEW, and report for each line the latest
commit up to which the line survives in the original form.

If you say "git blame --reverse NEW -- PATH" by mistake, we complain
about the missing OLD, but we phrased it as "No commit to dig down
to?"  In this case, however, we are digging up from OLD, so say so.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-14 12:12:15 -07:00
Jeff King
9e70233a17 fetch: document that pruning happens before fetching
This was changed in 10a6cc8 (fetch --prune: Run prune before
fetching, 2014-01-02), but it seems that nobody in that
discussion realized we were advertising the "after"
explicitly.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-14 10:56:27 -07:00
Nguyễn Thái Ngọc Duy
cccf74e2da fetch, upload-pack: --deepen=N extends shallow boundary by N commits
In git-fetch, --depth argument is always relative with the latest
remote refs. This makes it a bit difficult to cover this use case,
where the user wants to make the shallow history, say 3 levels
deeper. It would work if remote refs have not moved yet, but nobody
can guarantee that, especially when that use case is performed a
couple months after the last clone or "git fetch --depth". Also,
modifying shallow boundary using --depth does not work well with
clones created by --since or --not.

This patch fixes that. A new argument --deepen=<N> will add <N> more (*)
parent commits to the current history regardless of where remote refs
are.

Have/Want negotiation is still respected. So if remote refs move, the
server will send two chunks: one between "have" and "want" and another
to extend shallow history. In theory, the client could send no "want"s
in order to get the second chunk only. But the protocol does not allow
that. Either you send no want lines, which means ls-remote; or you
have to send at least one want line that carries deep-relative to the
server..

The main work was done by Dongcan Jiang. I fixed it up here and there.
And of course all the bugs belong to me.

(*) We could even support --deepen=<N> where <N> is negative. In that
case we can cut some history from the shallow clone. This operation
(and --depth=<shorter depth>) does not require interaction with remote
side (and more complicated to implement as a result).

Helped-by: Duy Nguyen <pclouds@gmail.com>
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Dongcan Jiang <dongcan.jiang@gmail.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-13 14:38:16 -07:00
Nguyễn Thái Ngọc Duy
859e5df916 clone: define shallow clone boundary with --shallow-exclude
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-13 14:38:16 -07:00
Nguyễn Thái Ngọc Duy
a45a260086 fetch: define shallow boundary with --shallow-exclude
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-13 14:38:16 -07:00
Nguyễn Thái Ngọc Duy
269a7a8316 upload-pack: support define shallow boundary by excluding revisions
This should allow the user to say "create a shallow clone of this branch
after version <some-tag>".

Short refs are accepted and expanded at the server side with expand_ref()
because we cannot expand (unknown) refs from the client side.

Like deepen-since, deepen-not cannot be used with deepen. But deepen-not
can be mixed with deepen-since. The result is exactly how you do the
command "git rev-list --since=... --not ref".

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-13 14:38:16 -07:00
Nguyễn Thái Ngọc Duy
994c2aaf31 clone: define shallow clone boundary based on time with --shallow-since
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-13 14:38:16 -07:00
Nguyễn Thái Ngọc Duy
508ea88226 fetch: define shallow boundary with --shallow-since
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-13 14:38:16 -07:00
Nguyễn Thái Ngọc Duy
569e554be9 upload-pack: add deepen-since to cut shallow repos based on time
This should allow the user to say "create a shallow clone containing the
work from last year" (once the client side is fixed up, of course).

In theory deepen-since and deepen (aka --depth) can be used together to
draw the shallow boundary (whether it's intersection or union is up to
discussion, but if rev-list is used, it's likely intersection). However,
because deepen goes with a custom commit walker, we can't mix the two
yet.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-13 14:38:16 -07:00
Junio C Hamano
05219a1276 Git 2.9
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-13 10:42:13 -07:00
Junio C Hamano
a28705da92 Hopefully the final last-minute update before 2.9 final
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-10 15:30:19 -07:00
Junio C Hamano
e5f7675544 Merge branch 'jk/diff-compact-heuristic'
It turns out that the earlier effort to update the heuristics may
want to use a bit more time to mature.  Turn it off by default.

* jk/diff-compact-heuristic:
  diff: disable compaction heuristic for now
2016-06-10 15:26:06 -07:00
Junio C Hamano
5580b271af diff: disable compaction heuristic for now
http://lkml.kernel.org/g/20160610075043.GA13411@sigill.intra.peff.net
reports that a change to add a new "function" with common ending
with the existing one at the end of the file is shown like this:

    def foo
      do_foo_stuff()

   +  common_ending()
   +end
   +
   +def bar
   +  do_bar_stuff()
   +
      common_ending()
    end

when the new heuristic is in use.  In reality, the change is to add
the blank line before "def bar" and everything below, which is what
the code without the new heuristic shows.

Disable the heuristics by default, and resurrect the documentation
for the option and the configuration variables, while clearly
marking the feature as still experimental.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-10 13:45:23 -07:00
Tom Russello
ae9f6311e9 doc: change configuration variables format
This change configuration variables that where in italic style
to monospace font according to the guideline. It was obtained with

	grep '[[:alpha:]]*\.[[:alpha:]]*::$' config.txt | \
	sed -e 's/::$//' -e 's/\./\\\\./' | \
	xargs -iP perl -pi -e "s/\'P\'/\`P\`/g" ./*.txt

Signed-off-by: Tom Russello <tom.russello@grenoble-inp.org>
Signed-off-by: Erwan Mathoniere <erwan.mathoniere@grenoble-inp.org>
Signed-off-by: Samuel Groot <samuel.groot@grenoble-inp.org>
Signed-off-by: Matthieu Moy <matthieu.moy@grenoble-inp.fr>
Reviewed-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-08 12:04:55 -07:00
Tom Russello
47d81b5c7a doc: more consistency in environment variables format
Wrap with backticks (monospaced font) unwrapped or single-quotes wrapped
(italic type) environment variables which are followed by the word
"environment". It was obtained with:

perl -pi -e "s/\'?(\\\$?[0-9A-Z\_]+)\'?(?= environment ?)/\`\1\`/g" *.txt

One of the main purposes is to stick to the CodingGuidelines as possible so
that people writting new documentation by mimicking the existing are more likely
to have it right (even if they didn't read the CodingGuidelines).

Signed-off-by: Tom Russello <tom.russello@grenoble-inp.org>
Signed-off-by: Erwan Mathoniere <erwan.mathoniere@grenoble-inp.org>
Signed-off-by: Samuel Groot <samuel.groot@grenoble-inp.org>
Signed-off-by: Matthieu Moy <matthieu.moy@grenoble-inp.fr>
Reviewed-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-08 12:04:37 -07:00
Tom Russello
eee7f4a233 doc: change environment variables format
This change GIT_* variables that where in italic style to monospaced font
according to the guideline. It was obtained with

	perl -pi -e "s/\'(GIT_.*?)\'/\`\1\`/g" *.txt

One of the main purposes is to stick to the CodingGuidelines as possible so
that people writting new documentation by mimicking the existing are more likely
to have it right (even if they didn't read the CodingGuidelines).

Signed-off-by: Tom Russello <tom.russello@grenoble-inp.org>
Signed-off-by: Erwan Mathoniere <erwan.mathoniere@grenoble-inp.org>
Signed-off-by: Samuel Groot <samuel.groot@grenoble-inp.org>
Signed-off-by: Matthieu Moy <matthieu.moy@grenoble-inp.fr>
Reviewed-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-08 12:04:37 -07:00
Tom Russello
41f5b21f84 doc: clearer rule about formatting literals
Make the guideline text that we want for our documentation clearer.

Signed-off-by: Tom Russello <tom.russello@grenoble-inp.org>
Signed-off-by: Erwan Mathoniere <erwan.mathoniere@grenoble-inp.org>
Signed-off-by: Samuel Groot <samuel.groot@grenoble-inp.org>
Signed-off-by: Matthieu Moy <matthieu.moy@grenoble-inp.fr>
Reviewed-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-08 12:04:37 -07:00
Junio C Hamano
49fa3dc761 Git 2.9-rc2
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-06 14:34:52 -07:00
Junio C Hamano
c42b5d8e69 Sync with 2.8.4
* maint:
  Git 2.8.4
2016-06-06 14:30:49 -07:00
Junio C Hamano
0b65a8dbdb Git 2.8.4
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-06 14:29:32 -07:00
Junio C Hamano
7dcbf891d9 Merge branch 'tb/core-eol-fix' into maint
A couple of bugs around core.autocrlf have been fixed.

* tb/core-eol-fix:
  convert.c: ident + core.autocrlf didn't work
  t0027: test cases for combined attributes
  convert: allow core.autocrlf=input and core.eol=crlf
  t0027: make commit_chk_wrnNNO() reliable
2016-06-06 14:27:36 -07:00
Eric Wong
d9925d1a71 am: support --patch-format=mboxrd
Combined with "git format-patch --pretty=mboxrd", this should
allow us to round-trip commit messages with embedded mbox
"From " lines without corruption.

Signed-off-by: Eric Wong <e@80x24.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-06 11:40:15 -07:00
Eric Wong
c88098d7f1 mailsplit: support unescaping mboxrd messages
This will allow us to parse the output of --pretty=mboxrd
and the output of other mboxrd generators.

Signed-off-by: Eric Wong <e@80x24.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-06 11:14:43 -07:00
William Duclot
0719f3eecd userdiff: add built-in pattern for CSS
CSS is widely used, motivating it being included as a built-in pattern.

It must be noted that the word_regex for CSS (i.e. the regex defining
what is a word in the language) does not consider '.' and '#' characters
(in CSS selectors) to be part of the word. This behavior is documented
by the test t/t4018/css-rule.
The logic behind this behavior is the following: identifiers in CSS
selectors are identifiers in a HTML/XML document. Therefore, the '.'/'#'
character are not part of the identifier, but an indicator of the nature
of the identifier in HTML/XML (class or id). Diffing ".class1" and
".class2" must show that the class name is changed, but we still are
selecting a class.

Logic behind the "pattern" regex is:
    1. reject lines ending with a colon/semicolon (properties)
    2. if a line begins with a name in column 1, pick the whole line

Credits to Johannes Sixt (j6t@kdbg.org) for the pattern regex and most
of the tests.

Signed-off-by: William Duclot <william.duclot@ensimag.grenoble-inp.fr>
Signed-off-by: Matthieu Moy <matthieu.moy@grenoble-inp.fr>
Reviewed-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-03 14:45:56 -07:00
Junio C Hamano
6326f19925 Almost ready for 2.9-rc2
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-03 14:38:35 -07:00
Junio C Hamano
a8398b952d Merge branch 'em/man-bold-literal'
The manpage output of our documentation did not render well in
terminal; typeset literals in bold by default to make them stand
out more.

* em/man-bold-literal:
  Documentation: bold literals in man
2016-06-03 14:38:02 -07:00
Junio C Hamano
1df2d6e8df Merge branch 'pa/cherry-pick-doc-typo'
"git cherry-pick --help" had three instances of word "behavior",
one of which was spelled "behaviour", which is updated to match the
other two.

* pa/cherry-pick-doc-typo:
  git-cherry-pick.txt: correct a small typo
2016-06-03 14:38:02 -07:00
Junio C Hamano
160ef79cec Merge branch 'mr/send-email-doc-gmail-2fa'
Typofix.

* mr/send-email-doc-gmail-2fa:
  Documentation/git-send-email: fix typo in gmail 2FA section
2016-06-03 14:38:01 -07:00
Jeff King
20b20a22f8 upload-pack: provide a hook for running pack-objects
When upload-pack serves a client request, it turns to
pack-objects to do the heavy lifting of creating a
packfile. There's no easy way to intercept the call to
pack-objects, but there are a few good reasons to want to do
so:

  1. If you're debugging a client or server issue with
     fetching, you may want to store a copy of the generated
     packfile.

  2. If you're gathering data from real-world fetches for
     performance analysis or debugging, storing a copy of
     the arguments and stdin lets you replay the pack
     generation at your leisure.

  3. You may want to insert a caching layer around
     pack-objects; it is the most CPU- and memory-intensive
     part of serving a fetch, and its output is a pure
     function[1] of its input, making it an ideal place to
     consolidate identical requests.

This patch adds a simple "hook" interface to intercept calls
to pack-objects. The new test demonstrates how it can be
used for debugging (using it for caching is a
straightforward extension; the tricky part is writing the
actual caching layer).

This hook is unlike the normal hook scripts found in the
"hooks/" directory of a repository. Because we promise that
upload-pack is safe to run in an untrusted repository, we
cannot execute arbitrary code or commands found in the
repository (neither in hooks/, nor in the config). So
instead, this hook is triggered from a config variable that
is explicitly ignored in the per-repo config.

The config variable holds the actual shell command to run as
the hook.  Another approach would be to simply treat it as a
boolean: "should I respect the upload-pack hooks in this
repo?", and then run the script from "hooks/" as we usually
do. However, that isn't as flexible; there's no way to run a
hook approved by the site administrator (e.g., in
"/etc/gitconfig") on a repository whose contents are not
trusted. The approach taken by this patch is more
fine-grained, if a little less conventional for git hooks
(it does behave similar to other configured commands like
diff.external, etc).

[1] Pack-objects isn't _actually_ a pure function. Its
    output depends on the exact packing of the object
    database, and if multi-threading is used for delta
    compression, can even differ racily. But for the
    purposes of caching, that's OK; of the many possible
    outputs for a given input, it is sufficient only that we
    output one of them.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-02 15:22:24 -07:00