"git pack-objects" learns to find delta bases from blobs at the
same path, using the --path-walk API.
* ds/path-walk-2:
pack-objects: allow --shallow and --path-walk
path-walk: add new 'edge_aggressive' option
pack-objects: thread the path-based compression
pack-objects: refactor path-walk delta phase
scalar: enable path-walk during push via config
pack-objects: enable --path-walk via config
repack: add --path-walk option
t5538: add tests to confirm deltas in shallow pushes
pack-objects: introduce GIT_TEST_PACK_PATH_WALK
p5313: add performance tests for --path-walk
pack-objects: update usage to match docs
pack-objects: add --path-walk option
pack-objects: extract should_attempt_deltas()
There are many tests that validate whether 'git pack-objects' works as
expected. Instead of duplicating these tests, add a new test environment
variable, GIT_TEST_PACK_PATH_WALK, that implies --path-walk by default
when specified.
This was useful in testing the implementation of the --path-walk
implementation, helping to find tests that are overly specific to the
default object walk. These include:
- t0411-clone-from-partial.sh : One test fetches from a repo that does
not have the boundary objects. This causes the path-based walk to
fail. Disable the variable for this test.
- t5306-pack-nobase.sh : Similar to t0411, one test fetches from a repo
without a boundary object.
- t5310-pack-bitmaps.sh : One test compares the case when packing with
bitmaps to the case when packing without them. Since we disable the
test variable when writing bitmaps, this causes a difference in the
object list (the --path-walk option adds an extra object). Specify
--no-path-walk in both processes for the comparison. Another test
checks for a specific delta base, but when computing dynamically
without using bitmaps, the base object it too small to be considered
in the delta calculations so no base is used.
- t5316-pack-delta-depth.sh : This script cares about certain delta
choices and their chain lengths. The --path-walk option changes how
these chains are selected, and thus changes the results of this test.
- t5322-pack-objects-sparse.sh : This demonstrates the effectiveness of
the --sparse option and how it combines with --path-walk.
- t5332-multi-pack-reuse.sh : This test verifies that the preferred
pack is used for delta reuse when possible. The --path-walk option is
not currently aware of the preferred pack at all, so finds a
different delta base.
- t7406-submodule-update.sh : When using the variable, the --depth
option collides with the --path-walk feature, resulting in a warning
message. Disable the variable so this warning does not appear.
I want to call out one specific test change that is only temporary:
- t5530-upload-pack-error.sh : One test cares specifically about an
"unable to read" error message. Since the current implementation
performs delta calculations within the path-walk API callback, a
different "unable to get size" error message appears. When this
is changed in a future refactoring, this test change can be reverted.
Similar to GIT_TEST_NAME_HASH_VERSION, we do not add this option to the
linux-TEST-vars CI build as that's already an overloaded build.
Signed-off-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The `max_chain()` helper function is used to extract the maximum delta
chain of a packfile as printed by git-index-pack(1). The script uses
Perl to extract that data, but it can be trivially refactored to use
awk(1) instead.
Refactor the helper accordingly so that we can drop a couple of
PERL_TEST_HELPERS prerequisites.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In the early days of Git, Perl was used quite prominently throughout the
project. This has changed significantly as almost all of the executables
we ship nowadays have eventually been rewritten in C. Only a handful of
subsystems remain that require Perl:
- gitweb, a read-only web interface.
- A couple of scripts that allow importing repositories from GNU Arch,
CVS and Subversion.
- git-send-email(1), which can be used to send mails.
- git-request-pull(1), which is used to request somebody to pull from
a URL by sending an email.
- git-filter-branch(1), which uses Perl with the `--state-branch`
option. This command is typically recommended against nowadays in
favor of git-filter-repo(1).
- Our Perl bindings for Git.
- The netrc Git credential helper.
None of these subsystems can really be considered to be part of the
"core" of Git, and an installation without them is fully functional.
It is more likely than not that an end user wouldn't even notice that
any features are missing if those tools weren't installed. But while
Perl nowadays very much is an optional dependency of Git, there is a
significant limitation when Perl isn't available: developers cannot run
our test suite.
Preceding commits have started to lift this restriction by removing the
strict dependency on Perl in many central parts of the test library. But
there are still many tests that rely on small Perl helpers to do various
different things.
Introduce a new PERL_TEST_HELPERS prerequisite that guards all tests
that require Perl. This prerequisite is explicitly different than the
preexisting PERL prerequisite:
- PERL records whether or not features depending on the Perl
interpreter are built.
- PERL_TEST_HELPERS records whether or not a Perl interpreter is
available for our tests.
By having these two separate prerequisites we can thus distinguish
between tests that inherently depend on Perl because the underlying
feature does, and those tests that depend on Perl because the test
itself is using Perl.
Adapt all tests to set the PERL_TEST_HELPERS prerequisite as needed.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Now that the default value for TEST_PASSES_SANITIZE_LEAK is `true` there
is no longer a need to have that variable declared in all of our tests.
Drop it.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Extend the the release_revisions() function so that it frees the
"filter" in the "struct rev_info". This in combination with a
preceding change to free "cmdline" means that we can mark another set
of tests as passing under "TEST_PASSES_SANITIZE_LEAK=true".
The "filter" member was added recently in ffaa137f646 (revision: put
object filter into struct rev_info, 2022-03-09), and this fixes leaks
intruded in the subsequent leak 7940941de1f (pack-objects: use
rev.filter when possible, 2022-03-09) and 105c6f14ad3 (bundle: parse
filter capability, 2022-03-09).
The "builtin/pack-objects.c" leak in 7940941de1f was effectively with
us already, but the variable was referred to by a "static" file-scoped
variable. The "bundle.c " leak in 105c6f14ad3 was newly introduced
with the new "filter" feature for bundles.
The "t5600-clone-fail-cleanup.sh" change here to add
"TEST_PASSES_SANITIZE_LEAK=true" is one of the cases where
run-command.c in not carrying the abort() exit code upwards would have
had that test passing before, but now it *actually* passes[1]. We
should fix the lack of 1=1 mapping of SANITIZE=leak testing to actual
leaks some other time, but it's an existing edge case, let's just mark
the really-passing test as passing for now.
1. https://lore.kernel.org/git/220303.86fsnz5o9w.gmgdl@evledraar.gmail.com/
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Further tweaks on progress API.
* ab/only-single-progress-at-once:
pack-bitmap-write.c: don't return without stop_progress()
progress API: unify stop_progress{,_msg}(), fix trace2 bug
progress.c: refactor stop_progress{,_msg}() to use helpers
progress.c: use dereferenced "progress" variable, not "(*p_progress)"
progress.h: format and be consistent with progress.c naming
progress.c tests: test some invalid usage
progress.c tests: make start/stop commands on stdin
progress.c test helper: add missing braces
leak tests: fix a memory leak in "test-progress" helper
Fix a bug that's been with us ever since 98a13647408 (trace2: log
progress time and throughput, 2020-05-12), when the
stop_progress_msg() API was used we didn't log a "region_leave" for
the "region_enter" we start in "start_progress_delay()".
The only user of the "stop_progress_msg()" function is
"index-pack". Let's add a previously failing test to check that we
have the same number of "region_enter" and "region_leave" events, with
"-v" we'll log progress even in the test environment.
In addition to that we've had a submarine bug here introduced with
9d81ecb52b5 (progress: add sparse mode to force 100% complete message,
2019-03-21). The "start_sparse_progress()" API would only do the right
thing if the progress was ended with "stop_progress()", not
"stop_progress_msg()".
The only user of that API uses "stop_progress()", but let's still fix
that along with the trace2 issue by making "stop_progress()" a trivial
wrapper for "stop_progress_msg()".
We can also drop the "if (progress)" test from
"finish_if_sparse()". It's now a helper for the small
"stop_progress_msg()" function. We'll already have returned from it if
"progress" is "NULL".
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The top-level &&-chain checker built into t/test-lib.sh causes tests to
magically exit with code 117 if the &&-chain is broken. However, it has
the shortcoming that the magic does not work within `{...}` groups,
`(...)` subshells, `$(...)` substitutions, or within bodies of compound
statements, such as `if`, `for`, `while`, `case`, etc. `chainlint.sed`
partly fills in the gap by catching broken &&-chains in `(...)`
subshells, but bugs can still lurk behind broken &&-chains in the other
cases.
Fix broken &&-chains in `{...}` groups in order to reduce the number of
possible lurking bugs.
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A negative delta depth makes no sense, and the code is not prepared to
handle it. If passed "--depth=-1" on the command line, then this line
from break_delta_chains():
cur->depth = (total_depth--) % (depth + 1);
triggers a divide-by-zero. This is undefined behavior according to the C
standard, but on POSIX systems results in SIGFPE killing the process.
This is certainly one way to inform the use that the command was
invalid, but it's a bit friendlier to just treat it as "don't allow any
deltas", which we already do for --depth=0.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We'd expect this to cleanly produce no deltas at all (as opposed to
getting confused by an out-of-bounds value), and it does.
Note we have to adjust our max_chain test helper, which expected to find
at least one delta.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As a follow-up to d162b25f956 (tests: remove support for
GIT_TEST_GETTEXT_POISON, 2021-01-20) remove most uses of test_i18ncmp
via a simple s/test_i18ncmp/test_cmp/g search-replacement.
I'm leaving t6300-for-each-ref.sh out due to a conflict with in-flight
changes between "master" and "seen", as well as the prerequisite
itself due to other changes between "master" and "next/seen" which add
new test_i18ncmp uses.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The GETTEXT_POISON=YesPlease compile-time testing option added in my
bb946bba76 ("i18n: add GETTEXT_POISON to simulate unfriendly
translator", 2011-02-22) has been slowly bitrotting as strings have
been marked for translation, and new tests have been added without
running it.
I brought this up on the list ("[BUG] test suite broken with
GETTEXT_POISON=YesPlease", [1]) asking whether this mode was useful at
all anymore. At least one person occasionally uses it, and Lars
Schneider offered to change one of the the Travis builds to run in
this mode, so fix up the failing ones.
My test setup runs most of the tests, with the notable exception of
skipping all the p4 tests, so it's possible that there's still some
lurking regressions I haven't fixed.
1. <CACBZZX62+acvi1dpkknadTL827mtCm_QesGSZ=6+UnyeMpg8+Q@mail.gmail.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Since 898b14c (pack-objects: rework check_delta_limit usage,
2007-04-16), we check the delta depth limit only when
figuring out whether we should make a new delta. We don't
consider it at all when reusing deltas, which means that
packing once with --depth=250, and then again with
--depth=50, the second pack may still contain chains larger
than 50.
This is generally considered a feature, as the results of
earlier high-depth repacks are carried forward, used for
serving fetches, etc. However, since we started using
cross-pack deltas in c9af708b1 (pack-objects: use mru list
when iterating over packs, 2016-08-11), we are no longer
bounded by the length of an existing delta chain in a single
pack.
Here's one particular pathological case: a sequence of N
packs, each with 2 objects, the base of which is stored as a
delta in a previous pack. If we chain all the deltas
together, we have a cycle of length N. We break the cycle,
but the tip delta is still at depth N-1.
This is less unlikely than it might sound. See the included
test for a reconstruction based on real-world actions. I
ran into such a case in the wild, where a client was rapidly
sending packs, and we had accumulated 10,000 before doing a
server-side repack. The pack that "git repack" tried to
generate had a very deep chain, which caused pack-objects to
run out of stack space in the recursive write_one().
This patch bounds the length of delta chains in the output
pack based on --depth, regardless of whether they are caused
by cross-pack deltas or existed in the input packs. This
fixes the problem, but does have two possible downsides:
1. High-depth aggressive repacks followed by "normal"
repacks will throw away the high-depth chains.
In the long run this is probably OK; investigation
showed that high-depth repacks aren't actually
beneficial, and we dropped the aggressive depth default
to match the normal case in 07e7dbf0d (gc: default
aggressive depth to 50, 2016-08-11).
2. If you really do want to store high-depth deltas on
disk, they may be discarded and new delta computed when
serving a fetch, unless you set pack.depth to match
your high-depth size.
The implementation uses the existing search for delta
cycles. That lets us compute the depth of any node based on
the depth of its base, because we know the base is DFS_DONE
by the time we look at it (modulo any cycles in the graph,
but we know there cannot be any because we break them as we
see them).
There is some subtlety worth mentioning, though. We record
the depth of each object as we compute it. It might seem
like we could save the per-object storage space by just
keeping track of the depth of our traversal (i.e., have
break_delta_chains() report how deep it went). But we may
visit an object through multiple delta paths, and on
subsequent paths we want to know its depth immediately,
without having to walk back down to its final base (doing so
would make our graph walk quadratic rather than linear).
Likewise, one could try to record the depth not from the
base, but from our starting point (i.e., start
recursion_depth at 0, and pass "recursion_depth + 1" to each
invocation of break_delta_chains()). And then when
recursion_depth gets too big, we know that we must cut the
delta chain. But that technique is wrong if we do not visit
the nodes in topological order. In a chain A->B->C, it
if we visit "C", then "B", then "A", we will never recurse
deeper than 1 link (because we see at each node that we have
already visited it).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
