Commit Graph

100 Commits

Author SHA1 Message Date
Ævar Arnfjörð Bjarmason
5cf88fd8b0 git-compat-util.h: use "UNUSED", not "UNUSED(var)"
As reported in [1] the "UNUSED(var)" macro introduced in
2174b8c75de (Merge branch 'jk/unused-annotation' into next,
2022-08-24) breaks coccinelle's parsing of our sources in files where
it occurs.

Let's instead partially go with the approach suggested in [2] of
making this not take an argument. As noted in [1] "coccinelle" will
ignore such tokens in argument lists that it doesn't know about, and
it's less of a surprise to syntax highlighters.

This undoes the "help us notice when a parameter marked as unused is
actually use" part of 9b24034754 (git-compat-util: add UNUSED macro,
2022-08-19), a subsequent commit will further tweak the macro to
implement a replacement for that functionality.

1. https://lore.kernel.org/git/220825.86ilmg4mil.gmgdl@evledraar.gmail.com/
2. https://lore.kernel.org/git/220819.868rnk54ju.gmgdl@evledraar.gmail.com/

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-09-01 10:49:48 -07:00
Jeff King
63e14ee2d6 refs: mark unused each_ref_fn parameters
Functions used with for_each_ref(), etc, need to conform to the
each_ref_fn interface. But most of them don't need every parameter;
let's annotate the unused ones to quiet -Wunused-parameter.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-08-19 12:18:54 -07:00
Alexander Shopov
325240dfd7 name-rev: prefix annotate-stdin with '--' in message
This is an option rather than command.  Make the message convey this
similar to the other messages in the file.

Signed-off-by: Alexander Shopov <ash@kambanaria.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-06-20 16:20:45 -07:00
Junio C Hamano
096b082b2a Merge branch 'rs/name-rev-fix-free-after-use'
Regression fix for 2.36 where "git name-rev" started to sometimes
reference strings after they are freed.

* rs/name-rev-fix-free-after-use:
  Revert "name-rev: release unused name strings"
2022-04-28 10:46:04 -07:00
René Scharfe
45a14f578e Revert "name-rev: release unused name strings"
This reverts commit 2d53975488.

3656f84278 (name-rev: prefer shorter names over following merges,
2021-12-04) broke the assumption of 2d53975488 (name-rev: release unused
name strings, 2020-02-04) that a better name for a child is a better
name for all of its ancestors as well, because it added a penalty for
generation > 0.  This leads to strings being free(3)'d that are still
needed.

079f970971 (name-rev: sort tip names before applying, 2020-02-05)
already reduced the number of free(3) calls for the use case that
motivated the original patch (name-rev --all in the Chromium repository)
from ca. 44000 to 5, and 3656f84278 eliminated even those few.  So this
revert won't affect name-rev's performance on that particular repo.

Reported-by: Thomas Hurst <tom@hur.st>
Helped-by: Elijah Newren <newren@gmail.com>
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-04-23 09:46:40 -07:00
Jacob Keller
2e8ea40fe3 name-rev: use generation numbers if available
If a commit in a sequence of linear history has a non-monotonically
increasing commit timestamp, git name-rev might not properly name the
commit.

This occurs because name-rev uses a heuristic of the commit date to
avoid searching down tags which lead to commits that are older than the
named commit. This is intended to avoid work on larger repositories.

This heuristic impacts git name-rev, and by extension git describe
--contains which is built on top of name-rev.

Further more, if --all or --annotate-stdin is used, the heuristic is not
enabled because the full history has to be analyzed anyways. This
results in some confusion if a user sees that --annotate-stdin works but
a normal name-rev does not.

If the repository has a commit graph, we can use the generation numbers
instead of using the commit dates. This is essentially the same check
except that generation numbers make it exact, where the commit date
heuristic could be incorrect due to clock errors.

Since we're extending the notion of cutoff to more than one variable,
create a series of functions for setting and checking the cutoff. This
avoids duplication and moves access of the global cutoff and
generation_cutoff to as few functions as possible.

Add several test cases including a test that covers the new commitGraph
behavior, as well as tests for --all and --annotate-stdin with and
without commitGraphs.

Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-03-13 18:39:29 +00:00
John Cai
d271892fbc name-rev: replace --stdin with --annotate-stdin in synopsis
34ae3b70 (name-rev: deprecate --stdin in favor of --annotate-stdin,
2022-01-05) added --annotate-stdin to replace --stdin as a clearer
flag name. Since --stdin is to be deprecated, we should replace
--stdin in the output from "git name-rev -h".

Signed-off-by: John Cai <johncai86@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-02-15 17:37:43 -08:00
John Cai
a2585719b3 name-rev.c: use strbuf_getline instead of limited size buffer
Using a buffer limited to 2048 is unnecessarily limiting. Switch to
using a string buffer to read in stdin for annotation.

Signed-off-by: "John Cai" <johncai86@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-10 09:39:26 -08:00
John Cai
34ae3b7071 name-rev: deprecate --stdin in favor of --annotate-stdin
Introduce a --annotate-stdin that is functionally equivalent of --stdin.
--stdin does not behave as --stdin in other subcommands, such as
pack-objects whereby it takes one argument per line. Since --stdin can
be a confusing and misleading name, rename it to --annotate-stdin.

This change adds a warning to --stdin warning that it will be removed in
the future.

Signed-off-by: "John Cai" <johncai86@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-10 09:39:26 -08:00
Elijah Newren
3656f84278 name-rev: prefer shorter names over following merges
name-rev has a MERGE_TRAVERSAL_WEIGHT to say that traversing a second or
later parent of a merge should be 65535 times more expensive than a
first-parent traversal, as per ac076c29ae (name-rev: Fix non-shortest
description, 2007-08-27).  The point of this weight is to prefer names
like

    v2.32.0~1471^2

over names like

    v2.32.0~43^2~15^2~11^2~20^2~31^2

which are two equally valid names in git.git for the same commit.  Note
that the first follows 1472 parent traversals compared to a mere 125 for
the second.  Weighting all traversals equally would clearly prefer the
second name since it has fewer parent traversals, but humans aren't
going to be traversing commits and they tend to have an easier time
digesting names with fewer segments.  The fact that the former only has
two segments (~1471, ^2) makes it much simpler than the latter which has
six segments (~43, ^2, ~15, etc.).  Since name-rev is meant to "find
symbolic names suitable for human digestion", we prefer fewer segments.

However, the particular rule implemented in name-rev would actually
prefer

    v2.33.0-rc0~11^2~1

over

    v2.33.0-rc0~20^2

because both have precisely one second parent traversal, and it gives
the tie breaker to shortest number of total parent traversals.  Fewer
segments is more important for human consumption than number of hops, so
we'd rather see the latter which has one fewer segment.

Include the generation in is_better_name() and use a new
effective_distance() calculation so that we prefer fewer segments in
the printed name over fewer total parent traversals performed to get the
answer.

== Side-note on tie-breakers ==

When there are the same number of segments for two different names, we
actually use the name of an ancestor commit as a tie-breaker as well.
For example, for the commit cbdca289fb in the git.git repository, we
prefer the name v2.33.0-rc0~112^2~1 over v2.33.0-rc0~57^2~5.  This is
because:

  * cbdca289fb is the parent of 25e65b6dd5, which implies the name for
    cbdca289fb should be the first parent of the preferred name for
    25e65b6dd5
  * 25e65b6dd5 could be named either v2.33.0-rc0~112^2 or
    v2.33.0-rc0~57^2~4, but the former is preferred over the latter due
    to fewer segments
  * combine the two previous facts, and the name we get for cbdca289fb
    is "v2.33.0-rc0~112^2~1" rather than "v2.33.0-rc0~57^2~5".

Technically, we get this for free out of the implementation since we
only keep track of one name for each commit as we walk history (and
re-add parents to the queue if we find a better name for those parents),
but the first bullet point above ensures users get results that feel
more consistent.

== Alternative Ideas and Meanings Discussed ==

One suggestion that came up during review was that shortest
string-length might be easiest for users to consume.  However, such a
scheme would be rather computationally expensive (we'd have to track all
names for each commit as we traversed the graph) and would additionally
come with the possibly perplexing result that on a linear segment of
history we could rapidly swap back and forth on names:
   MYTAG~3^2     would     be preferred over   MYTAG~9998
   MYTAG~3^2~1   would NOT be preferred over   MYTAG~9999
   MYTAG~3^2~2   might     be preferred over   MYTAG~10000

Another item that came up was possible auxiliary semantic meanings for
name-rev results either before or after this patch.  The basic answer
was that the previous implementation had no known useful auxiliary
semantics, but that for many repositories (most in my experience), the
new scheme does.  In particular, the new name-rev output can often be
used to answer the question, "How or when did this commit get merged?"
Since that usefulness depends on how merges happen within the repository
and thus isn't universally applicable, details are omitted here but you
can see them at [1].

[1] https://lore.kernel.org/git/CABPp-BEeUM+3NLKDVdak90_UUeNghYCx=Dgir6=8ixvYmvyq3Q@mail.gmail.com/

Finally, it was noted that the algorithm could be improved by just
explicitly tracking the number of segments and using both it and
distance in the comparison, instead of giving a magic number that tries
to blend the two (and which therefore might give suboptimal results in
repositories with really huge numbers of commits that periodically merge
older code).  However, "[this patch] seems to give us a much better
results than the current code, so let's take it and leave further
futzing outside the scope."

Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Acked-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-04 23:39:34 -08:00
Jeff King
8380dcd700 oid_pos(): access table through const pointers
When we are looking up an oid in an array, we obviously don't need to
write to the array. Let's mark it as const in the function interfaces,
as well as in the local variables we use to derference the void pointer
(note a few cases use pointers-to-pointers, so we mark everything
const).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-28 12:03:26 -08:00
Jeff King
45ee13b942 hash_pos(): convert to oid_pos()
All of our callers are actually looking up an object_id, not a bare
hash. Likewise, the arrays they are looking in are actual arrays of
object_id (not just raw bytes of hashes, as we might find in a pack
.idx; those are handled by bsearch_hash()).

Using an object_id gives us more type safety, and makes the callers
slightly shorter. It also gets rid of the word "sha1" from several
access functions, though we could obviously also rename those with
s/sha1/hash/.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-28 12:02:39 -08:00
Martin Ågren
bc62692757 hash-lookup: rename from sha1-lookup
Change all remnants of "sha1" in hash-lookup.c and .h and rename them to
reflect that we're not just able to handle SHA-1 these days.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Reviewed-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-04 13:01:55 -08:00
Martin Ågren
7a7d992d0d sha1-lookup: rename sha1_pos() as hash_pos()
Rename this function to reflect that we're not just able to handle SHA-1
these days. There are a few instances of "sha1" left in sha1-lookup.[ch]
after this, but those will be addressed in the next commit.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Reviewed-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-04 13:01:55 -08:00
Junio C Hamano
4279000d3e messages: avoid SHA-1 in end-user facing messages
There are still a handful mentions of SHA-1 when we meant the
(hexadecimal) object names in end-user facing messages.  Rewrite
them.

I was hoping that this can mostly be s/SHA-1/object name/, but
a few messages needed rephrasing to keep the result readable.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-08-14 09:33:37 -07:00
René Scharfe
079f970971 name-rev: sort tip names before applying
name_ref() is called for each ref and checks if its a better name for
the referenced commit.  If that's the case it remembers it and checks if
a name based on it is better for its ancestors as well.  This in done in
the the order for_each_ref() imposes on us.

That might not be optimal.  If bad names happen to be encountered first
(as defined by is_better_name()), names derived from them may spread to
a lot of commits, only to be replaced by better names later.  Setting
better names first can avoid that.

is_better_name() prefers tags, short distances and old references.  The
distance is a measure that we need to calculate for each candidate
commit, but the other two properties are not dependent on the
relationships of commits.  Sorting the refs by them should yield better
performance than the essentially random order we currently use.

And applying older references first should also help to reduce rework
due to the fact that older commits have less ancestors than newer ones.

So add all details of names to the tip table first, then sort them
to prefer tags and older references and then apply them in this order.
Here's the performance as measures by hyperfine for the Linux repo
before:

Benchmark #1: ./git -C ../linux/ name-rev --all
  Time (mean ± σ):     851.1 ms ±   4.5 ms    [User: 806.7 ms, System: 44.4 ms]
  Range (min … max):   845.9 ms … 859.5 ms    10 runs

... and with this patch:

Benchmark #1: ./git -C ../linux/ name-rev --all
  Time (mean ± σ):     736.2 ms ±   8.7 ms    [User: 688.4 ms, System: 47.5 ms]
  Range (min … max):   726.0 ms … 755.2 ms    10 runs

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:36:33 -08:00
René Scharfe
2d53975488 name-rev: release unused name strings
name_rev() assigns a name to a commit and its parents and grandparents
and so on.  Commits share their name string with their first parent,
which in turn does the same, recursively to the root.  That saves a lot
of allocations.  When a better name is found, the old name is replaced,
but its memory is not released.  That leakage can become significant.

Can we release these old strings exactly once even though they are
referenced multiple times?  Yes, indeed -- we can make use of the fact
that name_rev() visits the ancestors of a commit after it set a new name
for it and tries to update their names as well.

Members of the first ancestral line have the same taggerdate and
from_tag values, but a higher distance value than their child commit at
generation 0.  These are the only criteria used by is_better_name().
Lower distance values are considered better, so a name that is better
for a child will also be better for its parent and grandparent etc.

That means we can free(3) an inferior name at generation 0 and rely on
name_rev() to replace all references in ancestors as well.

If we do that then we need to stop using the string pointer alone to
distinguish new empty rev_name slots from initialized ones, though, as
it technically becomes invalid after the free(3) call -- even though its
value is still different from NULL.

We can check the generation value first, as empty slots will have it
initialized to 0, and for the actual generation 0 we'll set a new valid
name right after the create_or_update_name() call that releases the
string.

For the Chromium repo, releasing superceded names reduces the memory
footprint of name-rev --all significantly.  Here's the output of GNU
time before:

0.98user 0.48system 0:01.46elapsed 99%CPU (0avgtext+0avgdata 2601812maxresident)k
0inputs+0outputs (0major+571470minor)pagefaults 0swaps

... and with this patch:

1.01user 0.26system 0:01.28elapsed 100%CPU (0avgtext+0avgdata 1559196maxresident)k
0inputs+0outputs (0major+314370minor)pagefaults 0swaps

It also gets faster; hyperfine before:

Benchmark #1: ./git -C ../chromium/src name-rev --all
  Time (mean ± σ):      1.534 s ±  0.006 s    [User: 1.039 s, System: 0.494 s]
  Range (min … max):    1.522 s …  1.542 s    10 runs

... and with this patch:

Benchmark #1: ./git -C ../chromium/src name-rev --all
  Time (mean ± σ):      1.338 s ±  0.006 s    [User: 1.047 s, System: 0.291 s]
  Range (min … max):    1.327 s …  1.346 s    10 runs

For the Linux repo it doesn't pay off; memory usage only gets down from:

0.76user 0.03system 0:00.80elapsed 99%CPU (0avgtext+0avgdata 292848maxresident)k
0inputs+0outputs (0major+44579minor)pagefaults 0swaps

... to:

0.78user 0.03system 0:00.81elapsed 100%CPU (0avgtext+0avgdata 284696maxresident)k
0inputs+0outputs (0major+44892minor)pagefaults 0swaps

The runtime actually increases slightly from:

Benchmark #1: ./git -C ../linux/ name-rev --all
  Time (mean ± σ):     828.8 ms ±   5.0 ms    [User: 797.2 ms, System: 31.6 ms]
  Range (min … max):   824.1 ms … 838.9 ms    10 runs

... to:

Benchmark #1: ./git -C ../linux/ name-rev --all
  Time (mean ± σ):     847.6 ms ±   3.4 ms    [User: 807.9 ms, System: 39.6 ms]
  Range (min … max):   843.4 ms … 854.3 ms    10 runs

Why is that?  In the Chromium repo, ca. 44000 free(3) calls in
create_or_update_name() release almost 1GB, while in the Linux repo
240000+ calls release a bit more than 5MB, so the average discarded
name is ca.  1000x longer in the latter.

Overall I think it's the right tradeoff to make, as it helps curb the
memory usage in repositories with big discarded names, and the added
overhead is small.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:24:15 -08:00
René Scharfe
977dc1912b name-rev: generate name strings only if they are better
Leave setting the tip_name member of struct rev_name to callers of
create_or_update_name().  This avoids allocations for names that are
rejected by that function.  Here's how this affects the runtime when
working with a fresh clone of Git's own repository; performance numbers
by hyperfine before:

Benchmark #1: ./git -C ../git-pristine/ name-rev --all
  Time (mean ± σ):     437.8 ms ±   4.0 ms    [User: 422.5 ms, System: 15.2 ms]
  Range (min … max):   432.8 ms … 446.3 ms    10 runs

... and with this patch:

Benchmark #1: ./git -C ../git-pristine/ name-rev --all
  Time (mean ± σ):     408.5 ms ±   1.4 ms    [User: 387.2 ms, System: 21.2 ms]
  Range (min … max):   407.1 ms … 411.7 ms    10 runs

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:24:15 -08:00
René Scharfe
1c56fc2084 name-rev: pre-size buffer in get_parent_name()
We can calculate the size of new name easily and precisely. Open-code
the xstrfmt() calls and grow the buffers as needed before filling them.
This provides a surprisingly large benefit when working with the
Chromium repository; here are the numbers measured using hyperfine
before:

Benchmark #1: ./git -C ../chromium/src name-rev --all
  Time (mean ± σ):      5.822 s ±  0.013 s    [User: 5.304 s, System: 0.516 s]
  Range (min … max):    5.803 s …  5.837 s    10 runs

... and with this patch:

Benchmark #1: ./git -C ../chromium/src name-rev --all
  Time (mean ± σ):      1.527 s ±  0.003 s    [User: 1.015 s, System: 0.511 s]
  Range (min … max):    1.524 s …  1.535 s    10 runs

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:24:15 -08:00
René Scharfe
ddc42ec786 name-rev: factor out get_parent_name()
Reduce nesting by moving code to come up with a name for the parent into
its own function.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:24:15 -08:00
René Scharfe
f13ca7cef5 name-rev: put struct rev_name into commit slab
The commit slab commit_rev_name contains a pointer to a struct rev_name,
and the actual struct is allocated separatly.  Avoid that allocation and
pointer indirection by storing the full struct in the commit slab.  Use
the tip_name member pointer to determine if the returned struct is
initialized.

Performance in the Linux repository measured with hyperfine before:

Benchmark #1: ./git -C ../linux/ name-rev --all
  Time (mean ± σ):     953.5 ms ±   6.3 ms    [User: 901.2 ms, System: 52.1 ms]
  Range (min … max):   945.2 ms … 968.5 ms    10 runs

... and with this patch:

Benchmark #1: ./git -C ../linux/ name-rev --all
  Time (mean ± σ):     851.0 ms ±   3.1 ms    [User: 807.4 ms, System: 43.6 ms]
  Range (min … max):   846.7 ms … 857.0 ms    10 runs

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:24:15 -08:00
René Scharfe
d689d6d82f name-rev: don't _peek() in create_or_update_name()
Look up the commit slab slot for the commit once using
commit_rev_name_at() and populate it in case it is empty, instead of
checking for emptiness in a separate step using commit_rev_name_peek()
via get_commit_rev_name().

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:24:15 -08:00
René Scharfe
15a4205d96 name-rev: don't leak path copy in name_ref()
name_ref() duplicates the path string and passes it to name_rev(), which
either puts it into a commit slab or ignores it if there is already a
better name, leaking it.  Move the duplication to name_rev() and release
the copy in the latter case.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:24:15 -08:00
René Scharfe
36d2419c9a name-rev: respect const qualifier
Keep the const qualifier of the first parameter of get_rev_name() even
when casting the object pointer to a commit pointer, and further for the
parameter of get_commit_rev_name(), as all these uses are read-only.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:24:15 -08:00
René Scharfe
71620ca86c name-rev: remove unused typedef
The type alias became unused with bf43abc6e6 (name-rev: use sizeof(*ptr)
instead of sizeof(type) in allocation, 2019-11-12); remove it.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:24:15 -08:00
Martin Ågren
3e2feb0d64 name-rev: rewrite create_or_update_name()
This code was moved straight out of name_rev(). As such, we inherited
the "goto" to jump from an if into an else-if. We also inherited the
fact that "nothing to do -- return NULL" is handled last.

Rewrite the function to first handle the "nothing to do" case. Then we
can handle the conditional allocation early before going on to populate
the struct. No need for goto-ing.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:23:42 -08:00
Junio C Hamano
f3c520e17f Merge branch 'sg/name-rev-wo-recursion'
Redo "git name-rev" to avoid recursive calls.

* sg/name-rev-wo-recursion:
  name-rev: cleanup name_ref()
  name-rev: eliminate recursion in name_rev()
  name-rev: use 'name->tip_name' instead of 'tip_name'
  name-rev: drop name_rev()'s 'generation' and 'distance' parameters
  name-rev: restructure creating/updating 'struct rev_name' instances
  name-rev: restructure parsing commits and applying date cutoff
  name-rev: pull out deref handling from the recursion
  name-rev: extract creating/updating a 'struct name_rev' into a helper
  t6120: add a test to cover inner conditions in 'git name-rev's name_rev()
  name-rev: use sizeof(*ptr) instead of sizeof(type) in allocation
  name-rev: avoid unnecessary cast in name_ref()
  name-rev: use strbuf_strip_suffix() in get_rev_name()
  t6120-describe: modernize the 'check_describe' helper
  t6120-describe: correct test repo history graph in comment
2019-12-25 11:21:58 -08:00
SZEDER Gábor
2866fd284c name-rev: cleanup name_ref()
Earlier patches in this series moved a couple of conditions from the
recursive name_rev() function into its caller name_ref(), for no other
reason than to make eliminating the recursion a bit easier to follow.

Since the previous patch name_rev() is not recursive anymore, so let's
move all those conditions back into name_rev().

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-12-09 13:33:01 -08:00
SZEDER Gábor
49f7a2fde9 name-rev: eliminate recursion in name_rev()
The name_rev() function calls itself recursively for each interesting
parent of the commit it got as parameter, and, consequently, it can
segfault when processing a deep history if it exhausts the available
stack space.  E.g. running 'git name-rev --all' and 'git name-rev
HEAD~100000' in the gcc, gecko-dev, llvm, and WebKit repositories
results in segfaults on my machine ('ulimit -s' reports 8192kB of
stack size limit), and nowadays the former segfaults in the Linux repo
as well (it reached the necessasry depth sometime between v5.3-rc4 and
-rc5).

Eliminate the recursion by inserting the interesting parents into a
LIFO 'prio_queue' [1] and iterating until the queue becomes empty.

Note that the parent commits must be added in reverse order to the
LIFO 'prio_queue', so their relative order is preserved during
processing, i.e. the first parent should come out first from the
queue, because otherwise performance greatly suffers on mergy
histories [2].

The stacksize-limited test 'name-rev works in a deep repo' in
't6120-describe.sh' demonstrated this issue and expected failure.  Now
the recursion is gone, so flip it to expect success.  Also gone are
the dmesg entries logging the segfault of that segfaulting 'git
name-rev' process on every execution of the test suite.

Note that this slightly changes the order of lines in the output of
'git name-rev --all', usually swapping two lines every 35 lines in
git.git or every 150 lines in linux.git.  This shouldn't matter in
practice, because the output has always been unordered anyway.

This patch is best viewed with '--ignore-all-space'.

[1] Early versions of this patch used a 'commit_list', resulting in
    ~15% performance penalty for 'git name-rev --all' in 'linux.git',
    presumably because of the memory allocation and release for each
    insertion and removal. Using a LIFO 'prio_queue' has basically no
    effect on performance.

[2] We prefer shorter names, i.e. 'v0.1~234' is preferred over
    'v0.1^2~5', meaning that usually following the first parent of a
    merge results in the best name for its ancestors.  So when later
    we follow the remaining parent(s) of a merge, and reach an already
    named commit, then we usually find that we can't give that commit
    a better name, and thus we don't have to visit any of its
    ancestors again.

    OTOH, if we were to follow the Nth parent of the merge first, then
    the name of all its ancestors would include a corresponding '^N'.
    Those are not the best names for those commits, so when later we
    reach an already named commit following the first parent of that
    merge, then we would have to update the name of that commit and
    the names of all of its ancestors as well.  Consequently, we would
    have to visit many commits several times, resulting in a
    significant slowdown.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-12-09 13:33:01 -08:00
SZEDER Gábor
fee984bcab name-rev: use 'name->tip_name' instead of 'tip_name'
Following the previous patches in this series we can get the value of
'name_rev()'s 'tip_name' parameter from the 'struct rev_name'
associated with the commit as well.

So let's use 'name->tip_name' instead, which makes the patch
eliminating the recursion of name_rev() a bit easier to follow.

Note that at this point we could drop the 'tip_name' parameter as
well, but that parameter will be necessary later, after the recursion
is eliminated.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-12-09 13:33:01 -08:00
SZEDER Gábor
8c5724c585 name-rev: drop name_rev()'s 'generation' and 'distance' parameters
Following the previous patches in this series we can get the values of
name_rev()'s 'generation' and 'distance' parameters from the 'stuct
rev_name' associated with the commit as well.

Let's simplify the function's signature and remove these two
unnecessary parameters.

Note that at this point we could do the same with the 'tip_name',
'taggerdate' and 'from_tag' parameters as well, but those parameters
will be necessary later, after the recursion is eliminated.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-12-06 13:29:04 -08:00
SZEDER Gábor
3a52150301 name-rev: restructure creating/updating 'struct rev_name' instances
At the beginning of the recursive name_rev() function it creates a new
'struct rev_name' instance for each previously unvisited commit or, if
this visit results in better name for an already visited commit, then
updates the 'struct rev_name' instance attached to the commit, or
returns early.

Restructure this so it's caller creates or updates the 'struct
rev_name' instance associated with the commit to be passed as
parameter, i.e. both name_ref() before calling name_rev() and
name_rev() itself as it iterates over the parent commits.

This makes eliminating the recursion a bit easier to follow, and the
condition moved to name_ref() will be moved back to name_rev() after
the recursion is eliminated.

This change also plugs the memory leak that was temporarily unplugged
in the earlier "name-rev: pull out deref handling from the recursion"
patch in this series.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-12-06 13:29:04 -08:00
SZEDER Gábor
dd432a6ecf name-rev: restructure parsing commits and applying date cutoff
At the beginning of the recursive name_rev() function it parses the
commit it got as parameter, and returns early if the commit is older
than a cutoff limit.

Restructure this so the caller parses the commit and checks its date,
and doesn't invoke name_rev() if the commit to be passed as parameter
is older than the cutoff, i.e. both name_ref() before calling
name_rev() and name_rev() itself as it iterates over the parent
commits.

This makes eliminating the recursion a bit easier to follow, and the
condition moved to name_ref() will be moved back to name_rev() after
the recursion is eliminated.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-12-06 13:29:04 -08:00
SZEDER Gábor
dd090a8a37 name-rev: pull out deref handling from the recursion
The 'if (deref) { ... }' condition near the beginning of the recursive
name_rev() function can only ever be true in the first invocation,
because the 'deref' parameter is always 0 in the subsequent recursive
invocations.

Extract this condition from the recursion into name_rev()'s caller and
drop the function's 'deref' parameter.  This makes eliminating the
recursion a bit easier to follow, and it will be moved back into
name_rev() after the recursion is eliminated.

Furthermore, drop the condition that die()s when both 'deref' and
'generation' are non-null (which should have been a BUG() to begin
with).

Note that this change reintroduces the memory leak that was plugged in
in commit 5308224633 (name-rev: avoid leaking memory in the `deref`
case, 2017-05-04), but a later patch (name-rev: restructure
creating/updating 'struct rev_name' instances) in this series will
plug it in again.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-12-06 13:29:04 -08:00
SZEDER Gábor
766f9e39c0 name-rev: extract creating/updating a 'struct name_rev' into a helper
In a later patch in this series we'll want to do this in two places.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-12-06 13:29:04 -08:00
SZEDER Gábor
bf43abc6e6 name-rev: use sizeof(*ptr) instead of sizeof(type) in allocation
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-12-06 13:29:04 -08:00
SZEDER Gábor
e0c4da6f2a name-rev: avoid unnecessary cast in name_ref()
Casting a 'struct object' to 'struct commit' is unnecessary there,
because it's already available in the local 'commit' variable.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-12-06 13:29:04 -08:00
René Scharfe
c3794d4ccb name-rev: use strbuf_strip_suffix() in get_rev_name()
get_name_rev() basically open-codes strip_suffix() before adding a
string to a strbuf.

Let's use the strbuf right from the beginning, i.e. add the whole
string to the strbuf and then use strbuf_strip_suffix(), making the
code more idiomatic.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-12-06 13:29:04 -08:00
René Scharfe
2059e79c0d name-rev: use skip_prefix() instead of starts_with()
Let skip_prefix() advance refname to get rid of two magic numbers.

Signed-off-by: René Scharfe <l.s.r@web.de>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-11-27 11:21:18 +09:00
SZEDER Gábor
2e09c01232 name-rev: avoid cutoff timestamp underflow
When 'git name-rev' is invoked with commit-ish parameters, it tries to
save some work, and doesn't visit commits older than the committer
date of the oldest given commit minus a one day worth of slop.  Since
our 'timestamp_t' is an unsigned type, this leads to a timestamp
underflow when the committer date of the oldest given commit is within
a day of the UNIX epoch.  As a result the cutoff timestamp ends up
far-far in the future, and 'git name-rev' doesn't visit any commits,
and names each given commit as 'undefined'.

Check whether subtracting the slop from the oldest committer date
would lead to an underflow, and use no cutoff in that case.  We don't
have a TIME_MIN constant, dddbad728c (timestamp_t: a new data type for
timestamps, 2017-04-26) didn't add one, so do it now.

Note that the type of the cutoff timestamp variable used to be signed
before 5589e87fd8 (name-rev: change a "long" variable to timestamp_t,
2017-05-20).  The behavior was still the same even back then, but the
underflow didn't happen when substracting the slop from the oldest
committer date, but when comparing the signed cutoff timestamp with
unsigned committer dates in name_rev().  IOW, this underflow bug is as
old as 'git name-rev' itself.

Helped-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-09-28 13:36:04 +09:00
Jeff King
d0229abd93 object: convert lookup_object() to use object_id
There are no callers left of lookup_object() that aren't just passing us
the "hash" member of a "struct object_id". Let's take the whole struct,
which gets us closer to removing all raw sha1 variables.  It also
matches the existing conversions of lookup_blob(), etc.

The conversions of callers were done by hand, but they're all mechanical
one-liners.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-20 10:18:09 -07:00
Jeff King
c016579895 name-rev: drop unused parameters from is_better_name()
When this function was extracted in 0041bf6544 (name-rev: refactor logic
to see if a new candidate is a better name, 2017-03-29), it ended up
getting more arguments than it needs.

It's possible we may later use these values to evaluate the name, but
since it's a static function with a single caller, it will be easy to
add them back then.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-05-13 14:22:54 +09:00
brian m. carlson
1c4675dc57 builtin/name-rev: make hash-size independent
Use the_hash_algo when parsing instead of GIT_SHA1_HEXSZ so that this
function works with any size hash.  Rename the variable forty to
counter, as this is a better name and is independent of the hash size.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-04-01 11:57:38 +09:00
Stefan Beller
a74093da5e tag: add repository argument to deref_tag
Add a repository argument to allow the callers of deref_tag
to be more specific about which repository to act on. This is a small
mechanical change; it doesn't change the implementation to handle
repositories other than the_repository yet.

As with the previous commits, use a macro to catch callers passing a
repository other than the_repository at compile time.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-06-29 10:43:39 -07:00
Stefan Beller
5abddd1eb7 object: add repository argument to lookup_object
Add a repository argument to allow callers of lookup_object to be more
specific about which repository to handle. This is a small mechanical
change; it doesn't change the implementation to handle repositories
other than the_repository yet.

As with the previous commits, use a macro to catch callers passing a
repository other than the_repository at compile time.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-06-29 10:43:38 -07:00
Stefan Beller
109cd76dd3 object: add repository argument to parse_object
Add a repository argument to allow the callers of parse_object
to be more specific about which repository to act on. This is a small
mechanical change; it doesn't change the implementation to handle
repositories other than the_repository yet.

As with the previous commits, use a macro to catch callers passing a
repository other than the_repository at compile time.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-06-29 10:43:38 -07:00
Nguyễn Thái Ngọc Duy
8fd79a7304 name-rev: use commit-slab for rev-name instead of commit->util
It's done so that commit->util can be removed. See more explanation in
the commit that removes commit->util.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-05-21 14:07:20 +09:00
brian m. carlson
aab9583f7b Convert find_unique_abbrev* to struct object_id
Convert find_unique_abbrev and find_unique_abbrev_r to each take a
pointer to struct object_id.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-03-14 09:23:48 -07:00
Junio C Hamano
5261fefa4a Merge branch 'ma/builtin-unleak'
Many variables that points at a region of memory that will live
throughout the life of the program have been marked with UNLEAK
marker to help the leak checkers concentrate on real leaks..

* ma/builtin-unleak:
  builtin/: add UNLEAKs
2017-10-07 16:27:55 +09:00
Martin Ågren
886e1084d7 builtin/: add UNLEAKs
Add some UNLEAKs where we are about to return from `cmd_*`. UNLEAK the
variables in the same order as we've declared them. While addressing
`msg` in builtin/tag.c, convert the existing `strbuf_release()` calls as
well.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-10-02 13:03:10 +09:00