Commit e3696980 (diff: halt tree-diff early after max_changes,
2020-03-30) intended to create a mechanism to short-circuit a diff
calculation after a certain number of paths were modified. By
incrementing a "num_changes" counter throughout the recursive
ll_diff_tree_paths(), this was supposed to match the number of changes
that would be written into the changed-path Bloom filters.
Unfortunately, this was not implemented correctly and instead misses
simple cases like file modifications. This then does not stop very
large changed-path filters from being written (unless they add or remove
many files).
To start, change the implementation in ll_diff_tree_paths() to instead
use the global diff_queue_diff struct's 'nr' member as the count. This
is a way to simplify the logic instead of making more mistakes in the
complicated diff code.
This has a drawback: the diff_queue_diff struct only lists the paths
corresponding to blob changes, not their leading directories. Thus,
get_or_compute_bloom_filter() needs an additional check to see if the
hashmap with the leading directories becomes too large.
One reason why this was not caught by test cases was that the test in
t4216-log-bloom.sh that was supposed to check this "too many changes"
condition only checked this on the initial commit of a repository. The
old logic counted these values correctly. Update this test in a few
ways:
1. Use GIT_TEST_BLOOM_SETTINGS_MAX_CHANGED_PATHS to reduce the limit,
allowing smaller commits to engage with this logic.
2. Create several interesting cases of edits, adds, removes, and mode
changes (in the second commit). By testing both sides of the
inequality with the *_MAX_CHANGED_PATHS variable, we can see that
the count is exactly correct, so none of these changes are missed
or over-counted.
3. Use the trace2 data value filter_found_large to verify that these
commits are on the correct side of the limit.
Another way to verify the behavior is correct is through performance
tests. By testing on my local copies of the Git repository and the Linux
kernel repository, I could measure the effect of these short-circuits
when computing a fresh commit-graph file with changed-path Bloom filters
using the command
GIT_TEST_BLOOM_SETTINGS_MAX_CHANGED_PATHS=N time \
git commit-graph write --reachable --changed-paths
and reporting the wall time and resulting commit-graph size.
For Git, the results are
| | N=1 | N=10 | N=512 |
|--------|----------------|----------------|----------------|
| HEAD~1 | 10.90s 9.18MB | 11.11s 9.34MB | 11.31s 9.35MB |
| HEAD | 9.21s 8.62MB | 11.11s 9.29MB | 11.29s 9.34MB |
For Linux, the results are
| | N=1 | N=20 | N=512 |
|--------|----------------|---------------|---------------|
| HEAD~1 | 61.28s 64.3MB | 76.9s 72.6MB | 77.6s 72.6MB |
| HEAD | 49.44s 56.3MB | 68.7s 65.9MB | 69.2s 65.9MB |
Naturally, the improvement becomes much less as the limit grows, as
fewer commits satisfy the short-circuit.
Reported-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When 'get_or_compute_bloom_filter()' needs to compute a Bloom filter
from scratch, it looks to the default 'struct bloom_filter_settings' in
order to determine the maximum number of changed paths, number of bits
per entry, and so on.
All of these values have so far been constant, and so there was no need
to pass in a pointer from the caller (eg., the one that is stored in the
'struct write_commit_graph_context').
Start passing in a 'struct bloom_filter_settings *' instead of using the
default values to respect graph-specific settings (eg., in the case of
setting 'GIT_TEST_BLOOM_SETTINGS_MAX_CHANGED_PATHS').
In order to have an initialized value for these settings, move its
initialization to earlier in the commit-graph write.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
'get_bloom_filter' takes a flag to control whether it will compute a
Bloom filter if the requested one is missing. In the next patch, we'll
add yet another parameter to this method, which would force all but one
caller to specify an extra 'NULL' parameter at the end.
Instead of doing this, split 'get_bloom_filter' into two functions:
'get_bloom_filter' and 'get_or_compute_bloom_filter'. The former only
looks up a Bloom filter (and does not compute one if it's missing,
thus dropping the 'compute_if_not_present' flag). The latter does
compute missing Bloom filters, with an additional parameter to store
whether or not it needed to do so.
This simplifies many call-sites, since the majority of existing callers
to 'get_bloom_filter' do not want missing Bloom filters to be computed
(so they can drop the parameter entirely and use the simpler version of
the function).
While we're at it, instrument the new 'get_or_compute_bloom_filter()'
with counters in the 'write_commit_graph_context' struct which store
the number of filters that we did and didn't compute, as well as filters
that were truncated.
It would be nice to drop the 'compute_if_not_present' flag entirely,
since all remaining callers of 'get_or_compute_bloom_filter' pass it as
'1', but this will change in a future patch and hence cannot be removed.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
For now, we assume that there is a fixed constant describing the
maximum number of changed paths we are willing to store in a Bloom
filter.
Prepare for that to (at least partially) not be the case by making it a
member of the 'struct bloom_filter_settings'. This will be helpful in
the subsequent patches by reducing the size of test cases that exercise
storing too many changed paths, as well as preparing for an eventual
future in which this value might change.
This patch alone does not cause newly generated Bloom filters to use
a custom upper-bound on the maximum number of changed paths a single
Bloom filter can hold, that will occur in a later patch.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git uses the 'core.commitGraph' configuration value to control whether
or not the commit graph is used when parsing commits or performing a
traversal.
Now that commit-graphs can also contain a section for changed-path Bloom
filters, administrators that already have commit-graphs may find it
convenient to use those graphs without relying on their changed-path
Bloom filters. This can happen, for example, during a staged roll-out,
or in the event of an incident.
Introduce 'commitGraph.readChangedPaths' to control whether or not Bloom
filters are read. Note that this configuration is independent from both:
- 'core.commitGraph', to allow flexibility in using all parts of a
commit-graph _except_ for its Bloom filters.
- The '--changed-paths' option for 'git commit-graph write', to allow
reading and writing Bloom filters to be controlled independently.
When the variable is set, pretend as if no Bloom data was specified at
all. This avoids adding additional special-casing outside of the
commit-graph internals.
Suggested-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The read-graph test-tool is used by a number of the commit-graph test to
assert various properties about a commit-graph. Previously, this program
never ran 'prepare_repo_settings()'. There was no need to do so, since
none of the commit-graph machinery is affected by the repo settings.
In the next patch, the commit-graph machinery's behavior will become
dependent on the repo settings, and so loading them before running the
rest of the test tool is critical.
As such, teach the test tool to call 'prepare_repo_settings()'.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In a future commit, some commit-graph internals will want access to
'r->settings', but we only have the 'struct object_directory *'
corresponding to that repository.
Add an additional parameter to pass the repository around in more
places.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In a759bfa9ee (t4216: add end to end tests for git log with Bloom
filters, 2020-04-06), a 'rm' invocation was added without a
corresponding '&&' chain.
When 'trace.perf' already exists, everything works fine. However, the
function can be executed without 'trace.perf' on disk (eg., when the
subset of tests run is altered with '--run'), and so the bare 'rm'
complains about a missing file.
To remove some noise from the test log, invoke 'rm' with '-f', at which
point it is sensible to place the 'rm -f' in an '&&'-chain, which is
both (1) our usual style, and (2) avoids a broken chain in the future if
more commands are added at the beginning of the function.
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Many places in the code often need a pointer to the commit-graph's
'struct bloom_filter_settings', in which case they often take the value
from the top-most commit-graph.
In the non-split case, this works as expected. In the split case,
however, things get a little tricky. Not all layers in a chain of
incremental commit-graphs are required to themselves have Bloom data,
and so whether or not some part of the code uses Bloom filters depends
entirely on whether or not the top-most level of the commit-graph chain
has Bloom filters.
This has been the behavior since Bloom filters were introduced, and has
been codified into the tests since a759bfa9ee (t4216: add end to end
tests for git log with Bloom filters, 2020-04-06). In fact, t4216.130
requires that Bloom filters are not used in exactly the case described
earlier.
There is no reason that this needs to be the case, since it is perfectly
valid for commits in an earlier layer to have Bloom filters when commits
in a newer layer do not.
Since Bloom settings are guaranteed in practice to be the same for any
layer in a chain that has Bloom data, it is sufficient to traverse the
'->base_graph' pointer until either (1) a non-null 'struct
bloom_filter_settings *' is found, or (2) until we are at the root of
the commit-graph chain.
Introduce a 'get_bloom_filter_settings()' function that does just this,
and use it instead of purely dereferencing the top-most graph's
'->bloom_filter_settings' pointer.
While we're at it, add an additional test in t5324 to guard against code
in the commit-graph writing machinery that doesn't correctly handle a
NULL 'struct bloom_filter *'.
Co-authored-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The pretend-object mechanism checks if the given object already
exists in the object store before deciding to keep the data
in-core, but the check would have triggered lazy fetching of such
an object from a promissor remote.
* jt/pretend-object-never-come-from-elsewhere:
sha1-file: make pretend_object_file() not prefetch
While packing many objects in a repository with a promissor remote,
lazily fetching missing objects from the promissor remote one by
one may be inefficient---the code now attempts to fetch all the
missing objects in batch (obviously this won't work for a lazy
clone that lazily fetches tree objects as you cannot even enumerate
what blobs are missing until you learn which trees are missing).
* jt/pack-objects-prefetch-in-batch:
pack-objects: prefetch objects to be packed
pack-objects: refactor to oid_object_info_extended
"git merge" learned to selectively omit " into <branch>" at the end
of the title of default merge message with merge.suppressDest
configuration.
* jc/fmt-merge-msg-suppress-destination:
fmt-merge-msg: allow merge destination to be omitted again
Revert "fmt-merge-msg: stop treating `master` specially"
b6839fda68 (ref-filter: add support for %(contents:size), 2020-07-16)
added a new format for ref-filter, and added a function to generate
tests for this new feature in t6300. Unfortunately, it tries to run
`test_expect_sucess' instead of `test_expect_success', and writes
$expect to `expected', but tries to read `expect'. Those two issues
were probably unnoticed because the script only printed errors, but did
not crash. This fixes these issues.
Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
523fa69c (reflog: cleanse messages in the refs.c layer, 2020-07-10)
centralized reflog normalizaton. However, the normalizaton added a
leading "\t" to the message. This is an artifact of the reflog
storage format in the files backend, so it should be added there.
Routines that parse back the reflog (such as grab_nth_branch_switch)
expect the "\t" to not be in the message, so without this fix, git
with reftable cannot process the "@{-1}" syntax.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
CI fixup---tests of Python scripts didn't use the version of Git
that is being tested.
* sg/ci-git-path-fix-with-pyenv:
ci: use absolute PYTHON_PATH in the Linux jobs
"git mv src dst", when src is an unmerged path, errored out
correctly but with an incorrect error message to claim that src is
not tracked, which has been clarified.
* ct/mv-unmerged-path-error:
git-mv: improve error message for conflicted file
Pushing a ref whose name contains non-ASCII character with the
"--force-with-lease" option did not work over smart HTTP protocol,
which has been corrected.
* bc/push-cas-cquoted-refname:
remote-curl: make --force-with-lease work with non-ASCII ref names
"git for-each-ref --format=<>" learned %(contents:size).
* cc/pretty-contents-size:
ref-filter: add support for %(contents:size)
t6300: test refs pointing to tree and blob
Documentation: clarify %(contents:XXXX) doc
Fetching from a lazily cloned repository resulted at the server
side in attempts to lazy fetch objects that the client side has,
many of which will not be available from the third-party anyway.
* jt/avoid-lazy-fetching-upon-have-check:
upload-pack: do not lazy-fetch "have" objects
Dev support to limit the use of test_must_fail to only git commands.
* dl/test-must-fail-fixes-6:
test-lib-functions: restrict test_must_fail usage
t9400: don't use test_must_fail with cvs
t9834: remove use of `test_might_fail p4`
t7107: don't use test_must_fail()
t5324: reorder `run_with_limited_open_files test_might_fail`
t3701: stop using `env` in force_color()
With the base fix to 2.27 regresion, any new extensions in a v0
repository would still be silently honored, which is not quite
right. Instead, complain and die loudly.
* jk/reject-newer-extensions-in-v0:
verify_repository_format(): complain about new extensions in v0 repo
Preliminary clean-up of the refs API in preparation for adding a
new refs backend "reftable".
* hn/reftable:
reflog: cleanse messages in the refs.c layer
bisect: treat BISECT_HEAD as a pseudo ref
t3432: use git-reflog to inspect the reflog for HEAD
lib-t6000.sh: write tag using git-update-ref
"git clone --separate-git-dir=$elsewhere" used to stomp on the
contents of the existing directory $elsewhere, which has been
taught to fail when $elsewhere is not an empty directory.
* bw/fail-cloning-into-non-empty:
git clone: don't clone into non-empty directory
"git help log" has been enhanced by sharing more material from the
documentation for the underlying "git rev-list" command.
* pb/log-rev-list-doc:
git-log.txt: include rev-list-description.txt
git-rev-list.txt: move description to separate file
git-rev-list.txt: tweak wording in set operations
git-rev-list.txt: fix Asciidoc syntax
revisions.txt: describe 'rev1 rev2 ...' meaning for ranges
git-log.txt: add links to 'rev-list' and 'diff' docs
The test framework has been updated so that most tests will run
with predictable (artificial) timestamps.
* jk/tests-timestamp-fix:
t9100: stop depending on commit timestamps
test-lib: set deterministic default author/committer date
t9100: explicitly unset GIT_COMMITTER_DATE
t5539: make timestamp requirements more explicit
t9700: loosen ident timezone regex
t6000: use test_tick consistently
Updates to the changed-paths bloom filter.
* ds/commit-graph-bloom-updates:
commit-graph: check all leading directories in changed path Bloom filters
revision: empty pathspecs should not use Bloom filters
revision.c: fix whitespace
commit-graph: check chunk sizes after writing
commit-graph: simplify chunk writes into loop
commit-graph: unify the signatures of all write_graph_chunk_*() functions
commit-graph: persist existence of changed-paths
bloom: fix logic in get_bloom_filter()
commit-graph: change test to die on parse, not load
commit-graph: place bloom_settings in context
The changed-path Bloom filter is improved using ideas from an
independent implementation.
* sg/commit-graph-cleanups:
commit-graph: simplify write_commit_graph_file() #2
commit-graph: simplify write_commit_graph_file() #1
commit-graph: simplify parse_commit_graph() #2
commit-graph: simplify parse_commit_graph() #1
commit-graph: clean up #includes
diff.h: drop diff_tree_oid() & friends' return value
commit-slab: add a function to deep free entries on the slab
commit-graph-format.txt: all multi-byte numbers are in network byte order
commit-graph: fix parsing the Chunk Lookup table
tree-walk.c: don't match submodule entries for 'submod/anything'
In Git 2.28, we stopped special casing 'master' when producing the
default merge message by just removing the code to squelch "into
'master'" at the end of the message.
Introduce multi-valued merge.suppressDest configuration variable
that gives a set of globs to match against the name of the branch
into which the merge is being made, to let users specify for which
branch fmt-merge-msg's output should be shortened. When it is not
set, 'master' is used as the sole value of the variable by default.
The above move mostly reverts the pre-2.28 default in repositories
that have no relevant configuration.
Add a few tests to protect the behaviour with the new configuration
variable from future regression.
Helped-by: Linus Torvalds <torvalds@linux-foundation.org>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This reverts commit 489947cee5, which
stopped treating merges into the 'master' branch as special when
preparing the default merge message. As the goal was not to have
any single branch designated as special, it solved it by leaving the
"into <branchname>" at the end of the title of the default merge
message for any and all branches. An obvious and easy alternative
to treat everybody equally could have been to remove it for every
branch, but that involves loss of information.
We'll introduce a new mechanism to let end-users specify merges into
which branches would omit the "into <branchname>" from the title of
the default merge message, and make the mechanism, when unconfigured,
treat the traditional 'master' special again, so all the changes to
the tests we made earlier will become unnecessary, as these tests
will be run without configuring the said new mechanism.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit fixes a couple of minor spelling mistakes inside
comments.
Signed-off-by: Steve Kemp <steve@steve.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fix typos introduced in commit a133737b80 ("doc: include --guide option
description for "git help"", 2013-04-02).
Signed-off-by: Andrei Rybak <rybak.a.v@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
parse_object_or_die() is passed an object ID and a name to show if the
object cannot be parsed. If the name is NULL then it shows the
hexadecimal object ID. Use that feature instead of preparing and
passing the hexadecimal representation to the function proactively.
That's shorter and a bit more efficient.
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
