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240 commits

Author SHA1 Message Date
brian m. carlson 5951bf467e Use the final_oid_fn to finalize hashing of object IDs
When we're hashing a value which is going to be an object ID, we want to
zero-pad that value if necessary.  To do so, use the final_oid_fn
instead of the final_fn anytime we're going to create an object ID to
ensure we perform this operation.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-04-27 16:31:38 +09:00
brian m. carlson 92e2cab96b Always use oidread to read into struct object_id
In the future, we'll want oidread to automatically set the hash
algorithm member for an object ID we read into it, so ensure we use
oidread instead of hashcpy everywhere we're copying a hash value into a
struct object_id.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-04-27 16:31:38 +09:00
Junio C Hamano 5644419d04 Merge branch 'ab/fsck-api-cleanup'
Fsck API clean-up.

* ab/fsck-api-cleanup:
  fetch-pack: use new fsck API to printing dangling submodules
  fetch-pack: use file-scope static struct for fsck_options
  fetch-pack: don't needlessly copy fsck_options
  fsck.c: move gitmodules_{found,done} into fsck_options
  fsck.c: add an fsck_set_msg_type() API that takes enums
  fsck.c: pass along the fsck_msg_id in the fsck_error callback
  fsck.[ch]: move FOREACH_FSCK_MSG_ID & fsck_msg_id from *.c to *.h
  fsck.c: give "FOREACH_MSG_ID" a more specific name
  fsck.c: undefine temporary STR macro after use
  fsck.c: call parse_msg_type() early in fsck_set_msg_type()
  fsck.h: re-order and re-assign "enum fsck_msg_type"
  fsck.h: move FSCK_{FATAL,INFO,ERROR,WARN,IGNORE} into an enum
  fsck.c: refactor fsck_msg_type() to limit scope of "int msg_type"
  fsck.c: rename remaining fsck_msg_id "id" to "msg_id"
  fsck.c: remove (mostly) redundant append_msg_id() function
  fsck.c: rename variables in fsck_set_msg_type() for less confusion
  fsck.h: use "enum object_type" instead of "int"
  fsck.h: use designed initializers for FSCK_OPTIONS_{DEFAULT,STRICT}
  fsck.c: refactor and rename common config callback
2021-04-07 16:54:09 -07:00
Ævar Arnfjörð Bjarmason 3745e2693d fetch-pack: use new fsck API to printing dangling submodules
Refactor the check added in 5476e1efde (fetch-pack: print and use
dangling .gitmodules, 2021-02-22) to make use of us now passing the
"msg_id" to the user defined "error_func". We can now compare against
the FSCK_MSG_GITMODULES_MISSING instead of parsing the generated
message.

Let's also replace register_found_gitmodules() with directly
manipulating the "gitmodules_found" member. A recent commit moved it
into "fsck_options" so we could do this here.

I'm sticking this callback in fsck.c. Perhaps in the future we'd like
to accumulate such callbacks into another file (maybe fsck-cb.c,
similar to parse-options-cb.c?), but while we've got just the one
let's just put it into fsck.c.

A better alternative in this case would be some library some more
obvious library shared by fetch-pack.c ad builtin/index-pack.c, but
there isn't such a thing.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-28 19:03:10 -07:00
Ævar Arnfjörð Bjarmason 462f5cae0f fetch-pack: don't needlessly copy fsck_options
Change the behavior of the .gitmodules validation added in
5476e1efde (fetch-pack: print and use dangling .gitmodules,
2021-02-22) so we're using one "fsck_options".

I found that code confusing to read. One might think that not setting
up the error_func earlier means that we're relying on the "error_func"
not being set in some code in between the two hunks being modified
here.

But we're not, all we're doing in the rest of "cmd_index_pack()" is
further setup by calling fsck_set_msg_types(), and assigning to
do_fsck_object.

So there was no reason in 5476e1efde to make a shallow copy of the
fsck_options struct before setting error_func. Let's just do this
setup at the top of the function, along with the "walk" assignment.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-28 19:03:10 -07:00
Ævar Arnfjörð Bjarmason 394d5d31b0 fsck.c: pass along the fsck_msg_id in the fsck_error callback
Change the fsck_error callback to also pass along the
fsck_msg_id. Before this change the only way to get the message id was
to parse it back out of the "message".

Let's pass it down explicitly for the benefit of callers that might
want to use it, as discussed in [1].

Passing the msg_type is now redundant, as you can always get it back
from the msg_id, but I'm not changing that convention. It's really
common to need the msg_type, and the report() function itself (which
calls "fsck_error") needs to call fsck_msg_type() to discover
it. Let's not needlessly re-do that work in the user callback.

1. https://lore.kernel.org/git/87blcja2ha.fsf@evledraar.gmail.com/

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-28 19:03:10 -07:00
Ævar Arnfjörð Bjarmason 1b32b59f9b fsck.h: move FSCK_{FATAL,INFO,ERROR,WARN,IGNORE} into an enum
Move the FSCK_{FATAL,INFO,ERROR,WARN,IGNORE} defines into a new
fsck_msg_type enum.

These defines were originally introduced in:

 - ba002f3b28 (builtin-fsck: move common object checking code to
   fsck.c, 2008-02-25)
 - f50c440730 (fsck: disallow demoting grave fsck errors to warnings,
   2015-06-22)
 - efaba7cc77 (fsck: optionally ignore specific fsck issues
   completely, 2015-06-22)
 - f27d05b170 (fsck: allow upgrading fsck warnings to errors,
   2015-06-22)

The reason these were defined in two different places is because we
use FSCK_{IGNORE,INFO,FATAL} only in fsck.c, but FSCK_{ERROR,WARN} are
used by external callbacks.

Untangling that would take some more work, since we expose the new
"enum fsck_msg_type" to both. Similar to "enum object_type" it's not
worth structuring the API in such a way that only those who need
FSCK_{ERROR,WARN} pass around a different type.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-28 19:03:10 -07:00
Ævar Arnfjörð Bjarmason a1aad71601 fsck.h: use "enum object_type" instead of "int"
Change the fsck_walk_func to use an "enum object_type" instead of an
"int" type. The types are compatible, and ever since this was added in
355885d531 (add generic, type aware object chain walker, 2008-02-25)
we've used entries from object_type (OBJ_BLOB etc.).

So this doesn't really change anything as far as the generated code is
concerned, it just gives the compiler more information and makes this
easier to read.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-28 19:03:10 -07:00
René Scharfe ca56dadb4b use CALLOC_ARRAY
Add and apply a semantic patch for converting code that open-codes
CALLOC_ARRAY to use it instead.  It shortens the code and infers the
element size automatically.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-13 16:00:09 -08:00
Junio C Hamano 6ee353d42f Merge branch 'jt/transfer-fsck-across-packs'
The approach to "fsck" the incoming objects in "index-pack" is
attractive for performance reasons (we have them already in core,
inflated and ready to be inspected), but fundamentally cannot be
applied fully when we receive more than one pack stream, as a tree
object in one pack may refer to a blob object in another pack as
".gitmodules", when we want to inspect blobs that are used as
".gitmodules" file, for example.  Teach "index-pack" to emit
objects that must be inspected later and check them in the calling
"fetch-pack" process.

* jt/transfer-fsck-across-packs:
  fetch-pack: print and use dangling .gitmodules
  fetch-pack: with packfile URIs, use index-pack arg
  http-fetch: allow custom index-pack args
  http: allow custom index-pack args
2021-03-01 14:02:57 -08:00
Jonathan Tan 5476e1efde fetch-pack: print and use dangling .gitmodules
Teach index-pack to print dangling .gitmodules links after its "keep" or
"pack" line instead of declaring an error, and teach fetch-pack to check
such lines printed.

This allows the tree side of the .gitmodules link to be in one packfile
and the blob side to be in another without failing the fsck check,
because it is now fetch-pack which checks such objects after all
packfiles have been downloaded and indexed (and not index-pack on an
individual packfile, as it is before this commit).

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-02-22 12:07:40 -08:00
Taylor Blau e8c58f894b t: support GIT_TEST_WRITE_REV_INDEX
Add a new option that unconditionally enables the pack.writeReverseIndex
setting in order to run the whole test suite in a mode that generates
on-disk reverse indexes. Additionally, enable this mode in the second
run of tests under linux-gcc in 'ci/run-build-and-tests.sh'.

Once on-disk reverse indexes are proven out over several releases, we
can change the default value of that configuration to 'true', and drop
this patch.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-25 18:32:44 -08:00
Taylor Blau e37d0b8730 builtin/index-pack.c: write reverse indexes
Teach 'git index-pack' to optionally write and verify reverse index with
'--[no-]rev-index', as well as respecting the 'pack.writeReverseIndex'
configuration option.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-25 18:32:43 -08:00
Taylor Blau 84d544943c builtin/index-pack.c: allow stripping arbitrary extensions
To derive the filename for a .idx file, 'git index-pack' uses
derive_filename() to strip the '.pack' suffix and add the new suffix.

Prepare for stripping off suffixes other than '.pack' by making the
suffix to strip a parameter of derive_filename(). In order to make this
consistent with the "suffix" parameter which does not begin with a ".",
an additional check in derive_filename.

Suggested-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-25 18:32:43 -08:00
Martin Ågren e5afd4449d object-file.c: rename from sha1-file.c
Drop the last remnant of "sha1" in this file and rename it 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
Jeff King f86f769550 compute pack .idx byte offsets using size_t
A pack and its matching .idx file are limited to 2^32 objects, because
the pack format contains a 32-bit field to store the number of objects.
Hence we use uint32_t in the code.

But the byte count of even a .idx file can be much larger than that,
because it stores at least a hash and an offset for each object. So
using SHA-1, a v2 .idx file will cross the 4GB boundary at 153,391,650
objects. This confuses load_idx(), which computes the minimum size like
this:

  unsigned long min_size = 8 + 4*256 + nr*(hashsz + 4 + 4) + hashsz + hashsz;

Even though min_size will be big enough on most 64-bit platforms, the
actual arithmetic is done as a uint32_t, resulting in a truncation. We
actually exceed that min_size, but then we do:

  unsigned long max_size = min_size;
  if (nr)
          max_size += (nr - 1)*8;

to account for the variable-sized table. That computation doesn't
overflow quite so low, but with the truncation for min_size, we end up
with a max_size that is much smaller than our actual size. So we
complain that the idx is invalid, and can't find any of its objects.

We can fix this case by casting "nr" to a size_t, which will do the
multiplication in 64-bits (assuming you're on a 64-bit platform; this
will never work on a 32-bit system since we couldn't map the whole .idx
anyway). Likewise, we don't have to worry about further additions,
because adding a smaller number to a size_t will convert the other side
to a size_t.

A few notes:

  - obviously we could just declare "nr" as a size_t in the first place
    (and likewise, packed_git.num_objects).  But it's conceptually a
    uint32_t because of the on-disk format, and we correctly treat it
    that way in other contexts that don't need to compute byte offsets
    (e.g., iterating over the set of objects should and generally does
    use a uint32_t). Switching to size_t would make all of those other
    cases look wrong.

  - it could be argued that the proper type is off_t to represent the
    file offset. But in practice the .idx file must fit within memory,
    because we mmap the whole thing. And the rest of the code (including
    the idx_size variable we're comparing against) uses size_t.

  - we'll add the same cast to the max_size arithmetic line. Even though
    we're adding to a larger type, which will convert our result, the
    multiplication is still done as a 32-bit value and can itself
    overflow. I didn't check this with my test case, since it would need
    an even larger pack (~530M objects), but looking at compiler output
    shows that it works this way. The standard should agree, but I
    couldn't find anything explicit in 6.3.1.8 ("usual arithmetic
    conversions").

The case in load_idx() was the most immediate one that I was able to
trigger. After fixing it, looking up actual objects (including the very
last one in sha1 order) works in a test repo with 153,725,110 objects.
That's because bsearch_hash() works with uint32_t entry indices, and the
actual byte access:

  int cmp = hashcmp(table + mi * stride, sha1);

is done with "stride" as a size_t, causing the uint32_t "mi" to be
promoted to a size_t. This is the way most code will access the index
data.

However, I audited all of the other byte-wise accesses of
packed_git.index_data, and many of the others are suspect (they are
similar to the max_size one, where we are adding to a properly sized
offset or directly to a pointer, but the multiplication in the
sub-expression can overflow). I didn't trigger any of these in practice,
but I believe they're potential problems, and certainly adding in the
cast is not going to hurt anything here.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-11-16 13:41:35 -08:00
Junio C Hamano c7ac8c0a7c Merge branch 'jk/index-pack-hotfixes'
Hotfix and clean-up for the jt/threaded-index-pack topic that has
graduated to v2.29-rc0.

* jk/index-pack-hotfixes:
  index-pack: make get_base_data() comment clearer
  index-pack: drop type_cas mutex
  index-pack: restore "resolving deltas" progress meter
2020-10-08 21:53:26 -07:00
Jonathan Tan ec6a8f9705 index-pack: make get_base_data() comment clearer
A comment mentions that we may free cached delta bases via
find_unresolved_deltas(), but that function went away in f08cbf60fe
(index-pack: make quantum of work smaller, 2020-09-08). Since we need to
rewrite that comment anyway, make the entire comment clearer.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-07 13:32:27 -07:00
Jeff King bebe171947 index-pack: drop type_cas mutex
The type_cas lock lost all of its callers in f08cbf60fe (index-pack:
make quantum of work smaller, 2020-09-08), so we can safely delete it.
The compiler didn't alert us that the variable became unused, because we
still call pthread_mutex_init() and pthread_mutex_destroy() on it.

It's worth considering also whether that commit was in error to remove
the use of the lock. Why don't we need it now, if we did before, as
described in ab791dd138 (index-pack: fix race condition with duplicate
bases, 2014-08-29)? I think the answer is that we now look at and assign
the child_obj->real_type field in the main thread while holding the
work_lock(). So we don't have to worry about racing with the worker
threads.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-07 11:51:26 -07:00
Jeff King cea69151a4 index-pack: restore "resolving deltas" progress meter
Commit f08cbf60fe (index-pack: make quantum of work smaller, 2020-09-08)
refactored the main loop in threaded_second_pass(), but also deleted the
call to display_progress() at the top of the loop. This means that users
typically see no progress at all during the delta resolution phase (and
for large repositories, Git appears to hang).

This looks like an accident that was unrelated to the intended change of
that commit, since we continue to update nr_resolved_deltas in
resolve_delta(). Let's restore the call to get that progress back.

We'll also add a test that confirms we generate the expected progress.
This isn't perfect, as it wouldn't catch a bug where progress was
delayed to the end. That was probably possible to trigger when receiving
a thin pack, because we'd eventually call display_progress() from
fix_unresolved_deltas(), but only once after doing all the work.
However, since our test case generates a complete pack, it reliably
demonstrates this particular bug and its fix. And we can't do better
without making the test racy.

Signed-off-by: Jeff King <peff@peff.net>
Acked-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-07 11:50:09 -07:00
Junio C Hamano b7e65b51e5 Merge branch 'jt/threaded-index-pack'
"git index-pack" learned to resolve deltified objects with greater
parallelism.

* jt/threaded-index-pack:
  index-pack: make quantum of work smaller
  index-pack: make resolve_delta() assume base data
  index-pack: calculate {ref,ofs}_{first,last} early
  index-pack: remove redundant child field
  index-pack: unify threaded and unthreaded code
  index-pack: remove redundant parameter
  Documentation: deltaBaseCacheLimit is per-thread
2020-09-22 12:36:28 -07:00
Jonathan Tan f08cbf60fe index-pack: make quantum of work smaller
Currently, when index-pack resolves deltas, it does not split up delta
trees into threads: each delta base root (an object that is not a
REF_DELTA or OFS_DELTA) can go into its own thread, but all deltas on
that root (direct or indirect) are processed in the same thread.

This is a problem when a repository contains a large text file (thus,
delta-able) that is modified many times - delta resolution time during
fetching is dominated by processing the deltas corresponding to that
text file.

This patch contains a solution to that. When cloning using

  git -c core.deltabasecachelimit=1g clone \
    https://fuchsia.googlesource.com/third_party/vulkan-cts

on my laptop, clone time improved from 3m2s to 2m5s (using 3 threads,
which is the default).

The solution is to have a global work stack. This stack contains delta
bases (objects, whether appearing directly in the packfile or generated
by delta resolution, that themselves have delta children) that need to
be processed; whenever a thread needs work, it peeks at the top of the
stack and processes its next unprocessed child. If a thread finds the
stack empty, it will look for more delta base roots to push on the stack
instead.

The main weakness of having a global work stack is that more time is
spent in the mutex, but profiling has shown that most time is spent in
the resolution of the deltas themselves, so this shouldn't be an issue
in practice. In any case, experimentation (as described in the clone
command above) shows that this patch is a net improvement.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-08 15:52:17 -07:00
Jonathan Tan ee6f058384 index-pack: make resolve_delta() assume base data
A subsequent commit will make the quantum of work smaller, necessitating
more locking. This commit allows resolve_delta() to be called outside
the lock.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-08-24 14:14:52 -07:00
Jonathan Tan b4718cae51 index-pack: calculate {ref,ofs}_{first,last} early
This is refactoring 2 of 2 to simplify struct base_data.

Whenever we make a struct base_data, immediately calculate its delta
children. This eliminates confusion as to when the
{ref,ofs}_{first,last} fields are initialized.

Before this patch, the delta children were calculated at the last
possible moment. This allowed the members of struct base_data to be
populated in any order, superficially useful when we have the object
contents before the struct object_entry. But this makes reasoning about
the state of struct base_data more complicated, hence this patch.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-08-24 14:12:58 -07:00
Jonathan Tan a7f7e84a49 index-pack: remove redundant child field
This is refactoring 1 of 2 to simplify struct base_data.

In index-pack, each thread maintains a doubly-linked list of the delta
chain that it is currently processing (the "base" and "child" pointers
in struct base_data). When a thread exceeds the delta base cache limit
and needs to reclaim memory, it uses the "child" pointers to traverse
the lineage, reclaiming the memory of the eldest delta bases first.

A subsequent patch will perform memory reclaiming in a different way and
will thus no longer need the "child" pointer. Because the "child"
pointer is redundant even now, remove it so that the aforementioned
subsequent patch will be clearer. In the meantime, reclaim memory in the
reverse order of the "base" pointers.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-08-24 14:11:14 -07:00
Jonathan Tan 46e6fb1e44 index-pack: unify threaded and unthreaded code
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-08-24 14:02:31 -07:00
Jonathan Tan fc968e26c2 index-pack: remove redundant parameter
find_{ref,ofs}_delta_{,children} take an enum object_type parameter, but
the object type is already present in the name of the function. Remove
that parameter from these functions.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-08-24 13:55:57 -07:00
Jeff King fbff95b67f index-pack: adjust default threading cap
Commit b8a2486f15 (index-pack: support multithreaded delta resolving,
2012-05-06) describes an experiment that shows that setting the number
of threads for index-pack higher than 3 does not help.

I repeated that experiment using a more modern version of Git and a more
modern CPU and got different results.

Here are timings for p5302 against linux.git run on my laptop, a Core
i9-9880H with 8 cores plus hyperthreading (so online-cpus returns 16):

  5302.3: index-pack 0 threads                   256.28(253.41+2.79)
  5302.4: index-pack 1 threads                   257.03(254.03+2.91)
  5302.5: index-pack 2 threads                   149.39(268.34+3.06)
  5302.6: index-pack 4 threads                   94.96(294.10+3.23)
  5302.7: index-pack 8 threads                   68.12(339.26+3.89)
  5302.8: index-pack 16 threads                  70.90(655.03+7.21)
  5302.9: index-pack default number of threads   116.91(290.05+3.21)

You can see that wall-clock times continue to improve dramatically up to
the number of cores, but bumping beyond that (into hyperthreading
territory) does not help (and in fact hurts a little).

Here's the same experiment on a machine with dual Xeon 6230's, totaling
40 cores (80 with hyperthreading):

  5302.3: index-pack 0 threads                    310.04(302.73+6.90)
  5302.4: index-pack 1 threads                    310.55(302.68+7.40)
  5302.5: index-pack 2 threads                    178.17(304.89+8.20)
  5302.6: index-pack 5 threads                    99.53(315.54+9.56)
  5302.7: index-pack 10 threads                   72.80(327.37+12.79)
  5302.8: index-pack 20 threads                   60.68(357.74+21.66)
  5302.9: index-pack 40 threads                   58.07(454.44+67.96)
  5302.10: index-pack 80 threads                  59.81(720.45+334.52)
  5302.11: index-pack default number of threads   134.18(309.32+7.98)

The results are similar; things stop improving at 40 threads. Curiously,
going from 20 to 40 really doesn't help much, either (and increases CPU
time considerably). So that may represent an actual barrier to
parallelism, where we lose out due to context-switching and loss of
cache locality, but don't reap the wall-clock benefits due to contention
of our coarse-grained locks.

So what's a good default value? It's clear that the current cap of 3 is
too low; our default values are 42% and 57% slower than the best times
on each machine. The results on the 40-core machine imply that 20
threads is an actual barrier regardless of the number of cores, so we'll
take that as a maximum. We get the best results on these machines at
half of the online-cpus value. That's presumably a result of the
hyperthreading. That's common on multi-core Intel processors, but not
necessarily elsewhere. But if we take it as an assumption, we can
perform optimally on hyperthreaded machines and still do much better
than the status quo on other machines, as long as we never half below
the current value of 3.

So that's what this patch does.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-08-21 12:02:36 -07:00
brian m. carlson 586740aa6e builtin/index-pack: add option to specify hash algorithm
git index-pack is usually run in a repository, but need not be. Since
packs don't contains information on the algorithm in use, instead
relying on context, add an option to index-pack to tell it which one
we're using in case someone runs it outside of a repository.  Since
using --stdin necessarily implies a repository, don't allow specifying
an object format if it's provided to prevent users from passing an
option that won't work.  Add documentation for this option.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-19 14:04:08 -07:00
brian m. carlson 629dffc461 packfile: compute and use the index CRC offset
Both v2 pack index files and the v3 format specified as part of the
NewHash work have similar data starting at the CRC table.  Much of the
existing code wants to read either this table or the offset entries
following it, and in doing so computes the offset each time.

In order to share as much code between v2 and v3, compute the offset of
the CRC table and store it when the pack is opened.  Use this value to
compute offsets to not only the CRC table, but to the offset entries
beyond it.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-05-27 10:07:07 -07:00
Jonathan Tan db7ed7418b promisor-remote: accept 0 as oid_nr in function
There are 3 callers to promisor_remote_get_direct() that first check if
the number of objects to be fetched is equal to 0. Fold that check into
promisor_remote_get_direct(), and in doing so, be explicit as to what
promisor_remote_get_direct() does if oid_nr is 0 (it returns 0, success,
immediately).

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-02 12:42:32 -07:00
Junio C Hamano 7b029ebaef Merge branch 'jk/index-pack-dupfix'
The index-pack code now diagnoses a bad input packstream that
records the same object twice when it is used as delta base; the
code used to declare a software bug when encountering such an
input, but it is an input error.

* jk/index-pack-dupfix:
  index-pack: downgrade twice-resolved REF_DELTA to die()
2020-02-14 12:54:24 -08:00
Jeff King a21781011f index-pack: downgrade twice-resolved REF_DELTA to die()
When we're resolving a REF_DELTA, we compare-and-swap its type from
REF_DELTA to whatever real type the base object has, as discussed in
ab791dd138 (index-pack: fix race condition with duplicate bases,
2014-08-29). If the old type wasn't a REF_DELTA, we consider that a
BUG(). But as discussed in that commit, we might see this case whenever
we try to resolve an object twice, which may happen because we have
multiple copies of the base object.

So this isn't a bug at all, but rather a sign that the input pack is
broken. And indeed, this case is triggered already in t5309.5 and
t5309.6, which create packs with delta cycles and duplicate bases. But
we never noticed because those tests are marked expect_failure.

Those tests were added by b2ef3d9ebb (test index-pack on packs with
recoverable delta cycles, 2013-08-23), which was leaving the door open
for cases that we theoretically _could_ handle. And when we see an
already-resolved object like this, in theory we could keep going after
confirming that the previously resolved child->real_type matches
base->obj->real_type. But:

  - enforcing the "only resolve once" rule here saves us from an
    infinite loop in other parts of the code. If we keep going, then the
    delta cycle in t5309.5 causes us to loop infinitely, as
    find_ref_delta_children() doesn't realize which objects have already
    been resolved. So there would be more changes needed to make this
    case work, and in the meantime we'd be worse off.

  - any pack that triggers this is broken anyway. It either has a
    duplicate base object, or it has a cycle which causes us to bring in
    a duplicate via --fix-thin. In either case, we'd end up rejecting
    the pack in write_idx_file(), which also detects duplicates.

So the tests have little value in documenting what we _could_ be doing
(and have been neglected for 6+ years). Let's switch them to confirming
that we handle this case cleanly (and switch out the BUG() for a more
informative die() so that we do so).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-04 13:19:11 -08:00
Matheus Tavares b98d188581 sha1-file: allow check_object_signature() to handle any repo
Some callers of check_object_signature() can work on arbitrary
repositories, but the repo does not get passed to this function.
Instead, the_repository is always used internally. To fix possible
inconsistencies, allow the function to receive a struct repository and
make those callers pass on the repo being handled.

Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-31 10:45:39 -08:00
Matheus Tavares 2dcde20e1c sha1-file: pass git_hash_algo to hash_object_file()
Allow hash_object_file() to work on arbitrary repos by introducing a
git_hash_algo parameter. Change callers which have a struct repository
pointer in their scope to pass on the git_hash_algo from the said repo.
For all other callers, pass on the_hash_algo, which was already being
used internally at hash_object_file(). This functionality will be used
in the following patch to make check_object_signature() be able to work
on arbitrary repos (which, in turn, will be used to fix an
inconsistency at object.c:parse_object()).

Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-31 10:45:39 -08:00
Matheus Tavares c8123e72f6 streaming: allow open_istream() to handle any repo
Some callers of open_istream() at archive-tar.c and archive-zip.c are
capable of working on arbitrary repositories but the repo struct is not
passed down to open_istream(), which uses the_repository internally. For
now, that's not a problem since the said callers are only being called
with the_repository. But to be consistent and avoid future problems,
let's allow open_istream() to receive a struct repository and use that
instead of the_repository. This parameter addition will also be used in
a future patch to make sha1-file.c:check_object_signature() be able to
work on arbitrary repos.

Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-31 10:45:39 -08:00
Junio C Hamano 676278f8ea Merge branch 'bc/object-id-part17'
Preparation for SHA-256 upgrade continues.

* bc/object-id-part17: (26 commits)
  midx: switch to using the_hash_algo
  builtin/show-index: replace sha1_to_hex
  rerere: replace sha1_to_hex
  builtin/receive-pack: replace sha1_to_hex
  builtin/index-pack: replace sha1_to_hex
  packfile: replace sha1_to_hex
  wt-status: convert struct wt_status to object_id
  cache: remove null_sha1
  builtin/worktree: switch null_sha1 to null_oid
  builtin/repack: write object IDs of the proper length
  pack-write: use hash_to_hex when writing checksums
  sequencer: convert to use the_hash_algo
  bisect: switch to using the_hash_algo
  sha1-lookup: switch hard-coded constants to the_hash_algo
  config: use the_hash_algo in abbrev comparison
  combine-diff: replace GIT_SHA1_HEXSZ with the_hash_algo
  bundle: switch to use the_hash_algo
  connected: switch GIT_SHA1_HEXSZ to the_hash_algo
  show-index: switch hard-coded constants to the_hash_algo
  blame: remove needless comparison with GIT_SHA1_HEXSZ
  ...
2019-10-11 14:24:46 +09:00
brian m. carlson 69fa337060 builtin/index-pack: replace sha1_to_hex
Since sha1_to_hex is limited to SHA-1, replace it with hash_to_hex so
this code works with other algorithms.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-08-19 15:04:59 -07:00
Christian Couder b14ed5adaf Use promisor_remote_get_direct() and has_promisor_remote()
Instead of using the repository_format_partial_clone global
and fetch_objects() directly, let's use has_promisor_remote()
and promisor_remote_get_direct().

This way all the configured promisor remotes will be taken
into account, not only the one specified by
extensions.partialClone.

Also when cloning or fetching using a partial clone filter,
remote.origin.promisor will be set to "true" instead of
setting extensions.partialClone to "origin". This makes it
possible to use many promisor remote just by fetching from
them.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-25 14:05:37 -07:00
Jonathan Tan 8a30a1efd1 index-pack: prefetch missing REF_DELTA bases
When fetching, the client sends "have" commit IDs indicating that the
server does not need to send any object referenced by those commits,
reducing network I/O. When the client is a partial clone, the client
still sends "have"s in this way, even if it does not have every object
referenced by a commit it sent as "have".

If a server omits such an object, it is fine: the client could lazily
fetch that object before this fetch, and it can still do so after.

The issue is when the server sends a thin pack containing an object that
is a REF_DELTA against such a missing object: index-pack fails to fix
the thin pack. When support for lazily fetching missing objects was
added in 8b4c0103a9 ("sha1_file: support lazily fetching missing
objects", 2017-12-08), support in index-pack was turned off in the
belief that it accesses the repo only to do hash collision checks.
However, this is not true: it also needs to access the repo to resolve
REF_DELTA bases.

Support for lazy fetching should still generally be turned off in
index-pack because it is used as part of the lazy fetching process
itself (if not, infinite loops may occur), but we do need to fetch the
REF_DELTA bases. (When fetching REF_DELTA bases, it is unlikely that
those are REF_DELTA themselves, because we do not send "have" when
making such fetches.)

To resolve this, prefetch all missing REF_DELTA bases before attempting
to resolve them. This both ensures that all bases are attempted to be
fetched, and ensures that we make only one request per index-pack
invocation, and not one request per missing object.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-05-15 11:01:40 +09:00
SZEDER Gábor 79e3aa6624 index-pack: show progress while checking objects
When 'git index-pack' is run by 'git clone', its check_objects()
function usually doesn't take long enough to be a concern, but I just
run into a situation where it took about a minute or so: I
inadvertently put some memory pressure on my tiny laptop while cloning
linux.git, and then there was quite a long silence between the
"Resolving deltas" and "Checking connectivity" progress bars.

Show a progress bar during the loop of check_objects() to let the user
know that something is still going on.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-04-01 18:08:05 +09:00
Jeff King 98374a07c9 convert has_sha1_file() callers to has_object_file()
The only remaining callers of has_sha1_file() actually have an object_id
already. They can use the "object" variant, rather than dereferencing
the hash themselves.

The code changes here were completely generated by the included
coccinelle patch.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-01-08 09:41:06 -08:00
Junio C Hamano f5f0f68d61 Merge branch 'tb/print-size-t-with-uintmax-format'
Code preparation to replace ulong vars with size_t vars where
appropriate.

* tb/print-size-t-with-uintmax-format:
  Upcast size_t variables to uintmax_t when printing
2018-11-19 16:24:41 +09:00
Torsten Bögershausen ca473cef91 Upcast size_t variables to uintmax_t when printing
When printing variables which contain a size, today "unsigned long"
is used at many places.
In order to be able to change the type from "unsigned long" into size_t
some day in the future, we need to have a way to print 64 bit variables
on a system that has "unsigned long" defined to be 32 bit, like Win64.

Upcast all those variables into uintmax_t before they are printed.
This is to prepare for a bigger change, when "unsigned long"
will be converted into size_t for variables which may be > 4Gib.

Signed-off-by: Torsten Bögershausen <tboegi@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-11-12 16:43:52 +09:00
Nguyễn Thái Ngọc Duy 2094c5e582 index-pack: remove #ifdef NO_PTHREADS
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-11-05 13:42:11 +09:00
Jeff King 67947c34ae convert "hashcmp() != 0" to "!hasheq()"
This rounds out the previous three patches, covering the
inequality logic for the "hash" variant of the functions.

As with the previous three, the accompanying code changes
are the mechanical result of applying the coccinelle patch;
see those patches for more discussion.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-29 11:32:49 -07:00
Jeff King 4a7e27e957 convert "oidcmp() == 0" to oideq()
Using the more restrictive oideq() should, in the long run,
give the compiler more opportunities to optimize these
callsites. For now, this conversion should be a complete
noop with respect to the generated code.

The result is also perhaps a little more readable, as it
avoids the "zero is equal" idiom. Since it's so prevalent in
C, I think seasoned programmers tend not to even notice it
anymore, but it can sometimes make for awkward double
negations (e.g., we can drop a few !!oidcmp() instances
here).

This patch was generated almost entirely by the included
coccinelle patch. This mechanical conversion should be
completely safe, because we check explicitly for cases where
oidcmp() is compared to 0, which is what oideq() is doing
under the hood. Note that we don't have to catch "!oidcmp()"
separately; coccinelle's standard isomorphisms make sure the
two are treated equivalently.

I say "almost" because I did hand-edit the coccinelle output
to fix up a few style violations (it mostly keeps the
original formatting, but sometimes unwraps long lines).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-29 11:32:49 -07:00
Junio C Hamano 1689c22c1c Merge branch 'jk/core-use-replace-refs'
A new configuration variable core.usereplacerefs has been added,
primarily to help server installations that want to ignore the
replace mechanism altogether.

* jk/core-use-replace-refs:
  add core.usereplacerefs config option
  check_replace_refs: rename to read_replace_refs
  check_replace_refs: fix outdated comment
2018-08-15 15:08:23 -07:00
Jeff King 6ebd1cafe2 check_replace_refs: rename to read_replace_refs
This was added as a NEEDSWORK in c3c36d7de2 (replace-object:
check_replace_refs is safe in multi repo environment, 2018-04-11),
waiting for a calmer period. Since doing so now doesn't conflict
with anything in 'pu', it seems as good a time as any.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-07-18 15:45:14 -07:00
Stefan Beller da14a7ff99 blob: add repository argument to lookup_blob
Add a repository argument to allow the callers of lookup_blob
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