Summary:
(Copied from https://www.internalfb.com/diff/D46606060)
This diff makes its files safe for use with -Wimplicit-fallthrough. Now that we're using C+20 there's no reason not to use this C++17 feature to make our code safer.
It's currently possible to write code like this:
```
switch(x){
case 1:
foo1();
case 2:
foo2();
break;
case 3:
foo3();
}
```
But that's scary because we don't know whether the fallthrough from case 1 was intentional or not.
The -Wimplicit-fallthrough flag will make this an error. The solution is to either fix the bug by inserting break or indicating intention by using [[fallthrough]]; (from C++17).
```
switch(x){
case 1:
foo1();
[[fallthrough]]; // Solution if we intended to fallthrough
break; // Solution if we did not intend to fallthrough
case 2:
foo2();
break;
case 3:
foo3();
}
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11663
Test Plan: Existing tests
Reviewed By: jowlyzhang
Differential Revision: D47961248
Pulled By: jaykorean
fbshipit-source-id: 0d374c721bf1b328c14949dc5c17693da7311d03
Summary:
https://github.com/facebook/rocksdb/issues/11653 broke some crash tests.
Apparently these Rollbacks are needed for pessimistic transaction cases. (I'm still not sure if the API makes any sense with regard to safe usage. It's certainly not documented. Will consider in follow-up PRs.)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11656
Test Plan: manual crash test runs, crash_test_with_multiops_wc_txn and crash_test_with_multiops_wp_txn
Reviewed By: cbi42
Differential Revision: D47906280
Pulled By: pdillinger
fbshipit-source-id: d058a01b6dbb47a4f08d199e335364168304f81b
Summary:
In rare cases, optimistic transaction commit returns TryAgain. This change tolerates that intentional behavior in db_stress, up to a small limit in a row. This way, we don't miss a possible regression with excessive TryAgain, and trying again (rolling back the transaction) should have a well renewed chance of success as the writes will be associated with fresh sequence numbers.
Also, some of the APIs were not clear about Transaction semantics, so I have clarified:
* (Best I can tell....) Destroying a Transaction is safe without calling Rollback() (or at least should be). I don't know why it's a common pattern in our test code and examples to rollback before unconditional destruction. Stress test updated not to call Rollback unnecessarily (to test safe destruction).
* Despite essentially doing what is asked, simply trying Commit() again when it returns TryAgain does not have a chance of success, because of the transaction being bound to the DB state at the time of operations before Commit. Similar logic applies to Busy AFAIK. Commit() API comments updated, and expanded unit test in optimistic_transaction_test.
Also also, because I can't stop myself, I refactored a good portion of the transaction handling code in db_stress.
* Avoid existing and new copy-paste for most transaction interactions with a new ExecuteTransaction (higher-order) function.
* Use unique_ptr (nicely complements removing unnecessary Rollbacks)
* Abstract out a pattern for safely calling std::terminate() and use it in more places. (The TryAgain errors we saw did not have stack traces because of "terminate called recursively".)
Intended follow-up: resurrect use of `FLAGS_rollback_one_in` but also include non-trivial cases
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11653
Test Plan:
this is the test :)
Also, temporarily bypassed the new retry logic and boosted the chance of hitting TryAgain. Quickly reproduced the TryAgain error. Then re-enabled the new retry logic, and was not able to hit the error after running for tens of minutes, even with the boosted chances.
Reviewed By: cbi42
Differential Revision: D47882995
Pulled By: pdillinger
fbshipit-source-id: 21eadb1525423340dbf28d17cf166b9583311a0d
Summary:
... instead of race-condition-laden FaultInjectionTestEnv. See https://app.circleci.com/pipelines/github/facebook/rocksdb/27912/workflows/4c63e5a8-597e-439d-8c7e-82308056af02/jobs/609648 and similar PR https://github.com/facebook/rocksdb/issues/11271
Had to fix the semantics of FaultInjectionTestFS Close() operations to allow a non-OK Close() to fulfill the obligation to close before destruction. To me, this is the obvious choice of Close contract, because what is the caller supposed to do if Close() fails and they still have an obligation to successfully close before object destruction? Call Close() in an infinite loop? Leak the object? I have added API comments to the Env and Filesystem Close() functions to clarify the contracts.
Note that `DB::Close()` has one exception to this kind of Close contract, but it is clearly described in API comments and it is really only for catching programming mistakes, not for dealing with exogenous errors.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11499
Test Plan: watch CI
Reviewed By: jowlyzhang
Differential Revision: D46375708
Pulled By: pdillinger
fbshipit-source-id: 03d4d8251e5df50a82ecd139f7e83f613015fe40
Summary:
Context:
This is the first PR for WaitForCompact() Implementation with WaitForCompactOptions. In this PR, we are introducing `Status WaitForCompact(const WaitForCompactOptions& wait_for_compact_options)` in the public API. This currently utilizes the existing internal `WaitForCompact()` implementation (with default abort_on_pause = false). `abort_on_pause` has been moved to `WaitForCompactOptions&`. In the later PRs, we will introduce the following two options in `WaitForCompactOptions`
1. `bool flush = false` by default - If true, flush before waiting for compactions to finish. Must be set to true to ensure no immediate compactions (except perhaps periodic compactions) after closing and re-opening the DB.
2. `bool close_db = false` by default - If true, will also close the DB upon compactions finishing.
1. struct `WaitForCompactOptions` added to options.h and `abort_on_pause` in the internal API moved to the option struct.
2. `Status WaitForCompact(const WaitForCompactOptions& wait_for_compact_options)` introduced in `db.h`
3. Changed the internal WaitForCompact() to `WaitForCompact(const WaitForCompactOptions& wait_for_compact_options)` and checks for the `abort_on_pause` inside the option.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11436
Test Plan:
Following tests added
- `DBCompactionTest::WaitForCompactWaitsOnCompactionToFinish`
- `DBCompactionTest::WaitForCompactAbortOnPauseAborted`
- `DBCompactionTest::WaitForCompactContinueAfterPauseNotAborted`
- `DBCompactionTest::WaitForCompactShutdownWhileWaiting`
- `TransactionTest::WaitForCompactAbortOnPause`
NOTE: `TransactionTest::WaitForCompactAbortOnPause` was added to use `StackableDB` to ensure the wrapper function is in place.
Reviewed By: pdillinger
Differential Revision: D45799659
Pulled By: jaykorean
fbshipit-source-id: b5b58f95957f2ab47d1221dee32a61d6cdc4685b
Summary:
Currently it's easy to use a ton of memory with many small OptimisticTransactionDB instances, because each one by default allocates a million mutexes (40 bytes each on my compiler) for validating transactions. It even puts a lot of pressure on the allocator by allocating each one individually!
In this change:
* Create a new object and option that enables sharing these buckets of mutexes between instances. This is generally good for load balancing potential contention as various DBs become hotter or colder with txn writes. About the only cases where this sharing wouldn't make sense (e.g. each DB usually written by one thread) are cases that would be better off with OccValidationPolicy::kValidateSerial which doesn't use the buckets anyway.
* Allocate the mutexes in a contiguous array, for efficiency
* Add an option to ensure the mutexes are cache-aligned. In several other places we use cache-aligned mutexes but OptimisticTransactionDB historically does not. It should be a space-time trade-off the user can choose.
* Provide some visibility into the memory used by the mutex buckets with an ApproximateMemoryUsage() function (also used in unit testing)
* Share code with other users of "striped" mutexes, appropriate refactoring for customization & efficiency (e.g. using FastRange instead of modulus)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11439
Test Plan: unit tests added. Ran sized-up versions of stress test in unit test, including a before-and-after performance test showing no consistent difference. (NOTE: OptimisticTransactionDB not currently covered by db_stress!)
Reviewed By: ltamasi
Differential Revision: D45796393
Pulled By: pdillinger
fbshipit-source-id: ae2b3a26ad91ceeec15debcdc63ff48df6736a54
Summary:
This patch remove the "stress" aspect from the WriteUnpreparedStressTest and leave it to be a unit test for some correctness testing w.r.t. snapshot functionality. I added some read-your-write verification to the transaction test in db_stress.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11424
Test Plan:
`./write_unprepared_transaction_test`
`./db_crashtest.py whitebox --txn`
`./db_crashtest.py blackbox --txn`
Reviewed By: hx235
Differential Revision: D45551521
Pulled By: jowlyzhang
fbshipit-source-id: 20c3d510eb4255b08ddd7b6c85bdb4945436f6e8
Summary:
Context:
In pull request https://github.com/facebook/rocksdb/issues/11436, we are introducing a new public API `waitForCompact(const WaitForCompactOptions& wait_for_compact_options)`. This API invokes the internal implementation `waitForCompact(bool wait_unscheduled=false)`. The unscheduled parameter indicates the compactions that are not yet scheduled but are required to process items in the queue.
In certain cases, we are unable to wait for compactions, such as during a shutdown or when background jobs are paused. It is important to return the appropriate status in these scenarios. For all other cases, we should wait for all compaction and flush jobs, including the unscheduled ones. The primary purpose of this new API is to wait until the system has resolved its compaction debt. Currently, the usage of `wait_unscheduled` is limited to test code.
This pull request eliminates the usage of wait_unscheduled. The internal `waitForCompact()` API now waits for unscheduled compactions unless the db is undergoing a shutdown. In the event of a shutdown, the API returns `Status::ShutdownInProgress()`.
Additionally, a new parameter, `abort_on_pause`, has been introduced with a default value of `false`. This parameter addresses the possibility of waiting indefinitely for unscheduled jobs if `PauseBackgroundWork()` was called before `waitForCompact()` is invoked. By setting `abort_on_pause` to `true`, the API will immediately return `Status::Aborted`.
Furthermore, all tests that previously called `waitForCompact(true)` have been fixed.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11443
Test Plan:
Existing tests that involve a shutdown in progress:
- DBCompactionTest::CompactRangeShutdownWhileDelayed
- DBTestWithParam::PreShutdownMultipleCompaction
- DBTestWithParam::PreShutdownCompactionMiddle
Reviewed By: pdillinger
Differential Revision: D45923426
Pulled By: jaykorean
fbshipit-source-id: 7dc93fe6a6841a7d9d2d72866fa647090dba8eae
Summary:
**Context:**
The existing stat rocksdb.sst.read.micros does not reflect each of compaction and flush cases but aggregate them, which is not so helpful for us to understand IO read behavior of each of them.
**Summary**
- Update `StopWatch` and `RandomAccessFileReader` to record `rocksdb.sst.read.micros` and `rocksdb.file.{flush/compaction}.read.micros`
- Fixed the default histogram in `RandomAccessFileReader`
- New field `ReadOptions/IOOptions::io_activity`; Pass `ReadOptions` through paths under db open, flush and compaction to where we can prepare `IOOptions` and pass it to `RandomAccessFileReader`
- Use `thread_status_util` for assertion in `DbStressFSWrapper` for continuous testing on we are passing correct `io_activity` under db open, flush and compaction
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11288
Test Plan:
- **Stress test**
- **Db bench 1: rocksdb.sst.read.micros COUNT ≈ sum of rocksdb.file.read.flush.micros's and rocksdb.file.read.compaction.micros's.** (without blob)
- May not be exactly the same due to `HistogramStat::Add` only guarantees atomic not accuracy across threads.
```
./db_bench -db=/dev/shm/testdb/ -statistics=true -benchmarks="fillseq" -key_size=32 -value_size=512 -num=50000 -write_buffer_size=655 -target_file_size_base=655 -disable_auto_compactions=false -compression_type=none -bloom_bits=3 (-use_plain_table=1 -prefix_size=10)
```
```
// BlockBasedTable
rocksdb.sst.read.micros P50 : 2.009374 P95 : 4.968548 P99 : 8.110362 P100 : 43.000000 COUNT : 40456 SUM : 114805
rocksdb.file.read.flush.micros P50 : 1.871841 P95 : 3.872407 P99 : 5.540541 P100 : 43.000000 COUNT : 2250 SUM : 6116
rocksdb.file.read.compaction.micros P50 : 2.023109 P95 : 5.029149 P99 : 8.196910 P100 : 26.000000 COUNT : 38206 SUM : 108689
// PlainTable
Does not apply
```
- **Db bench 2: performance**
**Read**
SETUP: db with 900 files
```
./db_bench -db=/dev/shm/testdb/ -benchmarks="fillseq" -key_size=32 -value_size=512 -num=50000 -write_buffer_size=655 -disable_auto_compactions=true -target_file_size_base=655 -compression_type=none
```run till convergence
```
./db_bench -seed=1678564177044286 -use_existing_db=true -db=/dev/shm/testdb -benchmarks=readrandom[-X60] -statistics=true -num=1000000 -disable_auto_compactions=true -compression_type=none -bloom_bits=3
```
Pre-change
`readrandom [AVG 60 runs] : 21568 (± 248) ops/sec`
Post-change (no regression, -0.3%)
`readrandom [AVG 60 runs] : 21486 (± 236) ops/sec`
**Compaction/Flush**run till convergence
```
./db_bench -db=/dev/shm/testdb2/ -seed=1678564177044286 -benchmarks="fillseq[-X60]" -key_size=32 -value_size=512 -num=50000 -write_buffer_size=655 -disable_auto_compactions=false -target_file_size_base=655 -compression_type=none
rocksdb.sst.read.micros COUNT : 33820
rocksdb.sst.read.flush.micros COUNT : 1800
rocksdb.sst.read.compaction.micros COUNT : 32020
```
Pre-change
`fillseq [AVG 46 runs] : 1391 (± 214) ops/sec; 0.7 (± 0.1) MB/sec`
Post-change (no regression, ~-0.4%)
`fillseq [AVG 46 runs] : 1385 (± 216) ops/sec; 0.7 (± 0.1) MB/sec`
Reviewed By: ajkr
Differential Revision: D44007011
Pulled By: hx235
fbshipit-source-id: a54c89e4846dfc9a135389edf3f3eedfea257132
Summary:
Fixes https://github.com/facebook/rocksdb/issues/11160
By counting the number of stalls placed on a write queue, we can check in UnlockWAL() whether the stall present at the start of UnlockWAL() has been cleared by the end, or wait until it's cleared.
More details in code comments and new unit test.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11172
Test Plan: unit test added. Yes, it uses sleep to amplify failure on buggy behavior if present, but using a sync point to only allow new behavior would fail with the old code only because it doesn't contain the new sync point. Basically, using a sync point in UnlockWAL() could easily mask a regression by artificially limiting key behaviors. The test would only check that UnlockWAL() invokes code that *should* do the right thing, without checking that it *does* the right thing.
Reviewed By: ajkr
Differential Revision: D42894341
Pulled By: pdillinger
fbshipit-source-id: 15c9da0ca383e6aec845b29f5447d76cecbf46c3
Summary:
We haven't been actively mantaining RocksDB LITE recently and the size must have been gone up significantly. We are removing the support.
Most of changes were done through following comments:
unifdef -m -UROCKSDB_LITE `git grep -l ROCKSDB_LITE | egrep '[.](cc|h)'`
by Peter Dillinger. Others changes were manually applied to build scripts, CircleCI manifests, ROCKSDB_LITE is used in an expression and file db_stress_test_base.cc.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11147
Test Plan: See CI
Reviewed By: pdillinger
Differential Revision: D42796341
fbshipit-source-id: 4920e15fc2060c2cd2221330a6d0e5e65d4b7fe2
Summary:
PR https://github.com/facebook/rocksdb/issues/11020 fixed a case where it was easy to deadlock the DB with LockWAL() but introduced a bug showing up as a rare assertion failure in the stress test. Specifically, `assert(w->state == STATE_INIT)` in `WriteThread::LinkOne()` called from `BeginWriteStall()`, `DelayWrite()`, `WriteImplWALOnly()`. I haven't been about to generate a unit test that reproduces this failure but I believe the root cause is that DelayWrite() was never meant to be re-entrant, only called from the DB's write_thread_ leader. https://github.com/facebook/rocksdb/issues/11020 introduced a call to DelayWrite() from the nonmem_write_thread_ group leader.
This fix is to make DelayWrite() apply to the specific write queue that it is being called from (inject a dummy write stall entry to the head of the appropriate write queue). WriteController is re-entrant, based on polling and state changes signalled with bg_cv_, so can manage stalling two queues. The only anticipated complication (called out by Andrew in previous PR) is that we don't want timed write delays being injected in parallel for the two queues, because that dimishes the intended throttling effect. Thus, we only allow timed delays for the primary write queue.
HISTORY not updated because this is intended for the same release where the bug was introduced.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11130
Test Plan:
Although I was not able to reproduce the assertion failure, I was able to reproduce a distinct flaw with what I believe is the same root cause: a kind of deadlock if both write queues need to wake up from stopped writes. Only one will be waiting on bg_cv_ (the other waiting in `LinkOne()` for the write queue to open up), so a single SignalAll() will only unblock one of the queues, with the other re-instating the stop until another signal on bg_cv_. A simple unit test is added for this case.
Will also run crash_test_with_multiops_wc_txn for a while looking for issues.
Reviewed By: ajkr
Differential Revision: D42749330
Pulled By: pdillinger
fbshipit-source-id: 4317dd899a93d57c26fd5af7143038f82d4d4d1b
Summary:
RocksDB has two public APIs: `DB::LockWAL()`/`DB::UnlockWAL()`. The current implementation acquires and
releases the internal `DBImpl::log_write_mutex_`.
According to the comment on `DBImpl::log_write_mutex_`: https://github.com/facebook/rocksdb/blob/7.8.fb/db/db_impl/db_impl.h#L2287:L2288
> Note: to avoid dealock, if needed to acquire both log_write_mutex_ and mutex_, the order should be first mutex_ and then log_write_mutex_.
This puts limitations on how applications can use the `LockWAL()` API. After `LockWAL()` returns ok, then application
should not perform any operation that acquires `mutex_`. Currently, the use case of `LockWAL()` is MyRocks implementing
the MySQL storage engine handlerton `lock_hton_log` interface. The operation that MyRocks performs after `LockWAL()`
is `GetSortedWalFiless()` which not only acquires mutex_, but also `log_write_mutex_`.
There are two issues:
1. Applications using these two APIs may hang if one thread calls `GetSortedWalFiles()` after
calling `LockWAL()` because log_write_mutex is not recursive.
2. Two threads may dead lock due to lock order inversion.
To fix these issues, we can modify the implementation of LockWAL so that it does not keep
`log_write_mutex_` held until UnlockWAL. To achieve the goal of locking the WAL, we can
instead manually inject a write stall so that all future writes will be stopped.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11020
Test Plan: make check
Reviewed By: ajkr
Differential Revision: D41785203
Pulled By: riversand963
fbshipit-source-id: 5ccb7a9c6eb9a2c3fa80fd2c399cc2568b8f89ce
Summary:
In transaction unit tests, replace a few member variable lambdas with
non-static methods. It's easier for gdb to work with variables in methods than in lambdas.
(Seen similar things to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86675).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10924
Test Plan: make check
Reviewed By: jay-zhuang
Differential Revision: D41072241
Pulled By: riversand963
fbshipit-source-id: e4fa491de573c4656225a86a75af926c1df827f6
Summary:
With TSAN build on CircleCI (see mini-tsan in .circleci/config).
Sometimes `SeqAdvanceConcurrentTest.SeqAdvanceConcurrent` will get stuck when an experimental feature called
"unordered write" is enabled. Stack trace will be the following
```
Thread 7 (Thread 0x7f2284a1c700 (LWP 481523) "write_prepared_"):
#0 0x00000000004fa3f5 in __tsan_atomic64_load () at ./db/merge_context.h:15
https://github.com/facebook/rocksdb/issues/1 0x00000000005e5942 in std::__atomic_base<unsigned long>::load (this=0x7b74000012f8, __m=std::memory_order_seq_cst) at /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/atomic_base.h:481
https://github.com/facebook/rocksdb/issues/2 std::__atomic_base<unsigned long>::operator unsigned long (this=0x7b74000012f8) at /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/atomic_base.h:341
https://github.com/facebook/rocksdb/issues/3 0x00000000005bf001 in rocksdb::SeqAdvanceConcurrentTest_SeqAdvanceConcurrent_Test::TestBody()::$_9::operator()(void*) const (this=0x7b14000085e8) at utilities/transactions/write_prepared_transaction_test.cc:1702
Thread 6 (Thread 0x7f228421b700 (LWP 481521) "write_prepared_"):
#0 0x000000000052178c in __tsan::MetaMap::GetAndLock(__tsan::ThreadState*, unsigned long, unsigned long, bool, bool) () at ./db/merge_context.h:15
https://github.com/facebook/rocksdb/issues/1 0x00000000004fa48e in __tsan_atomic64_load () at ./db/merge_context.h:15
https://github.com/facebook/rocksdb/issues/2 0x00000000005e5942 in std::__atomic_base<unsigned long>::load (this=0x7b74000012f8, __m=std::memory_order_seq_cst) at /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/atomic_base.h:481
https://github.com/facebook/rocksdb/issues/3 std::__atomic_base<unsigned long>::operator unsigned long (this=0x7b74000012f8) at /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/atomic_base.h:341
https://github.com/facebook/rocksdb/issues/4 0x00000000005bf001 in rocksdb::SeqAdvanceConcurrentTest_SeqAdvanceConcurrent_Test::TestBody()::$_9::operator()(void*) const (this=0x7b14000085e8) at utilities/transactions/write_prepared_transaction_test.cc:1702
```
This is problematic and suspicious. Two threads will get stuck in the same place trying to load from an atomic variable.
https://github.com/facebook/rocksdb/blob/7.8.fb/utilities/transactions/write_prepared_transaction_test.cc#L1694:L1707. Not sure why two threads can reach the same point.
The stack trace shows that there may be a deadlock, since the two threads are on the same write thread (one is doing Prepare, while the other is trying to commit).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10909
Test Plan:
On CircleCI mini-tsan, apply a patch first so that we have a higher chance of hitting the same problematic situation,
```
diff --git a/utilities/transactions/write_prepared_transaction_test.cc b/utilities/transactions/write_prepared_transaction_test.cc
index 4bc1f3744..bd5dc4924 100644
--- a/utilities/transactions/write_prepared_transaction_test.cc
+++ b/utilities/transactions/write_prepared_transaction_test.cc
@@ -1714,13 +1714,13 @@ TEST_P(SeqAdvanceConcurrentTest, SeqAdvanceConcurrent) {
size_t d = (n % base[bi + 1]) / base[bi];
switch (d) {
case 0:
- threads.emplace_back(txn_t0, bi);
+ threads.emplace_back(txn_t3, bi);
break;
case 1:
- threads.emplace_back(txn_t1, bi);
+ threads.emplace_back(txn_t3, bi);
break;
case 2:
- threads.emplace_back(txn_t2, bi);
+ threads.emplace_back(txn_t3, bi);
break;
case 3:
threads.emplace_back(txn_t3, bi);
```
then build and run tests
```
COMPILE_WITH_TSAN=1 CC=clang-13 CXX=clang++-13 ROCKSDB_DISABLE_ALIGNED_NEW=1 USE_CLANG=1 make V=1 -j32 check
gtest-parallel -r 100 ./write_prepared_transaction_test --gtest_filter=TwoWriteQueues/SeqAdvanceConcurrentTest.SeqAdvanceConcurrent/19
```
In the above, `SeqAdvanceConcurrent/19`. The tests 10 to 19 correspond to unordered write in which Prepare() and Commit() can both enter the same write thread.
Before this PR, there is a high chance of hitting the deadlock. With this PR, no deadlock has been encountered so far.
Reviewed By: ltamasi
Differential Revision: D40869387
Pulled By: riversand963
fbshipit-source-id: 81e82a70c263e4f3417597a201b081ee54f1deab
Summary:
This PR implements the originally disabled `Merge()` APIs when user-defined timestamp is enabled.
Simplest usage:
```cpp
// assume string append merge op is used with '.' as delimiter.
// ts1 < ts2
db->Put(WriteOptions(), "key", ts1, "v0");
db->Merge(WriteOptions(), "key", ts2, "1");
ReadOptions ro;
ro.timestamp = &ts2;
db->Get(ro, "key", &value);
ASSERT_EQ("v0.1", value);
```
Some code comments are added for clarity.
Note: support for timestamp in `DB::GetMergeOperands()` will be done in a follow-up PR.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10819
Test Plan: make check
Reviewed By: ltamasi
Differential Revision: D40603195
Pulled By: riversand963
fbshipit-source-id: f96d6f183258f3392d80377025529f7660503013
Summary:
The motivation and benefit of current behavior of passing `LockInfo&&` as argument to AcquireLocked() and AcquireWithTimeout() is not clear to me. Furthermore, in AcquireWithTimeout(), we access members of `LockInfo&&` after it is passed to AcquireLocked() as rvalue ref. In addition, we may call `AcquireLocked()` with `std::move(lock_info)` multiple times.
This leads to linter warning of use-after-move. If future implementation of AcquireLocked() does something like moving-construct a new `LockedInfo` using the passed-in `LockInfo&&`, then the caller cannot use it because `LockInfo` has a member of type `autovector`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10874
Test Plan: make check
Reviewed By: ltamasi
Differential Revision: D40704210
Pulled By: riversand963
fbshipit-source-id: 20091df65b4fc63b072bcec9809efc49955d6d35
Summary:
Instead of existing calls to ps from gnu_parallel, call a new wrapper that does ps, looks for unit test like processes, and uses pstack or gdb to print thread stack traces. Also, using `ps -wwf` instead of `ps -wf` ensures output is not cut off.
For security, CircleCI runs with security restrictions on ptrace (/proc/sys/kernel/yama/ptrace_scope = 1), and this change adds a work-around to `InstallStackTraceHandler()` (only used by testing tools) to allow any process from the same user to debug it. (I've also touched >100 files to ensure all the unit tests call this function.)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10828
Test Plan: local manual + temporary infinite loop in a unit test to observe in CircleCI
Reviewed By: hx235
Differential Revision: D40447634
Pulled By: pdillinger
fbshipit-source-id: 718a4c4a5b54fa0f9af2d01a446162b45e5e84e1
Summary:
Currently, without this fix, DBImpl::GetLatestSequenceForKey() may not return the latest sequence number for merge operands of the key. This can cause conflict checking during optimistic transaction commit phase to fail. Fix it by always returning the latest sequence number of the key, also considering range tombstones.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10724
Test Plan: make check
Reviewed By: cbi42
Differential Revision: D39756847
Pulled By: riversand963
fbshipit-source-id: 0764c3dd4cb24960b37e18adccc6e7feed0e6876
Summary:
RocksDB allows reusing old `Transaction` objects when creating new ones. Therefore, we need to
reset the transaction's read and commit timestamps back to default values `kMaxTxnTimestamp`.
Otherwise, `CommitAndTryCreateSnapshot()` may fail with "Status::InvalidArgument("Different commit ts specified")".
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10677
Test Plan: make check
Reviewed By: ltamasi
Differential Revision: D39513543
Pulled By: riversand963
fbshipit-source-id: bea01cac149bff3a23a2978fc0c3b198243a6291
Summary:
Fix copyright for two more extra headers to make internal tool happy.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10525
Reviewed By: jay-zhuang
Differential Revision: D38661390
fbshipit-source-id: ab2d055bfd145dfe82b5bae7a6c25cc338c8de94
Summary:
Some files miss headers. Also some headers are irregular. Fix them to make an internal checkup tool happy.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10519
Reviewed By: jay-zhuang
Differential Revision: D38603291
fbshipit-source-id: 13b1bbd6d48f5ee15ba20da67544396de48238f1
Summary:
Moved linux builds to using docker to avoid CI instability caused by dependency installation site down.
Added the `Dockerfile` which is used to build the image.
The build time is also significantly reduced, because no dependencies installation and with using 2xlarge+ instance for slow build (like tsan test).
Also fixed a few issues detected while building this:
* `DestoryDB()` Status not checked for a few tests
* nullptr might be used in `inlineskiplist.cc`
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10496
Test Plan: CI
Reviewed By: ajkr
Differential Revision: D38554200
Pulled By: jay-zhuang
fbshipit-source-id: 16e8fb2bf07b9c84bb27fb18421c4d54f2f248fd
Summary:
Travis CI is depreciated and haven't been maintained for some time.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10407
Reviewed By: ajkr
Differential Revision: D38078382
Pulled By: jay-zhuang
fbshipit-source-id: f42057f2f41f722bdce56bf195f67a94835191fb
Summary:
This overrides `CreateColumnFamilies` and `DropColumnFamilies` in `PessimisticTransactionDB` in order to add/remove the created column families to/from the lock manager.
Fixes https://github.com/facebook/rocksdb/issues/10322.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10332
Reviewed By: ajkr
Differential Revision: D37841079
Pulled By: riversand963
fbshipit-source-id: 854d7d9948b0089e0054a8f2875485ba44436fd2
Summary:
Added an option, `WriteOptions::protection_bytes_per_key`, that controls how many bytes per key we use for integrity protection in `WriteBatch`. It takes effect when `WriteBatch::GetProtectionBytesPerKey() == 0`.
Currently the only supported value is eight. Invoking a user API with it set to any other nonzero value will result in `Status::NotSupported` returned to the user.
There is also a bug fix for integrity protection with `inplace_callback`, where we forgot to take into account the possible change in varint length when calculating KV checksum for the final encoded buffer.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10037
Test Plan:
- Manual
- Set default value of `WriteOptions::protection_bytes_per_key` to eight and ran `make check -j24`
- Enabled in MyShadow for 1+ week
- Automated
- Unit tests have a `WriteMode` that enables the integrity protection via `WriteOptions`
- Crash test - in most cases, use `WriteOptions::protection_bytes_per_key` to enable integrity protection
Reviewed By: cbi42
Differential Revision: D36614569
Pulled By: ajkr
fbshipit-source-id: 8650087ceac9b61b560f1e5fafe5e1baf9c725fb
Summary:
In RocksDB, keys are associated with (internal) sequence numbers which denote when the keys are written
to the database. Sequence numbers in different RocksDB instances are unrelated, thus not comparable.
It is nice if we can associate sequence numbers with their corresponding actual timestamps. One thing we can
do is to support user-defined timestamp, which allows the applications to specify the format of custom timestamps
and encode a timestamp with each key. More details can be found at https://github.com/facebook/rocksdb/wiki/User-defined-Timestamp-%28Experimental%29.
This PR provides a different but complementary approach. We can associate rocksdb snapshots (defined in
https://github.com/facebook/rocksdb/blob/7.2.fb/include/rocksdb/snapshot.h#L20) with **user-specified** timestamps.
Since a snapshot is essentially an object representing a sequence number, this PR establishes a bi-directional mapping between sequence numbers and timestamps.
In the past, snapshots are usually taken by readers. The current super-version is grabbed, and a `rocksdb::Snapshot`
object is created with the last published sequence number of the super-version. You can see that the reader actually
has no good idea of what timestamp to assign to this snapshot, because by the time the `GetSnapshot()` is called,
an arbitrarily long period of time may have already elapsed since the last write, which is when the last published
sequence number is written.
This observation motivates the creation of "timestamped" snapshots on the write path. Currently, this functionality is
exposed only to the layer of `TransactionDB`. Application can tell RocksDB to create a snapshot when a transaction
commits, effectively associating the last sequence number with a timestamp. It is also assumed that application will
ensure any two snapshots with timestamps should satisfy the following:
```
snapshot1.seq < snapshot2.seq iff. snapshot1.ts < snapshot2.ts
```
If the application can guarantee that when a reader takes a timestamped snapshot, there is no active writes going on
in the database, then we also allow the user to use a new API `TransactionDB::CreateTimestampedSnapshot()` to create
a snapshot with associated timestamp.
Code example
```cpp
// Create a timestamped snapshot when committing transaction.
txn->SetCommitTimestamp(100);
txn->SetSnapshotOnNextOperation();
txn->Commit();
// A wrapper API for convenience
Status Transaction::CommitAndTryCreateSnapshot(
std::shared_ptr<TransactionNotifier> notifier,
TxnTimestamp ts,
std::shared_ptr<const Snapshot>* ret);
// Create a timestamped snapshot if caller guarantees no concurrent writes
std::pair<Status, std::shared_ptr<const Snapshot>> snapshot = txn_db->CreateTimestampedSnapshot(100);
```
The snapshots created in this way will be managed by RocksDB with ref-counting and potentially shared with
other readers. We provide the following APIs for readers to retrieve a snapshot given a timestamp.
```cpp
// Return the timestamped snapshot correponding to given timestamp. If ts is
// kMaxTxnTimestamp, then we return the latest timestamped snapshot if present.
// Othersise, we return the snapshot whose timestamp is equal to `ts`. If no
// such snapshot exists, then we return null.
std::shared_ptr<const Snapshot> TransactionDB::GetTimestampedSnapshot(TxnTimestamp ts) const;
// Return the latest timestamped snapshot if present.
std::shared_ptr<const Snapshot> TransactionDB::GetLatestTimestampedSnapshot() const;
```
We also provide two additional APIs for stats collection and reporting purposes.
```cpp
Status TransactionDB::GetAllTimestampedSnapshots(
std::vector<std::shared_ptr<const Snapshot>>& snapshots) const;
// Return timestamped snapshots whose timestamps fall in [ts_lb, ts_ub) and store them in `snapshots`.
Status TransactionDB::GetTimestampedSnapshots(
TxnTimestamp ts_lb,
TxnTimestamp ts_ub,
std::vector<std::shared_ptr<const Snapshot>>& snapshots) const;
```
To prevent the number of timestamped snapshots from growing infinitely, we provide the following API to release
timestamped snapshots whose timestamps are older than or equal to a given threshold.
```cpp
void TransactionDB::ReleaseTimestampedSnapshotsOlderThan(TxnTimestamp ts);
```
Before shutdown, RocksDB will release all timestamped snapshots.
Comparison with user-defined timestamp and how they can be combined:
User-defined timestamp persists every key with a timestamp, while timestamped snapshots maintain a volatile
mapping between snapshots (sequence numbers) and timestamps.
Different internal keys with the same user key but different timestamps will be treated as different by compaction,
thus a newer version will not hide older versions (with smaller timestamps) unless they are eligible for garbage collection.
In contrast, taking a timestamped snapshot at a certain sequence number and timestamp prevents all the keys visible in
this snapshot from been dropped by compaction. Here, visible means (seq < snapshot and most recent).
The timestamped snapshot supports the semantics of reading at an exact point in time.
Timestamped snapshots can also be used with user-defined timestamp.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9879
Test Plan:
```
make check
TEST_TMPDIR=/dev/shm make crash_test_with_txn
```
Reviewed By: siying
Differential Revision: D35783919
Pulled By: riversand963
fbshipit-source-id: 586ad905e169189e19d3bfc0cb0177a7239d1bd4
Summary:
With this change, when a given read timestamp is smaller than the column-family's full_history_ts_low, Get(), MultiGet() and iterators APIs will return Status::InValidArgument().
Test plan
```
$COMPILE_WITH_ASAN=1 make -j24 all
$./db_with_timestamp_basic_test --gtest_filter=DBBasicTestWithTimestamp.UpdateFullHistoryTsLow
$ make -j24 check
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10109
Reviewed By: riversand963
Differential Revision: D36901126
Pulled By: jowlyzhang
fbshipit-source-id: 255feb1a66195351f06c1d0e42acb1ff74527f86
Summary:
If caller specifies a non-null `timestamp` argument in `DB::Get()` or a non-null `timestamps` in `DB::MultiGet()`,
RocksDB will return the timestamps of the point tombstones.
Note: DeleteRange is still unsupported.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10056
Test Plan: make check
Reviewed By: ltamasi
Differential Revision: D36677956
Pulled By: riversand963
fbshipit-source-id: 2d7af02cc7237b1829cd269086ea895a49d501ae
Summary:
TSAN test is slower, for `TransactionStressTest` and
`DeadlockStress`, they're reaching the timeout limit of 600 seconds.
Decreasing the transaction test number.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10063
Test Plan: CI
Reviewed By: ajkr
Differential Revision: D36711727
Pulled By: jay-zhuang
fbshipit-source-id: 600f82a6d32108f52fbe5572fcc7497607b7fe98
Summary:
Changed the static objects that had non-trivial destructors to use the STATIC_AVOID_DESTRUCTION construct.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9958
Reviewed By: pdillinger
Differential Revision: D36442982
Pulled By: mrambacher
fbshipit-source-id: 029d47b1374d30d198bfede369a4c0ae7a4eb519
Summary:
ToString() is created as some platform doesn't support std::to_string(). However, we've already used std::to_string() by mistake for 16 months (in db/db_info_dumper.cc). This commit just remove ToString().
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9955
Test Plan: Watch CI tests
Reviewed By: riversand963
Differential Revision: D36176799
fbshipit-source-id: bdb6dcd0e3a3ab96a1ac810f5d0188f684064471
Summary:
Enforce the contract of SingleDelete so that they are not mixed with
Delete for the same key. Otherwise, it will lead to undefined behavior.
See https://github.com/facebook/rocksdb/wiki/Single-Delete#notes.
Also fix unit tests and write-unprepared.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9888
Test Plan: make check
Reviewed By: ajkr
Differential Revision: D35837817
Pulled By: riversand963
fbshipit-source-id: acd06e4dcba8cb18df92b44ed18c57e10e5a7635
Summary:
Adds more coverage to `MultiOpsTxnsStressTest` with a focus on write-prepared transactions.
1. Add a hack to manually evict commit cache entries. We currently cannot assign small values to `wp_commit_cache_bits` because it requires a prepared transaction to commit within a certain range of sequence numbers, otherwise it will throw.
2. Add coverage for commit-time-write-batch. If write policy is write-prepared, we need to set `use_only_the_last_commit_time_batch_for_recovery` to true.
3. After each flush/compaction, verify data consistency. This is possible since data size can be small: default numbers of primary/secondary keys are just 1000.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9829
Test Plan:
```
TEST_TMPDIR=/dev/shm/rocksdb_crashtest_blackbox/ make blackbox_crash_test_with_multiops_wp_txn
```
Reviewed By: pdillinger
Differential Revision: D35806678
Pulled By: riversand963
fbshipit-source-id: d7fde7a29fda0fb481a61f553e0ca0c47da93616
Summary:
The current locktree implementation stores the address of the
PessimisticTransactions object as the TXNID. However, when a transaction
is blocked on a lock, it records the list of waitees with conflicting
locks using the rocksdb assigned TransactionID. This is performed by
calling GetID() on PessimisticTransactions objects of the waitees,
and then recorded in the waiter's list.
However, there is no guarantee the objects are valid when recording the
waitee list during the conflict callbacks because the waitee
could have released the lock and freed the PessimisticTransactions
object.
The waitee/txnid values are only valid PessimisticTransaction objects
while the mutex for the root of the locktree is held.
The simplest fix for this problem is to use the address of the
PessimisticTransaction as the TransactionID so that it is consistent
with its usage in the locktree. The TXNID is only converted back to a
PessimisticTransaction for the report_wait callbacks. Since
these callbacks are now all made within the critical section where the
lock_request queue mutx is held, these conversions will be safe.
Otherwise, only the uint64_t TXNID of the waitee is registerd
with the waiter transaction. The PessimisitcTransaction object of the
waitee is never referenced.
The main downside of this approach is the TransactionID will not change
if the PessimisticTransaction object is reused for new transactions.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9898
Test Plan:
Add a new test case and run unit tests.
Also verified with MyRocks workloads using range locks that the
crash no longer happens.
Reviewed By: riversand963
Differential Revision: D35950376
Pulled By: hermanlee
fbshipit-source-id: 8c9cae272e23e487fc139b6a8ed5b8f8f24b1570
Summary:
This PR does not affect write-committed.
Add a member, `rollback_deletion_type_callback` to TransactionDBOptions
so that a write-prepared transaction, when rolling back, can call this
callback to decide if a `Delete` or `SingleDelete` should be used to
cancel a prior `Put` written to the database during prepare phase.
The purpose of this PR is to prevent mixing `Delete` and `SingleDelete`
for the same key, causing undefined behaviors. Without this PR, the
following can happen:
```
// The application always issues SingleDelete when deleting keys.
txn1->Put('a');
txn1->Prepare(); // writes to memtable and potentially gets flushed/compacted to Lmax
txn1->Rollback(); // inserts DELETE('a')
txn2->Put('a');
txn2->Commit(); // writes to memtable and potentially gets flushed/compacted
```
In the database, we may have
```
L0: [PUT('a', s=100)]
L1: [DELETE('a', s=90)]
Lmax: [PUT('a', s=0)]
```
If a compaction compacts L0 and L1, then we have
```
L1: [PUT('a', s=100)]
Lmax: [PUT('a', s=0)]
```
If a future transaction issues a SingleDelete, we have
```
L0: [SD('a', s=110)]
L1: [PUT('a', s=100)]
Lmax: [PUT('a', s=0)]
```
Then, a compaction including L0, L1 and Lmax leads to
```
Lmax: [PUT('a', s=0)]
```
which is incorrect.
Similar bugs reported and addressed in
https://github.com/cockroachdb/pebble/issues/1255. Based on our team's
current priority, we have decided to take this approach for now. We may
come back and revisit in the future.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9873
Test Plan: make check
Reviewed By: ltamasi
Differential Revision: D35762170
Pulled By: riversand963
fbshipit-source-id: b28d56eefc786b53c9844b9ef4a7807acdd82c8d
Summary:
Especially after updating to C++17, I don't see a compelling case for
*requiring* any folly components in RocksDB. I was able to purge the existing
hard dependencies, and it can be quite difficult to strip out non-trivial components
from folly for use in RocksDB. (The prospect of doing that on F14 has changed
my mind on the best approach here.)
But this change creates an optional integration where we can plug in
components from folly at compile time, starting here with F14FastMap to replace
std::unordered_map when possible (probably no public APIs for example). I have
replaced the biggest CPU users of std::unordered_map with compile-time
pluggable UnorderedMap which will use F14FastMap when USE_FOLLY is set.
USE_FOLLY is always set in the Meta-internal buck build, and a simulation of
that is in the Makefile for public CI testing. A full folly build is not needed, but
checking out the full folly repo is much simpler for getting the dependency,
and anything else we might want to optionally integrate in the future.
Some picky details:
* I don't think the distributed mutex stuff is actually used, so it was easy to remove.
* I implemented an alternative to `folly::constexpr_log2` (which is much easier
in C++17 than C++11) so that I could pull out the hard dependencies on
`ConstexprMath.h`
* I had to add noexcept move constructors/operators to some types to make
F14's complainUnlessNothrowMoveAndDestroy check happy, and I added a
macro to make that easier in some common cases.
* Updated Meta-internal buck build to use folly F14Map (always)
No updates to HISTORY.md nor INSTALL.md as this is not (yet?) considered a
production integration for open source users.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9546
Test Plan:
CircleCI tests updated so that a couple of them use folly.
Most internal unit & stress/crash tests updated to use Meta-internal latest folly.
(Note: they should probably use buck but they currently use Makefile.)
Example performance improvement: when filter partitions are pinned in cache,
they are tracked by PartitionedFilterBlockReader::filter_map_ and we can build
a test that exercises that heavily. Build DB with
```
TEST_TMPDIR=/dev/shm/rocksdb ./db_bench -benchmarks=fillrandom -num=10000000 -disable_wal=1 -write_buffer_size=30000000 -bloom_bits=16 -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=0 -partition_index_and_filters
```
and test with (simultaneous runs with & without folly, ~20 times each to see
convergence)
```
TEST_TMPDIR=/dev/shm/rocksdb ./db_bench_folly -readonly -use_existing_db -benchmarks=readrandom -num=10000000 -bloom_bits=16 -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=0 -partition_index_and_filters -duration=40 -pin_l0_filter_and_index_blocks_in_cache
```
Average ops/s no folly: 26229.2
Average ops/s with folly: 26853.3 (+2.4%)
Reviewed By: ajkr
Differential Revision: D34181736
Pulled By: pdillinger
fbshipit-source-id: ffa6ad5104c2880321d8a1aa7187e00ab0d02e94
Summary:
For write-prepared/write-unprepared transactions,
GetCommitTimeWriteBatch() can be used only if the transaction is started
with `TransactionOptions::use_only_the_last_commit_time_batch_for_recovery` set
to true. Otherwise, it is possible that multiple uncommitted versions of the
same key exist in the database. During bottommost compaction, RocksDB may
set the sequence numbers of both to zero once they become committed, causing
output SST file to have two identical internal keys.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9794
Test Plan:
make check
pay special attention to the following
```
transaction_test --gtest_filter=MySQLStyleTransactionTest/MySQLStyleTransactionTest.TransactionStressTest/*
```
Reviewed By: lth
Differential Revision: D35327214
Pulled By: riversand963
fbshipit-source-id: 3bae00a28359c10e96e4c6f676d20de5610d8a0f
Summary:
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9629
Pessimistic transactions use pessimistic concurrency control, i.e. locking. Keys are
locked upon first operation that writes the key or has the intention of writing. For example,
`PessimisticTransaction::Put()`, `PessimisticTransaction::Delete()`,
`PessimisticTransaction::SingleDelete()` will write to or delete a key, while
`PessimisticTransaction::GetForUpdate()` is used by application to indicate
to RocksDB that the transaction has the intention of performing write operation later
in the same transaction.
Pessimistic transactions support two-phase commit (2PC). A transaction can be
`Prepared()`'ed and then `Commit()`. The prepare phase is similar to a promise: once
`Prepare()` succeeds, the transaction has acquired the necessary resources to commit.
The resources include locks, persistence of WAL, etc.
Write-committed transaction is the default pessimistic transaction implementation. In
RocksDB write-committed transaction, `Prepare()` will write data to the WAL as a prepare
section. `Commit()` will write a commit marker to the WAL and then write data to the
memtables. While writing to the memtables, different keys in the transaction's write batch
will be assigned different sequence numbers in ascending order.
Until commit/rollback, the transaction holds locks on the keys so that no other transaction
can write to the same keys. Furthermore, the keys' sequence numbers represent the order
in which they are committed and should be made visible. This is convenient for us to
implement support for user-defined timestamps.
Since column families with and without timestamps can co-exist in the same database,
a transaction may or may not involve timestamps. Based on this observation, we add two
optional members to each `PessimisticTransaction`, `read_timestamp_` and
`commit_timestamp_`. If no key in the transaction's write batch has timestamp, then
setting these two variables do not have any effect. For the rest of this commit, we discuss
only the cases when these two variables are meaningful.
read_timestamp_ is used mainly for validation, and should be set before first call to
`GetForUpdate()`. Otherwise, the latter will return non-ok status. `GetForUpdate()` calls
`TryLock()` that can verify if another transaction has written the same key since
`read_timestamp_` till this call to `GetForUpdate()`. If another transaction has indeed
written the same key, then validation fails, and RocksDB allows this transaction to
refine `read_timestamp_` by increasing it. Note that a transaction can still use `Get()`
with a different timestamp to read, but the result of the read should not be used to
determine data that will be written later.
commit_timestamp_ must be set after finishing writing and before transaction commit.
This applies to both 2PC and non-2PC cases. In the case of 2PC, it's usually set after
prepare phase succeeds.
We currently require that the commit timestamp be chosen after all keys are locked. This
means we disallow the `TransactionDB`-level APIs if user-defined timestamp is used
by the transaction. Specifically, calling `PessimisticTransactionDB::Put()`,
`PessimisticTransactionDB::Delete()`, `PessimisticTransactionDB::SingleDelete()`,
etc. will return non-ok status because they specify timestamps before locking the keys.
Users are also prompted to use the `Transaction` APIs when they receive the non-ok status.
Reviewed By: ltamasi
Differential Revision: D31822445
fbshipit-source-id: b82abf8e230216dc89cc519564a588224a88fd43
Summary:
This PR supports inserting keys to a `WriteBatchWithIndex` for column families that enable user-defined timestamps
and reading the keys back. **The index does not have timestamps.**
Writing a key to WBWI is unchanged, because the underlying WriteBatch already supports it.
When reading the keys back, we need to make sure to distinguish between keys with and without timestamps before
comparison.
When user calls `GetFromBatchAndDB()`, no timestamp is needed to query the batch, but a timestamp has to be
provided to query the db. The assumption is that data in the batch must be newer than data from the db.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9603
Test Plan: make check
Reviewed By: ltamasi
Differential Revision: D34354849
Pulled By: riversand963
fbshipit-source-id: d25d1f84e2240ce543e521fa30595082fb8db9a0
Summary:
The following sequence of events can cause silent data loss for write-committed
transactions.
```
Time thread 1 bg flush
| db->Put("a")
| txn = NewTxn()
| txn->Put("b", "v")
| txn->Prepare() // writes only to 5.log
| db->SwitchMemtable() // memtable 1 has "a"
| // close 5.log,
| // creates 8.log
| trigger flush
| pick memtable 1
| unlock db mutex
| write new sst
| txn->ctwb->Put("gtid", "1") // writes 8.log
| txn->Commit() // writes to 8.log
| // writes to memtable 2
| compute min_log_number_to_keep_2pc, this
| will be 8 (incorrect).
|
| Purge obsolete wals, including 5.log
|
V
```
At this point, writes of txn exists only in memtable. Close db without flush because db thinks the data in
memtable are backed by log. Then reopen, the writes are lost except key-value pair {"gtid"->"1"},
only the commit marker of txn is in 8.log
The reason lies in `PrecomputeMinLogNumberToKeep2PC()` which calls `FindMinPrepLogReferencedByMemTable()`.
In the above example, when bg flush thread tries to find obsolete wals, it uses the information
computed by `PrecomputeMinLogNumberToKeep2PC()`. The return value of `PrecomputeMinLogNumberToKeep2PC()`
depends on three components
- `PrecomputeMinLogNumberToKeepNon2PC()`. This represents the WAL that has unflushed data. As the name of this method suggests, it does not account for 2PC. Although the keys reside in the prepare section of a previous WAL, the column family references the current WAL when they are actually inserted into the memtable during txn commit.
- `prep_tracker->FindMinLogContainingOutstandingPrep()`. This represents the WAL with a prepare section but the txn hasn't committed.
- `FindMinPrepLogReferencedByMemTable()`. This represents the WAL on which some memtables (mutable and immutable) depend for their unflushed data.
The bug lies in `FindMinPrepLogReferencedByMemTable()`. Originally, this function skips checking the column families
that are being flushed, but the unit test added in this PR shows that they should not be. In this unit test, there is
only the default column family, and one of its memtables has unflushed data backed by a prepare section in 5.log.
We should return this information via `FindMinPrepLogReferencedByMemTable()`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9571
Test Plan:
```
./transaction_test --gtest_filter=*/TransactionTest.SwitchMemtableDuringPrepareAndCommit_WC/*
make check
```
Reviewed By: siying
Differential Revision: D34235236
Pulled By: riversand963
fbshipit-source-id: 120eb21a666728a38dda77b96276c6af72b008b1
Summary:
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9562
With per-transaction `read_timestamp_`, it is possible to perform transaction validation after
locking a key in addition to sequence-based validation. Specifically, if a transaction has a
read_timestamp, then we perform timestamp-based validation as well after the key is locked
via `GetForUpdate()`. This is to make sure that no other transaction has modified the key and
committed successfully since the read timestamp (but before the locking operation) which
represents a consistent view of the database.
Reviewed By: ltamasi
Differential Revision: D31822034
fbshipit-source-id: c6f1828b7fc23e4f85e2d1ed73ff51464a058d91
Summary:
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9537
Add `Transaction::SetReadTimestampForValidation()` and
`Transaction::SetCommitTimestamp()` APIs with default implementation
returning `Status::NotSupported()`. Currently, calling these two APIs do not
have any effect.
Also add checks to `PessimisticTransactionDB`
to enforce that column families in the same db either
- disable user-defined timestamp
- enable 64-bit timestamp
Just to clarify, a `PessimisticTransactionDB` can have some column families without
timestamps as well as column families that enable timestamp.
Each `PessimisticTransaction` can have two optional timestamps, `read_timestamp_`
used for additional validation and `commit_timestamp_` which denotes when the transaction commits.
For now, we are going to support `WriteCommittedTxn` (in a series of subsequent PRs)
Once set, we do not allow decreasing `read_timestamp_`. The `commit_timestamp_` must be
greater than `read_timestamp_` for each transaction and must be set before commit, unless
the transaction does not involve any column family that enables user-defined timestamp.
TransactionDB builds on top of RocksDB core `DB` layer. Though `DB` layer assumes
that user-defined timestamps are byte arrays, `TransactionDB` uses uint64_t to store
timestamps. When they are passed down, they are still interpreted as
byte-arrays by `DB`.
Reviewed By: ltamasi
Differential Revision: D31567959
fbshipit-source-id: b0b6b69acab5d8e340cf174f33e8b09f1c3d3502
Summary:
ajkr reminded me that we have a rule of not including per-kv related data in `WriteOptions`.
Namely, `WriteOptions` should not include information about "what-to-write", but should just
include information about "how-to-write".
According to this rule, `WriteOptions::timestamp` (experimental) is clearly a violation. Therefore,
this PR removes `WriteOptions::timestamp` for compliance.
After the removal, we need to pass timestamp info via another set of APIs. This PR proposes a set
of overloaded functions `Put(write_opts, key, value, ts)`, `Delete(write_opts, key, ts)`, and
`SingleDelete(write_opts, key, ts)`. Planned to add `Write(write_opts, batch, ts)`, but its complexity
made me reconsider doing it in another PR (maybe).
For better checking and returning error early, we also add a new set of APIs to `WriteBatch` that take
extra `timestamp` information when writing to `WriteBatch`es.
These set of APIs in `WriteBatchWithIndex` are currently not supported, and are on our TODO list.
Removed `WriteBatch::AssignTimestamps()` and renamed `WriteBatch::AssignTimestamp()` to
`WriteBatch::UpdateTimestamps()` since this method require that all keys have space for timestamps
allocated already and multiple timestamps can be updated.
The constructor of `WriteBatch` now takes a fourth argument `default_cf_ts_sz` which is the timestamp
size of the default column family. This will be used to allocate space when calling APIs that do not
specify a column family handle.
Also, updated `DB::Get()`, `DB::MultiGet()`, `DB::NewIterator()`, `DB::NewIterators()` methods, replacing
some assertions about timestamp to returning Status code.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8946
Test Plan:
make check
./db_bench -benchmarks=fillseq,fillrandom,readrandom,readseq,deleterandom -user_timestamp_size=8
./db_stress --user_timestamp_size=8 -nooverwritepercent=0 -test_secondary=0 -secondary_catch_up_one_in=0 -continuous_verification_interval=0
Make sure there is no perf regression by running the following
```
./db_bench_opt -db=/dev/shm/rocksdb -use_existing_db=0 -level0_stop_writes_trigger=256 -level0_slowdown_writes_trigger=256 -level0_file_num_compaction_trigger=256 -disable_wal=1 -duration=10 -benchmarks=fillrandom
```
Before this PR
```
DB path: [/dev/shm/rocksdb]
fillrandom : 1.831 micros/op 546235 ops/sec; 60.4 MB/s
```
After this PR
```
DB path: [/dev/shm/rocksdb]
fillrandom : 1.820 micros/op 549404 ops/sec; 60.8 MB/s
```
Reviewed By: ltamasi
Differential Revision: D33721359
Pulled By: riversand963
fbshipit-source-id: c131561534272c120ffb80711d42748d21badf09
Jay Huh