The common code to deal with "chunked file format" that is shared
by the multi-pack-index and commit-graph files have been factored
out, to help codepaths for both filetypes to become more robust.
* ds/chunked-file-api:
commit-graph.c: display correct number of chunks when writing
chunk-format: add technical docs
chunk-format: restore duplicate chunk checks
midx: use 64-bit multiplication for chunk sizes
midx: use chunk-format read API
commit-graph: use chunk-format read API
chunk-format: create read chunk API
midx: use chunk-format API in write_midx_internal()
midx: drop chunk progress during write
midx: return success/failure in chunk write methods
midx: add num_large_offsets to write_midx_context
midx: add pack_perm to write_midx_context
midx: add entries to write_midx_context
midx: use context in write_midx_pack_names()
midx: rename pack_info to write_midx_context
commit-graph: use chunk-format write API
chunk-format: create chunk format write API
commit-graph: anonymize data in chunk_write_fn
* ds/chunked-file-api:
commit-graph.c: display correct number of chunks when writing
chunk-format: add technical docs
chunk-format: restore duplicate chunk checks
midx: use 64-bit multiplication for chunk sizes
midx: use chunk-format read API
commit-graph: use chunk-format read API
chunk-format: create read chunk API
midx: use chunk-format API in write_midx_internal()
midx: drop chunk progress during write
midx: return success/failure in chunk write methods
midx: add num_large_offsets to write_midx_context
midx: add pack_perm to write_midx_context
midx: add entries to write_midx_context
midx: use context in write_midx_pack_names()
midx: rename pack_info to write_midx_context
commit-graph: use chunk-format write API
chunk-format: create chunk format write API
commit-graph: anonymize data in chunk_write_fn
When calculating the sizes of certain chunks, we should use 64-bit
multiplication always. This allows us to properly predict the chunk
sizes without risk of overflow.
Other possible overflows were discovered by evaluating each
multiplication in midx.c and ensuring that at least one side of the
operator was of type size_t or off_t.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Instead of parsing the table of contents directly, use the chunk-format
API methods read_table_of_contents() and pair_chunk(). In particular, we
can use the return value of pair_chunk() to generate an error when a
required chunk is missing.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The chunk-format API allows writing the table of contents and all chunks
using the anonymous 'struct chunkfile' type. We only need to convert our
local chunk logic to this API for the multi-pack-index writes to share
that logic with the commit-graph file writes.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Most expensive operations in write_midx_internal() use the context
struct's progress member, and these indicate the process of the
expensive operations within the chunk writing methods. However, there is
a competing progress struct that counts the progress over all chunks.
This is not very helpful compared to the others, so drop it.
This also reduces our barriers to combining the chunk writing code with
chunk-format.c.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Historically, the chunk-writing methods in midx.c have returned the
amount of data written so the writer method could compare this with the
table of contents. This presents with some interesting issues:
1. If a chunk writing method has a bug that miscalculates the written
bytes, then we can satisfy the table of contents without actually
writing the right amount of data to the hashfile. The commit-graph
writing code checks the hashfile struct directly for a more robust
verification.
2. There is no way for a chunk writing method to gracefully fail.
Returning an int presents an opportunity to fail without a die().
3. The current pattern doesn't match chunk_write_fn type exactly, so we
cannot share code with commit-graph.c
For these reasons, convert the midx chunk writer methods to return an
'int'. Since none of them fail at the moment, they all return 0.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In an effort to align write_midx_internal() with the chunk-format API,
continue to group necessary data into "struct write_midx_context". This
change collects the "uint32_t num_large_offsets" into the context. With
this new data, write_midx_large_offsets() now matches the
chunk_write_fn type.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In an effort to align write_midx_internal() with the chunk-format API,
continue to group necessary data into "struct write_midx_context". This
change collects the "uint32_t *pack_perm" and large_offsets_needed bit
into the context.
Update write_midx_object_offsets() to match chunk_write_fn.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In an effort to align write_midx_internal() with the chunk-format API,
continue to group necessary data into "struct write_midx_context". This
change collects the "struct pack_midx_entry *entries" list and its count
into the context.
Update write_midx_oid_fanout() and write_midx_oid_lookup() to take the
context directly, as these are easy conversions with this new data.
Only the callers of write_midx_object_offsets() and
write_midx_large_offsets() are updated here, since additional data in
the context before those methods can match chunk_write_fn.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In an effort to align the write_midx_internal() to use the chunk-format
API, start converting chunk writing methods to match chunk_write_fn. The
first case is to convert write_midx_pack_names() to take "void *data".
We already have the necessary data in "struct write_midx_context", so
this conversion is rather mechanical.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In an effort to streamline our chunk-based file formats, align some of
the code structure in write_midx_internal() to be similar to the
patterns in write_commit_graph_file().
Specifically, let's create a "struct write_midx_context" that can be
used as a data parameter to abstract function types.
This change only renames "struct pack_info" to "struct
write_midx_context" and the names of instances from "packs" to "ctx". In
future changes, we will expand the data inside "struct
write_midx_context" and align our chunk-writing method with the
chunk-format API.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Similar to the previous commits, avoid peeking into the `struct
lock_file`. Use the lock file API instead.
The two functions we're calling here double-check that the tempfile is
indeed "active", which is arguably overkill considering how we took the
lock on the line immediately above. More importantly, this future-proofs
us against, e.g., other code appearing between these two lines or the
lock file and/or tempfile internals changing.
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>
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>
Processes that access packdata while the .idx file gets removed
(e.g. while repacking) did not fail or fall back gracefully as they
could.
* tb/idx-midx-race-fix:
midx.c: protect against disappearing packs
packfile.c: protect against disappearing indexes
When a packed object is stored in a multi-pack index, but that pack has
racily gone away, the MIDX code simply calls die(), when it could be
returning an error to the caller, which would in turn lead to
re-scanning the pack directory.
A pack can racily disappear, for example, due to a simultaneous 'git
repack -ad',
You can also reproduce this with two terminals, where one is running:
git init
while true; do
git commit -q --allow-empty -m foo
git repack -ad
git multi-pack-index write
done
(in effect, constantly writing new MIDXs), and the other is running:
obj=$(git rev-parse HEAD)
while true; do
echo $obj | git cat-file --batch-check='%(objectsize:disk)' || break
done
That will sometimes hit the error preparing packfile from
multi-pack-index message, which this patch fixes.
Right now, that path to discovering a missing pack looks something like
'find_pack_entry()' calling 'fill_midx_entry()' and eventually making
its way to call 'nth_midxed_pack_entry()'.
'nth_midxed_pack_entry()' already checks 'is_pack_valid()' and
propagates an error if the pack is invalid. So, this works if the pack
has gone away between calling 'prepare_midx_pack()' and before calling
'is_pack_valid()', but not if it disappears before then.
Catch the case where the pack has already disappeared before
'prepare_midx_pack()' by returning an error in that case, too.
Co-authored-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Call hashwrite_be64() to write 64-bit values instead of open-coding it
using hashwrite_be32() and sizeof. This shortens the code and makes its
intent clearer.
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Now that the multi-pack-index may be written as part of auto maintenance
at the end of a command, reduce the progress output when the operations
are quick. Use start_delayed_progress() instead of start_progress().
Update t5319-multi-pack-index.sh to use GIT_PROGRESS_DELAY=0 now that
the progress indicators are conditional.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The core.multiPackIndex setting has been around since c4d25228eb
(config: create core.multiPackIndex setting, 2018-07-12), but has been
disabled by default. If a user wishes to use the multi-pack-index
feature, then they must enable this config and run 'git multi-pack-index
write'.
The multi-pack-index feature is relatively stable now, so make the
config option true by default. For users that do not use a
multi-pack-index, the only extra cost will be a file lookup to see if a
multi-pack-index file exists (once per process, per object directory).
Also, this config option will be referenced by an upcoming
"incremental-repack" task in the maintenance builtin, so move the config
option into the repository settings struct. Note that if
GIT_TEST_MULTI_PACK_INDEX=1, then we want to ignore the config option
and treat core.multiPackIndex as enabled.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Misc cleanups.
* rs/misc-cleanups:
pack-bitmap-write: use hashwrite_be32() in write_hash_cache()
midx: use hashwrite_u8() in write_midx_header()
fast-import: use write_pack_header()
When a packfile is removed by "git repack", multi-pack-index gets
cleared; the code was taught to do so less aggressively by first
checking if the midx actually refers to a pack that no longer
exists.
* tb/repack-clearing-midx:
midx: traverse the local MIDX first
builtin/repack.c: invalidate MIDX only when necessary
Emit byte-sized values using hashwrite_u8() instead of buffering them
locally first. The hashwrite functions already do their own buffering,
so this double-buffering does not reduce the number of system calls.
Getting rid of it shortens and simplifies the code a bit.
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When a repository has an alternate object directory configured, callers
can traverse through each alternate's MIDX by walking the '->next'
pointer.
But, when 'prepare_multi_pack_index_one()' loads multiple MIDXs, it
places the new ones at the front of this pointer chain, not at the end.
This can be confusing for callers such as 'git repack -ad', causing test
failures like in t7700.6 with 'GIT_TEST_MULTI_PACK_INDEX=1'.
The occurs when dropping a pack known to the local MIDX with alternates
configured that have their own MIDX. Since the alternate's MIDX is
returned via 'get_multi_pack_index()', 'midx_contains_pack()' returns
true (which is correct, since it traverses through the '->next' pointer
to find the MIDX in the chain that does contain the requested object).
But, we call 'clear_midx_file()' on 'the_repository', which drops the
MIDX at the path of the first MIDX in the chain, which (in the case of
t7700.6 is the one in the alternate).
This patch addresses that by:
- placing the local MIDX first in the chain when calling
'prepare_multi_pack_index_one()', and
- introducing a new 'get_local_multi_pack_index()', which explicitly
returns the repository-local MIDX, if any.
Don't impose an additional order on the MIDX's '->next' pointer beyond
that the first item in the chain must be local if one exists so that we
avoid a quadratic insertion.
Likewise, use 'get_local_multi_pack_index()' in
'remove_redundant_pack()' to fix the formerly broken t7700.6 when run
with 'GIT_TEST_MULTI_PACK_INDEX=1'.
Finally, note that the MIDX ordering invariant is only preserved by the
insertion order in 'prepare_packed_git()', which traverses through the
ODB's '->next' pointer, meaning we visit the local object store first.
This fragility makes this an undesirable long-term solution if more
callers are added, but it is acceptable for now since this is the only
caller.
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Use more buffered I/O where we used to call many small write(2)s.
* rs/more-buffered-io:
upload-pack: use buffered I/O to talk to rev-list
midx: use buffered I/O to talk to pack-objects
connected: use buffered I/O to talk to rev-list
The "--batch-size" option of "git multi-pack-index repack" command
is now used to specify that very small packfiles are collected into
one until the total size roughly exceeds it.
* ds/midx-repack-to-batch-size:
multi-pack-index: repack batches below --batch-size
Similar to the commit-graph format, the multi-pack-index format has a
byte in the header intended to track the hash version used to write the
file. This allows one to interpret the hash length without having the
context of the repository config specifying the hash length. This was
not modified as part of the SHA-256 work because the hash length was
automatically up-shifted due to that config.
Since we have this byte available, we can make the file formats more
obviously incompatible instead of relying on other context from the
repository.
Add a new oid_version() method in midx.c similar to the one in
commit-graph.c. This is specifically made separate from that
implementation to avoid artificially linking the formats.
The test impact requires a few more things than the corresponding change
in the commit-graph format. Specifically, 'test-tool read-midx' was not
writing anything about this header value to output. Since the value
available in 'struct multi_pack_index' is hash_len instead of a version
value, we output "20" or "32" instead of "1" or "2".
Since we want a user to not have their Git commands fail if their
multi-pack-index has the incorrect hash version compared to the
repository's hash version, we relax the die() to an error() in
load_multi_pack_index(). This has some effect on 'git multi-pack-index
verify' as we need to check that a failed parse of a file that exists is
actually a verify error. For that test that checks the hash version
matches, we change the corrupted byte from "2" to "3" to ensure the test
fails for both hash algorithms.
Helped-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Reviewed-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Like f0bca72dc7 (send-pack: use buffered I/O to talk to pack-objects,
2016-06-08), significantly reduce the number of system calls and
simplify the code for sending object IDs to pack-objects by using
stdio's buffering.
Helped-by: Chris Torek <chris.torek@gmail.com>
Helped-by: Johannes Sixt <j6t@kdbg.org>
Encouraged-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The point of UNLEAK() is to make a reference to a variable that is about
to go out of scope so that leak-checkers will consider it to be
not-leaked. Doing so right before die() is therefore pointless; even
though we are about to exit the program, the variable will still be on
the stack and accessible to leak-checkers.
These annotations aren't really hurting anything, but they clutter the
code and set a bad example of how to use UNLEAK().
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The --batch-size=<size> option of 'git multi-pack-index repack' is
intended to limit the amount of work done by the repack. In the case of
a large repository, this command should repack a number of small
pack-files but leave the large pack-files alone. Most often, the
repository has one large pack-file from a 'git clone' operation and
number of smaller pack-files from incremental 'git fetch' operations.
The issue with '--batch-size' is that it also _prevents_ the repack from
happening if the expected size of the resulting pack-file is too small.
This was intended as a way to avoid frequent churn of small pack-files,
but it has mostly caused confusion when a repository is of "medium"
size. That is, not enormous like the Windows OS repository, but also not
so small that this incremental repack isn't valuable.
The solution presented here is to collect pack-files for repack if their
expected size is smaller than the batch-size parameter until either the
total expected size exceeds the batch-size or all pack-files are
considered. If there are at least two pack-files, then these are
combined to a new pack-file whose size should not be too much larger
than the batch-size.
This new strategy should succeed in keeping the number of pack-files
small in these "medium" size repositories. The concern about churn is
likely not interesting, as the real control over that is the frequency
in which the repack command is run.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We eventually want to drop the argv_array name and just use strvec
consistently. There's no particular reason we have to do it all at once,
or care about interactions between converted and unconverted bits.
Because of our preprocessor compat layer, the names are interchangeable
to the compiler (so even a definition and declaration using different
names is OK).
This patch converts all of the remaining files, as the resulting diff is
reasonably sized.
The conversion was done purely mechanically with:
git ls-files '*.c' '*.h' |
xargs perl -i -pe '
s/ARGV_ARRAY/STRVEC/g;
s/argv_array/strvec/g;
'
We'll deal with any indentation/style fallouts separately.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When selecting a batch of pack-files to repack in the "git
multi-pack-index repack" command, Git should respect the
repack.packKeptObjects config option. When false, this option says that
the pack-files with an associated ".keep" file should not be repacked.
This config value is "false" by default.
There are two cases for selecting a batch of objects. The first is the
case where the input batch-size is zero, which specifies "repack
everything". The second is with a non-zero batch size, which selects
pack-files using a greedy selection criteria. Both of these cases are
updated and tested.
Reported-by: Son Luong Ngoc <sluongng@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When the "repack" subcommand of "git multi-pack-index" command
creates new packfile(s), it does not call the "git repack"
command but instead directly calls the "git pack-objects"
command, and the configuration variables meant for the "git
repack" command, like "repack.usedaeltabaseoffset", are ignored.
Check the configuration variables used by "git repack" ourselves
in "git multi-index-pack" and pass the corresponding options to
underlying "git pack-objects".
Note that `repack.writeBitmaps` configuration is ignored, as the
pack bitmap facility is useful only with a single packfile.
Signed-off-by: Son Luong Ngoc <sluongng@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The multi-pack-index left mmapped file descriptors open when it
does not have to.
* ds/multi-pack-index:
multi-pack-index: close file descriptor after mmap
The multi-pack-index subsystem was not closing its file descriptor
after memory-mapping the file contents. After this mmap() succeeds,
there is no need to keep the file descriptor open. In fact, there
is signficant reason to close it so we do not run out of
descriptors.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When verifying a midx index with 0 objects, the
m->num_objects - 1
underflows and wraps around to 4294967295.
Fix this both by checking that the midx contains at least one oid,
and also that we don't write any midx when there is no packfiles.
Update the tests to check that `git multi-pack-index write` does
not write an midx when there is no objects, and another to check
that `git multi-pack-index verify` warns when it verifies an midx with no
objects. For this last test, use t5319/no-objects.midx which was
generated by an older version of git.
Signed-off-by: Damien Robert <damien.olivier.robert+git@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Our nth_packed_object_sha1() function returns NULL for error. So when we
wrapped it with nth_packed_object_oid(), we kept the same semantics. But
it's a bit funny, because the caller actually passes in an out
parameter, and the pointer we return is just that same struct they
passed to us (or NULL).
It's not too terrible, but it does make the interface a little
non-idiomatic. Let's switch to our usual "0 for success, negative for
error" return value. Most callers either don't check it, or are
trivially converted. The one that requires the biggest change is
actually improved, as we can ditch an extra aliased pointer variable.
Since we are changing the interface in a subtle way that the compiler
wouldn't catch, let's also change the name to catch any topics in
flight. We can drop the 'o' and make it nth_packed_object_id(). That's
slightly shorter, but also less redundant since the 'o' stands for
"object" already.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Update midx_repack to only display progress when
the MIDX_PROGRESS flag is set.
Signed-off-by: William Baker <William.Baker@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Update verify_midx_file to only display progress when
the MIDX_PROGRESS flag is set.
Signed-off-by: William Baker <William.Baker@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add progress to expire_midx_packs. Progress is
displayed when the MIDX_PROGRESS flag is set.
Signed-off-by: William Baker <William.Baker@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add progress to write_midx_file. Progress is displayed
when the MIDX_PROGRESS flag is set.
Signed-off-by: William Baker <William.Baker@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add the MIDX_PROGRESS flag and update the
write|verify|expire|repack functions in midx.h
to accept a flags parameter. The MIDX_PROGRESS
flag indicates whether the caller of the function
would like progress information to be displayed.
This patch only changes the method prototypes
and does not change the functionality. The
functionality change will be handled by a later patch.
Signed-off-by: William Baker <William.Baker@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Instead of hard-coding the hash size, use the_hash_algo to look up the
hash size at runtime. Remove the #define constant which was used to
hold the hash length, since writing the expression with the_hash_algo
provide enough documentary value on its own.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
To repack with a non-zero batch-size, first sort all pack-files by
their modified time. Second, walk those pack-files from oldest
to newest, compute their expected size, and add the packs to a list
if they are smaller than the given batch-size. Stop when the total
expected size is at least the batch size.
If the batch size is zero, select all packs in the multi-pack-index.
Finally, collect the objects from the multi-pack-index that are in
the selected packs and send them to 'git pack-objects'. Write a new
multi-pack-index that includes the new pack.
Using a batch size of zero is very similar to a standard 'git repack'
command, except that we do not delete the old packs and instead rely
on the new multi-pack-index to prevent new processes from reading the
old packs. This does not disrupt other Git processes that are currently
reading the old packs based on the old multi-pack-index.
While first designing a 'git multi-pack-index repack' operation, I
started by collecting the batches based on the actual size of the
objects instead of the size of the pack-files. This allows repacking
a large pack-file that has very few referencd objects. However, this
came at a significant cost of parsing pack-files instead of simply
reading the multi-pack-index and getting the file information for
the pack-files. The "expected size" version provides similar
behavior, but could skip a pack-file if the average object size is
much larger than the actual size of the referenced objects, or
can create a large pack if the actual size of the referenced objects
is larger than the expected size.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In an environment where the multi-pack-index is useful, it is due
to many pack-files and an inability to repack the object store
into a single pack-file. However, it is likely that many of these
pack-files are rather small, and could be repacked into a slightly
larger pack-file without too much effort. It may also be important
to ensure the object store is highly available and the repack
operation does not interrupt concurrent git commands.
Introduce a 'repack' subcommand to 'git multi-pack-index' that
takes a '--batch-size' option. The subcommand will inspect the
multi-pack-index for referenced pack-files whose size is smaller
than the batch size, until collecting a list of pack-files whose
sizes sum to larger than the batch size. Then, a new pack-file
will be created containing the objects from those pack-files that
are referenced by the multi-pack-index. The resulting pack is
likely to actually be smaller than the batch size due to
compression and the fact that there may be objects in the pack-
files that have duplicate copies in other pack-files.
The current change introduces the command-line arguments, and we
add a test that ensures we parse these options properly. Since
we specify a small batch size, we will guarantee that future
implementations do not change the list of pack-files.
In addition, we hard-code the modified times of the packs in
the pack directory to ensure the list of packs sorted by modified
time matches the order if sorted by size (ascending). This will
be important in a future test.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The 'git multi-pack-index expire' subcommand looks at the existing
mult-pack-index, counts the number of objects referenced in each
pack-file, deletes the pack-fils with no referenced objects, and
rewrites the multi-pack-index to no longer reference those packs.
Refactor the write_midx_file() method to call write_midx_internal()
which now takes an existing 'struct multi_pack_index' and a list
of pack-files to drop (as specified by the names of their pack-
indexes). As we write the new multi-pack-index, we drop those
file names from the list of known pack-files.
The expire_midx_packs() method removes the unreferenced pack-files
after carefully closing the packs to avoid open handles.
Test that a new pack-file that covers the contents of two other
pack-files leads to those pack-files being deleted during the
expire subcommand. Be sure to read the multi-pack-index to ensure
it no longer references those packs.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In anticipation of the expire subcommand, refactor the way we sort
the packfiles by name. This will greatly simplify our approach to
dropping expired packs from the list.
First, create 'struct pack_info' to replace 'struct pack_pair'.
This struct contains the necessary information about a pack,
including its name, a pointer to its packfile struct (if not
already in the multi-pack-index), and the original pack-int-id.
Second, track the pack information using an array of pack_info
structs in the pack_list struct. This simplifies the logic around
the multiple arrays we were tracking in that struct.
Finally, update get_sorted_entries() to not permute the pack-int-id
and instead supply the permutation to write_midx_object_offsets().
This requires sorting the packs after get_sorted_entries().
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Before writing the multi-pack-index, we compute the length of the
pack-index names concatenated together. This forms the data in the
pack name chunk, and we precompute it to compute chunk offsets.
The value is also modified to fit alignment needs.
Previously, this computation was coupled with adding packs from
the existing multi-pack-index and the remaining packs in the object
dir not already covered by the multi-pack-index.
In anticipation of this becoming more complicated with the 'expire'
subcommand, simplify the computation by centralizing it to a single
loop before writing the file.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The multi-pack-index tracks objects in a collection of pack-files.
Only one copy of each object is indexed, using the modified time
of the pack-files to determine tie-breakers. It is possible to
have a pack-file with no referenced objects because all objects
have a duplicate in a newer pack-file.
Introduce a new 'expire' subcommand to the multi-pack-index builtin.
This subcommand will delete these unused pack-files and rewrite the
multi-pack-index to no longer refer to those files. More details
about the specifics will follow as the method is implemented.
Add a test that verifies the 'expire' subcommand is correctly wired,
but will still be valid when the verb is implemented. Specifically,
create a set of packs that should all have referenced objects and
should not be removed during an 'expire' operation. The packs are
created carefully to ensure they have a specific order when sorted
by size. This will be important in a later test.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The multi-pack-index allows searching for objects across multiple
packs using one object list. The original design gains many of
these performance benefits by keeping the packs in the
multi-pack-index out of the packed_git list.
Unfortunately, this has one major drawback. If the multi-pack-index
covers thousands of packs, and a command loads many of those packs,
then we can hit the limit for open file descriptors. The
close_one_pack() method is used to limit this resource, but it
only looks at the packed_git list, and uses an LRU cache to prevent
thrashing.
Instead of complicating this close_one_pack() logic to include
direct references to the multi-pack-index, simply add the packs
opened by the multi-pack-index to the packed_git list. This
immediately solves the file-descriptor limit problem, but requires
some extra steps to avoid performance issues or other problems:
1. Create a multi_pack_index bit in the packed_git struct that is
one if and only if the pack was loaded from a multi-pack-index.
2. Skip packs with the multi_pack_index bit when doing object
lookups and abbreviations. These algorithms already check the
multi-pack-index before the packed_git struct. This has a very
small performance hit, as we need to walk more packed_git
structs. This is acceptable, since these operations run binary
search on the other packs, so this walk-and-ignore logic is
very fast by comparison.
3. When closing a multi-pack-index file, do not close its packs,
as those packs will be closed using close_all_packs(). In some
cases, such as 'git repack', we run 'close_midx()' without also
closing the packs, so we need to un-set the multi_pack_index bit
in those packs. This is necessary, and caught by running
t6501-freshen-objects.sh with GIT_TEST_MULTI_PACK_INDEX=1.
To manually test this change, I inserted trace2 logging into
close_pack_fd() and set pack_max_fds to 10, then ran 'git rev-list
--all --objects' on a copy of the Git repo with 300+ pack-files and
a multi-pack-index. The logs verified the packs are closed as
we read them beyond the file descriptor limit.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Much of the multi-pack-index code focuses on the multi_pack_index
struct, and so we only pass a pointer to the current one. However,
we will insert a dependency on the packed_git linked list in a
future change, so we will need a repository reference. Inserting
these parameters is a significant enough change to split out.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Code clean-up around a much-less-important-than-it-used-to-be
update_server_info() funtion.
* jk/server-info-rabbit-hole:
update_info_refs(): drop unused force parameter
server-info: drop objdirlen pointer arithmetic
server-info: drop nr_alloc struct member
server-info: use strbuf to read old info/packs file
server-info: simplify cleanup in parse_pack_def()
server-info: fix blind pointer arithmetic
http: simplify parsing of remote objects/info/packs
packfile: fix pack basename computation
midx: check both pack and index names for containment
t5319: drop useless --buffer from cat-file
t5319: fix bogus cat-file argument
pack-revindex: open index if necessary
packfile.h: drop extern from function declarations
A midx file (and the struct we parse from it) contains a list of all of
the covered packfiles, mentioned by their ".idx" names (e.g.,
"pack-1234.idx", etc). And thus calls to midx_contains_pack() expect
callers to provide the idx name.
This works for most of the calls, but the one in open_packed_git_1()
tries to feed a packed_git->pack_name, which is the ".pack" name,
meaning we'll never find a match (even if the pack is covered by the
midx).
We can fix this by converting the ".pack" to ".idx" in the caller.
However, that requires allocating a new string. Instead, let's make
midx_contains_pack() a bit friendlier, and allow it take _either_ the
.pack or .idx variant.
All cleverness in the matching code is credited to René. Bugs are mine.
There's no test here, because while this does fix _a_ bug, it's masked
by another bug in that same caller. That will be covered (with a test)
in the next patch.
Helped-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Teach `multi-pack-index verify` to sort the set of object by
packfile so that only one packfile needs to be open at a time.
This is a performance improvement. Previously, objects were
verified in OID order. This essentially requires all packfiles
to be open at the same time. If the number of packfiles exceeds
the open file limit, packfiles would be LRU-closed and re-opened
many times.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add progress indicators to more parts of midx verify.
Use sparse progress indicator for object iteration.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Log multi-pack-index command mode.
Log number of objects and packfiles in the midx.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Code clean-up with optimization for the codepath that checks
(non-)existence of loose objects.
* jk/loose-object-cache:
odb_load_loose_cache: fix strbuf leak
fetch-pack: drop custom loose object cache
sha1-file: use loose object cache for quick existence check
object-store: provide helpers for loose_objects_cache
sha1-file: use an object_directory for the main object dir
handle alternates paths the same as the main object dir
sha1_file_name(): overwrite buffer instead of appending
rename "alternate_object_database" to "object_directory"
submodule--helper: prefer strip_suffix() to ends_with()
fsck: do not reuse child_process structs
Translating the new strings introduced for v2.20 showed some typos.
Signed-off-by: Jean-Noël Avila <jn.avila@free.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Various functions have been audited for "-Wunused-parameter" warnings
and bugs in them got fixed.
* jk/unused-parameter-fixes:
midx: double-check large object write loop
assert NOARG/NONEG behavior of parse-options callbacks
parse-options: drop OPT_DATE()
apply: return -1 from option callback instead of calling exit(1)
cat-file: report an error on multiple --batch options
tag: mark "--message" option with NONEG
show-branch: mark --reflog option as NONEG
format-patch: mark "--no-numbered" option with NONEG
status: mark --find-renames option with NONEG
cat-file: mark batch options with NONEG
pack-objects: mark index-version option as NONEG
ls-files: mark exclude options as NONEG
am: handle --no-patch-format option
apply: mark include/exclude options as NONEG
Tests for the recently introduced multi-pack index machinery.
* ds/test-multi-pack-index:
packfile: close multi-pack-index in close_all_packs
multi-pack-index: define GIT_TEST_MULTI_PACK_INDEX
midx: close multi-pack-index on repack
midx: fix broken free() in close_midx()
The write_midx_large_offsets() function takes an array of object
entries, the number of entries in the array (nr_objects), and the number
of entries with large offsets (nr_large_offset). But we never actually
use nr_objects; instead we keep walking down the array and counting down
nr_large_offset until we've seen all of the large entries.
This is correct, but we can be a bit more defensive. If there were ever
a mismatch between nr_large_offset and the actual set of large-offset
objects, we'd walk off the end of the array.
Since we know the size of the array, we can use nr_objects to make sure
we don't walk too far.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The multi-pack-index feature is tested in isolation by
t5319-multi-pack-index.sh, but there are many more interesting
scenarios in the test suite surrounding pack-file data shapes
and interactions. Since the multi-pack-index is an optional
data structure, it does not make sense to include it by default
in those tests.
Instead, add a new GIT_TEST_MULTI_PACK_INDEX environment variable
that enables core.multiPackIndex and writes a multi-pack-index
after each 'git repack' command. This adds extra test coverage
when needed.
There are a few spots in the test suite that need to react to this
change:
* t5319-multi-pack-index.sh: there is a test that checks that
'git repack' deletes the multi-pack-index. Disable the environment
variable to ensure this still happens.
* t5310-pack-bitmaps.sh: One test moves a pack-file from the object
directory to an alternate. This breaks the multi-pack-index, so
delete the multi-pack-index at this point, if it exists.
* t9300-fast-import.sh: One test verifies the number of files in
the .git/objects/pack directory is exactly 8. Exclude the
multi-pack-index from this count so it is still 8 in all cases.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When repacking, we may remove pack-files. This invalidates the
multi-pack-index (if it exists). Previously, we removed the
multi-pack-index file before removing any pack-file. In some cases,
the repack command may load the multi-pack-index into memory. This
may lead to later in-memory references to the non-existent pack-
files.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
it is initialized unconditionally by a call to start_progress
below.
Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When closing a multi-pack-index, we intend to close each pack-file
and free the struct packed_git that represents it. However, this
line was previously freeing the array of pointers, not the
pointer itself. This leads to a double-free issue.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We added faster equality-comparison functions for hashes in
14438c4497 (introduce hasheq() and oideq(), 2018-08-28). A
few topics were in-flight at the time, and can now be
converted. This covers all spots found by "make coccicheck"
in master (the coccicheck results were tweaked by hand for
style).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When verifying a multi-pack-index, the only action that takes
significant time is checking the object offsets. For example,
to verify a multi-pack-index containing 6.2 million objects in
the Linux kernel repository takes 1.3 seconds on my machine.
99% of that time is spent looking up object offsets in each of
the packfiles and comparing them to the multi-pack-index offset.
Add a progress indicator for that section of the 'verify' verb.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The 'git multi-pack-index verify' command must verify the object
offsets stored in the multi-pack-index are correct. There are two
ways the offset chunk can be incorrect: the pack-int-id and the
object offset.
Replace the BUG() statement with a die() statement, now that we
may hit a bad pack-int-id during a 'verify' command on a corrupt
multi-pack-index, and it is covered by a test.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When loading a 64-bit offset, we intend to check that off_t can store
the resulting offset. However, the condition accidentally checks the
32-bit offset to see if it is smaller than a 64-bit value. Fix it,
and this will be covered by a test in the 'git multi-pack-index verify'
command in a later commit.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The final check we make while loading a multi-pack-index is that
the packfile names are in lexicographical order. Make this error
be a die() instead.
In order to test this condition, we need multiple packfiles.
Earlier in t5319-multi-pack-index.sh, we tested the interaction with
'git repack' but this limits us to one packfile in our object dir.
Move these repack tests until after the 'verify' tests.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When verifying if a multi-pack-index file is valid, we want the
command to fail to signal an invalid file. Previously, we wrote
an error to stderr and continued as if we had no multi-pack-index.
Now, die() instead of error().
Add tests that check corrupted headers in a few ways:
* Bad signature
* Bad file version
* Bad hash version
* Truncated hash count
* Extended hash count
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The multi-pack-index builtin writes multi-pack-index files, and
uses a 'write' verb to do so. Add a 'verify' verb that checks this
file matches the contents of the pack-indexes it replaces.
The current implementation is a no-op, but will be extended in
small increments in later commits.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If a repo contains a multi-pack-index, then the packed_git list
does not contain the packfiles that are covered by the multi-pack-index.
This is important for doing object lookups, abbreviations, and
approximating object count. However, there are many operations that
really want to iterate over all packfiles.
Create a new 'all_packs' linked list that contains this list, starting
with the packfiles in the multi-pack-index and then continuing along
the packed_git linked list.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The logic for constructing the linked list of multi-pack-indexes
in the object store is incorrect. If the local object store has
a multi-pack-index, but an alternate does not, then the list is
dropped.
Add tests that would have revealed this bug.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When an object fails to decompress from a pack-file, we mark the object
as 'bad' so we can retry with a different copy of the object (if such a
copy exists).
Before now, the multi-pack-index did not update the bad objects list for
the pack-files it contains, and we did not check the bad objects list
when reading an object. Now, do both.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A pack-file is 'local' if it is stored within the usual object
directory. If it is stored in an alternate, it is non-local.
Pack-files are stored using a 'pack_local' member in the packed_git
struct. Add a similar 'local' member to the multi_pack_index struct
and 'local' parameters to the methods that load and prepare multi-
pack-indexes.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If a 'git repack' command replaces existing packfiles, then we must
clear the existing multi-pack-index before moving the packfiles it
references.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Due to how Windows handles replacing a lockfile when there is an open
handle, create the close_midx() method to close the existing midx before
writing the new one.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The core.multiPackIndex config setting controls the multi-pack-
index (MIDX) feature. If false, the setting will disable all reads
from the multi-pack-index file.
Read this config setting in the new prepare_multi_pack_index_one()
which is called during prepare_packed_git(). This check is run once
per repository.
Add comparison commands in t5319-multi-pack-index.sh to check
typical Git behavior remains the same as the config setting is turned
on and off. This currently includes 'git rev-list' and 'git log'
commands to trigger several object database reads. Currently, these
would only catch an error in the prepare_multi_pack_index_one(), but
with later commits will catch errors in object lookups, abbreviations,
and approximate object counts.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The final pair of chunks for the multi-pack-index file stores the object
offsets. We default to using 32-bit offsets as in the pack-index version
1 format, but if there exists an offset larger than 32-bits, we use a
trick similar to the pack-index version 2 format by storing all offsets
at least 2^31 in a 64-bit table; we use the 32-bit table to point into
that 64-bit table as necessary.
We only store these 64-bit offsets if necessary, so create a test that
manipulates a version 2 pack-index to fake a large offset. This allows
us to test that the large offset table is created, but the data does not
match the actual packfile offsets. The multi-pack-index offset does match
the (corrupted) pack-index offset, so a future feature will compare these
offsets during a 'verify' step.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Before writing a list of objects and their offsets to a multi-pack-index,
we need to collect the list of objects contained in the packfiles. There
may be multiple copies of some objects, so this list must be deduplicated.
It is possible to artificially get into a state where there are many
duplicate copies of objects. That can create high memory pressure if we
are to create a list of all objects before de-duplication. To reduce
this memory pressure without a significant performance drop,
automatically group objects by the first byte of their object id. Use
the IDX fanout tables to group the data, copy to a local array, then
sort.
Copy only the de-duplicated entries. Select the duplicate based on the
most-recent modified time of a packfile containing the object.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The multi-pack-index needs to track which packfiles it indexes. Store
these in our first required chunk. Since filenames are not well
structured, add padding to keep good alignment in later chunks.
Modify the 'git multi-pack-index read' subcommand to output the
existence of the pack-file name chunk. Modify t5319-multi-pack-index.sh
to reflect this new output and the new expected number of chunks.
Defense in depth: A pattern we are using in the multi-pack-index feature
is to verify the data as we write it. We want to ensure we never write
invalid data to the multi-pack-index. There are many checks that verify
that the values we are writing fit the format definitions. This mainly
helps developers while working on the feature, but it can also identify
issues that only appear when dealing with very large data sets. These
large sets are hard to encode into test cases.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When constructing a multi-pack-index file for a given object directory,
read the files within the enclosed pack directory and find matches that
end with ".idx" and find the correct paired packfile using
add_packed_git().
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Create a new multi_pack_index struct for loading multi-pack-indexes into
memory. Create a test-tool builtin for reading basic information about
that multi-pack-index to verify the correct data is written.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As we begin writing the multi-pack-index format to disk, start with
the basics: the 12-byte header and the 20-byte checksum footer. Start
with these basics so we can add the rest of the format in small
increments.
As we implement the format, we will use a technique to check that our
computed offsets within the multi-pack-index file match what we are
actually writing. Each method that writes to the hashfile will return
the number of bytes written, and we will track that those values match
our expectations.
Currently, write_midx_header() returns 12, but is not checked. We will
check the return value in a later commit.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In anticipation of writing multi-pack-indexes, add a skeleton
'git multi-pack-index write' subcommand and send the options to a
write_midx_file() method. Also create a skeleton test script that
tests the 'write' subcommand.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
