More codepaths are moving away from hardcoded hash sizes.
* bc/hash-transition-part-15:
rerere: convert to use the_hash_algo
submodule: make zero-oid comparison hash function agnostic
apply: rename new_sha1_prefix and old_sha1_prefix
apply: replace hard-coded constants
tag: express constant in terms of the_hash_algo
transport: use parse_oid_hex instead of a constant
upload-pack: express constants in terms of the_hash_algo
refs/packed-backend: express constants using the_hash_algo
packfile: express constants in terms of the_hash_algo
pack-revindex: express constants in terms of the_hash_algo
builtin/fetch-pack: remove constants with parse_oid_hex
builtin/mktree: remove hard-coded constant
builtin/repack: replace hard-coded constants
pack-bitmap-write: use GIT_MAX_RAWSZ for allocation
object_id.cocci: match only expressions of type 'struct object_id'
Breaks the majority of check_packed_git_idx() into a separate function,
load_idx(). The latter function operates on arbitrary buffers, which
makes it suitable as a fuzzing test target.
Signed-off-by: Josh Steadmon <steadmon@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Replace uses of GIT_SHA1_RAWSZ with references to the_hash_algo to avoid
dependence on a particular hash length.
It's likely that in the future, we'll update the pack format to indicate
what hash algorithm it uses, and then this code will change. However,
at least on an interim basis, make it easier to develop on a pure
SHA-256 Git by using the_hash_algo here.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
spatch transformation to replace boolean uses of !hashcmp() to
newly introduced oideq() is added, and applied, to regain
performance lost due to support of multiple hash algorithms.
* jk/cocci:
show_dirstat: simplify same-content check
read-cache: use oideq() in ce_compare functions
convert hashmap comparison functions to oideq()
convert "hashcmp() != 0" to "!hasheq()"
convert "oidcmp() != 0" to "!oideq()"
convert "hashcmp() == 0" to hasheq()
convert "oidcmp() == 0" to oideq()
introduce hasheq() and oideq()
coccinelle: use <...> for function exclusion
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>
This is the partner patch to the previous one, but covering
the "hash" variants instead of "oid". Note that our
coccinelle rule is slightly more complex to avoid triggering
the call in hasheq().
I didn't bother to add a new rule to convert:
- hasheq(E1->hash, E2->hash)
+ oideq(E1, E2)
Since these are new functions, there won't be any such
existing callers. And since most of the code is already
using oideq, we're not likely to introduce new ones.
We might still see "!hashcmp(E1->hash, E2->hash)" from topics
in flight. But because our new rule comes after the existing
ones, that should first get converted to "!oidcmp(E1, E2)"
and then to "oideq(E1, E2)".
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There are many places in the codebase that want to iterate over
all packfiles known to Git. The purposes are wide-ranging, and
those that can take advantage of the multi-pack-index already
do. So, use get_all_packs() instead of get_packed_git() to be
sure we are iterating over all packfiles.
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>
When prepare_packed_git is called with the report_garbage method
initialized, we report unexpected files in the objects directory
as garbage. Stop reporting the multi-pack-index and the pack-files
it covers as garbage.
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>
* ds/multi-pack-index: (23 commits)
midx: clear midx on repack
packfile: skip loading index if in multi-pack-index
midx: prevent duplicate packfile loads
midx: use midx in approximate_object_count
midx: use existing midx when writing new one
midx: use midx in abbreviation calculations
midx: read objects from multi-pack-index
config: create core.multiPackIndex setting
midx: write object offsets
midx: write object id fanout chunk
midx: write object ids in a chunk
midx: sort and deduplicate objects from packfiles
midx: read pack names into array
multi-pack-index: write pack names in chunk
multi-pack-index: read packfile list
packfile: generalize pack directory list
t5319: expand test data
multi-pack-index: load into memory
midx: write header information to lockfile
multi-pack-index: add 'write' verb
...
We currently iterate over objects within a pack in .idx
order, which uses the object hashes. That means that it
is effectively random with respect to the location of the
object within the pack. If you're going to access the actual
object data, there are two reasons to move linearly through
the pack itself:
1. It improves the locality of access in the packfile. In
the cold-cache case, this may mean fewer disk seeks, or
better usage of disk cache.
2. We store related deltas together in the packfile. Which
means that the delta base cache can operate much more
efficiently if we visit all of those related deltas in
sequence, as the earlier items are likely to still be
in the cache. Whereas if we visit the objects in
random order, our cache entries are much more likely to
have been evicted by unrelated deltas in the meantime.
So in general, if you're going to access the object contents
pack order is generally going to end up more efficient.
But if you're simply generating a list of object names, or
if you're going to end up sorting the result anyway, you're
better off just using the .idx order, as finding the pack
order means generating the in-memory pack-revindex.
According to the numbers in 8b8dfd5132 (pack-revindex:
radix-sort the revindex, 2013-07-11), that takes about 200ms
for linux.git, and 20ms for git.git (those numbers are a few
years old but are still a good ballpark).
That makes it a good optimization for some cases (we can
save tens of seconds in git.git by having good locality of
delta access, for a 20ms cost), but a bad one for others
(e.g., right now "cat-file --batch-all-objects
--batch-check="%(objectname)" is 170ms in git.git, so adding
20ms to that is noticeable).
Hence this patch makes it an optional flag. You can't
actually do any interesting timings yet, as it's not plumbed
through to any user-facing tools like cat-file. That will
come in a later patch.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It's not wrong to pass our flags in an "unsigned", as we
know it will be at least as large as the enum. However,
using the enum in the declaration makes it more obvious
where to find the list of flags.
While we're here, let's also drop the "extern" noise-words
from the declarations, per our modern coding style.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The multi-pack-index, when present, tracks the existence of objects and
their offsets within a list of packfiles. This allows us to use the
multi-pack-index for object lookups, abbreviations, and object counts.
When the multi-pack-index tracks a packfile, then we do not need to add
that packfile to the packed_git linked list or the MRU list.
We still need to load the packfiles that are not tracked by the
multi-pack-index.
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>
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>
In anticipation of sharing the pack directory listing with the
multi-pack-index, generalize prepare_packed_git_one() into
for_each_file_in_pack_dir().
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a repository argument to allow the callers of parse_object
to be more specific about which repository to act on. This is a small
mechanical change; it doesn't change the implementation to handle
repositories other than the_repository yet.
As with the previous commits, use a macro to catch callers passing a
repository other than the_repository at compile time.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Make zlib inflate codepath more robust against versions of zlib
that clobber unused portion of outbuf.
* jl/zlib-restore-nul-termination:
packfile: correct zlib buffer handling
The buffer being passed to zlib includes a NUL terminator that git
needs to keep in place. unpack_compressed_entry() attempts to detect
the case that the source buffer hasn't been fully consumed by
checking to see if the destination buffer has been over consumed.
This causes a problem, that more recent zlib patches have been
poisoning the unconsumed portions of the buffer which overwrites
the NUL byte, while correctly returning length and status.
Let's place the NUL at the end of the buffer after inflate returns
to assure that it doesn't result in problems for git even if its
been overwritten by zlib.
Signed-off-by: Jeremy Linton <lintonrjeremy@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Conversion from uchar[20] to struct object_id continues.
* bc/object-id: (42 commits)
merge-one-file: compute empty blob object ID
add--interactive: compute the empty tree value
Update shell scripts to compute empty tree object ID
sha1_file: only expose empty object constants through git_hash_algo
dir: use the_hash_algo for empty blob object ID
sequencer: use the_hash_algo for empty tree object ID
cache-tree: use is_empty_tree_oid
sha1_file: convert cached object code to struct object_id
builtin/reset: convert use of EMPTY_TREE_SHA1_BIN
builtin/receive-pack: convert one use of EMPTY_TREE_SHA1_HEX
wt-status: convert two uses of EMPTY_TREE_SHA1_HEX
submodule: convert several uses of EMPTY_TREE_SHA1_HEX
sequencer: convert one use of EMPTY_TREE_SHA1_HEX
merge: convert empty tree constant to the_hash_algo
builtin/merge: switch tree functions to use object_id
builtin/am: convert uses of EMPTY_TREE_SHA1_BIN to the_hash_algo
sha1-file: add functions for hex empty tree and blob OIDs
builtin/receive-pack: avoid hard-coded constants for push certs
diff: specify abbreviation size in terms of the_hash_algo
upload-pack: replace use of several hard-coded constants
...
Developer support update, by using BUG() macro instead of die() to
mark codepaths that should not happen more clearly.
* js/use-bug-macro:
BUG_exit_code: fix sparse "symbol not declared" warning
Convert remaining die*(BUG) messages
Replace all die("BUG: ...") calls by BUG() ones
run-command: use BUG() to report bugs, not die()
test-tool: help verifying BUG() code paths
The codepath around object-info API has been taught to take the
repository object (which in turn tells the API which object store
the objects are to be located).
* sb/oid-object-info:
cache.h: allow oid_object_info to handle arbitrary repositories
packfile: add repository argument to cache_or_unpack_entry
packfile: add repository argument to unpack_entry
packfile: add repository argument to read_object
packfile: add repository argument to packed_object_info
packfile: add repository argument to packed_to_object_type
packfile: add repository argument to retry_bad_packed_offset
cache.h: add repository argument to oid_object_info
cache.h: add repository argument to oid_object_info_extended
The code has been taught to use the duplicated information stored
in the commit-graph file to learn the tree object name for a commit
to avoid opening and parsing the commit object when it makes sense
to do so.
* ds/lazy-load-trees:
coccinelle: avoid wrong transformation suggestions from commit.cocci
commit-graph: lazy-load trees for commits
treewide: replace maybe_tree with accessor methods
commit: create get_commit_tree() method
treewide: rename tree to maybe_tree
Precompute and store information necessary for ancestry traversal
in a separate file to optimize graph walking.
* ds/commit-graph:
commit-graph: implement "--append" option
commit-graph: build graph from starting commits
commit-graph: read only from specific pack-indexes
commit: integrate commit graph with commit parsing
commit-graph: close under reachability
commit-graph: add core.commitGraph setting
commit-graph: implement git commit-graph read
commit-graph: implement git-commit-graph write
commit-graph: implement write_commit_graph()
commit-graph: create git-commit-graph builtin
graph: add commit graph design document
commit-graph: add format document
csum-file: refactor finalize_hashfile() method
csum-file: rename hashclose() to finalize_hashfile()
In d8193743e0 (usage.c: add BUG() function, 2017-05-12), a new macro
was introduced to use for reporting bugs instead of die(). It was then
subsequently used to convert one single caller in 588a538ae5
(setup_git_env: convert die("BUG") to BUG(), 2017-05-12).
The cover letter of the patch series containing this patch
(cf 20170513032414.mfrwabt4hovujde2@sigill.intra.peff.net) is not
terribly clear why only one call site was converted, or what the plan
is for other, similar calls to die() to report bugs.
Let's just convert all remaining ones in one fell swoop.
This trick was performed by this invocation:
sed -i 's/die("BUG: /BUG("/g' $(git grep -l 'die("BUG' \*.c)
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There are several instances of the constant 20 and 20-based values in
the packfile code. Abstract away dependence on SHA-1 by using the
values from the_hash_algo instead.
Use unsigned values for temporary constants to provide the compiler with
more information about what kinds of values it should expect.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Convert find_pack_entry and the static function fill_pack_entry to take
pointers to struct object_id.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Convert this function to take a pointer to struct object_id and rename
it has_object_pack for consistency with has_object_file.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The sha1 member in struct pack_entry is unused except for one instance
in which we store a value in it. Since nobody ever reads this value,
don't bother to compute it and remove the member from struct pack_entry.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This involves also adapting oid_object_info_extended and a some
internal functions that are used to implement these. It all has to
happen in one patch, because of a single recursive chain of calls visits
all these functions.
oid_object_info_extended is also used in partial clones, which allow
fetching missing objects. As this series will not add the repository
struct to the transport code and fetch_object(), add a TODO note and
omit fetching if a user tries to use a partial clone in a repository
other than the_repository.
Among the functions modified to handle arbitrary repositories,
unpack_entry() is one of them. Note that it still references the globals
"delta_base_cache" and "delta_base_cached", but those are safe to be
referenced (the former is indexed partly by "struct packed_git *", which
is repo-specific, and the latter is only used to limit the size of the
former as an optimization).
Helped-by: Brandon Williams <bmwill@google.com>
Helped-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a repository argument to allow the callers of cache_or_unpack_entry
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>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a repository argument to allow the callers of unpack_entry
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>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a repository argument to allow the callers of read_object
to be more specific about which repository to act on. This is a small
mechanical change; it doesn't change the implementation to handle
repositories other than the_repository yet.
As with the previous commits, use a macro to catch callers passing a
repository other than the_repository at compile time.
Signed-off-by: Stefan Beller <sbeller@google.com>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a repository argument to allow callers of packed_object_info to be
more specific about which repository to handle. This is a small
mechanical change; it doesn't change the implementation to handle
repositories other than the_repository yet.
As with the previous commits, use a macro to catch callers passing a
repository other than the_repository at compile time.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a repository argument to allow the callers of packed_to_object_type
to be more specific about which repository to handle. This is a small
mechanical change; it doesn't change the implementation to handle
repositories other than the_repository yet.
As with the previous commits, use a macro to catch callers passing a
repository other than the_repository at compile time.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a repository argument to allow the callers of retry_bad_packed_offset
to be more specific about which repository to handle. This is a small
mechanical change; it doesn't change the implementation to handle
repositories other than the_repository yet.
As with the previous commits, use a macro to catch callers passing a
repository other than the_repository at compile time.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a repository argument to allow the callers of oid_object_info
to be more specific about which repository to handle. This is a small
mechanical change; it doesn't change the implementation to handle
repositories other than the_repository yet.
As with the previous commits, use a macro to catch callers passing a
repository other than the_repository at compile time.
Signed-off-by: Stefan Beller <sbeller@google.com>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a repository argument to allow oid_object_info_extended callers
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.
Signed-off-by: Stefan Beller <sbeller@google.com>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Refactoring the internal global data structure to make it possible
to open multiple repositories, work with and then close them.
Rerolled by Duy on top of a separate preliminary clean-up topic.
The resulting structure of the topics looked very sensible.
* sb/object-store: (27 commits)
sha1_file: allow sha1_loose_object_info to handle arbitrary repositories
sha1_file: allow map_sha1_file to handle arbitrary repositories
sha1_file: allow map_sha1_file_1 to handle arbitrary repositories
sha1_file: allow open_sha1_file to handle arbitrary repositories
sha1_file: allow stat_sha1_file to handle arbitrary repositories
sha1_file: allow sha1_file_name to handle arbitrary repositories
sha1_file: add repository argument to sha1_loose_object_info
sha1_file: add repository argument to map_sha1_file
sha1_file: add repository argument to map_sha1_file_1
sha1_file: add repository argument to open_sha1_file
sha1_file: add repository argument to stat_sha1_file
sha1_file: add repository argument to sha1_file_name
sha1_file: allow prepare_alt_odb to handle arbitrary repositories
sha1_file: allow link_alt_odb_entries to handle arbitrary repositories
sha1_file: add repository argument to prepare_alt_odb
sha1_file: add repository argument to link_alt_odb_entries
sha1_file: add repository argument to read_info_alternates
sha1_file: add repository argument to link_alt_odb_entry
sha1_file: add raw_object_store argument to alt_odb_usable
pack: move approximate object count to object store
...
In anticipation of making trees load lazily, create a Coccinelle
script (contrib/coccinelle/commit.cocci) to ensure that all
references to the 'maybe_tree' member of struct commit are either
mutations or accesses through get_commit_tree() or
get_commit_tree_oid().
Apply the Coccinelle script to create the rest of the patch.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Using the commit-graph file to walk commit history removes the large
cost of parsing commits during the walk. This exposes a performance
issue: lookup_tree() takes a large portion of the computation time,
even when Git never uses those trees.
In anticipation of lazy-loading these trees, rename the 'tree' member
of struct commit to 'maybe_tree'. This serves two purposes: it hints
at the future role of possibly being NULL even if the commit has a
valid tree, and it allows for unambiguous transformation from simple
member access (i.e. commit->maybe_tree) to method access.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Teach git-commit-graph to inspect the objects only in a certain list
of pack-indexes within the given pack directory. This allows updating
the commit graph iteratively.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The reason callers have to call this is to make sure either packed_git
or packed_git_mru pointers are initialized since we don't do that by
default. Sometimes it's hard to see this connection between where the
function is called and where packed_git pointer is used (sometimes in
separate functions).
Keep this dependency internal because now all access to packed_git and
packed_git_mru must go through get_xxx() wrappers.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Junio C Hamano
Josh Steadmon
brian m. carlson
Jeff King
Derrick Stolee
Derrick Stolee
Stefan Beller
Jeremy Linton
Johannes Schindelin
Jonathan Nieder
Nguyễn Thái Ngọc Duy