Merge branch 'np/log-graph-octopus-fix'

"git log --graph" showing an octopus merge sometimes miscounted the
number of display columns it is consuming to show the merge and its
parent commits, which has been corrected.

* np/log-graph-octopus-fix:
log: fix coloring of certain octopus merge shapes

Merge branch 'sg/split-index-racefix'

The codepath to support the experimental split-index mode had
remaining "racily clean" issues fixed.

* sg/split-index-racefix:
split-index: BUG() when cache entry refers to non-existing shared entry
split-index: smudge and add racily clean cache entries to split index
split-index: don't compare cached data of entries already marked for split index
split-index: count the number of deleted entries
t1700-split-index: date back files to avoid racy situations
split-index: add tests to demonstrate the racy split index problem
t1700-split-index: document why FSMONITOR is disabled in this test script

Merge branch 'ds/coverage-diff'

The result of coverage test can be combined with "git blame" to
check the test coverage of code introduced recently with a new
'coverage-diff' tool (in contrib/).

* ds/coverage-diff:
contrib: add coverage-diff script

Merge branch 'bc/editorconfig'

To help developers, an EditorConfig file that attempts to follow
the project convention has been added.

* bc/editorconfig:
editorconfig: indicate settings should be kept in sync
editorconfig: provide editor settings for Git developers

Merge branch 'ma/t7005-bash-workaround'

Test fix.

* ma/t7005-bash-workaround:
t7005-editor: quote filename to fix whitespace-issue

Merge branch 'rs/subtree-fixes'

Various subtree fixes.

* rs/subtree-fixes:
subtree: performance improvement for finding unexpected parent commits
subtree: improve decision on merges kept in split
subtree: use commits before rejoins for splits
subtree: make --ignore-joins pay attention to adds
subtree: refactor split of a commit into standalone method

Fifth batch for 2.20

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Merge branch 'jt/cache-tree-allow-missing-object-in-partial-clone'

In a partial clone that will lazily be hydrated from the
originating repository, we generally want to avoid "does this
object exist (locally)?" on objects that we deliberately omitted
when we created the clone. The cache-tree codepath (which is used
to write a tree object out of the index) however insisted that the
object exists, even for paths that are outside of the partial
checkout area. The code has been updated to avoid such a check.

* jt/cache-tree-allow-missing-object-in-partial-clone:
cache-tree: skip some blob checks in partial clone

Merge branch 'tb/filter-alternate-refs'

When pushing into a repository that borrows its objects from an
alternate object store, "git receive-pack" that responds to the
push request on the other side lists the tips of refs in the
alternate to reduce the amount of objects transferred. This
sometimes is detrimental when the number of refs in the alternate
is absurdly large, in which case the bandwidth saved in potentially
fewer objects transferred is wasted in excessively large ref
advertisement. The alternate refs that are advertised are now
configurable with a pair of configuration variables.

* tb/filter-alternate-refs:
transport.c: introduce core.alternateRefsPrefixes
transport.c: introduce core.alternateRefsCommand
transport.c: extract 'fill_alternate_refs_command'
transport: drop refnames from for_each_alternate_ref

Merge branch 'jt/avoid-ls-refs'

Over some transports, fetching objects with an exact commit object
name can be done without first seeing the ref advertisements. The
code has been optimized to exploit this.

* jt/avoid-ls-refs:
fetch: do not list refs if fetching only hashes
transport: list refs before fetch if necessary
transport: do not list refs if possible
transport: allow skipping of ref listing

Merge branch 'ds/commit-graph-leakfix'

Code clean-up.

* ds/commit-graph-leakfix:
commit-graph: reduce initial oid allocation
builtin/commit-graph.c: UNLEAK variables
commit-graph: clean up leaked memory during write

Merge branch 'jt/non-blob-lazy-fetch'

A partial clone that is configured to lazily fetch missing objects
will on-demand issue a "git fetch" request to the originating
repository to fill not-yet-obtained objects. The request has been
optimized for requesting a tree object (and not the leaf blob
objects contained in it) by telling the originating repository that
no blobs are needed.

* jt/non-blob-lazy-fetch:
fetch-pack: exclude blobs when lazy-fetching trees
fetch-pack: avoid object flags if no_dependents

Merge branch 'pw/diff-color-moved-ws-fix'

Various fixes to "diff --color-moved-ws".

* pw/diff-color-moved-ws-fix:
diff --color-moved: fix a memory leak
diff --color-moved-ws: fix another memory leak
diff --color-moved-ws: fix a memory leak
diff --color-moved-ws: fix out of bounds string access
diff --color-moved-ws: fix double free crash

Merge branch 'rs/oidset-on-khash'

The oidset API was built on top of the oidmap API which in turn is
on the hashmap API. Replace the implementation to build on top of
the khash API and gain performance.

* rs/oidset-on-khash:
oidset: uninline oidset_init()
oidset: use khash
khash: factor out kh_release_*
fetch-pack: load tip_oids eagerly iff needed
fetch-pack: factor out is_unmatched_ref()

Merge branch 'rs/grep-no-recursive'

Unlike "grep", "git grep" by default recurses to the whole tree.
The command learned "git grep --recursive" option, so that "git
grep --no-recursive" can serve as a synonym to setting the
max-depth to 0.

* rs/grep-no-recursive:
grep: add -r/--[no-]recursive

Merge branch 'nd/help-commands-verbose-by-default'

"git help -a" and "git help -av" give different pieces of
information, and generally the "verbose" version is more friendly
to the new users. "git help -a" by default now uses the more
verbose output (with "--no-verbose", you can go back to the
original). Also "git help -av" now lists aliases and external
commands, which it did not used to.

* nd/help-commands-verbose-by-default:
help -a: improve and make --verbose default

Merge branch 'jc/how-to-document-api'

Doc update.

* jc/how-to-document-api:
CodingGuidelines: document the API in *.h files

Merge branch 'sm/show-superproject-while-conflicted'

A corner-case bugfix.

* sm/show-superproject-while-conflicted:
rev-parse: --show-superproject-working-tree should work during a merge

Merge branch 'jt/fetch-tips-in-partial-clone'

"git fetch $repo $object" in a partial clone did not correctly
fetch the asked-for object that is referenced by an object in
promisor packfile, which has been fixed.

* jt/fetch-tips-in-partial-clone:
fetch: in partial clone, check presence of targets
connected: document connectivity in partial clones

Merge branch 'nd/status-refresh-progress'

"git status" learns to show progress bar when refreshing the index
takes a long time.

* nd/status-refresh-progress:
status: show progress bar if refreshing the index takes too long

Merge branch 'bp/read-cache-parallel'

A new extension to the index file has been introduced, which allows
the file to be read in parallel.

* bp/read-cache-parallel:
read-cache: load cache entries on worker threads
ieot: add Index Entry Offset Table (IEOT) extension
read-cache: load cache extensions on a worker thread
config: add new index.threads config setting
eoie: add End of Index Entry (EOIE) extension
read-cache: clean up casting and byte decoding
read-cache.c: optimize reading index format v4

Merge branch 'bp/rename-test-env-var'

Some environment variables that control the runtime options of Git
used during tests are getting renamed for consistency.

* bp/rename-test-env-var:
t0000: do not get self-test disrupted by environment warnings
preload-index: update GIT_FORCE_PRELOAD_TEST support
read-cache: update TEST_GIT_INDEX_VERSION support
fsmonitor: update GIT_TEST_FSMONITOR support
preload-index: use git_env_bool() not getenv() for customization
t/README: correct spelling of "uncommon"

Merge branch 'ss/wt-status-committable'

Code clean-up in the internal machinery used by "git status" and
"git commit --dry-run".

* ss/wt-status-committable:
roll wt_status_state into wt_status and populate in the collect phase
wt-status.c: set the committable flag in the collect phase
t7501: add test of "commit --dry-run --short"
wt-status: rename commitable to committable
wt-status.c: move has_unmerged earlier in the file

Merge branch 'nd/the-index'

Various codepaths in the core-ish part learn to work on an
arbitrary in-core index structure, not necessarily the default
instance "the_index".

* nd/the-index: (23 commits)
revision.c: reduce implicit dependency the_repository
revision.c: remove implicit dependency on the_index
ws.c: remove implicit dependency on the_index
tree-diff.c: remove implicit dependency on the_index
submodule.c: remove implicit dependency on the_index
line-range.c: remove implicit dependency on the_index
userdiff.c: remove implicit dependency on the_index
rerere.c: remove implicit dependency on the_index
sha1-file.c: remove implicit dependency on the_index
patch-ids.c: remove implicit dependency on the_index
merge.c: remove implicit dependency on the_index
merge-blobs.c: remove implicit dependency on the_index
ll-merge.c: remove implicit dependency on the_index
diff-lib.c: remove implicit dependency on the_index
read-cache.c: remove implicit dependency on the_index
diff.c: remove implicit dependency on the_index
grep.c: remove implicit dependency on the_index
diff.c: remove the_index dependency in textconv() functions
blame.c: rename "repo" argument to "r"
combine-diff.c: remove implicit dependency on the_index
...

Merge branch 'nd/complete-fetch-multiple-args'

Teach bash completion that "git fetch --multiple" only takes remote
names as arguments and no refspecs.

* nd/complete-fetch-multiple-args:
completion: support "git fetch --multiple"

Fourth batch for 2.20

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Merge branch 'sf/complete-stash-list'

The completion script (in contrib/) learned to complete a handful of
options "git stash list" command takes.

* sf/complete-stash-list:
git-completion.bash: add completion for stash list

Merge branch 'mw/doc-typofixes'

Typofixes.

* mw/doc-typofixes:
docs: typo: s/isimilar/similar/
docs: graph: remove unnecessary `graph_update()' call
docs: typo: s/go/to/

Merge branch 'js/mingw-wants-vista-or-above'

The minimum version of Windows supported by Windows port fo Git is
now set to Vista.

* js/mingw-wants-vista-or-above:
mingw: bump the minimum Windows version to Vista
mingw: set _WIN32_WINNT explicitly for Git for Windows
compat/poll: prepare for targeting Windows Vista

Merge branch 'rs/sequencer-oidset-insert-avoids-dups'

Code clean-up.

* rs/sequencer-oidset-insert-avoids-dups:
sequencer: use return value of oidset_insert()

Merge branch 'jk/oideq-hasheq-cleanup'

Code clean-up.

* jk/oideq-hasheq-cleanup:
more oideq/hasheq conversions

Merge branch 'ma/mailing-list-address-in-git-help'

Doc update.

* ma/mailing-list-address-in-git-help:
git doc: direct bug reporters to mailing list archive

Merge branch 'nd/packobjectshook-doc-fix'

Doc update.

* nd/packobjectshook-doc-fix:
config.txt: correct the note about uploadpack.packObjectsHook

Merge branch 'rt/rebase-typofix'

Typofix.

* rt/rebase-typofix:
git-rebase.sh: fix typos in error messages

Merge branch 'ma/t1400-undebug-test'

Test fix.

* ma/t1400-undebug-test:
t1400: drop debug `echo` to actually execute `test`

Merge branch 'ma/commit-graph-docs'

Doc update.

* ma/commit-graph-docs:
Doc: refer to the "commit-graph file" with dash
git-commit-graph.txt: refer to "*commit*-graph file"
git-commit-graph.txt: typeset more in monospace
git-commit-graph.txt: fix bullet lists

Merge branch 'dz/credential-doc-url-matching-rules'

Doc update.

* dz/credential-doc-url-matching-rules:
doc: clarify gitcredentials path component matching

Merge branch 'en/status-multiple-renames-to-the-same-target-fix'

The code in "git status" sometimes hit an assertion failure. This
was caused by a structure that was reused without cleaning the data
used for the first run, which has been corrected.

* en/status-multiple-renames-to-the-same-target-fix:
commit: fix erroneous BUG, 'multiple renames on the same target? how?'

Merge branch 'ds/reachable-final-cleanup'

Code already in 'master' is further cleaned-up by this patch.

* ds/reachable-final-cleanup:
commit-reach: cleanups in can_all_from_reach...

Merge branch 'jk/check-everything-connected-is-long-gone'

Comment fix.

* jk/check-everything-connected-is-long-gone:
receive-pack: update comment with check_everything_connected

Merge branch 'jn/gc-auto'

"gc --auto" ended up calling exit(-1) upon error, which has been
corrected to use exit(1). Also the error reporting behaviour when
daemonized has been updated to exit with zero status when stopping
due to a previously discovered error (which implies there is no
point running gc to improve the situation); we used to exit with
failure in such a case.

* jn/gc-auto:
gc: do not return error for prior errors in daemonized mode

Merge branch 'jn/gc-auto-prep'

Code clean-up.

* jn/gc-auto-prep:
gc: exit with status 128 on failure
gc: improve handling of errors reading gc.log

Merge branch 'md/test-cleanup'

Various test scripts have been updated for style and also correct
handling of exit status of various commands.

* md/test-cleanup:
tests: order arguments to git-rev-list properly
t9109: don't swallow Git errors upstream of pipes
tests: don't swallow Git errors upstream of pipes
t/*: fix ordering of expected/observed arguments
tests: standardize pipe placement
Documentation: add shell guidelines
t/README: reformat Do, Don't, Keep in mind lists

Merge branch 'fe/doc-updates'

Doc updates.

* fe/doc-updates:
git-describe.1: clarify that "human readable" is also git-readable
git-column.1: clarify initial description, provide examples
git-archimport.1: specify what kind of Arch we're talking about

Merge branch 'jn/mailmap-update'

The mailmap file update.

* jn/mailmap-update:
mailmap: consistently normalize brian m. carlson's name

Merge branch 'tg/t5551-with-curl-7.61.1'

Test update.

* tg/t5551-with-curl-7.61.1:
t5551: compare sorted cookies files
t5551: move setup code inside test_expect blocks

Merge branch 'en/merge-cleanup'

Code clean-up.

* en/merge-cleanup:
merge-recursive: rename merge_file_1() and merge_content()
merge-recursive: remove final remaining caller of merge_file_one()
merge-recursive: avoid wrapper function when unnecessary and wasteful
merge-recursive: set paths correctly when three-way merging content

Merge branch 'rj/header-check'

Header files clean-up.

* rj/header-check:
delta-islands.h: add missing forward declarations (hdr-check)
midx.h: add missing forward declarations (hdr-check)
refs/refs-internal.h: add missing declarations (hdr-check)
refs/packed-backend.h: add missing declaration (hdr-check)
refs/ref-cache.h: add missing declarations (hdr-check)
ewah/ewok_rlw.h: add missing include (hdr-check)
json-writer.h: add missing include (hdr-check)
Makefile: add a hdr-check target

Merge branch 'ma/config-doc-update'

Doc update.

* ma/config-doc-update:
git-config.txt: fix 'see: above' note
Doc: use `--type=bool` instead of `--bool`

Merge branch 'jk/delta-islands-with-bitmap-reuse-delta-fix'

Fix interactions between two recent topics.

* jk/delta-islands-with-bitmap-reuse-delta-fix:
pack-objects: handle island check for "external" delta base

Merge branch 'tq/refs-internal-comment-fix'

Fix for typo in a sample code in comment.

* tq/refs-internal-comment-fix:
refs: docstring typo

Merge branch 'ts/alias-of-alias'

An alias that expands to another alias has so far been forbidden,
but now it is allowed to create such an alias.

* ts/alias-of-alias:
t0014: introduce an alias testing suite
alias: show the call history when an alias is looping
alias: add support for aliases of an alias

Merge branch 'ds/commit-graph-with-grafts'

The recently introduced commit-graph auxiliary data is incompatible
with mechanisms such as replace & grafts that "breaks" immutable
nature of the object reference relationship. Disable optimizations
based on its use (and updating existing commit-graph) when these
incompatible features are in use in the repository.

* ds/commit-graph-with-grafts:
commit-graph: close_commit_graph before shallow walk
commit-graph: not compatible with uninitialized repo
commit-graph: not compatible with grafts
commit-graph: not compatible with replace objects
test-repository: properly init repo
commit-graph: update design document
refs.c: upgrade for_each_replace_ref to be a each_repo_ref_fn callback
refs.c: migrate internal ref iteration to pass thru repository argument

Merge branch 'ab/commit-graph-progress'

Generation of (experimental) commit-graph files have so far been
fairly silent, even though it takes noticeable amount of time in a
meaningfully large repository. The users will now see progress
output.

* ab/commit-graph-progress:
gc: fix regression in 7b0f229222 impacting --quiet
commit-graph verify: add progress output
commit-graph write: add progress output

subtree: performance improvement for finding unexpected parent commits

After testing a previous patch at larger scale, a performance issue was
detected when using git show to locate parent revisions, with a single
run of the git show command taking 2 seconds or longer in a complex repo.
When the command is required tens or hundreds of times in a run of the
script, the additional wait time is unaccepatable. Replacing the command
with git rev-parse resulted in significantly increased performance, with
the command in question returning instantly.

Signed-off-by: Roger Strain <rstrain@swri.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

log: fix coloring of certain octopus merge shapes

For octopus merges where the first parent edge immediately merges into
the next column to the left, the number of columns should be one less
than the usual case.

First parent to the left case:

| *-.
| |\ \
|/ / /

The usual case:

| *-.
| |\ \
| | | *

Also refactor the code to iterate over columns rather than dashes,
building from an initial patch suggested by Jeff King.

Signed-off-by: Noam Postavsky <npostavs@users.sourceforge.net>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

split-index: BUG() when cache entry refers to non-existing shared entry

When the split index feature is in use, then a cache entry is:

- either only present in the split index, in which case its 'index'
field must be 0,

- or it should refer to an existing entry in the shared index, i.e.
the 'index' field can't be greater than the size of the shared
index.

If a cache entry were to refer to a non-existing entry in the shared
index, then that's a sign of something being wrong in the index state,
either as a result of a bug in dealing with the split/shared index
entries, or perhaps a (potentially unrelated) memory corruption issue.

prepare_to_write_split_index() already has a condition to catch cache
entries with such bogus 'index' field, but instead of calling BUG() it
just sets cache entry's 'index = 0', and the entry will then be
written to the new split index.

Don't write a new index file from bogus index state, and call BUG()
upon encountering an cache entry referring to a non-existing shared
index entry.

Running the test suite repeatedly with 'GIT_TEST_SPLIT_INDEX=yes'
doesn't trigger this condition.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

split-index: smudge and add racily clean cache entries to split index

Ever since the split index feature was introduced [1], refreshing a
split index is prone to a variant of the classic racy git problem.

Consider the following sequence of commands updating the split index
when the shared index contains a racily clean cache entry, i.e. an
entry whose cached stat data matches with the corresponding file in
the worktree and the cached mtime matches that of the index:

echo "cached content" >file
git update-index --split-index --add file
echo "dirty worktree" >file # size stays the same!
# ... wait ...
git update-index --add other-file

Normally, when a non-split index is updated, then do_write_index()
(the function responsible for writing all kinds of indexes, "regular",
split, and shared) recognizes racily clean cache entries, and writes
them with smudged stat data, i.e. with file size set to 0. When
subsequent git commands read the index, they will notice that the
smudged stat data doesn't match with the file in the worktree, and
then go on to check the file's content and notice its dirtiness.

In the above example, however, in the second 'git update-index'
prepare_to_write_split_index() decides which cache entries stored only
in the shared index should be replaced in the new split index. Alas,
this function never looks out for racily clean cache entries, and
since the file's stat data in the worktree hasn't changed since the
shared index was written, it won't be replaced in the new split index.
Consequently, do_write_index() doesn't even get this racily clean
cache entry, and can't smudge its stat data. Subsequent git commands
will then see that the index has more recent mtime than the file and
that the (not smudged) cached stat data still matches with the file in
the worktree, and, ultimately, will erroneously consider the file
clean.

Modify prepare_to_write_split_index() to recognize racily clean cache
entries, and mark them to be added to the split index. Note that
there are two places where it should check raciness: first those cache
entries that are only stored in the shared index, and then those that
have been copied by unpack_trees() from the shared index while it
constructed a new index. This way do_write_index() will get these
racily clean cache entries as well, and will then write them with
smudged stat data to the new split index.

This change makes all tests in 't1701-racy-split-index.sh' pass, so
flip the two 'test_expect_failure' tests to success. Also add the '#'
(as in nr. of trial) to those tests' description that were omitted
when the tests expected failure.

Note that after this change if the index is split when it contains a
racily clean cache entry, then a smudged cache entry will be written
both to the new shared and to the new split indexes. This doesn't
affect regular git commands: as far as they are concerned this is just
an entry in the split index replacing an outdated entry in the shared
index. It did affect a few tests in 't1700-split-index.sh', though,
because they actually check which entries are stored in the split
index; a previous patch in this series has already made the necessary
adjustments in 't1700'. And racily clean cache entries and index
splitting are rare enough to not worry about the resulting duplicated
smudged cache entries, and the additional complexity required to
prevent them is not worth it.

Several tests failed occasionally when the test suite was run with
'GIT_TEST_SPLIT_INDEX=yes'. Here are those that I managed to trace
back to this racy split index problem, starting with those failing
more frequently, with a link to a failing Travis CI build job for
each. The highlighted line [2] shows when the racy file was written,
which is not always in the failing test but in a preceeding setup
test.

t3903-stash.sh:
https://travis-ci.org/git/git/jobs/385542084#L5858

t4024-diff-optimize-common.sh:
https://travis-ci.org/git/git/jobs/386531969#L3174

t4015-diff-whitespace.sh:
https://travis-ci.org/git/git/jobs/360797600#L8215

t2200-add-update.sh:
https://travis-ci.org/git/git/jobs/382543426#L3051

t0090-cache-tree.sh:
https://travis-ci.org/git/git/jobs/416583010#L3679

There might be others, e.g. perhaps 't1000-read-tree-m-3way.sh' and
others using 'lib-read-tree-m-3way.sh', but I couldn't confirm yet.

[1] In the branch leading to the merge commit v2.1.0-rc0~45 (Merge
branch 'nd/split-index', 2014-07-16).

[2] Note that those highlighted lines are in the 'after failure' fold,
and your browser might unhelpfully fold it up before you could
take a good look.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

split-index: don't compare cached data of entries already marked for split index

When unpack_trees() constructs a new index, it copies cache entries
from the original index [1]. prepare_to_write_split_index() has to
deal with this, and it has a dedicated code path for copied entries
that are present in the shared index, where it compares the cached
data in the corresponding copied and original entries. If the cached
data matches, then they are considered the same; if it differs, then
the copied entry will be marked for inclusion as a replacement entry
in the just about to be written split index by setting the
CE_UPDATE_IN_BASE flag.

However, a cache entry already has its CE_UPDATE_IN_BASE flag set upon
reading the split index, if the entry already has a replacement entry
there, or upon refreshing the cached stat data, if the corresponding
file was modified. The state of this flag is then preserved when
unpack_trees() copies a cache entry from the shared index.

So modify prepare_to_write_split_index() to check the copied cache
entries' CE_UPDATE_IN_BASE flag first, and skip the thorough
comparison of cached data if the flag is already set. Those couple of
lines comparing the cached data would then have too many levels of
indentation, so extract them into a helper function.

Note that comparing the cached data in copied and original entries in
the shared index might actually be entirely unnecessary. In theory
all code paths refreshing the cached stat data of an entry in the
shared index should set the CE_UPDATE_IN_BASE flag in that entry, and
unpack_trees() should preserve this flag when copying cache entries.
This means that the cached data is only ever changed if the
CE_UPDATE_IN_BASE flag is set as well. Our test suite seems to
confirm this: instrumenting the conditions in question and running the
test suite repeatedly with 'GIT_TEST_SPLIT_INDEX=yes' showed that the
cached data in a copied entry differs from the data in the shared
entry only if its CE_UPDATE_IN_BASE flag is indeed set.

In practice, however, our test suite doesn't have 100% coverage,
GIT_TEST_SPLIT_INDEX is inherently random, and I certainly can't claim
to possess complete understanding of what goes on in unpack_trees()...
Therefore I kept the comparison of the cached data when
CE_UPDATE_IN_BASE is not set, just in case that an unnoticed or future
code path were to accidentally miss setting this flag upon refreshing
the cached stat data or unpack_trees() were to drop this flag while
copying a cache entry.

[1] Note that when unpack_trees() constructs the new index and decides
that a cache entry should now refer to different content than what
was recorded in the original index (e.g. 'git read-tree -m
HEAD^'), then that can't really be considered a copy of the
original, but rather the creation of a new entry. Notably and
pertinent to the split index feature, such a new entry doesn't
have a reference to the original's shared index entry anymore,
i.e. its 'index' field is set to 0. Consequently, such an entry
is treated by prepare_to_write_split_index() as an entry not
present in the shared index and it will be added to the new split
index, while the original entry will be marked as deleted, and
neither the above discussion nor the changes in this patch apply
to them.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

split-index: count the number of deleted entries

'struct split_index' contains the field 'nr_deletions', whose name
with the 'nr_' prefix suggests that it contains the number of deleted
cache entries. However, barring its initialization to 0, this field
is only ever set to 1, indicating that there is at least one deleted
entry, but not the number of deleted entries. Luckily, this doesn't
cause any issues (other than confusing the reader, that is), because
the only place reading this field uses it in the same sense, i.e.: 'if
(si->nr_deletions)'.

To avoid confusion, we could either rename this field to something
like 'has_deletions' to make its name match its role, or make it a
counter of deleted cache entries to match its name.

Let's make it a counter, to keep it in sync with the related field
'nr_replacements', which does contain the number of replaced cache
entries. This will also give developers debugging the split index
code easy access to the number of deleted cache entries.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t1700-split-index: date back files to avoid racy situations

't1700-split-index.sh' checks that the index was split correctly under
various circumstances and that all the different ways to turn the
split index feature on and off work correctly. To do so, most of its
tests use 'test-tool dump-split-index' to see which files have their
cache entries in the split index. All these tests assume that all
cache entries are written to the shared index (called "base"
throughout these tests) when a new shared index is created. This is
an implementation detail: most git commands (basically all except 'git
update-index') don't care or know at all about split index or whether
a cache entry is stored in the split or shared index.

As demonstrated in the previous patch, refreshing a split index is
prone to a variant of the classic racy git issue. The next patch will
fix this issue, but while doing so it will also slightly change this
behaviour: only cache entries with mtime in the past will be written
only to the newly created shared index, but racily clean cache entries
will be written to the new split index (with smudged stat data).

While this upcoming change won't at all affect any git commands, it
will violate the above mentioned assumption of 't1700's tests. Since
these tests create or modify files and create or refresh the split
index in rapid succession, there are plenty of racily clean cache
entries to be dealt with, which will then be written to the new split
indexes, and, ultimately, will cause several tests in 't1700' to fail.

Let's prepare 't1700-split-index.sh' for this upcoming change and
modify its tests to avoid racily clean files by backdating the mtime
of any file modifications (and since a lot of tests create or modify
files, encapsulate it into a helper function).

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

split-index: add tests to demonstrate the racy split index problem

Ever since the split index feature was introduced [1], refreshing a
split index is prone to a variant of the classic racy git problem.
There are a couple of unrelated tests in the test suite that
occasionally fail when run with 'GIT_TEST_SPLIT_INDEX=yes', but
't1700-split-index.sh', the only test script focusing solely on split
index, has never noticed this issue, because it only cares about how
the index is split under various circumstances and all the different
ways to turn the split index feature on and off.

Add a dedicated test script 't1701-racy-split-index.sh' to exercise
the split index feature in racy situations as well; kind of a
"t0010-racy-git.sh for split index" but with modern style (the tests
do everything in &&-chained list of commands in 'test_expect_...'
blocks, and use 'test_cmp' for more informative output on failure).

The tests cover the following sequences of index splitting, updating,
and racy file modifications, with the last two cases demonstrating the
racy split index problem:

1. Split the index while adding a racily clean file:

echo "cached content" >file
git update-index --split-index --add file
echo "dirty worktree" >file # size stays the same

This case already works properly. Even though the cache entry's
stat data matches with the modifid file in the worktree,
subsequent git commands will notice that the (split) index and
the file have the same mtime, and then will go on to check the
file's content and notice its dirtiness.

2. Add a racily clean file to an already split index:

git update-index --split-index
echo "cached content" >file
git update-index --add file
echo "dirty worktree" >file

This case already works properly. After the second 'git
update-index' writes the newly added file's cache entry to the
new split index, it basically works in the same way as case #1.

3. Split the index when it (i.e. the not yet splitted index)
contains a racily clean cache entry, i.e. an entry whose cached
stat data matches with the corresponding file in the worktree and
the cached mtime matches that of the index:

echo "cached content" >file
git update-index --add file
echo "dirty worktree" >file
# ... wait ...
git update-index --split-index --add other-file

This case already works properly. The shared index is written by
do_write_index(), i.e. the same function that is responsible for
writing "regular" and split indexes as well. This function
cleverly notices the racily clean cache entry, and writes the
entry to the new shared index with smudged stat data, i.e. file
size set to 0. When subsequent git commands read the index, they
will notice that the smudged stat data doesn't match with the
file in the worktree, and then go on to check the file's content
and notice its dirtiness.

4. Update the split index when it contains a racily clean cache
entry:

git update-index --split-index
echo "cached content" >file
git update-index --add file
echo "dirty worktree" >file
# ... wait ...
git update-index --add other-file

This case already works properly. After the second 'git
update-index' the newly added file's cache entry is only stored
in the split index. If a cache entry is present in the split
index (even if it is a replacement of an outdated entry in the
shared index), then it will always be included in the new split
index on subsequent split index updates (until the file is
removed or a new shared index is written), independently from
whether the entry is racily clean or not. When do_write_index()
writes the new split index, it notices the racily clean cache
entry, and smudges its stat date. Subsequent git commands
reading the index will notice the smudged stat data and then go
on to check the file's content and notice its dirtiness.

5. Update the split index when a racily clean cache entry is stored
only in the shared index:

echo "cached content" >file
git update-index --split-index --add file
echo "dirty worktree" >file
# ... wait ...
git update-index --add other-file

This case fails due to the racy split index problem. In the
second 'git update-index' prepare_to_write_split_index() decides,
among other things, which cache entries stored only in the shared
index should be replaced in the new split index. Alas, this
function never looks out for racily clean cache entries, and
since the file's stat data in the worktree hasn't changed since
the shared index was written, the entry won't be replaced in the
new split index. Consequently, do_write_index() doesn't even get
this racily clean cache entry, and can't smudge its stat data.
Subsequent git commands will then see that the index has more
recent mtime than the file and that the (not smudged) cached stat
data still matches with the file in the worktree, and,
ultimately, will erroneously consider the file clean.

6. Update the split index after unpack_trees() copied a racily clean
cache entry from the shared index:

echo "cached content" >file
git update-index --split-index --add file
echo "dirty worktree" >file
# ... wait ...
git read-tree -m HEAD

This case fails due to the racy split index problem. This
basically fails for the same reason as case #5 above, but there
is one important difference, which warrants the dedicated test.
While that second 'git update-index' in case #5 updates
index_state in place, in this case 'git read-tree -m' calls
unpack_trees(), which throws out the entire index, and constructs
a new one from the (potentially updated) copies of the original's
cache entries. Consequently, when prepare_to_write_split_index()
gets to work on this reconstructed index, it takes a different
code path than in case #5 when deciding which cache entries in
the shared index should be replaced. The result is the same,
though: the racily clean cache entry goes unnoticed, it isn't
added to the split index with smudged stat data, and subsequent
git commands will then erroneously consider the file clean.

Note that in the last two 'test_expect_failure' cases I omitted the
'#' (as in nr. of trial) from the tests' description on purpose for
now, as it breakes the TAP output [2]; it will be added at the end of
the series, when those two tests will be flipped to
'test_expect_success'.

[1] In the branch leading to the merge commit v2.1.0-rc0~45 (Merge
branch 'nd/split-index', 2014-07-16).

[2] In the TAP output a '#' should separate the test's description
from the TODO directive emitted by 'test_expect_failure'. The
additional '#' in "#$trial" interferes with this, the test harness
won't recognize the TODO directive, and will report that those
tests failed unexpectedly.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

read-cache: load cache entries on worker threads

This patch helps address the CPU cost of loading the index by utilizing
the Index Entry Offset Table (IEOT) to divide loading and conversion of
the cache entries across multiple threads in parallel.

I used p0002-read-cache.sh to generate some performance data:

Test w/100,000 files reduced the time by 32.24%
Test w/1,000,000 files reduced the time by -4.77%

Note that on the 1,000,000 files case, multi-threading the cache entry parsing
does not yield a performance win. This is because the cost to parse the
index extensions in this repo, far outweigh the cost of loading the cache
entries.

The high cost of parsing the index extensions is driven by the cache tree
and the untracked cache extensions. As this is currently the longest pole,
any reduction in this time will reduce the overall index load times so is
worth further investigation in another patch series.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

ieot: add Index Entry Offset Table (IEOT) extension

This patch enables addressing the CPU cost of loading the index by adding
additional data to the index that will allow us to efficiently multi-
thread the loading and conversion of cache entries.

It accomplishes this by adding an (optional) index extension that is a
table of offsets to blocks of cache entries in the index file. To make
this work for V4 indexes, when writing the cache entries, it periodically
"resets" the prefix-compression by encoding the current entry as if the
path name for the previous entry is completely different and saves the
offset of that entry in the IEOT. Basically, with V4 indexes, it
generates offsets into blocks of prefix-compressed entries.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

read-cache: load cache extensions on a worker thread

This patch helps address the CPU cost of loading the index by loading
the cache extensions on a worker thread in parallel with loading the cache
entries.

In some cases, loading the extensions takes longer than loading the
cache entries so this patch utilizes the new EOIE to start the thread to
load the extensions before loading all the cache entries in parallel.

This is possible because the current extensions don't access the cache
entries in the index_state structure so are OK that they don't all exist
yet.

The CACHE_EXT_TREE, CACHE_EXT_RESOLVE_UNDO, and CACHE_EXT_UNTRACKED
extensions don't even get a pointer to the index so don't have access to the
cache entries.

CACHE_EXT_LINK only uses the index_state to initialize the split index.
CACHE_EXT_FSMONITOR only uses the index_state to save the fsmonitor last
update and dirty flags.

I used p0002-read-cache.sh to generate some performance data:

Test w/100,000 files reduced the time by 0.53%
Test w/1,000,000 files reduced the time by 27.78%

Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

config: add new index.threads config setting

Add support for a new index.threads config setting which will be used to
control the threading code in do_read_index(). A value of 0 will tell the
index code to automatically determine the correct number of threads to use.
A value of 1 will make the code single threaded. A value greater than 1
will set the maximum number of threads to use.

For testing purposes, this setting can be overwritten by setting the
GIT_TEST_INDEX_THREADS=<n> environment variable to a value greater than 0.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

eoie: add End of Index Entry (EOIE) extension

The End of Index Entry (EOIE) is used to locate the end of the variable
length index entries and the beginning of the extensions. Code can take
advantage of this to quickly locate the index extensions without having
to parse through all of the index entries.

The EOIE extension is always written out to the index file including to
the shared index when using the split index feature. Because it is always
written out, the SHA checksums in t/t1700-split-index.sh were updated
to reflect its inclusion.

It is written as an optional extension to ensure compatibility with other
git implementations that do not yet support it. It is always written out
to ensure it is available as often as possible to speed up index operations.

Because it must be able to be loaded before the variable length cache
entries and other index extensions, this extension must be written last.
The signature for this extension is { 'E', 'O', 'I', 'E' }.

The extension consists of:

- 32-bit offset to the end of the index entries

- 160-bit SHA-1 over the extension types and their sizes (but not
their contents). E.g. if we have "TREE" extension that is N-bytes
long, "REUC" extension that is M-bytes long, followed by "EOIE",
then the hash would be:

SHA-1("TREE" + <binary representation of N> +
"REUC" + <binary representation of M>)

Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

read-cache: clean up casting and byte decoding

This patch does a clean up pass to minimize the casting required to work
with the memory mapped index (mmap).

It also makes the decoding of network byte order more consistent by using
get_be32() where possible.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Third batch for 2.20

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Merge branch 'ab/fsck-skiplist'

Update fsck.skipList implementation and documentation.

* ab/fsck-skiplist:
fsck: support comments & empty lines in skipList
fsck: use oidset instead of oid_array for skipList
fsck: use strbuf_getline() to read skiplist file
fsck: add a performance test for skipList
fsck: add a performance test
fsck: document that skipList input must be unabbreviated
fsck: document and test commented & empty line skipList input
fsck: document and test sorted skipList input
fsck tests: add a test for no skipList input
fsck tests: setup of bogus commit object

Merge branch 'ds/multi-pack-verify'

"git multi-pack-index" learned to detect corruption in the .midx
file it uses, and this feature has been integrated into "git fsck".

* ds/multi-pack-verify:
fsck: verify multi-pack-index
multi-pack-index: report progress during 'verify'
multi-pack-index: verify object offsets
multi-pack-index: fix 32-bit vs 64-bit size check
multi-pack-index: verify oid lookup order
multi-pack-index: verify oid fanout order
multi-pack-index: verify missing pack
multi-pack-index: verify packname order
multi-pack-index: verify corrupt chunk lookup table
multi-pack-index: verify bad header
multi-pack-index: add 'verify' verb

Merge branch 'bc/hash-independent-tests'

Various tests have been updated to make it easier to swap the
hash function used for object identification.

* bc/hash-independent-tests:
t5318: use test_oid for HASH_LEN
t1407: make hash size independent
t1406: make hash-size independent
t1405: make hash size independent
t1400: switch hard-coded object ID to variable
t1006: make hash size independent
t0064: make hash size independent
t0002: abstract away SHA-1 specific constants
t0000: update tests for SHA-256
t0000: use hash translation table
t: add test functions to translate hash-related values

Merge branch 'nd/test-tool'

Test helper binaries clean-up.

* nd/test-tool:
Makefile: add a hint about TEST_BUILTINS_OBJS
t/helper: merge test-dump-fsmonitor into test-tool
t/helper: merge test-parse-options into test-tool
t/helper: merge test-pkt-line into test-tool
t/helper: merge test-dump-untracked-cache into test-tool
t/helper: keep test-tool command list sorted

Merge branch 'nd/config-split'

Split Documentation/config.txt for easier maintenance.

* nd/config-split:
config.txt: move submodule part out to a separate file
config.txt: move sequence.editor out of "core" part
config.txt: move sendemail part out to a separate file
config.txt: move receive part out to a separate file
config.txt: move push part out to a separate file
config.txt: move pull part out to a separate file
config.txt: move gui part out to a separate file
config.txt: move gitcvs part out to a separate file
config.txt: move format part out to a separate file
config.txt: move fetch part out to a separate file
config.txt: follow camelCase naming

cache-tree: skip some blob checks in partial clone

In a partial clone, whenever a sparse checkout occurs, the existence of
all blobs in the index is verified, whether they are included or
excluded by the .git/info/sparse-checkout specification. This
significantly degrades performance because a lazy fetch occurs whenever
the existence of a missing blob is checked.

This is because cache_tree_update() checks the existence of all objects
in the index, whether or not CE_SKIP_WORKTREE is set on them. Teach
cache_tree_update() to skip checking CE_SKIP_WORKTREE objects when the
repository is a partial clone. This improves performance for sparse
checkout and also other operations that use cache_tree_update().

Instead of completely removing the check, an argument could be made that
the check should instead be replaced by a check that the blob is
promised, but for performance reasons, I decided not to do this.
If the user needs to verify the repository, it can be done using fsck
(which will notify if a tree points to a missing and non-promised blob,
whether the blob is included or excluded by the sparse-checkout
specification).

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib: add coverage-diff script

We have coverage targets in our Makefile for using gcov to display line
coverage based on our test suite. The way I like to do it is to run:

make coverage-test
make coverage-report

This leaves the repo in a state where every X.c file that was covered has
an X.c.gcov file containing the coverage counts for every line, and "#####"
at every uncovered line.

There have been a few bugs in recent patches what would have been caught
if the test suite covered those blocks (including a few of mine). I want
to work towards a "sensible" amount of coverage on new topics. In my opinion,
this means that any logic should be covered, but the 'die()' blocks covering
very unlikely (or near-impossible) situations may not warrant coverage.

It is important to not measure the coverage of the codebase by what old code
is not covered. To help, I created the 'contrib/coverage-diff.sh' script.
After creating the coverage statistics at a version (say, 'topic') you can
then run

contrib/coverage-diff.sh base topic

to see the lines added between 'base' and 'topic' that are not covered by the
test suite. The output uses 'git blame -s' format so you can find the commits
responsible and view the line numbers for quick access to the context, but
trims leading tabs in the file contents to reduce output width.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Declare that the next one will be named 2.20

Signed-off-by: Junio C Hamano <gitster@pobox.com>

editorconfig: indicate settings should be kept in sync

Now that we have two places where we set code formatting settings,
.editorconfig and .clang-format, it's possible that they could fall out
of sync. This is relatively unlikely, since we're not likely to change
the tab width or our preference for tabs, but just in case, add comments
to both files reminding future developers to keep them in sync.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

editorconfig: provide editor settings for Git developers

Contributors to Git use a variety of editors, each with their own
configuration files. Because C lacks the defined norms on how to indent
and style code that other languages, such as Ruby and Rust, have, it's
possible for various contributors, especially new ones, to have
configured their editor to use a style other than the style the Git
community prefers.

To make automatically configuring one's editor easier, provide an
EditorConfig file. This is an INI-style configuration file that can be
used to specify editor settings and can be understood by a wide variety
of editors. Some editors include this support natively; others require
a plugin. Regardless, providing such a file allows users to
automatically configure their editor of choice with the correct settings
by default.

Provide global settings to set the character set to UTF-8 and insert a
final newline into files. Provide language-specific settings for C,
Shell, Perl, and Python files according to what CodingGuidelines already
specifies. Since the indentation of other files varies, especially
certain AsciiDoc files, don't provide any settings for them until a
clear consensus forward emerges.

Set the line length for commit messages to 72 characters, which is the
generally accepted line length for emails, since we send patches by
email.

Don't specify an end of line type. While the Git community uses
Unix-style line endings in the repository, some Windows users may use
Git's auto-conversion support and forcing Unix-style line endings might
cause problems for those users.

Finally, leave out a root directive, which would prevent reading other
EditorConfig files higher up in the tree, in case someone wants to set
the end of line type for their system in such a file.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

transport.c: introduce core.alternateRefsPrefixes

The recently-introduced "core.alternateRefsCommand" allows callers to
specify with high flexibility the tips that they wish to advertise from
alternates. This flexibility comes at the cost of some inconvenience
when the caller only wishes to limit the advertisement to one or more
prefixes.

For example, to advertise only tags, a caller using
'core.alternateRefsCommand' would have to do:

$ git config core.alternateRefsCommand ' \
f() { git -C "$1" for-each-ref \
refs/tags --format="%(objectname)" }; f "$@"'

The above is cumbersome to write, so let's introduce a
"core.alternateRefsPrefixes" to address this common case. Instead, the
caller can run:

$ git config core.alternateRefsPrefixes 'refs/tags'

Which will behave identically to the longer example using
"core.alternateRefsCommand".

Since the value of "core.alternateRefsPrefixes" is appended to 'git
for-each-ref' and then executed, include a "--" before taking the
configured value to avoid misinterpreting arguments as flags to 'git
for-each-ref'.

In the case that the caller wishes to specify multiple prefixes, they
may separate them by whitespace. If "core.alternateRefsCommand" is set,
it will take precedence over "core.alternateRefsPrefixes".

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

transport.c: introduce core.alternateRefsCommand

When in a repository containing one or more alternates, Git would
sometimes like to list references from those alternates. For example,
'git receive-pack' lists the "tips" pointed to by references in those
alternates as special ".have" references.

Listing ".have" references is designed to make pushing changes from
upstream to a fork a lightweight operation, by advertising to the pusher
that the fork already has the objects (via its alternate). Thus, the
client can avoid sending them.

However, when the alternate (upstream, in the previous example) has a
pathologically large number of references, the initial advertisement is
too expensive. In fact, it can dominate any such optimization where the
pusher avoids sending certain objects.

Introduce "core.alternateRefsCommand" in order to provide a facility to
limit or filter alternate references. This can be used, for example, to
filter out references the alternate does not wish to send (for space
concerns, or otherwise) during the initial advertisement.

Let the repository that has alternates configure this command to avoid
trusting the alternate to provide us a safe command to run in the shell.
To find the alternate, pass its absolute path as the first argument.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

transport.c: extract 'fill_alternate_refs_command'

To list alternate references, 'read_alternate_refs' creates a child
process running 'git for-each-ref' in the alternate's Git directory.

Prepare to run other commands besides 'git for-each-ref' by introducing
and moving the relevant code from 'read_alternate_refs' to
'fill_alternate_refs_command'.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

transport: drop refnames from for_each_alternate_ref

None of the current callers use the refname parameter we pass to their
callbacks. In theory somebody _could_ do so, but it's actually quite
weird if you think about it: it's a ref in somebody else's repository.
So the name has no meaning locally, and in fact there may be duplicates
if there are multiple alternates.

The users of this interface really only care about seeing some ref tips,
since that promises that the alternate has the full commit graph
reachable from there. So let's keep the information we pass back to the
bare minimum.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

docs: typo: s/isimilar/similar/

Signed-off-by: Michael Witten <mfwitten@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

docs: graph: remove unnecessary `graph_update()' call

The sample code calls `get_revision()' followed by `graph_update()',
but the documentation and source code indicate that `get_revision()'
already calls `graph_update()' for you.

Signed-off-by: Michael Witten <mfwitten@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

docs: typo: s/go/to/

Signed-off-by: Michael Witten <mfwitten@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-completion.bash: add completion for stash list

Since stash list accepts git-log options, add the following useful
options that make sense in the context of the `git stash list` command:

--name-status --oneline --patch-with-stat

Signed-off-by: Steven Fernandez <steve@lonetwin.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

fetch: do not list refs if fetching only hashes

If only hash literals are given on a "git fetch" command-line, tag
following is not requested, and the fetch is done using protocol v2, a
list of refs is not required from the remote. Therefore, optimize by
invoking transport_get_remote_refs() only if we need the refs.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

transport: list refs before fetch if necessary

The built-in bundle transport and the transport helper interface do not
work when transport_fetch_refs() is called immediately after transport
creation. This will be needed in a subsequent patch, so fix this.

Evidence: fetch_refs_from_bundle() relies on data->header being
initialized in get_refs_from_bundle(), and fetch() in transport-helper.c
relies on either data->fetch or data->import being set by get_helper(),
but neither transport_helper_init() nor fetch() calls get_helper().

Up until the introduction of the partial clone feature, this has not
been a problem, because transport_fetch_refs() is always called after
transport_get_remote_refs(). With the introduction of the partial clone
feature, which involves calling transport_fetch_refs() (to fetch objects
by their OIDs) without transport_get_remote_refs(), this is still not a
problem, but only coincidentally - we do not support partially cloning a
bundle, and as for cloning using a transport-helper-using protocol, it
so happens that before transport_fetch_refs() is called, fetch_refs() in
fetch-object.c calls transport_set_option(), which means that the
aforementioned get_helper() is invoked through set_helper_option() in
transport-helper.c.

This could be fixed by fixing the transports themselves, but it doesn't
seem like a good idea to me to open up previously untested code paths;
also, there may be transport helpers in the wild that assume that "list"
is always called before "fetch". Instead, fix this by having
transport_fetch_refs() call transport_get_remote_refs() to ensure that
the latter is always called at least once, unless the transport
explicitly states that it supports fetching without listing refs.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

transport: do not list refs if possible

When all refs to be fetched are exact OIDs, it is possible to perform a
fetch without requiring the remote to list refs if protocol v2 is used.
Teach Git to do this.

This currently has an effect only for lazy fetches done from partial
clones. The change necessary to likewise optimize "git fetch <remote>
<sha-1>" will be done in a subsequent patch.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

transport: allow skipping of ref listing

The get_refs_via_connect() function both performs the handshake
(including determining the protocol version) and obtaining the list of
remote refs. However, the fetch protocol v2 supports fetching objects
without the listing of refs, so make it possible for the user to skip
the listing by creating a new handshake() function. This will be used in
a subsequent commit.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

tests: order arguments to git-rev-list properly

It is a common mistake to put positional arguments before flags when
invoking git-rev-list. Order the positional arguments last.

This patch skips git-rev-list invocations which include the --not flag,
since the ordering of flags and positional arguments affects the
behavior. This patch also skips invocations of git-rev-list that occur
in command substitution in which the exit code is discarded, since
fixing those properly will require a more involved cleanup.

Signed-off-by: Matthew DeVore <matvore@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t9109: don't swallow Git errors upstream of pipes

'git ... | foo' will mask any errors or crashes in git, so split up such
pipes in this file.

One testcase uses several separate pipe sequences in a row which are
awkward to split up. Wrap the split-up pipe in a function so the
awkwardness is not repeated. Also change that testcase's surrounding
quotes from double to single to avoid premature string interpolation.

Signed-off-by: Matthew DeVore <matvore@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

tests: don't swallow Git errors upstream of pipes

Some pipes in tests lose the exit code of git processes, which can mask
unexpected behavior like crashes. Split these pipes up so that git
commands are only at the end of pipes rather than the beginning or
middle.

The violations fixed in this patch were found in the process of fixing
pipe placement in a prior patch.

Signed-off-by: Matthew DeVore <matvore@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/*: fix ordering of expected/observed arguments

Fix various places where the ordering was obviously wrong, meaning it
was easy to find with grep.

Signed-off-by: Matthew DeVore <matvore@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

tests: standardize pipe placement

Instead of using a line-continuation and pipe on the second line, take
advantage of the shell's implicit line continuation after a pipe
character. So for example, instead of

some long line \
| next line

use

some long line |
next line

And add a blank line before and after the pipe where it aids readability
(it usually does).

This better matches the coding style documented in
Documentation/CodingGuidelines and used in shell scripts elsewhere in
the tree.

Signed-off-by: Matthew DeVore <matvore@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation: add shell guidelines

Add the following guideline to Documentation/CodingGuidelines:

Break overlong lines after "&&", "||", and "|", not before
them; that way the command can continue to subsequent lines
without backslash at the end.

And the following to t/README (since it is specific to writing tests):

Pipes and $(git ...) should be avoided when they swallow exit
codes of Git processes

Signed-off-by: Matthew DeVore <matvore@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/README: reformat Do, Don't, Keep in mind lists

The list of Don'ts for test writing has grown large such that it is hard
to see at a glance which section an item is in. In other words, if I
ignore a little bit of surrounding context, the "don'ts" look like
"do's."

To make the list more readable, prefix "Don't" in front of every first
sentence in the items.

Also, the "Keep in mind" list is out of place and awkward, because it
was a very short "list" beneath two very long ones, and it seemed easy
to miss under the list of "don'ts," and it only had one item. So move
this item to the list of "do's" and phrase as "Remember..."

Signed-off-by: Matthew DeVore <matvore@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

commit-graph: reduce initial oid allocation

While writing a commit-graph file, we store the full list of
commits in a flat list. We use this list for sorting and ensuring
we are closed under reachability.

The initial allocation assumed that (at most) one in four objects
is a commit. This is a dramatic over-count for many repos,
especially large ones. Since we grow the repo dynamically, reduce
this count by a factor of eight. We still set it to a minimum of
1024 before allocating.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/commit-graph.c: UNLEAK variables

`graph_verify()`, `graph_read()` and `graph_write()` do the hard work of
`cmd_commit_graph()`. As soon as these return, so does
`cmd_commit_graph()`.

`strbuf_getline()` may allocate memory in the strbuf, yet return EOF.
We need to release the strbuf or UNLEAK it. Go for the latter since we
are close to returning from `graph_write()`.

`graph_write()` also fails to free the strings in the string list. They
have been added to the list with `strdup_strings` set to 0. We could
flip `strdup_strings` before clearing the list, which is our usual hack
in situations like this. But since we are about to exit, let's just
UNLEAK the whole string list instead.

UNLEAK `graph` in `graph_verify`. While at it, and for consistency,
UNLEAK in `graph_read()` as well, and remove an unnecessary UNLEAK just
before dying.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>