rocksdb/db/convenience.cc
Peter Dillinger fc9d4071f0 Fast path for detecting unchanged prefix_extractor (#9407)
Summary:
Fixes a major performance regression in 6.26, where
extra CPU is spent in SliceTransform::AsString when reads involve
a prefix_extractor (Get, MultiGet, Seek). Common case performance
is now better than 6.25.

This change creates a "fast path" for verifying that the current prefix
extractor is unchanged and compatible with what was used to
generate a table file. This fast path detects the common case by
pointer comparison on the current prefix_extractor and a "known
good" prefix extractor (if applicable) that is saved at the time the
table reader is opened. The "known good" prefix extractor is saved
as another shared_ptr copy (in an existing field, however) to ensure
the pointer is not recycled.

When the prefix_extractor has changed to a different instance but
same compatible configuration (rare, odd), performance is still a
regression compared to 6.25, but this is likely acceptable because
of the oddity of such a case. The performance of incompatible
prefix_extractor is essentially unchanged.

Also fixed a minor case (ForwardIterator) where a prefix_extractor
could be used via a raw pointer after being freed as a shared_ptr,
if replaced via SetOptions.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9407

Test Plan:
## Performance
Populate DB with `TEST_TMPDIR=/dev/shm/rocksdb ./db_bench -benchmarks=fillrandom -num=10000000 -disable_wal=1 -write_buffer_size=10000000 -bloom_bits=16 -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=0 -prefix_size=12`

Running head-to-head comparisons simultaneously with `TEST_TMPDIR=/dev/shm/rocksdb ./db_bench -use_existing_db -readonly -benchmarks=seekrandom -num=10000000 -duration=20 -disable_wal=1 -bloom_bits=16 -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=0 -prefix_size=12`

Below each is compared by ops/sec vs. baseline which is version 6.25 (multiple baseline runs because of variable machine load)

v6.26: 4833 vs. 6698 (<- major regression!)
v6.27: 4737 vs. 6397 (still)
New: 6704 vs. 6461 (better than baseline in common case)
Disabled fastpath: 4843 vs. 6389 (e.g. if prefix extractor instance changes but is still compatible)
Changed prefix size (no usable filter) in new: 787 vs. 5927
Changed prefix size (no usable filter) in new & baseline: 773 vs. 784

Reviewed By: mrambacher

Differential Revision: D33677812

Pulled By: pdillinger

fbshipit-source-id: 571d9711c461fb97f957378a061b7e7dbc4d6a76
2022-01-21 11:37:46 -08:00

79 lines
2.9 KiB
C++

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
#ifndef ROCKSDB_LITE
#include "rocksdb/convenience.h"
#include "db/db_impl/db_impl.h"
#include "util/cast_util.h"
namespace ROCKSDB_NAMESPACE {
void CancelAllBackgroundWork(DB* db, bool wait) {
(static_cast_with_check<DBImpl>(db->GetRootDB()))
->CancelAllBackgroundWork(wait);
}
Status DeleteFilesInRange(DB* db, ColumnFamilyHandle* column_family,
const Slice* begin, const Slice* end,
bool include_end) {
RangePtr range(begin, end);
return DeleteFilesInRanges(db, column_family, &range, 1, include_end);
}
Status DeleteFilesInRanges(DB* db, ColumnFamilyHandle* column_family,
const RangePtr* ranges, size_t n,
bool include_end) {
return (static_cast_with_check<DBImpl>(db->GetRootDB()))
->DeleteFilesInRanges(column_family, ranges, n, include_end);
}
Status VerifySstFileChecksum(const Options& options,
const EnvOptions& env_options,
const std::string& file_path) {
return VerifySstFileChecksum(options, env_options, ReadOptions(), file_path);
}
Status VerifySstFileChecksum(const Options& options,
const EnvOptions& env_options,
const ReadOptions& read_options,
const std::string& file_path) {
std::unique_ptr<FSRandomAccessFile> file;
uint64_t file_size;
InternalKeyComparator internal_comparator(options.comparator);
ImmutableOptions ioptions(options);
Status s = ioptions.fs->NewRandomAccessFile(file_path,
FileOptions(env_options),
&file, nullptr);
if (s.ok()) {
s = ioptions.fs->GetFileSize(file_path, IOOptions(), &file_size, nullptr);
} else {
return s;
}
std::unique_ptr<TableReader> table_reader;
std::unique_ptr<RandomAccessFileReader> file_reader(
new RandomAccessFileReader(std::move(file), file_path));
const bool kImmortal = true;
s = ioptions.table_factory->NewTableReader(
TableReaderOptions(ioptions, options.prefix_extractor, env_options,
internal_comparator, false /* skip_filters */,
!kImmortal, false /* force_direct_prefetch */,
-1 /* level */),
std::move(file_reader), file_size, &table_reader,
false /* prefetch_index_and_filter_in_cache */);
if (!s.ok()) {
return s;
}
s = table_reader->VerifyChecksum(read_options,
TableReaderCaller::kUserVerifyChecksum);
return s;
}
} // namespace ROCKSDB_NAMESPACE
#endif // ROCKSDB_LITE