Summary:
Under a certain sequence of accessing PreparedHeap, there was a bug that would not successfully empty the heap. This would result in performance issues when the heap content is moved to old_prepared_ after max_evicted_seq_ advances the orphan prepared sequence numbers. The patch fixed the bug and add more unit tests. It also does more logging when the unlikely scenarios are faced
Closes https://github.com/facebook/rocksdb/pull/3526
Differential Revision: D7038486
Pulled By: maysamyabandeh
fbshipit-source-id: f1e40bea558f67b03d2a29131fcb8734c65fce97
Summary:
These are optimization that we applied to improve sysbech's update_noindex performance.
1. Make use of LIKELY compiler hint
2. Move std::atomic so the subclass
3. Make use of skip_prepared in non-2pc transactions.
Closes https://github.com/facebook/rocksdb/pull/3512
Differential Revision: D7000075
Pulled By: maysamyabandeh
fbshipit-source-id: 1ab8292584df1f6305a4992973fb1b7933632181
Summary:
TransactionDB::Write can receive some optimization hints from the user. One is to skip the concurrency control mechanism. WritePreparedTxnDB is currently ignoring such hints. This patch optimizes WritePreparedTxnDB::Write for skip_concurrency_control and skip_duplicate_key_check hints.
Closes https://github.com/facebook/rocksdb/pull/3496
Differential Revision: D6971784
Pulled By: maysamyabandeh
fbshipit-source-id: cbab10ad538fa2b8bcb47e37c77724afe6e30f03
Summary:
This patch takes advantage of memtable being able to detect duplicate <key,seq> and returning TryAgain to handle duplicate keys in WritePrepared Txns. Through WriteBatchWithIndex's index it detects existence of at least a duplicate key in the write batch. If duplicate key was reported, it then pays the cost of counting the number of sub-patches by iterating over the write batch and pass it to DBImpl::Write. DB will make use of the provided batch_count to assign proper sequence numbers before sending them to the WAL. When later inserting the batch to the memtable, it increases the seq each time memtbale reports a duplicate (a sub-patch in our counting) and tries again.
Closes https://github.com/facebook/rocksdb/pull/3455
Differential Revision: D6873699
Pulled By: maysamyabandeh
fbshipit-source-id: db8487526c3a5dc1ddda0ea49f0f979b26ae648d
Summary:
This patch addresses a couple of minor TODOs for WritePrepared Txn such as double checking some assert statements at runtime as well, skip extra AddPrepared in non-2pc transactions, and safety check for infinite loops.
Closes https://github.com/facebook/rocksdb/pull/3302
Differential Revision: D6617002
Pulled By: maysamyabandeh
fbshipit-source-id: ef6673c139cb49f64c0879508d2f573b78609aca
Summary:
A proper implementation of Iterator::Refresh() for WritePreparedTxnDB would require release and acquire another snapshot. Since MyRocks don't make use of Iterator::Refresh(), we just simply mark it as not supported.
Closes https://github.com/facebook/rocksdb/pull/3290
Differential Revision: D6599931
Pulled By: yiwu-arbug
fbshipit-source-id: 4e1632d967316431424f6e458254ecf9a97567cf
Summary:
Add PreReleaseCallback to be called at the end of WriteImpl but before publishing the sequence number. The callback is used in WritePrepareTxn to i) update the commit map, ii) update the last published sequence number in the 2nd write queue. It also ensures that all the commits will go to the 2nd queue.
These changes will ensure that the commit map is updated before the sequence number is published and used by reading snapshots. If we use two write queues, the snapshots will use the seq number published by the 2nd queue. If we use one write queue (the default, the snapshots will use the last seq number in the memtable, which also indicates the last published seq number.
Closes https://github.com/facebook/rocksdb/pull/3205
Differential Revision: D6438959
Pulled By: maysamyabandeh
fbshipit-source-id: f8b6c434e94bc5f5ab9cb696879d4c23e2577ab9
Summary:
This patch implements MultiGet API for WritePreparedTxnDB and update the existing unit tests.
Closes https://github.com/facebook/rocksdb/pull/3196
Differential Revision: D6401493
Pulled By: maysamyabandeh
fbshipit-source-id: 51501a1e32645fc2da8680e77a50035f6530f2cc
Summary:
The sequence number was not properly advanced after a rollback marker. The patch extends the existing unit tests to detect the bug and also fixes it.
Closes https://github.com/facebook/rocksdb/pull/3157
Differential Revision: D6304291
Pulled By: maysamyabandeh
fbshipit-source-id: 1b519c44a5371b802da49c9e32bd00087a8da401
Summary:
This patch clarifies and refactors the logic around tracked keys in transactions.
Closes https://github.com/facebook/rocksdb/pull/3140
Differential Revision: D6290258
Pulled By: maysamyabandeh
fbshipit-source-id: 03b50646264cbcc550813c060b180fc7451a55c1
Summary:
Move WritePreparedTxnDB from pessimistic_transaction_db.h to its own header, write_prepared_txn_db.h
Closes https://github.com/facebook/rocksdb/pull/3114
Differential Revision: D6220987
Pulled By: maysamyabandeh
fbshipit-source-id: 18893fb4fdc6b809fe117dabb544080f9b4a301b
Summary:
Enable concurrent_prepare flag for WritePrepared transactions and extend the existing transaction tests with this config.
Closes https://github.com/facebook/rocksdb/pull/3046
Differential Revision: D6106534
Pulled By: maysamyabandeh
fbshipit-source-id: 88c8d21d45bc492beb0a131caea84a2ac5e7d38c
Summary:
On iterator create, take a snapshot, create a ReadCallback and pass the ReadCallback to the underlying DBIter to check if key is committed.
Closes https://github.com/facebook/rocksdb/pull/2981
Differential Revision: D6001471
Pulled By: yiwu-arbug
fbshipit-source-id: 3565c4cdaf25370ba47008b0e0cb65b31dfe79fe
Summary:
On WritePreparedTxnDB destruct there could be running compaction/flush holding a SnapshotChecker, which holds a pointer back to WritePreparedTxnDB. Make sure those jobs finished before destructing WritePreparedTxnDB.
This is caught by TransactionTest::SeqAdvanceTest.
Closes https://github.com/facebook/rocksdb/pull/2982
Differential Revision: D6002957
Pulled By: yiwu-arbug
fbshipit-source-id: f1e70390c9798d1bd7959f5c8e2a1c14100773c3
Summary:
Update Compaction/Flush to support WritePreparedTxnDB: Add SnapshotChecker which is a proxy to query WritePreparedTxnDB::IsInSnapshot. Pass SnapshotChecker to DBImpl on WritePreparedTxnDB open. CompactionIterator use it to check if a key has been committed and if it is visible to a snapshot. In CompactionIterator:
* check if key has been committed. If not, output uncommitted keys AS-IS.
* use SnapshotChecker to check if key is visible to a snapshot when in need.
* do not output key with seq = 0 if the key is not committed.
Closes https://github.com/facebook/rocksdb/pull/2926
Differential Revision: D5902907
Pulled By: yiwu-arbug
fbshipit-source-id: 945e037fdf0aa652dc5ba0ad879461040baa0320
Summary:
Compaction will output keys with sequence number 0, if it is visible to
earliest snapshot. Adding a test to make sure IsInSnapshot() report sequence number 0 is
visible to any snapshot.
Closes https://github.com/facebook/rocksdb/pull/2974
Differential Revision: D5990665
Pulled By: yiwu-arbug
fbshipit-source-id: ef50ebc777ff8ca688771f3ab598c7a609b0b65e
Summary:
With WriteCommitted, when the write batch has duplicate keys, the txn db simply inserts them to the db with different seq numbers and let the db ignore/merge the duplicate values at the read time. With WritePrepared all the entries of the batch are inserted with the same seq number which prevents us from benefiting from this simple solution.
This patch applies a hackish solution to unblock the end-to-end testing. The hack is to be replaced with a proper solution soon. The patch simply detects the duplicate key insertions, and mark the previous one as obsolete. Then before writing to the db it rewrites the batch eliminating the obsolete keys. This would incur a memcpy cost. Furthermore handing duplicate merge would require to do FullMerge instead of simply ignoring the previous value, which is not handled by this patch.
Closes https://github.com/facebook/rocksdb/pull/2969
Differential Revision: D5976337
Pulled By: maysamyabandeh
fbshipit-source-id: 114e65b66f137d8454ff2d1d782b8c05da95f989
Summary:
Implement the rollback of WritePrepared txns. For each modified value, it reads the value before the txn and write it back. This would cancel out the effect of transaction. It also remove the rolled back txn from prepared heap.
Closes https://github.com/facebook/rocksdb/pull/2946
Differential Revision: D5937575
Pulled By: maysamyabandeh
fbshipit-source-id: a6d3c47f44db3729f44b287a80f97d08dc4e888d
Summary:
Recover txns from the WAL. Also added some unit tests.
Closes https://github.com/facebook/rocksdb/pull/2901
Differential Revision: D5859596
Pulled By: maysamyabandeh
fbshipit-source-id: 6424967b231388093b4effffe0a3b1b7ec8caeb0
Summary:
Looks like the API is simply missing. Adding it.
Closes https://github.com/facebook/rocksdb/pull/2937
Differential Revision: D5919955
Pulled By: yiwu-arbug
fbshipit-source-id: 6e2e9c96c29882b0bb4113d1f8efb72bffc57878
Summary:
By default the seq number in DB is increased once per written key. WritePrepared txns requires the seq to be increased once per the entire batch so that the seq would be used as the prepare timestamp by which the transaction is identified. Also we need to increase seq for the commit marker since it would give a unique id to the commit timestamp of transactions.
Two unit tests are added to verify our understanding of how the seq should be increased. The recovery path requires much more work and is left to another patch.
Closes https://github.com/facebook/rocksdb/pull/2885
Differential Revision: D5837843
Pulled By: maysamyabandeh
fbshipit-source-id: a08960b93d727e1cf438c254d0c2636fb133cc1c
Summary:
We had two proposals for lock-free commit maps. This patch implements the latter one that was simpler. We can later experiment with both proposals.
In this impl each entry is an std::atomic of uint64_t, which are accessed via memory_order_acquire/release. In x86_64 arch this is compiled to simple reads and writes from memory.
Closes https://github.com/facebook/rocksdb/pull/2861
Differential Revision: D5800724
Pulled By: maysamyabandeh
fbshipit-source-id: 41abae9a4a5df050a8eb696c43de11c2770afdda
Summary:
This patch advances the max_evicted_seq_ is larger granularities to reduce the overhead of updating the relevant data structures.
It also refactor the related code and adds testing to that. As part of this patch some of the TODOs for removing usage of non-static const members are also addressed.
Closes https://github.com/facebook/rocksdb/pull/2844
Differential Revision: D5772928
Pulled By: maysamyabandeh
fbshipit-source-id: f4fcc2948be69c034f10812cf922ce5ab82ef98c
Summary:
Divide the old snapshots to two lists: a few that fit into a cached array and the rest in a vector, which is expected to be empty in normal cases. The former is to optimize concurrent reads from snapshots without requiring locks. It is done by an array of std::atomic, from which std::memory_order_acquire reads are compiled to simple read instructions in most of the x86_64 architectures.
Closes https://github.com/facebook/rocksdb/pull/2758
Differential Revision: D5660504
Pulled By: maysamyabandeh
fbshipit-source-id: 524fcf9a8e7f90a92324536456912a99aaa6740c
Summary:
Changes:
* extended the wait_txn_map to track additional information
* designed circular buffer to store n latest deadlocks' information
* added test coverage to verify the additional information tracked is accurately stored in the buffer
Closes https://github.com/facebook/rocksdb/pull/2630
Differential Revision: D5478025
Pulled By: armishra
fbshipit-source-id: 2b138de7b5a73f5ca554fc3ff8220a3be49f39e7
Summary:
Implement the main body of WritePrepared pseudo code. This includes PrepareInternal and CommitInternal, as well as AddCommitted which updates the commit map. It also provides a IsInSnapshot method that could be later called form the read path to decide if a version is in the read snapshot or it should other be skipped.
This patch lacks unit tests and does not attempt to offer an efficient implementation. The idea is that to have the API specified so that we can work on related tasks in parallel.
Closes https://github.com/facebook/rocksdb/pull/2713
Differential Revision: D5640021
Pulled By: maysamyabandeh
fbshipit-source-id: bfa7a05e8d8498811fab714ce4b9c21530514e1c
Summary:
This patch splits Commit and Prepare into lock-related logic and db-write-related logic. It moves lock-related logic to PessimisticTransaction to be reused by all children classes and movies the existing impl of db-write-related to PrepareInternal, CommitSingleInternal, and CommitInternal in WriteCommittedTxnImpl.
Closes https://github.com/facebook/rocksdb/pull/2691
Differential Revision: D5569464
Pulled By: maysamyabandeh
fbshipit-source-id: d1b8698e69801a4126c7bc211745d05c636f5325
Summary:
This opens space for the new implementations of TransactionDBImpl such as WritePreparedTxnDBImpl that has a different policy of how to write to DB.
Closes https://github.com/facebook/rocksdb/pull/2689
Differential Revision: D5568918
Pulled By: maysamyabandeh
fbshipit-source-id: f7eac866e175daf3793ae79da108f65cc7dc7b25
Summary:
This patch refactors TransactionImpl by separating the logic for pessimistic concurrency control from the implementation of how to write the data to rocksdb. The existing implementation is named WriteCommittedTxnImpl as it writes committed data to the db. A template named WritePreparedTxnImpl is also added which will be later completed to provide a an alternative implementation.
Closes https://github.com/facebook/rocksdb/pull/2676
Differential Revision: D5549998
Pulled By: maysamyabandeh
fbshipit-source-id: 16298e86b43ca4849324c1f35c731913c6d17bec
Summary:
Replace dynamic_cast<> so that users can choose to build with RTTI off, so that they can save several bytes per object, and get tiny more memory available.
Some nontrivial changes:
1. Add Comparator::GetRootComparator() to get around the internal comparator hack
2. Add the two experiemental functions to DB
3. Add TableFactory::GetOptionString() to avoid unnecessary casting to get the option string
4. Since 3 is done, move the parsing option functions for table factory to table factory files too, to be symmetric.
Closes https://github.com/facebook/rocksdb/pull/2645
Differential Revision: D5502723
Pulled By: siying
fbshipit-source-id: fd13cec5601cf68a554d87bfcf056f2ffa5fbf7c
Summary:
This is an implementation of non-exclusive locks for pessimistic transactions. It is relatively simple and does not prevent starvation (ie. it's possible that request for exclusive access will never be granted if there are always threads holding shared access). It is done by changing `KeyLockInfo` to hold an set a transaction ids, instead of just one, and adding a flag specifying whether this lock is currently held with exclusive access or not.
Some implementation notes:
- Some lock diagnostic functions had to be updated to return a set of transaction ids for a given lock, eg. `GetWaitingTxn` and `GetLockStatusData`.
- Deadlock detection is a bit more complicated since a transaction can now wait on multiple other transactions. A BFS is done in this case, and deadlock detection depth is now just a limit on the number of transactions we visit.
- Expirable transactions do not work efficiently with shared locks at the moment, but that's okay for now.
Closes https://github.com/facebook/rocksdb/pull/1573
Differential Revision: D4239097
Pulled By: lth
fbshipit-source-id: da7c074
Summary:
This exposes a transactions state through a public api rather than through a public member variable. I also do some name refactoring.
ExecutionStatus => TransactionState
exec_status_ => trx_state_
Test Plan: It compiles and transaction_test passes.
Reviewers: IslamAbdelRahman
Reviewed By: IslamAbdelRahman
Subscribers: andrewkr, mung, dhruba, sdong
Differential Revision: https://reviews.facebook.net/D64689
Summary:
This diff does 3 things:
Expose TransactionID so that we can identify transactions when we retrieve locking and lock wait information. This is exposed as `Transaction::GetID`.
Expose lock state information by locking all stripes in all column families and copying their contents to a data structure. This is exposed as `TransactionDB::GetLockStatusData`.
Adds support for tracking the transaction and the key being waited on, and exposes this as `Transaction::GetWaitingTxn`.
Test Plan: unit tests
Reviewers: horuff, sdong
Reviewed By: sdong
Subscribers: vasilep, hermanlee4, andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D64413
Summary: make transactionDB working with StackableDB
Test Plan: make all check -j64
Reviewers: andrewkr, yiwu, sdong
Reviewed By: sdong
Subscribers: andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D60705
Summary: use of dynamic_cast<TransactionImpl*> is unnecessary and also introduce difficulty for fbrocksdb support of TransactionDB
Test Plan: ./transaction_test
Reviewers: sdong, IslamAbdelRahman, andrewkr
Reviewed By: andrewkr
Subscribers: andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D60501
Summary: This tests that a prepared transaction is not lost after several crashes, restarts, and memtable flushes.
Test Plan: TwoPhaseLongPrepareTest
Reviewers: sdong
Subscribers: hermanlee4, andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D58185
Summary:
1. prepare()
2. crash
3. recover
4. commit()
5. crash
6. data is lost
This is due to the transaction data still only residing in the WAL but because the logs were flushed on the first recovery the data is ignored on the second recovery. We must scan all logs found on recovery and only ignore redundant data at the time of replay. It is not possible to know which logs still contain relevant data at time of recovery. We cannot simply ignore a log because all of the non-2pc data it contains has already been written to L0.
The changes made to MemTableInserter are to ensure that prepared sections are still recovered even if all of the non-2pc data in that log has already been flushed to L0.
Test Plan: Provided test.
Reviewers: sdong
Subscribers: andrewkr, hermanlee4, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D57729
Summary: Previously, reusing a transaction (by passing it as an argument to BeginTransaction) would not clear the transaction's snapshot. This is not a clear, well-definited behavior.
Test Plan: improved test
Reviewers: sdong, IslamAbdelRahman, horuff, jkedgar
Reviewed By: jkedgar
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D55053
Summary: Add function to reinitialize a transaction object so that it can be reused. This is an optimization so users can potentially avoid reallocating transaction objects.
Test Plan: added tests
Reviewers: yhchiang, kradhakrishnan, IslamAbdelRahman, sdong
Reviewed By: sdong
Subscribers: jkedgar, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D53835
Igor Sugak