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Author SHA1 Message Date
Junio C Hamano
17501ba1cd Merge branch 'nd/fbsd-lazy-mtime'
FreeBSD can lie when asked mtime of a directory, which made the
untracked cache code to fall back to a slow-path, which in turn
caused tests in t7063 to fail because it wanted to verify the
behaviour of the fast-path.

* nd/fbsd-lazy-mtime:
  t7063: work around FreeBSD's lazy mtime update feature
2016-08-08 14:48:42 -07:00
Junio C Hamano
3a3338d373 Merge branch 'nd/log-decorate-color-head-arrow'
An entry "git log --decorate" for the tip of the current branch is
shown as "HEAD -> name" (where "name" is the name of the branch);
paint the arrow in the same color as "HEAD", not in the color for
commits.

* nd/log-decorate-color-head-arrow:
  log: decorate HEAD -> branch with the same color for arrow and HEAD
2016-08-08 14:48:42 -07:00
Junio C Hamano
940622bc8b Merge branch 'rs/use-strbuf-addstr'
* rs/use-strbuf-addstr:
  use strbuf_addstr() instead of strbuf_addf() with "%s"
  use strbuf_addstr() for adding constant strings to a strbuf
2016-08-08 14:48:41 -07:00
Junio C Hamano
68e80da479 Merge branch 'rs/st-mult'
Micro optimization of st_mult() facility used to check the integer
overflow coming from multiplication to compute size of memory
allocation.

* rs/st-mult:
  pass constants as first argument to st_mult()
2016-08-08 14:48:41 -07:00
Junio C Hamano
09ee6444f2 Merge branch 'ib/t3700-add-chmod-x-updates'
The t3700 test about "add --chmod=-x" have been made a bit more
robust and generally cleaned up.

* ib/t3700-add-chmod-x-updates:
  t3700: add a test_mode_in_index helper function
  t3700: merge two tests into one
  t3700: remove unwanted leftover files before running new tests
2016-08-08 14:48:40 -07:00
Junio C Hamano
ae674b0130 Merge branch 'ab/gitweb-link-html-escape'
The characters in the label shown for tags/refs for commits in
"gitweb" output are now properly escaped for proper HTML output.

* ab/gitweb-link-html-escape:
  gitweb: escape link body in format_ref_marker
2016-08-08 14:48:40 -07:00
Junio C Hamano
78849622ec Merge branch 'jk/pack-objects-optim'
"git pack-objects" has a few options that tell it not to pack
objects found in certain packfiles, which require it to scan .idx
files of all available packs.  The codepaths involved in these
operations have been optimized for a common case of not having any
non-local pack and/or any .kept pack.

* jk/pack-objects-optim:
  pack-objects: compute local/ignore_pack_keep early
  pack-objects: break out of want_object loop early
  find_pack_entry: replace last_found_pack with MRU cache
  add generic most-recently-used list
  sha1_file: drop free_pack_by_name
  t/perf: add tests for many-pack scenarios
2016-08-08 14:48:39 -07:00
Junio C Hamano
7647537e3e Merge branch 'jk/difftool-in-subdir'
"git difftool <paths>..." started in a subdirectory failed to
interpret the paths relative to that directory, which has been
fixed.

* jk/difftool-in-subdir:
  difftool: use Git::* functions instead of passing around state
  difftool: avoid $GIT_DIR and $GIT_WORK_TREE
  difftool: fix argument handling in subdirs
2016-08-08 14:48:39 -07:00
Junio C Hamano
768ededa9c Merge branch 'va/i18n'
More i18n marking.

* va/i18n:
  i18n: config: unfold error messages marked for translation
  i18n: notes: mark comment for translation
2016-08-08 14:48:38 -07:00
Junio C Hamano
6b9114c649 Merge branch 'js/rebase-i-progress-tidy'
Regression fix for an i18n topic already in 'master'.

* js/rebase-i-progress-tidy:
  rebase-interactive: trim leading whitespace from progress count
2016-08-08 14:48:38 -07:00
Junio C Hamano
0d3279962a Merge branch 'jk/reflog-date'
The reflog output format is documented better, and a new format
--date=unix to report the seconds-since-epoch (without timezone)
has been added.

* jk/reflog-date:
  date: clarify --date=raw description
  date: add "unix" format
  date: document and test "raw-local" mode
  doc/pretty-formats: explain shortening of %gd
  doc/pretty-formats: describe index/time formats for %gd
  doc/rev-list-options: explain "-g" output formats
  doc/rev-list-options: clarify "commit@{Nth}" for "-g" option
2016-08-08 14:48:37 -07:00
Junio C Hamano
4c30ad8cc6 Merge branch 'cp/completion-clone-recurse-submodules'
* cp/completion-clone-recurse-submodules:
  completion: add option '--recurse-submodules' to 'git clone'
2016-08-08 14:48:37 -07:00
Junio C Hamano
4d7f59aece Merge branch 'jk/t4205-cleanup'
Test modernization.

* jk/t4205-cleanup:
  t4205: indent here documents
  t4205: drop top-level &&-chaining
2016-08-08 14:48:36 -07:00
Junio C Hamano
f2be3b73e0 Merge branch 'da/subtree-modernize'
Style fixes for "git subtree" (in contrib/).

* da/subtree-modernize:
  subtree: adjust function definitions to match CodingGuidelines
  subtree: adjust style to match CodingGuidelines
2016-08-08 14:48:35 -07:00
Junio C Hamano
abbf7bd495 Merge branch 'nd/fetch-ref-summary'
Hotfix of a test in a topic that has already been merged to 'master'.

* nd/fetch-ref-summary:
  t5510: skip tests under GETTEXT_POISON build
2016-08-08 14:48:35 -07:00
Junio C Hamano
612c3dfb06 Merge branch 'ew/git-svn-http-tests'
Tests for "git svn" have been taught to reuse the lib-httpd test
infrastructure when testing the subversion integration that
interacts with subversion repositories served over the http://
protocol.

* ew/git-svn-http-tests:
  git svn: migrate tests to use lib-httpd
  t/t91*: do not say how to avoid the tests
2016-08-08 14:48:34 -07:00
Junio C Hamano
3819fb9ab4 Merge branch 'js/t4130-rename-without-ino'
Windows port was failing some tests in t4130, due to the lack of
inum in the returned values by its lstat(2) emulation.

* js/t4130-rename-without-ino:
  t4130: work around Windows limitation
2016-08-08 14:48:33 -07:00
René Scharfe
bc57b9c0cc use strbuf_addstr() instead of strbuf_addf() with "%s"
Call strbuf_addstr() for adding a simple string to a strbuf instead of
using the heavier strbuf_addf().  This is shorter and documents the
intent more clearly.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-05 15:09:25 -07:00
Junio C Hamano
c6b0597e9a Tenth batch for 2.10
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-04 14:40:34 -07:00
Junio C Hamano
b422d99658 Merge branch 'jc/grep-commandline-vs-configuration'
"git -c grep.patternType=extended log --basic-regexp" misbehaved
because the internal API to access the grep machinery was not
designed well.

* jc/grep-commandline-vs-configuration:
  grep: further simplify setting the pattern type
2016-08-04 14:39:18 -07:00
Junio C Hamano
1e9a4856fb Merge branch 'sb/submodule-clone-retry'
An earlier tweak to make "submodule update" retry a failing clone
of submodules was buggy and caused segfault, which has been fixed.

* sb/submodule-clone-retry:
  submodule-helper: fix indexing in clone retry error reporting path
  git-submodule: forward exit code of git-submodule--helper more faithfully
2016-08-04 14:39:17 -07:00
Junio C Hamano
10881f076e Merge branch 'sb/pack-protocol-doc-nak'
A doc update.

* sb/pack-protocol-doc-nak:
  Documentation: pack-protocol correct NAK response
2016-08-04 14:39:16 -07:00
Nguyễn Thái Ngọc Duy
6b7728db81 t7063: work around FreeBSD's lazy mtime update feature
Let's start with the commit message of [1] from freebsd.git [2]

    Sync timestamp changes for inodes of special files to disk as late
    as possible (when the inode is reclaimed).  Temporarily only do
    this if option UFS_LAZYMOD configured and softupdates aren't
    enabled.  UFS_LAZYMOD is intentionally left out of
    /sys/conf/options.

    This is mainly to avoid almost useless disk i/o on battery powered
    machines.  It's silly to write to disk (on the next sync or when
    the inode becomes inactive) just because someone hit a key or
    something wrote to the screen or /dev/null.

    PR:             5577 [3]

The short version of that, in the context of t7063, is that when a
directory is updated, its mtime may be updated later, not
immediately. This can be shown with a simple command sequence

    date; sleep 1; touch abc; rm abc; sleep 10; ls -lTd .

One would expect that the date shown in `ls` would be one second from
`date`, but it's 10 seconds later. If we put another `ls -lTd .` in
front of `sleep 10`, then the date of the last `ls` comes as
expected. The first `ls` somehow forces mtime to be updated.

t7063 is really sensitive to directory mtime. When mtime is too "new",
git code suspects racy timestamps and will not trigger the shortcut in
untracked cache, in t7063.24 and eventually be detected in t7063.27

We have two options thanks to this special FreeBSD feature:

1) Stop supporting untracked cache on FreeBSD. Skip t7063 entirely
   when running on FreeBSD

2) Work around this problem (using the same 'ls' trick) and continue
   to support untracked cache on FreeBSD

I initially wanted to go with 1) because I didn't know the exact
nature of this feature and feared that it would make untracked cache
work unreliably, using the cached version when it should not.

Since the behavior of this thing is clearer now. The picture is not
that bad. If this indeed happens often, untracked cache would assume
racy condition more often and _fall back_ to non-untracked cache code
paths. Which means it may be less effective, but it will not show
wrong things.

This patch goes with option 2.

PS. For those who want to look further in FreeBSD source code, this
flag is now called IN_LAZYMOD. I can see it's effective in ext2 and
ufs. zfs is not affected.

[1] 660e6408e6df99a20dacb070c5e7f9739efdf96d
[2] git://github.com/freebsd/freebsd.git
[3] https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=5577

Reported-by: Eric Wong <e@80x24.org>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-04 09:51:42 -07:00
Junio C Hamano
80460f513e Ninth batch of topics for 2.10
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-03 15:13:16 -07:00
Junio C Hamano
767da54bf8 Merge branch 'jk/diff-do-not-reuse-wtf-needs-cleaning'
There is an optimization used in "git diff $treeA $treeB" to borrow
an already checked-out copy in the working tree when it is known to
be the same as the blob being compared, expecting that open/mmap of
such a file is faster than reading it from the object store, which
involves inflating and applying delta.  This however kicked in even
when the checked-out copy needs to go through the convert-to-git
conversion (including the clean filter), which defeats the whole
point of the optimization.  The optimization has been disabled when
the conversion is necessary.

* jk/diff-do-not-reuse-wtf-needs-cleaning:
  diff: do not reuse worktree files that need "clean" conversion
2016-08-03 15:10:29 -07:00
Junio C Hamano
f4fa8a9b18 Merge branch 'rs/submodule-config-code-cleanup'
Code cleanup.

* rs/submodule-config-code-cleanup:
  submodule-config: fix test binary crashing when no arguments given
  submodule-config: combine early return code into one goto
  submodule-config: passing name reference for .gitmodule blobs
  submodule-config: use explicit empty string instead of strbuf in config_from()
2016-08-03 15:10:28 -07:00
Junio C Hamano
a58a8e3f71 Merge branch 'jk/push-progress'
"git push" and "git clone" learned to give better progress meters
to the end user who is waiting on the terminal.

* jk/push-progress:
  receive-pack: send keepalives during quiet periods
  receive-pack: turn on connectivity progress
  receive-pack: relay connectivity errors to sideband
  receive-pack: turn on index-pack resolving progress
  index-pack: add flag for showing delta-resolution progress
  clone: use a real progress meter for connectivity check
  check_connected: add progress flag
  check_connected: relay errors to alternate descriptor
  check_everything_connected: use a struct with named options
  check_everything_connected: convert to argv_array
  rev-list: add optional progress reporting
  check_everything_connected: always pass --quiet to rev-list
2016-08-03 15:10:28 -07:00
Junio C Hamano
67b3a5d4c0 Merge branch 'jt/fetch-large-handshake-window-on-http'
"git fetch" exchanges batched have/ack messages between the sender
and the receiver, initially doubling every time and then falling
back to enlarge the window size linearly.  The "smart http"
transport, being an half-duplex protocol, outgrows the preset limit
too quickly and becomes inefficient when interacting with a large
repository.  The internal mechanism learned to grow the window size
more aggressively when working with the "smart http" transport.

* jt/fetch-large-handshake-window-on-http:
  fetch-pack: grow stateless RPC windows exponentially
2016-08-03 15:10:27 -07:00
Junio C Hamano
5569c01be8 Merge branch 'jk/git-jump'
"git jump" script (in contrib/) has been updated a bit.

* jk/git-jump:
  contrib/git-jump: fix typo in README
  contrib/git-jump: add whitespace-checking mode
  contrib/git-jump: fix greedy regex when matching hunks
2016-08-03 15:10:27 -07:00
Junio C Hamano
5a2f4d3eef Merge branch 'mm/status-suggest-merge-abort'
"git status" learned to suggest "merge --abort" during a conflicted
merge, just like it already suggests "rebase --abort" during a
conflicted rebase.

* mm/status-suggest-merge-abort:
  status: suggest 'git merge --abort' when appropriate
2016-08-03 15:10:26 -07:00
Junio C Hamano
d083d420b7 Merge branch 'jk/parse-options-concat'
Users of the parse_options_concat() API function need to allocate
extra slots in advance and fill them with OPT_END() when they want
to decide the set of supported options dynamically, which makes the
code error-prone and hard to read.  This has been corrected by tweaking
the API to allocate and return a new copy of "struct option" array.

* jk/parse-options-concat:
  parse_options: allocate a new array when concatenating
2016-08-03 15:10:25 -07:00
Junio C Hamano
cf27c7996e Merge branch 'sb/push-options'
"git push" learned to accept and pass extra options to the
receiving end so that hooks can read and react to them.

* sb/push-options:
  add a test for push options
  push: accept push options
  receive-pack: implement advertising and receiving push options
  push options: {pre,post}-receive hook learns about push options
2016-08-03 15:10:24 -07:00
Junio C Hamano
4067a45438 Merge branch 'ew/http-walker'
Dumb http transport on the client side has been optimized.

* ew/http-walker:
  list: avoid incompatibility with *BSD sys/queue.h
  http-walker: reduce O(n) ops with doubly-linked list
  http: avoid disconnecting on 404s for loose objects
  http-walker: remove unused parameter from fetch_object
2016-08-03 15:10:24 -07:00
Junio C Hamano
6395499a68 Merge branch 'pm/build-persistent-https-with-recent-go'
The build procedure for "git persistent-https" helper (in contrib/)
has been updated so that it can be built with more recent versions
of Go.

* pm/build-persistent-https-with-recent-go:
  contrib/persistent-https: use Git version for build label
  contrib/persistent-https: update ldflags syntax for Go 1.7+
2016-08-03 15:10:23 -07:00
Junio C Hamano
c0728edfb6 Merge branch 'da/subtree-2.9-regression'
"git merge" in Git v2.9 was taught to forbid merging an unrelated
lines of history by default, but that is exactly the kind of thing
the "--rejoin" mode of "git subtree" (in contrib/) wants to do.
"git subtree" has been taught to use the "--allow-unrelated-histories"
option to override the default.

* da/subtree-2.9-regression:
  subtree: fix "git subtree split --rejoin"
  t7900-subtree.sh: fix quoting and broken && chains
2016-08-03 15:10:22 -07:00
Junio C Hamano
a35031240b Merge branch 'os/no-verify-skips-commit-msg-too'
"git commit --help" said "--no-verify" is only about skipping the
pre-commit hook, and failed to say that it also skipped the
commit-msg hook.

* os/no-verify-skips-commit-msg-too:
  commit: describe that --no-verify skips the commit-msg hook in the help text
2016-08-03 15:10:22 -07:00
Johannes Sixt
54956df9bc t4130: work around Windows limitation
On Windows, it is already pretty expensive to try to recreate the stat()
data that Git assumes is cheap to obtain. To make things halfway decent
in performance, we even have to skip emulating the inode and to
determine the number of hard links.

This is not a huge problem, usually, as either the size or the mtime or
the ctime are tell-tale enough to say when a file has changed, and even
if not, those changes are typically made after the index file was
written, triggering a rehashing of the files' contents.

The t4130-apply-criss-cross-rename test case, however, requires the
inode to determine that files of equal size were swapped, as renaming
files does not update their mtime. Every once in a while, t4130 fails
on Windows because of this missing piece.

Equal file sizes are not crucial for the test cases, however. Hence,
generate files with different sizes so that there is some property that
the swapped files can be discovered reliably even on Windows.

Helped-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-03 08:47:38 -07:00
Ingo Brückl
766cdc4147 t3700: add a test_mode_in_index helper function
The case statement to check the file mode of a staged file appears
a number of times.

Simplify the test by utilizing a test_mode_in_index helper function.

Signed-off-by: Ingo Brückl <ib@wupperonline.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-01 14:25:30 -07:00
Ingo Brückl
b38ab197c2 t3700: merge two tests into one
Depending on the underlying platform a chmod may be a noop. Although it
wouldn't harm the result of the '--chmod=-x' test, there is a more
robust way to make sure the --chmod option works both ways.

Merge the two separate tests for the --chmod option into one, checking
both permissions on the same file.

Signed-off-by: Ingo Brückl <ib@wupperonline.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-01 14:20:53 -07:00
Ingo Brückl
c0fa44d8f1 t3700: remove unwanted leftover files before running new tests
When an earlier test that has prerequisite is skipped, files
used by later tests may be left in the working tree in an
unexpected state.  For example, a test runs this sequence:

        echo foo >xfoo1 && chmod 755 xfoo1

to create an executable file xfoo1, expecting that xfoo1
does not exist before it runs in the test sequence.
However, the absence of this file depends on "git reset
--hard" done in an earlier test, that is skipped when SANITY
prerequisite is not met, and worse yet, xfoo1 originally is
created as a symbolic link, which means the chmod does not
affect the modes of xfoo1 as this test expects.

Fix this by starting the test with "rm -f xfoo1" to make
sure the file is created from scratch, and do the same to
other similar tests.

Signed-off-by: Ingo Brückl <ib@wupperonline.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-01 14:20:51 -07:00
René Scharfe
50492f7b38 pass constants as first argument to st_mult()
The result of st_mult() is the same no matter the order of its
arguments.  It invokes the macro unsigned_mult_overflows(), which
divides the second parameter by the first one.  Pass constants
first to allow that division to be done already at compile time.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-01 14:01:03 -07:00
René Scharfe
02962d3684 use strbuf_addstr() for adding constant strings to a strbuf
Replace uses of strbuf_addf() for adding strings with more lightweight
strbuf_addstr() calls.

In http-push.c it becomes easier to see what's going on without having
to verfiy that the definition of PROPFIND_ALL_REQUEST doesn't contain
any format specifiers.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-01 13:42:10 -07:00
Andreas Brauchli
77947bbe24 gitweb: escape link body in format_ref_marker
Fix a case where an html link can be generated from unescaped input
resulting in invalid strict xhtml or potentially injected code.

An overview of a repo with a tag "1.0.0&0.0.1" would previously result
in an unescaped ampersand in the link body.

Signed-off-by: Andreas Brauchli <a.brauchli@elementarea.net>
Acked-by: Jakub Narębski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-01 12:55:40 -07:00
Jeff King
56dfeb6263 pack-objects: compute local/ignore_pack_keep early
In want_object_in_pack(), we can exit early from our loop if
neither "local" nor "ignore_pack_keep" are set. If they are,
however, we must examine each pack to see if it has the
object and is non-local or has a ".keep".

It's quite common for there to be no non-local or .keep
packs at all, in which case we know ahead of time that
looking further will be pointless. We can pre-compute this
by simply iterating over the list of packs ahead of time,
and dropping the flags if there are no packs that could
match.

Another similar strategy would be to modify the loop in
want_object_in_pack() to notice that we have already found
the object once, and that we are looping only to check for
"local" and "keep" attributes. If a pack has neither of
those, we can skip the call to find_pack_entry_one(), which
is the expensive part of the loop.

This has two advantages:

  - it isn't all-or-nothing; we still get some improvement
    when there's a small number of kept or non-local packs,
    and a large number of non-kept local packs

  - it eliminates any possible race where we add new
    non-local or kept packs after our initial scan. In
    practice, I don't think this race matters; we already
    cache the packed_git information, so somebody who adds a
    new pack or .keep file after we've started will not be
    noticed at all, unless we happen to need to call
    reprepare_packed_git() because a lookup fails.

    In other words, we're already racy, and the race is not
    a big deal (losing the race means we might include an
    object in the pack that would not otherwise be, which is
    an acceptable outcome).

However, it also has a disadvantage: we still loop over the
rest of the packs for each object to check their flags. This
is much less expensive than doing the object lookup, but
still not free. So if we wanted to implement that strategy
to cover the non-all-or-nothing cases, we could do so in
addition to this one (so you get the most speedup in the
all-or-nothing case, and the best we can do in the other
cases). But given that the all-or-nothing case is likely the
most common, it is probably not worth the trouble, and we
can revisit this later if evidence points otherwise.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-29 11:05:08 -07:00
Jeff King
cd37996795 pack-objects: break out of want_object loop early
When pack-objects collects the list of objects to pack
(either from stdin, or via its internal rev-list), it
filters each one through want_object_in_pack().

This function loops through each existing packfile, looking
for the object. When we find it, we mark the pack/offset
combo for later use. However, we can't just return "yes, we
want it" at that point. If --honor-pack-keep is in effect,
we must keep looking to find it in _all_ packs, to make sure
none of them has a .keep. Likewise, if --local is in effect,
we must make sure it is not present in any non-local pack.

As a result, the sum effort of these calls is effectively
O(nr_objects * nr_packs). In an ordinary repository, we have
only a handful of packs, and this doesn't make a big
difference. But in pathological cases, it can slow the
counting phase to a crawl.

This patch notices the case that we have neither "--local"
nor "--honor-pack-keep" in effect and breaks out of the loop
early, after finding the first instance. Note that our worst
case is still "objects * packs" (i.e., we might find each
object in the last pack we look in), but in practice we will
often break out early. On an "average" repo, my git.git with
8 packs, this shows a modest 2% (a few dozen milliseconds)
improvement in the counting-objects phase of "git
pack-objects --all <foo" (hackily instrumented by sticking
exit(0) right after list_objects).

But in a much more pathological case, it makes a bigger
difference. I ran the same command on a real-world example
with ~9 million objects across 1300 packs. The counting time
dropped from 413s to 45s, an improvement of about 89%.

Note that this patch won't do anything by itself for a
normal "git gc", as it uses both --honor-pack-keep and
--local.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-29 11:05:07 -07:00
Jeff King
a73cdd21c4 find_pack_entry: replace last_found_pack with MRU cache
Each pack has an index for looking up entries in O(log n)
time, but if we have multiple packs, we have to scan through
them linearly. This can produce a measurable overhead for
some operations.

We dealt with this long ago in f7c22cc (always start looking
up objects in the last used pack first, 2007-05-30), which
keeps what is essentially a 1-element most-recently-used
cache. In theory, we should be able to do better by keeping
a similar but longer cache, that is the same length as the
pack-list itself.

Since we now have a convenient generic MRU structure, we can
plug it in and measure. Here are the numbers for running
p5303 against linux.git:

Test                      HEAD^                HEAD
------------------------------------------------------------------------
5303.3: rev-list (1)      31.56(31.28+0.27)    31.30(31.08+0.20) -0.8%
5303.4: repack (1)        40.62(39.35+2.36)    40.60(39.27+2.44) -0.0%
5303.6: rev-list (50)     31.31(31.06+0.23)    31.23(31.00+0.22) -0.3%
5303.7: repack (50)       58.65(69.12+1.94)    58.27(68.64+2.05) -0.6%
5303.9: rev-list (1000)   38.74(38.40+0.33)    31.87(31.62+0.24) -17.7%
5303.10: repack (1000)    367.20(441.80+4.62)  342.00(414.04+3.72) -6.9%

The main numbers of interest here are the rev-list ones
(since that is exercising the normal object lookup code
path).  The single-pack case shouldn't improve at all; the
260ms speedup there is just part of the run-to-run noise
(but it's important to note that we didn't make anything
worse with the overhead of maintaining our cache). In the
50-pack case, we see similar results. There may be a slight
improvement, but it's mostly within the noise.

The 1000-pack case does show a big improvement, though. That
carries over to the repack case, as well. Even though we
haven't touched its pack-search loop yet, it does still do a
lot of normal object lookups (e.g., for the internal
revision walk), and so improves.

As a point of reference, I also ran the 1000-pack test
against a version of HEAD^ with the last_found_pack
optimization disabled. It takes ~60s, so that gives an
indication of how much even the single-element cache is
helping.

For comparison, here's a smaller repository, git.git:

Test                      HEAD^               HEAD
---------------------------------------------------------------------
5303.3: rev-list (1)      1.56(1.54+0.01)    1.54(1.51+0.02) -1.3%
5303.4: repack (1)        1.84(1.80+0.10)    1.82(1.80+0.09) -1.1%
5303.6: rev-list (50)     1.58(1.55+0.02)    1.59(1.57+0.01) +0.6%
5303.7: repack (50)       2.50(3.18+0.04)    2.50(3.14+0.04) +0.0%
5303.9: rev-list (1000)   2.76(2.71+0.04)    2.24(2.21+0.02) -18.8%
5303.10: repack (1000)    13.21(19.56+0.25)  11.66(18.01+0.21) -11.7%

You can see that the percentage improvement is similar.
That's because the lookup we are optimizing is roughly
O(nr_objects * nr_packs). Since the number of packs is
constant in both tests, we'd expect the improvement to be
linear in the number of objects. But the whole process is
also linear in the number of objects, so the improvement
is a constant factor.

The exact improvement does also depend on the contents of
the packs. In p5303, the extra packs all have 5 first-parent
commits in them, which is a reasonable simulation of a
pushed-to repository. But it also means that only 250
first-parent commits are in those packs (compared to almost
50,000 total in linux.git), and the rest are in the huge
"base" pack. So once we start looking at history in taht big
pack, that's where we'll find most everything, and even the
1-element cache gets close to 100% cache hits.  You could
almost certainly show better numbers with a more
pathological case (e.g., distributing the objects more
evenly across the packs). But that's simply not that
realistic a scenario, so it makes more sense to focus on
these numbers.

The implementation itself is a straightforward application
of the MRU code. We provide an MRU-ordered list of packs
that shadows the packed_git list. This is easy to do because
we only create and revise the pack list in one place. The
"reprepare" code path actually drops the whole MRU and
replaces it for simplicity. It would be more efficient to
just add new entries, but there's not much point in
optimizing here; repreparing happens rarely, and only after
doing a lot of other expensive work.  The key things to keep
optimized are traversal (which is just a normal linked list,
albeit with one extra level of indirection over the regular
packed_git list), and marking (which is a constant number of
pointer assignments, though slightly more than the old
last_found_pack was; it doesn't seem to create a measurable
slowdown, though).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-29 11:05:07 -07:00
Jeff King
002f206faf add generic most-recently-used list
There are a few places in Git that would benefit from a fast
most-recently-used cache (e.g., the list of packs, which we
search linearly but would like to order based on locality).
This patch introduces a generic list that can be used to
store arbitrary pointers in most-recently-used order.

The implementation is just a doubly-linked list, where
"marking" an item as used moves it to the front of the list.
Insertion and marking are O(1), and iteration is O(n).

There's no lookup support provided; if you need fast
lookups, you are better off with a different data structure
in the first place.

There is also no deletion support. This would not be hard to
do, but it's not necessary for handling pack structs, which
are created and never removed.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-29 11:05:07 -07:00
Jeff King
3157c880f6 sha1_file: drop free_pack_by_name
The point of this function is to drop an entry from the
"packed_git" cache that points to a file we might be
overwriting, because our contents may not be the same (and
hence the only caller was pack-objects as it moved a
temporary packfile into place).

In older versions of git, this could happen because the
names of packfiles were derived from the set of objects they
contained, not the actual bits on disk. But since 1190a1a
(pack-objects: name pack files after trailer hash,
2013-12-05), the name reflects the actual bits on disk, and
any two packfiles with the same name can be used
interchangeably.

Dropping this function not only saves a few lines of code,
it makes the lifetime of "struct packed_git" much easier to
reason about: namely, we now do not ever free these structs.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-29 11:05:06 -07:00
Jeff King
77023ea3c3 t/perf: add tests for many-pack scenarios
Git's pack storage does efficient (log n) lookups in a
single packfile's index, but if we have multiple packfiles,
we have to linearly search each for a given object.  This
patch introduces some timing tests for cases where we have a
large number of packs, so that we can measure any
improvements we make in the following patches.

The main thing we want to time is object lookup. To do this,
we measure "git rev-list --objects --all", which does a
fairly large number of object lookups (essentially one per
object in the repository).

However, we also measure the time to do a full repack, which
is interesting for two reasons. One is that in addition to
the usual pack lookup, it has its own linear iteration over
the list of packs. And two is that because it it is the tool
one uses to go from an inefficient many-pack situation back
to a single pack, we care about its performance not only at
marginal numbers of packs, but at the extreme cases (e.g.,
if you somehow end up with 5,000 packs, it is the only way
to get back to 1 pack, so we need to make sure it performs
well).

We measure the performance of each command in three
scenarios: 1 pack, 50 packs, and 1,000 packs.

The 1-pack case is a baseline; any optimizations we do to
handle multiple packs cannot possibly perform better than
this.

The 50-pack case is as far as Git should generally allow
your repository to go, if you have auto-gc enabled with the
default settings. So this represents the maximum performance
improvement we would expect under normal circumstances.

The 1,000-pack case is hopefully rare, though I have seen it
in the wild where automatic maintenance was broken for some
time (and the repository continued to receive pushes). This
represents cases where we care less about general
performance, but want to make sure that a full repack
command does not take excessively long.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-29 11:05:06 -07:00
Junio C Hamano
f8f7adce9f Sync with maint
* maint:
  Some fixes for 2.9.3
2016-07-28 14:21:18 -07:00