Summary:
The implementation of TransactionDB::WrapDB() and
TransactionDB::WrapStackableDB() are almost identical, except for the
type of the first argument `db`. This PR adds a new template function in
anonymous namespace, and calls it in the above two functions.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8079
Test Plan: make check
Reviewed By: lth
Differential Revision: D27184575
Pulled By: riversand963
fbshipit-source-id: f2855a6db3a7e897d0d611f7050ca4b696c56a7a
Summary:
For performance purposes, the lower level routines were changed to use a SystemClock* instead of a std::shared_ptr<SystemClock>. The shared ptr has some performance degradation on certain hardware classes.
For most of the system, there is no risk of the pointer being deleted/invalid because the shared_ptr will be stored elsewhere. For example, the ImmutableDBOptions stores the Env which has a std::shared_ptr<SystemClock> in it. The SystemClock* within the ImmutableDBOptions is essentially a "short cut" to gain access to this constant resource.
There were a few classes (PeriodicWorkScheduler?) where the "short cut" property did not hold. In those cases, the shared pointer was preserved.
Using db_bench readrandom perf_level=3 on my EC2 box, this change performed as well or better than 6.17:
6.17: readrandom : 28.046 micros/op 854902 ops/sec; 61.3 MB/s (355999 of 355999 found)
6.18: readrandom : 32.615 micros/op 735306 ops/sec; 52.7 MB/s (290999 of 290999 found)
PR: readrandom : 27.500 micros/op 871909 ops/sec; 62.5 MB/s (367999 of 367999 found)
(Note that the times for 6.18 are prior to revert of the SystemClock).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8033
Reviewed By: pdillinger
Differential Revision: D27014563
Pulled By: mrambacher
fbshipit-source-id: ad0459eba03182e454391b5926bf5cdd45657b67
Summary:
Fix this scenario:
trx1> acquire shared lock on $key
trx2> acquire shared lock on the same $key
trx1> attempt to acquire a unique lock on $key.
Lock acquisition will fail, and deadlock detection will start.
It will call iterate_and_get_overlapping_row_locks() which will
produce a list with two locks (shared locks by trx1 and trx2).
However the code in lock_request::build_wait_graph() was not prepared
to find the lock by the same transaction in the list of conflicting
locks. Fix it to ignore it.
(One may suggest to fix iterate_and_get_overlapping_row_locks() to not
include locks by trx1. This is not a good idea, because that function
is also used to report all locks currently held)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7938
Reviewed By: zhichao-cao
Differential Revision: D26529374
Pulled By: ajkr
fbshipit-source-id: d89cbed008db1a97a8f2351b9bfb75310750d16a
Summary:
TransactionDB uses read callback to filter out un-committed data before
a snapshot. But `MultiGet()` API doesn't use that at all, which causes
returning unwanted data.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7963
Test Plan: Added unittest to reproduce
Reviewed By: anand1976
Differential Revision: D26455851
Pulled By: jay-zhuang
fbshipit-source-id: 265276698cf9d8c4cd79e3250ef10d14375bac55
Summary:
Explicitly reject all range deletions on `TransactionDB` or `OptimisticTransactionDB`, except when the user provides sufficient promises that allow us to proceed safely. The necessary promises are described in the API doc for `TransactionDB::DeleteRange()`. There is currently no way to provide enough promises to make it safe in `OptimisticTransactionDB`.
Fixes https://github.com/facebook/rocksdb/issues/7913.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7929
Test Plan: unit tests covering the cases it's permitted/rejected
Reviewed By: ltamasi
Differential Revision: D26240254
Pulled By: ajkr
fbshipit-source-id: 2834a0ce64cc3e4c3799e35b885a5e79c2f4f6d9
Summary:
Memtable bloom filter is useful in many use cases. A default value on with conservative 1.5% memory can benefit more use cases than use cases impacted.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6584
Test Plan: Run all existing tests.
Reviewed By: pdillinger
Differential Revision: D20626739
fbshipit-source-id: 1dd45532b932139552519b8c2682bd954550c2f9
Summary:
BasicLockEscalation will cause false-positive warnings under TSAN (this is a known issue in TSAN, see details in https://gist.github.com/spetrunia/77274cf2d5848e0a7e090d622695ed4e), skip this test if TSAN is enabled, or if we are not sure whether TSAN is enabled.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7814
Test Plan: watch the tsan contrun test to pass.
Reviewed By: zhichao-cao
Differential Revision: D25708094
Pulled By: cheng-chang
fbshipit-source-id: 4fc813ff373301d033d086154cc7bb60a5e95889
Summary:
Range Locking - an implementation based on the locktree library
- Add a RangeTreeLockManager and RangeTreeLockTracker which implement
range locking using the locktree library.
- Point locks are handled as locks on single-point ranges.
- Add a unit test: range_locking_test
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7506
Reviewed By: akankshamahajan15
Differential Revision: D25320703
Pulled By: cheng-chang
fbshipit-source-id: f86347384b42ba2b0257d67eca0f45f806b69da7
Summary:
This disables Linux/amd64 builds in Travis for PRs, and adds a
gcc-10+c++20 build in CircleCI, which should fill out sufficient coverage
vs. what we had in Travis
Fixed a use of std::is_pod, which is deprecated in c++20
Fixed ++ on a volatile in db_repl_stress.cc, with bigger refactoring.
Although ++ on this volatile was probably ok with one thread writer and
one thread reader, the code was still overly complex. There was a
deadcode check for error
`if (replThread.no_read < dataPump.no_records)` which can be proven
never to happen based on the structure of the code. It infinite loops
instead for the case intended to be checked. I just simplified the code
for what should be the same checking power.
Also most configurations seem to be using make parallelism = 2 * vcores,
so fixing / using that.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7791
Test Plan:
CI
and `while ./db_repl_stress; do echo again; done` for a while
Reviewed By: siying
Differential Revision: D25669834
Pulled By: pdillinger
fbshipit-source-id: b2c688053d0b1d52c989903449d3cd27a04130d6
Summary:
Some clients do not close their iterators until after the transaction finishes. To handle this case, we will invalidate any iterators on transaction clear.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7733
Reviewed By: cheng-chang
Differential Revision: D25261158
Pulled By: lth
fbshipit-source-id: b91320f00c54cbe0e6882b794b34f3bb5640dbc0
Summary:
To be used for implementing Range Locking.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7753
Reviewed By: zhichao-cao
Differential Revision: D25378980
Pulled By: cheng-chang
fbshipit-source-id: 801a9c5cd92a84654ca2586b73e8f69001e89320
Summary:
This PR has two commits:
1. Modify the code to allow different Lock Managers (of any kind) to be used. It is implied that a LockManager uses its own custom LockTracker.
2. Add definitions for Range Locking (class Endpoint and GetRangeLock() function.
cheng-chang, is this what you've had in mind (should the PR have both item 1 and item 2?)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7443
Reviewed By: zhichao-cao
Differential Revision: D24123172
Pulled By: cheng-chang
fbshipit-source-id: c6548ad6d4cc3c25f68d13b29147bc6fdf357185
Summary:
The patch adds iterator support to the integrated BlobDB implementation.
Whenever a blob reference is encountered during iteration, the corresponding
blob is retrieved by calling `Version::GetBlob`, assuming the `expose_blob_index`
(formerly `allow_blob`) flag is *not* set. (Note: the flag is set by the old stacked
BlobDB implementation, which has its own blob file handling/blob retrieval logic.)
In addition, `DBIter` now uniformly returns `Status::NotSupported` with the error
message `"BlobDB does not support merge operator."` when encountering a
blob reference while performing a merge (instead of potentially returning a
message that implies the database should be opened using the stacked BlobDB's
`Open`.)
TODO: We can implement support for lazily retrieving the blob value (or in other
words, bypassing the retrieval of blob values based on key) by extending the `Iterator`
API with a new `PrepareValue` method (similarly to `InternalIterator`, which already
supports lazy values).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7731
Test Plan: `make check`
Reviewed By: riversand963
Differential Revision: D25256293
Pulled By: ltamasi
fbshipit-source-id: c39cd782011495a526cdff99c16f5fca400c4811
Summary:
An application may accidentally write merge operands without properly configuring `merge_operator`. We should alert them as early as possible that there's an API misuse. Previously RocksDB only notified them when a query or background operation needed to merge but couldn't. With this PR, RocksDB notifies them of the problem before applying the merge operand to the memtable (although it may already be in WAL, which seems it'd cause a crash loop until they enable `merge_operator`).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7667
Reviewed By: riversand963
Differential Revision: D24933360
Pulled By: ajkr
fbshipit-source-id: 3a4a2ceb0b7aed184113dd03b8efd735a8332f7f
Summary:
The tests often times out in internal infra, skipping fsync should reduce test time.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7641
Test Plan: watch existing tests to pass
Reviewed By: anand1976
Differential Revision: D24765098
Pulled By: cheng-chang
fbshipit-source-id: c62bf8110361aee901918d632cf4772435d05e8d
Summary:
This is a PR generated **semi-automatically** by an internal tool to remove unused includes and `using` statements.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7604
Test Plan: make check
Reviewed By: ajkr
Differential Revision: D24579392
Pulled By: riversand963
fbshipit-source-id: c4bfa6c6b08da1de186690d37eb73d8fff45aecd
Summary:
When `ASSERT_STATUS_CHECKED` is enabled, `transaction_test` does not pass without this PR.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7572
Test Plan: `ASSERT_STATUS_CHECKED=1 make -j32 transaction_test && ./transaction_test`
Reviewed By: zhichao-cao
Differential Revision: D24404319
Pulled By: cheng-chang
fbshipit-source-id: 13689035995366ab06d8eada3ea404e45fef8bc5
Summary:
In order to be able to introduce more locking protocols, we need to abstract out the locking subsystem in TransactionDB into a set of interfaces.
PR https://github.com/facebook/rocksdb/pull/7013 introduces interface `LockTracker`. This PR is a follow up to take the first step to abstract out a `LockManager` interface.
Further modifications to the interface may be needed when introducing the first implementation of range lock. But the idea here is to put the range lock implementation based on range tree under the `utilities/transactions/lock/range/range_tree`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7532
Test Plan: point_lock_manager_test
Reviewed By: ajkr
Differential Revision: D24238731
Pulled By: cheng-chang
fbshipit-source-id: 2a9458cd8b3fb008d9529dbc4d3b28c24631f463
Summary:
A generic algorithm in progress depends on a templatized
version of fastrange, so this change generalizes it and renames
it to fit our style guidelines, FastRange32, FastRange64, and now
FastRangeGeneric.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7436
Test Plan: added a few more test cases
Reviewed By: jay-zhuang
Differential Revision: D23958153
Pulled By: pdillinger
fbshipit-source-id: 8c3b76101653417804997e5f076623a25586f3e8
Summary:
SeqAdvanceConcurrentTest sometimes runs too long on some platforms. Disable fsync to speed it up.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7302
Test Plan: Run the tests and watch CI.
Reviewed By: ajkr
Differential Revision: D23298192
fbshipit-source-id: 2185eed4e0958c3de5e8a3f94ceed5be5945ed37
Summary:
We're going to support more locking protocols such as range lock in transaction.
However, in current design, `TransactionBase` has a member `tracked_keys` which assumes that point lock (lock a single key) is used, and is used in snapshot checking (isolation protocol). When using range lock, we may use read committed instead of snapshot checking as the isolation protocol.
The most significant usage scenarios of `tracked_keys` are:
1. pessimistic transaction uses it to track the locked keys, and unlock these keys when commit or rollback.
2. optimistic transaction does not lock keys upfront, it only tracks the lock intentions in tracked_keys, and do write conflict checking when commit.
3. each `SavePoint` tracks the keys that are locked since the `SavePoint`, `RollbackToSavePoint` or `PopSavePoint` relies on both the tracked keys in `SavePoint`s and `tracked_keys`.
Based on these scenarios, if we can abstract out a `LockTracker` interface to hold a set of tracked locks (can be keys or key ranges), and have methods that can be composed together to implement the scenarios, then `tracked_keys` can be an internal data structure of one implementation of `LockTracker`. See `utilities/transactions/lock/lock_tracker.h` for the detailed interface design, and `utilities/transactions/lock/point_lock_tracker.cc` for the implementation.
In the future, a `RangeLockTracker` can be implemented to track range locks without affecting other components.
After this PR, a clean interface for lock manager should be possible, and then ideally, we can have pluggable locking protocols.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7013
Test Plan: Run `transaction_test` and `optimistic_transaction_test`.
Reviewed By: ajkr
Differential Revision: D22163706
Pulled By: cheng-chang
fbshipit-source-id: f2860577b5334e31dd2994f5bc6d7c40d502b1b4
Summary:
CLANG analyze is useful before pull request. Add it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7114
Test Plan: Watch the CI results to succeed.
Reviewed By: riversand963
Differential Revision: D22491942
fbshipit-source-id: 9ccad91c6142fedc3d3dd491cf55054827908f36
Summary:
Cleans up some of the dependencies on test code in the Makefile while building tools:
- Moves the test::RandomString, DBBaseTest::RandomString into Random
- Moves the test::RandomHumanReadableString into Random
- Moves the DestroyDir method into file_utils
- Moves the SetupSyncPointsToMockDirectIO into sync_point.
- Moves the FaultInjection Env and FS classes under env
These changes allow all of the tools to build without dependencies on test_util, thereby simplifying the build dependencies. By moving the FaultInjection code, the dependency in db_stress on different libraries for debug vs release was eliminated.
Tested both release and debug builds via Make and CMake for both static and shared libraries.
More work remains to clean up how the tools are built and remove some unnecessary dependencies. There is also more work that should be done to get the Makefile and CMake to align in their builds -- what is in the libraries and the sizes of the executables are different.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7097
Reviewed By: riversand963
Differential Revision: D22463160
Pulled By: pdillinger
fbshipit-source-id: e19462b53324ab3f0b7c72459dbc73165cc382b2
Summary:
Confusing checks for null that are never null
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6933
Test Plan: make check
Reviewed By: cheng-chang
Differential Revision: D21885466
Pulled By: pdillinger
fbshipit-source-id: 4b48e03c2a33727f2702b0d12292f9fda5a3c475
Summary:
This reverts commit 8d87e9cea1.
Based on offline discussions, it's too early to upgrade to gtest 1.10, as it prevents some developers from using an older version of gtest to integrate to some other systems. Revert it for now.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6923
Reviewed By: pdillinger
Differential Revision: D21864799
fbshipit-source-id: d0726b1ff649fc911b9378f1763316200bd363fc
Summary:
x.size() -1 or y - 1 can overflow to an extremely large value when x.size() pr y is 0 when they are unsigned type. The end condition of i in the for loop will be extremely large, potentially causes segment fault. Fix them.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6902
Test Plan: pass make asan_check
Reviewed By: ajkr
Differential Revision: D21843767
Pulled By: zhichao-cao
fbshipit-source-id: 5b8b88155ac5a93d86246d832e89905a783bb5a1
Summary:
When expiration is set in a pessimistic transaction, `txn_state_` is already updated to `AWAITING_PREPARE` in the `if (expiration_time_ > 0)` block, there is no need to update the state in `if (can_prepare)` block again.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6778
Test Plan: make check
Reviewed By: lth
Differential Revision: D21335319
Pulled By: cheng-chang
fbshipit-source-id: 251d634cc7d1a0e86e673a59f0bda8584da5a35f
Summary:
In current commit protocol of pessimistic transaction, if the transaction is not prepared before commit, the commit protocol implicitly assumes that the user wants to commit without prepare.
This PR adds TransactionOptions::skip_prepare, the default value is `true` because if set to `false`, all existing users who commit without prepare need to update their code to set skip_prepare to true. Although this does not force the user to explicitly express their intention of skip_prepare, it at least lets the user be aware of the assumption of being able to commit without prepare.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6775
Test Plan: added a new unit test TransactionTest::CommitWithoutPrepare
Reviewed By: lth
Differential Revision: D21313270
Pulled By: cheng-chang
fbshipit-source-id: 3d95b7c9b2d6cdddc09bdd66c561bc4fae8c3251
Summary:
The dynamic_cast in the filter benchmark causes release mode to fail due to
no-rtti. Replace with static_cast_with_check.
Signed-off-by: Derrick Pallas <derrick@pallas.us>
Addition by peterd: Remove unnecessary 2nd template arg on all static_cast_with_check
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6732
Reviewed By: ltamasi
Differential Revision: D21304260
Pulled By: pdillinger
fbshipit-source-id: 6e8eb437c4ca5a16dbbfa4053d67c4ad55f1608c
Summary:
Based on https://github.com/facebook/rocksdb/issues/6648 (CLA Signed), but heavily modified / extended:
* Implicit capture of this via [=] deprecated in C++20, and [=,this] not standard before C++20 -> now using explicit capture lists
* Implicit copy operator deprecated in gcc 9 -> add explicit '= default' definition
* std::random_shuffle deprecated in C++17 and removed in C++20 -> migrated to a replacement in RocksDB random.h API
* Add the ability to build with different std version though -DCMAKE_CXX_STANDARD=11/14/17/20 on the cmake command line
* Minimal rebuild flag of MSVC is deprecated and is forbidden with /std:c++latest (C++20)
* Added MSVC 2019 C++11 & MSVC 2019 C++20 in AppVeyor
* Added GCC 9 C++11 & GCC9 C++20 in Travis
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6697
Test Plan: make check and CI
Reviewed By: cheng-chang
Differential Revision: D21020318
Pulled By: pdillinger
fbshipit-source-id: 12311be5dbd8675a0e2c817f7ec50fa11c18ab91
Summary:
Although there are tests related to locking in transaction_test, this new test directly tests against TransactionLockMgr.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6599
Test Plan: make transaction_lock_mgr_test && ./transaction_lock_mgr_test
Reviewed By: lth
Differential Revision: D20673749
Pulled By: cheng-chang
fbshipit-source-id: 1fa4a13218e68d785f5a99924556751a8c5c0f31
Summary:
1. If expiration_time is non-positive, no need to call NowMicros, save a syscall.
2. expire_time should only be set when expired is false.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6586
Test Plan: make check
Reviewed By: lth
Differential Revision: D20673730
Pulled By: cheng-chang
fbshipit-source-id: a69e8d7b16dc6d0d00487bb1c19f0710d79482e2
Summary:
The last key may hit index of out bound exception when id = 9.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6574
Reviewed By: riversand963
Differential Revision: D20699791
Pulled By: cheng-chang
fbshipit-source-id: 8e2c5be5ff0e53e9857cfd59cea97cff21446819
Summary:
In most places in the code the variable names are spelled correctly as
COMMITTED but in a couple places not. This fixes them and ensures the
variable is always called COMMITTED everywhere.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6481
Differential Revision: D20306776
Pulled By: pdillinger
fbshipit-source-id: b6c1bfe41db559b4bc6955c530934460c07f7022
Summary:
Today `WriteUnpreparedTxn::RollbackInternal` will write the rollback batch assuming that there is only a single subbatch. However, because untracked_keys_ are currently not deduplicated, it's possible for duplicate keys to exist, and thus split the batch. Also, tracked_keys_ also does not support compators outside of the bytewise comparators, so it's possible for duplicates to occur there as well.
To solve this, just pass in the correct subbatch count.
Also, removed `WriteUnpreparedRollbackPreReleaseCallback` to unify the Commit/Rollback codepaths some more.
Also, fixed a bug in `CommitInternal` where if 1. two_write_queue is true and 2. include_data is true, then `WriteUnpreparedCommitEntryPreReleaseCallback` ends up calling `AddCommitted` on the commit time write batch a second time on the second write. To fix, `WriteUnpreparedCommitEntryPreReleaseCallback` is re-initialized.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6463
Differential Revision: D20150153
Pulled By: lth
fbshipit-source-id: df0b42d39406c75af73df995aa1138f0db539cd1
Summary:
When dynamically linking two binaries together, different builds of RocksDB from two sources might cause errors. To provide a tool for user to solve the problem, the RocksDB namespace is changed to a flag which can be overridden in build time.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6433
Test Plan: Build release, all and jtest. Try to build with ROCKSDB_NAMESPACE with another flag.
Differential Revision: D19977691
fbshipit-source-id: aa7f2d0972e1c31d75339ac48478f34f6cfcfb3e
Summary:
For write unprepared, some applications may bypass the transaction api, and write keys directly into the write batch. However, since they are not tracked, rollbacks (both for savepoint and transaction) are not aware that these keys have to be rolled back.
The fix is to track them in `WriteUnpreparedTxn::untracked_keys_`. This is populated whenever we flush unprepared batches into the DB.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6404
Differential Revision: D19842023
Pulled By: lth
fbshipit-source-id: a9edfc643d5c905fc89da9a9a9094d30c9b70108
Summary:
I create a new branch from the branch new upsteram/master and "git merge --squash".
Maybe it will fix everything.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6420
Differential Revision: D19897152
Pulled By: zhichao-cao
fbshipit-source-id: 6575d9e3b23e360f42ee1480b43028b5fcc20136
Summary:
Unfortunately, it seems like mysqld reuses xids across machine restarts. When that happens, we could have something like the following happening:
```
BEGIN_PREPARE(unprepared) Put(a) END_PREPARE(xid = 1)
-- crash and recover with Put(a) rolled back as it was not prepared
BEGIN_PREPARE(prepared) Put(b) END_PREPARE(xid = 1)
COMMIT(xid = 1)
-- crash and recover with both a, b
```
To solve this, we will have to log the rollback batch into the WAL during recovery.
WritePrepared already logs the rollback batch into the WAL, if a rollback happens after prepare, so there is no problem there.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6418
Differential Revision: D19896151
Pulled By: lth
fbshipit-source-id: 2ff65ddc5fe75efd57736fed4b7cd7a109d26609
Summary:
A recent fix related to 2pc https://github.com/facebook/rocksdb/pull/6313/ writes something to WAL, but does not flush or sync. This causes assertion failure "impl->TEST_WALBufferIsEmpty()" if manual_wal_flush = true. We should fsync the entry to make sure a second power reset can recover.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6417
Test Plan: Add manual_wal_flush=true case in TransactionTest.DoubleCrashInRecovery and fix a bug in the test so that the bug can be reproduced. It passes with the fix.
Differential Revision: D19894537
fbshipit-source-id: f1e84e49e2269f583c6019743118292cd8b6598e
Yanqin Jin