Summary:
In FastLRUCache, we replace the current chained per-shard hash table by an open-addressing hash table. In particular, this allows us to preallocate all handles.
Because all handles are preallocated, this implementation doesn't support strict_capacity_limit = false (i.e., allowing insertions beyond the predefined capacity). This clashes with current assumptions of some tests, namely two tests in cache_test and the crash tests. We have disabled these for now.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10194
Test Plan: ``make -j24 check``
Reviewed By: pdillinger
Differential Revision: D37296770
Pulled By: guidotag
fbshipit-source-id: 232ff1b8260331d868ebf4e3e5d8ad709390b0ad
Summary:
There is currently no caching mechanism for blobs, which is not ideal especially when the database resides on remote storage (where we cannot rely on the OS page cache). As part of this task, we would like to make it possible for the application to configure a blob cache.
In this task, we formally introduced the blob source to RocksDB. BlobSource is a new abstraction layer that provides universal access to blobs, regardless of whether they are in the blob cache, secondary cache, or (remote) storage. Depending on user settings, it always fetch blobs from multi-tier cache and storage with minimal cost.
Note: The new `MultiGetBlob()` implementation is not included in the current PR. To go faster, we aim to create a separate PR for it in parallel!
This PR is a part of https://github.com/facebook/rocksdb/issues/10156
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10198
Reviewed By: ltamasi
Differential Revision: D37294735
Pulled By: gangliao
fbshipit-source-id: 9cb50422d9dd1bc03798501c2778b6c7520c7a1e
Summary:
One consistency check in SaveTo() is dupilcated with the one within Apply(). Remove one of then in release mode to reduce time spent in DB mutex.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10169
Test Plan: Run existing tests and see nothing breaks.
Reviewed By: ltamasi
Differential Revision: D37157821
fbshipit-source-id: 73b89443a20b43362ff66d10b9212022034a8234
Summary:
include "include/rocksdb/blah.h" is messing up some internal
builds vs. include "rocksdb/blah." This fixes the bad case and adds a
check for future instances.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10213
Test Plan: back-port to 7.4 release candidate and watch internal build
Reviewed By: hx235
Differential Revision: D37296202
Pulled By: pdillinger
fbshipit-source-id: d7cc6b2c57d858dff0444f19320d83c8b4f9b185
Summary:
This bug was discovered after write batch checksum verification before WAL is added (https://github.com/facebook/rocksdb/issues/10114) and stress test with write batch checksum protection is turned on (https://github.com/facebook/rocksdb/issues/10037). In this [line](d5d8920f2c/db/write_batch.cc (L2887)), the number of checksums may not be consistent with `batch->Count()`. This PR fixes this issue.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10201
Test Plan:
```
./db_stress --batch_protection_bytes_per_key=8 --destroy_db_initially=1 --max_key=100000 --use_txn=1
```
Reviewed By: ajkr
Differential Revision: D37260799
Pulled By: cbi42
fbshipit-source-id: ff8dce7dcce295d689333bc9d892d17a843bf0ea
Summary:
`FlushWAL(true /* sync */)` is used internally and for manual WAL sync. It had a bug when used together with `track_and_verify_wals_in_manifest` where the synced size tracked in MANIFEST was larger than the number of bytes actually synced.
The bug could be repro'd almost immediately with the following crash test command: `python3 tools/db_crashtest.py blackbox --simple --write_buffer_size=524288 --max_bytes_for_level_base=2097152 --target_file_size_base=524288 --duration=3600 --interval=10 --sync_fault_injection=1 --disable_wal=0 --checkpoint_one_in=1000 --max_key=10000 --value_size_mult=33`.
An example error message produced by the above command is shown below. The error sometimes arose from the checkpoint and other times arose from the main stress test DB.
```
Corruption: Size mismatch: WAL (log number: 119) in MANIFEST is 27938 bytes , but actually is 27859 bytes on disk.
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10185
Test Plan:
- repro unit test
- the above crash test command no longer finds the error. It does find a different error after a while longer such as "Corruption: WAL file 481 required by manifest but not in directory list"
Reviewed By: riversand963
Differential Revision: D37200993
Pulled By: ajkr
fbshipit-source-id: 98e0071c1a89f4d009888512ed89f9219779ae5f
Summary:
**Context/Summary:**
https://github.com/facebook/rocksdb/pull/9424 added rate-limiting support for user reads, which does not include batched `MultiGet()`s that call `RandomAccessFileReader::MultiRead()`. The reason is that it's harder (compared with RandomAccessFileReader::Read()) to implement the ideal rate-limiting where we first call `RateLimiter::RequestToken()` for allowed bytes to multi-read and then consume those bytes by satisfying as many requests in `MultiRead()` as possible. For example, it can be tricky to decide whether we want partially fulfilled requests within one `MultiRead()` or not.
However, due to a recent urgent user request, we decide to pursue an elementary (but a conditionally ineffective) solution where we accumulate enough rate limiter requests toward the total bytes needed by one `MultiRead()` before doing that `MultiRead()`. This is not ideal when the total bytes are huge as we will actually consume a huge bandwidth from rate-limiter causing a burst on disk. This is not what we ultimately want with rate limiter. Therefore a follow-up work is noted through TODO comments.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10159
Test Plan:
- Modified existing unit test `DBRateLimiterOnReadTest/DBRateLimiterOnReadTest.NewMultiGet`
- Traced the underlying system calls `io_uring_enter` and verified they are 10 seconds apart from each other correctly under the setting of `strace -ftt -e trace=io_uring_enter ./db_bench -benchmarks=multireadrandom -db=/dev/shm/testdb2 -readonly -num=50 -threads=1 -multiread_batched=1 -batch_size=100 -duration=10 -rate_limiter_bytes_per_sec=200 -rate_limiter_refill_period_us=1000000 -rate_limit_bg_reads=1 -disable_auto_compactions=1 -rate_limit_user_ops=1` where each `MultiRead()` read about 2000 bytes (inspected by debugger) and the rate limiter grants 200 bytes per seconds.
- Stress test:
- Verified `./db_stress (-test_cf_consistency=1/test_batches_snapshots=1) -use_multiget=1 -cache_size=1048576 -rate_limiter_bytes_per_sec=10241024 -rate_limit_bg_reads=1 -rate_limit_user_ops=1` work
Reviewed By: ajkr, anand1976
Differential Revision: D37135172
Pulled By: hx235
fbshipit-source-id: 73b8e8f14761e5d4b77235dfe5d41f4eea968bcd
Summary:
There is currently no caching mechanism for blobs, which is not ideal especially when the database resides on remote storage (where we cannot rely on the OS page cache). As part of this task, we would like to make it possible for the application to configure a blob cache.
In this task, we added a new abstraction layer `BlobSource` to retrieve blobs from either blob cache or raw blob file. Note: For simplicity, the current PR only includes `GetBlob()`. `MultiGetBlob()` will be included in the next PR.
This PR is a part of https://github.com/facebook/rocksdb/issues/10156
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10178
Reviewed By: ltamasi
Differential Revision: D37250507
Pulled By: gangliao
fbshipit-source-id: 3fc4a55a0cea955a3147bdc7dba06430e377259b
Summary:
folly DistributedMutex is faster than standard mutexes though
imposes some static obligations on usage. See
https://github.com/facebook/folly/blob/main/folly/synchronization/DistributedMutex.h
for details. Here we use this alternative for our Cache implementations
(especially LRUCache) for better locking performance, when RocksDB is
compiled with folly.
Also added information about which distributed mutex implementation is
being used to cache_bench output and to DB LOG.
Intended follow-up:
* Use DMutex in more places, perhaps improving API to support non-scoped
locking
* Fix linking with fbcode compiler (needs ROCKSDB_NO_FBCODE=1 currently)
Credit: Thanks Siying for reminding me about this line of work that was previously
left unfinished.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10179
Test Plan:
for correctness, existing tests. CircleCI config updated.
Also Meta-internal buck build updated.
For performance, ran simultaneous before & after cache_bench. Out of three
comparison runs, the middle improvement to ops/sec was +21%:
Baseline: USE_CLANG=1 DEBUG_LEVEL=0 make -j24 cache_bench (fbcode
compiler)
```
Complete in 20.201 s; Rough parallel ops/sec = 1584062
Thread ops/sec = 107176
Operation latency (ns):
Count: 32000000 Average: 9257.9421 StdDev: 122412.04
Min: 134 Median: 3623.0493 Max: 56918500
Percentiles: P50: 3623.05 P75: 10288.02 P99: 30219.35 P99.9: 683522.04 P99.99: 7302791.63
```
New: (add USE_FOLLY=1)
```
Complete in 16.674 s; Rough parallel ops/sec = 1919135 (+21%)
Thread ops/sec = 135487
Operation latency (ns):
Count: 32000000 Average: 7304.9294 StdDev: 108530.28
Min: 132 Median: 3777.6012 Max: 91030902
Percentiles: P50: 3777.60 P75: 10169.89 P99: 24504.51 P99.9: 59721.59 P99.99: 1861151.83
```
Reviewed By: anand1976
Differential Revision: D37182983
Pulled By: pdillinger
fbshipit-source-id: a17eb05f25b832b6a2c1356f5c657e831a5af8d1
Summary:
Ribbon micro-bench needs updating after re-numbering
`BloomLikeFilterPolicy::GetAllFixedImpls()` entries. (CircleCI nightly
failure.)
Also fixed memory leaks while using ASAN to validate my fix. (I assume
the leaks weren't intentional for some performance characteristic.)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10195
Test Plan: run with ASAN
Reviewed By: jay-zhuang
Differential Revision: D37244459
Pulled By: pdillinger
fbshipit-source-id: 5a363e10de3c4c9c88099c937e3dc3b4cf24fd30
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:
There was an interesting code path not covered by testing that
is difficult to replicate in a unit test, which is now covered using a
sync point. Specifically, the case of table_prefix_extractor == null and
!need_upper_bound_check in `BlockBasedTable::PrefixMayMatch`, which
can happen if table reader is open before extractor is registered with global
object registry, but is later registered and re-set with SetOptions. (We
don't have sufficient testing control over object registry to set that up
repeatedly.)
Also, this function has been renamed to `PrefixRangeMayMatch` for clarity
vs. other functions that are not the same.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10122
Test Plan: unit tests expanded
Reviewed By: siying
Differential Revision: D36944834
Pulled By: pdillinger
fbshipit-source-id: 9e52d9da1929a3e42bbc230fcdc3599949de7bdb
Summary:
In https://github.com/facebook/rocksdb/issues/9535, release 7.0, we hid the old block-based filter from being created using
the public API, because of its inefficiency. Although we normally maintain read compatibility
on old DBs forever, filters are not required for reading a DB, only for optimizing read
performance. Thus, it should be acceptable to remove this code and the substantial
maintenance burden it carries as useful features are developed and validated (such
as user timestamp).
This change completely removes the code for reading and writing the old block-based
filters, net removing about 1370 lines of code no longer needed. Options removed from
testing / benchmarking tools. The prior existence is only evident in a couple of places:
* `CacheEntryRole::kDeprecatedFilterBlock` - We can update this public API enum in
a major release to minimize source code incompatibilities.
* A warning is logged when an old table file is opened that used the old block-based
filter. This is provided as a courtesy, and would be a pain to unit test, so manual testing
should suffice. Unfortunately, sst_dump does not tell you whether a file uses
block-based filter, and the structure of the code makes it very difficult to fix.
* To detect that case, `kObsoleteFilterBlockPrefix` (renamed from `kFilterBlockPrefix`)
for metaindex is maintained (for now).
Other notes:
* In some cases where numbers are associated with filter configurations, we have had to
update the assigned numbers so that they all correspond to something that exists.
* Fixed potential stat counting bug by assuming `filter_checked = false` for cases
like `filter == nullptr` rather than assuming `filter_checked = true`
* Removed obsolete `block_offset` and `prefix_extractor` parameters from several
functions.
* Removed some unnecessary checks `if (!table_prefix_extractor() && !prefix_extractor)`
because the caller guarantees the prefix extractor exists and is compatible
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10184
Test Plan:
tests updated, manually test new warning in LOG using base version to
generate a DB
Reviewed By: riversand963
Differential Revision: D37212647
Pulled By: pdillinger
fbshipit-source-id: 06ee020d8de3b81260ffc36ad0c1202cbf463a80
Summary:
Add a couple of stats to help users estimate the impact of potential MultiGet perf improvements -
1. NUM_LEVEL_READ_PER_MULTIGET - A histogram stat for number of levels that required MultiGet to read from a file
2. MULTIGET_COROUTINE_COUNT - A ticker stat to count the number of times the coroutine version of MultiGetFromSST was used
The NUM_DATA_BLOCKS_READ_PER_LEVEL stat is obsoleted as it doesn't provide useful information for MultiGet optimization.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10182
Reviewed By: akankshamahajan15
Differential Revision: D37213296
Pulled By: anand1976
fbshipit-source-id: 5d2b7708017c0e278578ae4bffac3926f6530efb
Summary:
In CompactionIterator code, there are multiple places where the process
will abort in dbg mode before logging the error message describing the
cause. This PR changes only the logging behavior for compaction iterator so
that error message is written to LOG before the process aborts in debug
mode.
Also updated the triggering condition for an assertion for single delete with
user-defined timestamp.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10183
Test Plan: make check
Reviewed By: akankshamahajan15
Differential Revision: D37190218
Pulled By: riversand963
fbshipit-source-id: 741bb007067be7cfbe94ac9e530ad4b2b339c009
Summary:
This PR adds few optimizations for async_io for shorter scans.
1. If async_io is enabled, seek would create FilePrefetchBuffer object to fetch the data asynchronously. However `FilePrefetchbuffer::num_file_reads_` wasn't taken into consideration if it calls Next after Seek and would go for Prefetching. This PR fixes that and Next will go for prefetching only if `FilePrefetchbuffer::num_file_reads_` is greater than 2 along with if blocks are sequential. This scenario is only for implicit auto readahead.
2. For seek, when it calls TryReadFromCacheAsync to poll it makes async call as well because TryReadFromCacheAsync flow wasn't changed. So I updated to return after poll instead of further prefetching any data.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10140
Test Plan:
1. Added a unit test
2. Ran crash_test with async_io = 1 to make sure nothing crashes.
Reviewed By: anand1976
Differential Revision: D37042242
Pulled By: akankshamahajan15
fbshipit-source-id: b8e6b7cb2ee0886f37a8f53951948b9084e8ffda
Summary:
A consequence of https://github.com/facebook/rocksdb/issues/9990 was requiring a non-empty DB ID to generate
new SST files. But if the DB ID is not tracked in the manifest and the IDENTITY file
is somehow truncated to 0 bytes, then an empty DB ID would be assigned, leading
to crash. This change ensures a non-empty DB ID is assigned and set in the
IDENTITY file.
Also,
* Some light refactoring to clean up the logic
* (I/O efficiency) If the ID is tracked in the manifest and already matches the
IDENTITY file, don't needlessly overwrite the file.
* (Debugging) Log the DB ID to info log on open, because sometimes IDENTITY
can change if DB is moved around (though it would be unusual for info log to
be copied/moved without IDENTITY file)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10173
Test Plan: unit tests expanded/updated
Reviewed By: ajkr
Differential Revision: D37176545
Pulled By: pdillinger
fbshipit-source-id: a9b414cd35bfa33de48af322a36c24538d50bef1
Summary:
Fix existing usage of non-ASCII and add a check to prevent
future use. Added `-n` option to greps to provide line numbers.
Alternative to https://github.com/facebook/rocksdb/issues/10147
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10164
Test Plan:
used new checker to find & fix cases, manually check
db_bench output is preserved
Reviewed By: akankshamahajan15
Differential Revision: D37148792
Pulled By: pdillinger
fbshipit-source-id: 68c8b57e7ab829369540d532590bf756938855c7
Summary:
While the yield instruction conseptually sounds correct on most platforms it is
a simple nop that doesn't delay the execution anywhere close to what an x86
pause instruction does. In other projects with spin-wait loops an isb has been
observed to be much closer to the x86 behavior.
On a Graviton3 system the following test improves on average by 2x with this
change averaged over 20 runs:
```
./db_bench -benchmarks=fillrandom -threads=64 -batch_size=1
-memtablerep=skip_list -value_size=100 --num=100000
level0_slowdown_writes_trigger=9999 -level0_stop_writes_trigger=9999
-disable_auto_compactions --max_write_buffer_number=8 -max_background_flushes=8
--disable_wal --write_buffer_size=160000000 --block_size=16384
--allow_concurrent_memtable_write -compression_type none
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10118
Reviewed By: jay-zhuang
Differential Revision: D37120578
fbshipit-source-id: c20bde4298222edfab7ff7cb6d42497e7012400d
Summary:
A recent PR https://github.com/facebook/rocksdb/pull/10142 enabled fadvise for mmaped file. However, we were told that it might not take effective and madvise() should be used.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10170
Test Plan:
Run existing tests
Run a benchmark using mmap with advise random and see I/O size is indeed small.
Reviewed By: anand1976
Differential Revision: D37158582
fbshipit-source-id: 8b3a74f0e89d2e16aac78ee4124c05841d4135c3
Summary:
There is `Options::allow_data_in_errors` that controls whether RocksDB
is allowed to log data, e.g. key, value, etc in LOG files. It is false
by default. However, in db_bench and db_stress, it is often ok to log
data because there is no concern about privacy.
This PR allows db_stress and db_bench to set this option on the command
line, while it remains false by default. Furthermore, make
crash/recovery test driven by db_crashtest.py to opt-in.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10171
Test Plan: Stress test and db_bench
Reviewed By: hx235
Differential Revision: D37163787
Pulled By: riversand963
fbshipit-source-id: 0242f24d292ba15b6faf8ff903963b85d3e011f8
Summary:
This code is unreachable when `ROCKSDB_LITE` not defined. And it cause build fail on my environment VS2019 16.11.15.
```
-- Selecting Windows SDK version 10.0.19041.0 to target Windows 10.0.19044.
-- The CXX compiler identification is MSVC 19.29.30145.0
-- The C compiler identification is MSVC 19.29.30145.0
-- The ASM compiler identification is MSVC
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10146
Reviewed By: akankshamahajan15
Differential Revision: D37112916
Pulled By: ajkr
fbshipit-source-id: e0b2bf3055d6fac1b3fb40b9f02c4cbae3f82757
Summary:
`PinnableSlice` may hold a handle to a cache value which must be released to correctly decrement the ref-counter. However, when `PinnableSlice` variables are reused, e.g. like this:
```
PinnableSlice pin_slice;
db.Get("foo", &pin_slice);
db.Get("foo", &pin_slice);
```
then the second `Get` simply overwrites the old value in `pin_slice` and the handle returned by the first `Get` is _not_ released.
This PR adds `Reset` calls to the `Get`/`MultiGet` calls that accept `PinnableSlice` arguments to ensure proper cleanup of old values.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10166
Reviewed By: hx235
Differential Revision: D37151632
Pulled By: ajkr
fbshipit-source-id: 9dd3c3288300f560531b843f67db11aeb569a9ff
Summary:
__builtin_prefetch(...., 1) prefetches into the L2 cache on x86 while the same
emits a pldl3keep instruction on arm64 which doesn't seem to be close enough.
Testing on a Graviton3, and M1 system with memtablerep_bench fillrandom and
skiplist througpuh increased as follows adjusting the 1 to 2 or 3:
```
1 -> 2 1 -> 3
----------------------------
Graviton3 +10% +15%
M1 +10% +10%
```
Given that prefetching into the L1 cache seems to help, I chose that conversion
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10117
Reviewed By: pdillinger
Differential Revision: D37120475
fbshipit-source-id: db1ef43f941445019c68316500a2250acc643d5e
Summary:
This default is generally incompatible with other parts of mingw, and
can be applied by outside users as-needed.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9963
Reviewed By: akankshamahajan15
Differential Revision: D36302813
Pulled By: ajkr
fbshipit-source-id: 9456b41a96bde302bacbc39e092ccecfcb42f34f
Summary:
There is currently no caching mechanism for blobs, which is not ideal especially when the database resides on remote storage (where we cannot rely on the OS page cache). As part of this task, we would like to make it possible for the application to configure a blob cache.
This PR is a part of https://github.com/facebook/rocksdb/issues/10156
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10155
Reviewed By: ltamasi
Differential Revision: D37150819
Pulled By: gangliao
fbshipit-source-id: b807c7916ea5d411588128f8e22a49f171388fe2
Summary:
During options file parsing, reset table factory before attempting to parse it
from string. This avoids mistakenly treating the default table factory as a
newly created one.
Signed-off-by: tabokie <xy.tao@outlook.com>
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10094
Reviewed By: akankshamahajan15
Differential Revision: D36945378
Pulled By: ajkr
fbshipit-source-id: 94b2604e5e87682063b4b78f6370f3e8f101dc44
Summary:
Fix for Internal jobs are failing with
```
error: no matching function for call to 'io_uring_prep_cancel'
io_uring_prep_cancel(sqe, posix_handle, 0);
^~~~~~~~~~~~~~~~~~~~
note: candidate function not viable: no known conversion from 'rocksdb::Posix_IOHandle *' to '__u64' (aka 'unsigned long long') for 2nd argument
static inline void io_uring_prep_cancel(struct io_uring_sqe *sqe,
```
User data is set using `io_uring_set_data` API so no need to pass posix_handle here.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10165
Test Plan: CircleCI jobs
Reviewed By: jay-zhuang
Differential Revision: D37145233
Pulled By: akankshamahajan15
fbshipit-source-id: 05da650e1240e9c6fcc8aed5f0067308dccb164a
Summary:
We make the size of the per-shard hash table fixed. The base level of the hash table is now preallocated with the required capacity. The user must provide an estimate of the size of the values.
Notice that even though the base level becomes fixed, the chains are still dynamic. Overall, the shard capacity mechanisms haven't changed, so we don't need to test this.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10154
Test Plan: `make -j24 check`
Reviewed By: pdillinger
Differential Revision: D37124451
Pulled By: guidotag
fbshipit-source-id: cba6ac76052fe0ec60b8ff4211b3de7650e80d0c
Summary:
Before this PR, there can be a race condition between the thread calling
`StressTest::Open()` and a background compaction thread calling
`MultiOpsTxnsStressTest::VerifyPkSkFast()`.
```
Time thread1 bg_compact_thr
| TransactionDB::Open(..., &txn_db_)
| db_ is still nullptr
| db_->GetSnapshot() // segfault
| db_ = txn_db_
V
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10157
Test Plan: CI
Reviewed By: akankshamahajan15
Differential Revision: D37121653
Pulled By: riversand963
fbshipit-source-id: 6a53117f958e9ee86f77297fdeb843e5160a9331
Summary:
Implement AbortIO in posix using io_uring to cancel any pending read requests submitted. Its cancelled using io_uring_prep_cancel which sets the IORING_OP_ASYNC_CANCEL flag.
To cancel a request, the sqe must have ->addr set to the user_data of the request it wishes to cancel. If the request is cancelled successfully, the original request is completed with -ECANCELED and the cancel request is completed with a result of 0. If the request was already running, the original may or may not complete in error. The cancel request will complete with -EALREADY for that case. And finally, if the request to cancel wasn't found, the cancel request is completed with -ENOENT.
Reference: https://kernel.dk/io_uring-whatsnew.pdf,
https://lore.kernel.org/io-uring/d9a8d76d23690842f666c326631ecc2d85b6c1bc.1615566409.git.asml.silence@gmail.com/
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10125
Test Plan: Existing Posix tests.
Reviewed By: anand1976
Differential Revision: D36946970
Pulled By: akankshamahajan15
fbshipit-source-id: 3bc1f1521b3151d01a348fc6431eb3fc85db3a14
Summary:
See https://github.com/facebook/rocksdb/issues/10082 for more details. Trivial move
isn't done for universal when compaction is from L0 into L0. So a too small value for
num_levels with db_bench means there will be fewer trivial moves with universal and
that means that write-amp will increase.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10158
Test Plan: run it
Reviewed By: siying
Differential Revision: D37122519
Pulled By: mdcallag
fbshipit-source-id: 1cb39049676f68a6cc3ea8d105a9965f89d4d09e
Summary:
auto_prefix_mode is designed to use prefix filtering in a
particular "safe" set of cases where the upper bound and the seek key
have different prefixes: where the upper bound is the "same length
immediate successor". These conditions are not sufficient to guarantee
the same iteration results as total_order_seek if the DB contains
"short" keys, less than the "full" (maximum) prefix length.
We are not simply disabling the optimization in these successor cases
because it is likely that users are essentially getting what they want
out of existing usage. Especially if users are constructing successor
bounds with the intention of doing a prefix-bounded seek, the existing
behavior is more expected than the total_order_seek behavior.
Consequently, for now we reconcile the bad specification of behavior by
documenting the existing mismatch with total_order_seek.
A closely related issue affects hypothetical comparators like
ReverseBytewiseComparator: if they "correctly" implement
IsSameLengthImmediateSuccessor, auto_prefix_mode could omit more
entries (other than "short" keys noted above). Luckily, the built-in
ReverseBytewiseComparator has an "incorrect" implementation of
IsSameLengthImmediateSuccessor that effectively prevents prefix
optimization and, thus, the bug. This is now documented as a new
constraint on IsSameLengthImmediateSuccessor, and the implementation
tweaked to be simply "safe" rather than "incorrect".
This change also includes unit test updates to demonstrate the above
issues. (Test was cleaned up for readability and simplicity.)
Intended follow-up:
* Tweak documented axioms for prefix_extractor (more details then)
* Consider some sort of fix for this case. I don't know what that would
look like without breaking the performance of existing code. Perhaps
if all keys in an SST file have prefixes that are "full length," we can track
that fact and use it to allow optimization with the "same length
immediate successor", but that would only apply to new files.
* Consider a better system of specifying prefix bounds
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10144
Test Plan: test updates included
Reviewed By: siying
Differential Revision: D37052710
Pulled By: pdillinger
fbshipit-source-id: 5f63b7d65f3f214e4b143e0f9aa1749527c587db
Summary:
FastLRUCache now only supports 16B keys. The tests have changed to reflect this.
Because the unit tests were designed for caches that accept any string as keys, some tests are no longer compatible with FastLRUCache. We have disabled those for runs with FastLRUCache. (We could potentially change all tests to use 16B keys, but we don't because the cache public API does not require this.)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10137
Test Plan: make -j24 check
Reviewed By: gitbw95
Differential Revision: D37083934
Pulled By: guidotag
fbshipit-source-id: be1719cf5f8364a9a32bc4555bce1a0de3833b0d
Summary:
Right now with mmap file, we don't run fadvise following users' requests. There is no reason for that so this diff does that.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10142
Test Plan:
A simple readrandom against files with page cache dropped shows latency improvement from 7.8 us to 2.8:
./db_bench -use_existing_db --benchmarks=readrandom --num=100
Reviewed By: anand1976
Differential Revision: D37074975
fbshipit-source-id: ccc72bcac1b5fd634eb8fa2b6a5d9afe332e0bf6
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:
Update SecondaryCache::CreateFromString and enable it to create sec cache based on the uri for CompressedSecondaryCache.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10132
Test Plan: Add unit tests.
Reviewed By: anand1976
Differential Revision: D36996997
Pulled By: gitbw95
fbshipit-source-id: 882ad563cff6d38b306a53426ad7e47273f34edc
Summary:
When opening an SST file created using index_type=kHashSearch,
the *current* prefix_extractor would be saved, and used with hash index
if the *new current* prefix_extractor at query time is compatible with
the SST file. This is a problem if the prefix_extractor at SST open time
is not compatible but SetOptions later changes (back) to one that is
compatible.
This change fixes that by using the known compatible (or missing) prefix
extractor we save for use with prefix filtering. Detail: I have moved the
InternalKeySliceTransform wrapper to avoid some indirection and remove
unnecessary fields.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10128
Test Plan:
expanded unit test (using some logic from https://github.com/facebook/rocksdb/issues/10122) that fails
before fix and probably covers some other previously uncovered cases.
Reviewed By: siying
Differential Revision: D36955738
Pulled By: pdillinger
fbshipit-source-id: 0c78a6b0d24054ef2f3cb237bf010c1c5589fb10
Summary:
This PR helps handle the race condition mentioned in this comment thread: https://github.com/facebook/rocksdb/pull/7884#discussion_r572402281 In case where actual full_history_ts_low is higher than the user's requested ts, return a try again message so they don't have the misconception that data between [ts, full_history_ts_low) is kept.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10126
Test Plan:
```
$COMPILE_WITH_ASAN=1 make -j24 all
$./db_with_timestamp_basic_test --gtest_filter=UpdateFullHistoryTsLowTest.ConcurrentUpdate
$ make -j24 check
```
Reviewed By: riversand963
Differential Revision: D37055368
Pulled By: jowlyzhang
fbshipit-source-id: 787fd0984a246540fa03ac227b1d232590d27828
Summary:
As seen in https://github.com/facebook/rocksdb/issues/10137, simply churning the cache key hashes (e.g.
by changing the raw cache keys) could trigger failure in this test, due
to possibility of some cache shard exceeding its portion of capacity
and evicting entries. Updated the test to be less fragile by using
greater margins, and added a pre-check for evictions, which doesn't
manifest as a race condition, before the main check that can race.
Also added stack trace handler to cache_test for debugging.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10145
Test Plan:
test thousands of iterations with gtest-parallel, including
with changes in https://github.com/facebook/rocksdb/issues/10137 that were surfacing the problem. Pre-check
without the fix would always fail with https://github.com/facebook/rocksdb/issues/10137
Reviewed By: guidotag
Differential Revision: D37058771
Pulled By: pdillinger
fbshipit-source-id: a7cf137967aef49c07ae9602d8523c63e7388fab
