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:
GetCommitTimeWriteBatch is currently used to store some state as part of commit in 2PC. In MyRocks it is specifically used to store some data that would be needed only during recovery. So it is not need to be stored in memtable right after each commit.
This patch enables an optimization to write the GetCommitTimeWriteBatch only to the WAL. The batch will be written to memtable during recovery when the WAL is replayed. To cover the case when WAL is deleted after memtable flush, the batch is also buffered and written to memtable right before each memtable flush.
Closes https://github.com/facebook/rocksdb/pull/3071

Differential Revision: D6148023

Pulled By: maysamyabandeh

fbshipit-source-id: 2d09bae5565abe2017c0327421010d5c0d55eaa7

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:
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:
Implements CommitBatch and CommitWithoutPrepare for WritePreparedTxn
Closes https://github.com/facebook/rocksdb/pull/2854

Differential Revision: D5793999

Pulled By: maysamyabandeh

fbshipit-source-id: d8b9858221162c6ac7a1f6912cbd3481d0d8a503

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 reverts the previous commit 1d7048c5, which broke the build.

Did a `git revert 1d7048c5`.
Closes https://github.com/facebook/rocksdb/pull/2627

Differential Revision: D5476473

Pulled By: sagar0

fbshipit-source-id: 4756ff5c0dfc88c17eceb00e02c36176de728d06

Summary: This uses `clang-tidy` to comment out unused parameters (in functions, methods and lambdas) in fbcode. Cases that the tool failed to handle are fixed manually.

Reviewed By: igorsugak

Differential Revision: D5454343

fbshipit-source-id: 5dee339b4334e25e963891b519a5aa81fbf627b2

Summary: Closes https://github.com/facebook/rocksdb/pull/2589

Differential Revision: D5431502

Pulled By: siying

fbshipit-source-id: 8ebf8c87883daa9daa54b2303d11ce01ab1f6f75

Summary:
Throughput: 46k tps in our sysbench settings (filling the details later)

The idea is to have the simplest change that gives us a reasonable boost
in 2PC throughput.

Major design changes:
1. The WAL file internal buffer is not flushed after each write. Instead
it is flushed before critical operations (WAL copy via fs) or when
FlushWAL is called by MySQL. Flushing the WAL buffer is also protected
via mutex_.
2. Use two sequence numbers: last seq, and last seq for write. Last seq
is the last visible sequence number for reads. Last seq for write is the
next sequence number that should be used to write to WAL/memtable. This
allows to have a memtable write be in parallel to WAL writes.
3. BatchGroup is not used for writes. This means that we can have
parallel writers which changes a major assumption in the code base. To
accommodate for that i) allow only 1 WriteImpl that intends to write to
memtable via mem_mutex_--which is fine since in 2PC almost all of the memtable writes
come via group commit phase which is serial anyway, ii) make all the
parts in the code base that assumed to be the only writer (via
EnterUnbatched) to also acquire mem_mutex_, iii) stat updates are
protected via a stat_mutex_.

Note: the first commit has the approach figured out but is not clean.
Submitting the PR anyway to get the early feedback on the approach. If
we are ok with the approach I will go ahead with this updates:
0) Rebase with Yi's pipelining changes
1) Currently batching is disabled by default to make sure that it will be
consistent with all unit tests. Will make this optional via a config.
2) A couple of unit tests are disabled. They need to be updated with the
serial commit of 2PC taken into account.
3) Replacing BatchGroup with mem_mutex_ got a bit ugly as it requires
releasing mutex_ beforehand (the same way EnterUnbatched does). This
needs to be cleaned up.
Closes https://github.com/facebook/rocksdb/pull/2345

Differential Revision: D5210732

Pulled By: maysamyabandeh

fbshipit-source-id: 78653bd95a35cd1e831e555e0e57bdfd695355a4

Summary: Closes https://github.com/facebook/rocksdb/pull/2226

Differential Revision: D4967547

Pulled By: siying

fbshipit-source-id: dd3b58ae1e7a106ab6bb6f37ab5c88575b125ab4

Summary:
Upgrading a shared lock was silently succeeding because the actual locking code was skipped. This is because if the keys are tracked, it is assumed that they are already locked and do not require locking. Fix this by recording in tracked keys whether the key was locked exclusively or not.

Note that lock downgrades are impossible, which is the behaviour we expect.

This fixes facebook/mysql-5.6#587.
Closes https://github.com/facebook/rocksdb/pull/2122

Differential Revision: D4861489

Pulled By: IslamAbdelRahman

fbshipit-source-id: 58c7ebe7af098bf01b9774b666d3e9867747d8fd

Summary:
Extend TransactionOptions to include max_write_batch_size which determines the maximum size of the writebatch representation. If memory limit is exceeded, the operation will abort with subcode kMemoryLimit.
Closes https://github.com/facebook/rocksdb/pull/2124

Differential Revision: D4861842

Pulled By: lth

fbshipit-source-id: 46fd172ea67cc90bbba829bf0d70cfab2261c161

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: Implement deadlock detection. This is done by maintaining a TxnID -> TxnID map which represents the edges in the wait for graph (this is named `wait_txn_map_`).

Test Plan: transaction_test

Reviewers: IslamAbdelRahman, sdong

Reviewed By: sdong

Subscribers: andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D64491

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:
When constructing a write batch a client may now call MarkWalTerminationPoint() on that batch. No batch operations after this call will be added written to the WAL but will still be inserted into the Memtable. This facility is used to remove one of the three WriteImpl calls in 2PC transactions. This produces a ~1% perf improvement.

```
RocksDB - unoptimized 2pc, sync_binlog=1, disable_2pc=off
INFO 2016-08-31 14:30:38,814 [main]: REQUEST PHASE COMPLETED. 75000000 requests done in 2619 seconds. Requests/second = 28628

RocksDB - optimized 2pc , sync_binlog=1, disable_2pc=off
INFO 2016-08-31 16:26:59,442 [main]: REQUEST PHASE COMPLETED. 75000000 requests done in 2581 seconds. Requests/second = 29054
```

Test Plan: Two unit tests added.

Reviewers: sdong, yiwu, IslamAbdelRahman

Reviewed By: yiwu

Subscribers: hermanlee4, dhruba, andrewkr

Differential Revision: https://reviews.facebook.net/D64599

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: 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:
Two Phase Commit addition to RocksDB.

See wiki: https://github.com/facebook/rocksdb/wiki/Two-Phase-Commit-Implementation
Quip: https://fb.quip.com/pxZrAyrx53r3

Depends on:
WriteBatch modification: https://reviews.facebook.net/D54093
Memtable Log Referencing and Prepared Batch Recovery: https://reviews.facebook.net/D56919

Test Plan:
- SimpleTwoPhaseTransactionTest
- PersistentTwoPhaseTransactionTest.
- TwoPhaseRollbackTest
- TwoPhaseMultiThreadTest
- TwoPhaseLogRollingTest
- TwoPhaseEmptyWriteTest
- TwoPhaseExpirationTest

Reviewers: IslamAbdelRahman, sdong

Reviewed By: sdong

Subscribers: leveldb, hermanlee4, andrewkr, vasilep, dhruba, santoshb

Differential Revision: https://reviews.facebook.net/D56925

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

Summary: MyRocks wants to be able to un-lock a key that was just locked by GetForUpdate().  To do this safely, I am now keeping track of the number of reads(for update) and writes for each key in a transaction.  UndoGetForUpdate() will only unlock a key if it hasn't been written and the read count reaches 0.

Test Plan: more unit tests

Reviewers: igor, rven, yhchiang, spetrunia, sdong

Reviewed By: spetrunia, sdong

Subscribers: spetrunia, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D47043

Summary:
Doing inline checking of transaction expiration instead of
using a callback.

Test Plan: To be added

Reviewers: anthony

Reviewed By: anthony

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D53673

Summary: Removed a couple of memory allocations

Test Plan: changes covered by existing tests

Reviewers: rven, yhchiang, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D53523

Summary:
Currently, transactions can fail even if there is no actual write conflict.  This is due to relying on only the memtables to check for write-conflicts.  Users have to tune memtable settings to try to avoid this, but it's hard to figure out exactly how to tune these settings.

With this diff, TransactionDB will use both memtables and SST files to determine if there are any write conflicts.  This relies on the fact that BlockBasedTable stores sequence numbers for all writes that happen after any open snapshot.  Also, D50295 is needed to prevent SingleDelete from disappearing writes (the TODOs in this test code will be fixed once the other diff is approved and merged).

Note that Optimistic transactions will still rely on tuning memtable settings as we do not want to read from SST while on the write thread.  Also, memtable settings can still be used to reduce how often TransactionDB needs to read SST files.

Test Plan: unit tests, db bench

Reviewers: rven, yhchiang, kradhakrishnan, IslamAbdelRahman, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb, yoshinorim

Differential Revision: https://reviews.facebook.net/D50475

Summary: Support for Transaction::CreateSnapshotOnNextOperation().  This is to fix a write-conflict race-condition that Yoshinori was running into when testing MyRocks with LinkBench.

Test Plan: New tests

Reviewers: yhchiang, spetrunia, rven, igor, yoshinorim, sdong

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D48099

Summary: Should have used auto& instead of auto.  Also needed to change the code a bit due to const correctness.

Test Plan: unit tests

Reviewers: sdong, igor, yoshinorim, yhchiang

Reviewed By: yhchiang

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D47787

Summary: Transaction::RollbackToSavePoint() will now release any locks that were taken since the previous SavePoint.  To do this cleanly, I moved tracked_keys_ management into TransactionBase.

Test Plan: New Transaction test.

Reviewers: igor, rven, sdong

Reviewed By: sdong

Subscribers: dhruba, spetrunia, leveldb

Differential Revision: https://reviews.facebook.net/D46761

Summary: Added funtions to fetch the number of locked keys in a transaction, the number of pending puts/merge/deletes, and the elapsed time

Test Plan: unit tests

Reviewers: yoshinorim, jkedgar, rven, sdong, yhchiang, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D45417

Summary:
Prototype of API to allow MyRocks to override default Mutex/CondVar used by transactions with their own implementations.  They would simply need to pass their own implementations of Mutex/CondVar to the templated TransactionDB::Open().

Default implementation of TransactionDBMutex/TransactionDBCondVar provided (but the code is not currently changed to use this).

Let me know if this API makes sense or if it should be changed

Test Plan: n/a

Reviewers: yhchiang, rven, igor, sdong, spetrunia

Reviewed By: spetrunia

Subscribers: maykov, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D43761

Summary:
As I keep adding new features to transactions, I keep creating more duplicate code.  This diff cleans this up by creating a base implementation class for Transaction and OptimisticTransaction to inherit from.

The code in TransactionBase.h/.cc is all just copied from elsewhere.  The only entertaining part of this class worth looking at is the virtual TryLock method which allows OptimisticTransactions and Transactions to share the same common code for Put/Get/etc.

The rest of this diff is mostly red and easy on the eyes.

Test Plan: No functionality change.  existing tests pass.

Reviewers: sdong, jkedgar, rven, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D45135

Summary:
Clean up transactions to use the new RollbackToSavePoint api in WriteBatchWithIndex.

Note, this diff depends on Pessimistic Transactions diff and ManagedSnapshot diff (D40869 and D43293).

Test Plan: unit tests

Reviewers: rven, yhchiang, kradhakrishnan, spetrunia, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D43371

Summary:
Initial implementation of Pessimistic Transactions.  This diff contains the api changes discussed in D38913.  This diff is pretty large, so let me know if people would prefer to meet up to discuss it.

MyRocks folks:  please take a look at the API in include/rocksdb/utilities/transaction[_db].h and let me know if you have any issues.

Also, you'll notice a couple of TODOs in the implementation of RollbackToSavePoint().  After chatting with Siying, I'm going to send out a separate diff for an alternate implementation of this feature that implements the rollback inside of WriteBatch/WriteBatchWithIndex.  We can then decide which route is preferable.

Next, I'm planning on doing some perf testing and then integrating this diff into MongoRocks for further testing.

Test Plan: Unit tests, db_bench parallel testing.

Reviewers: igor, rven, sdong, yhchiang, yoshinorim

Reviewed By: sdong

Subscribers: hermanlee4, maykov, spetrunia, leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D40869