Revision 0bb555630f5e85a1471843f8dc0dabec297c1c49 authored by Siying Dong on 08 April 2019, 20:24:29 UTC, committed by Facebook Github Bot on 08 April 2019, 20:32:06 UTC
Summary: Create new function NPHash64() and GetSliceNPHash64(), which are currently implemented using murmurhash. Replace the current direct call of murmurhash() to use the new functions if the hash results are not used in on-disk format. This will make it easier to try out or switch to alternative functions in the uses where data format compatibility doesn't need to be considered. This part shouldn't have any performance impact. Also, the sharded cache hash function is changed to the new format, because it falls into this categoery. It doesn't show visible performance impact in db_bench results. CPU showed by perf is increased from about 0.2% to 0.4% in an extreme benchmark setting (4KB blocks, no-compression, everything cached in block cache). We've known that the current hash function used, our own Hash() has serious hash quality problem. It can generate a lots of conflicts with similar input. In this use case, it means extra lock contention for reads from the same file. This slight CPU regression is worthy to me to counter the potential bad performance with hot keys. And hopefully this will get further improved in the future with a better hash function. cache_test's condition is relaxed a little bit to. The new hash is slightly more skewed in this use case, but I manually checked the data and see the hash results are still in a reasonable range. Pull Request resolved: https://github.com/facebook/rocksdb/pull/5155 Differential Revision: D14834821 Pulled By: siying fbshipit-source-id: ec9a2c0a2f8ae4b54d08b13a5c2e9cc97aa80cb5
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db_impl_secondary.h
// 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).
#pragma once
#ifndef ROCKSDB_LITE
#include <string>
#include <vector>
#include "db/db_impl.h"
namespace rocksdb {
class DBImplSecondary : public DBImpl {
public:
DBImplSecondary(const DBOptions& options, const std::string& dbname);
~DBImplSecondary() override;
Status Recover(const std::vector<ColumnFamilyDescriptor>& column_families,
bool read_only, bool error_if_log_file_exist,
bool error_if_data_exists_in_logs) override;
// Implementations of the DB interface
using DB::Get;
Status Get(const ReadOptions& options, ColumnFamilyHandle* column_family,
const Slice& key, PinnableSlice* value) override;
Status GetImpl(const ReadOptions& options, ColumnFamilyHandle* column_family,
const Slice& key, PinnableSlice* value);
using DBImpl::NewIterator;
Iterator* NewIterator(const ReadOptions&,
ColumnFamilyHandle* column_family) override;
ArenaWrappedDBIter* NewIteratorImpl(const ReadOptions& read_options,
ColumnFamilyData* cfd,
SequenceNumber snapshot,
ReadCallback* read_callback);
Status NewIterators(const ReadOptions& options,
const std::vector<ColumnFamilyHandle*>& column_families,
std::vector<Iterator*>* iterators) override;
using DBImpl::Put;
Status Put(const WriteOptions& /*options*/,
ColumnFamilyHandle* /*column_family*/, const Slice& /*key*/,
const Slice& /*value*/) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
using DBImpl::Merge;
Status Merge(const WriteOptions& /*options*/,
ColumnFamilyHandle* /*column_family*/, const Slice& /*key*/,
const Slice& /*value*/) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
using DBImpl::Delete;
Status Delete(const WriteOptions& /*options*/,
ColumnFamilyHandle* /*column_family*/,
const Slice& /*key*/) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
using DBImpl::SingleDelete;
Status SingleDelete(const WriteOptions& /*options*/,
ColumnFamilyHandle* /*column_family*/,
const Slice& /*key*/) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
Status Write(const WriteOptions& /*options*/,
WriteBatch* /*updates*/) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
using DBImpl::CompactRange;
Status CompactRange(const CompactRangeOptions& /*options*/,
ColumnFamilyHandle* /*column_family*/,
const Slice* /*begin*/, const Slice* /*end*/) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
using DBImpl::CompactFiles;
Status CompactFiles(
const CompactionOptions& /*compact_options*/,
ColumnFamilyHandle* /*column_family*/,
const std::vector<std::string>& /*input_file_names*/,
const int /*output_level*/, const int /*output_path_id*/ = -1,
std::vector<std::string>* const /*output_file_names*/ = nullptr,
CompactionJobInfo* /*compaction_job_info*/ = nullptr) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
Status DisableFileDeletions() override {
return Status::NotSupported("Not supported operation in read only mode.");
}
Status EnableFileDeletions(bool /*force*/) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
Status GetLiveFiles(std::vector<std::string>&,
uint64_t* /*manifest_file_size*/,
bool /*flush_memtable*/ = true) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
using DBImpl::Flush;
Status Flush(const FlushOptions& /*options*/,
ColumnFamilyHandle* /*column_family*/) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
using DBImpl::SyncWAL;
Status SyncWAL() override {
return Status::NotSupported("Not supported operation in read only mode.");
}
using DB::IngestExternalFile;
Status IngestExternalFile(
ColumnFamilyHandle* /*column_family*/,
const std::vector<std::string>& /*external_files*/,
const IngestExternalFileOptions& /*ingestion_options*/) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
// Try to catch up with the primary by reading as much as possible from the
// log files until there is nothing more to read or encounters an error. If
// the amount of information in the log files to process is huge, this
// method can take long time due to all the I/O and CPU costs.
Status TryCatchUpWithPrimary() override;
private:
friend class DB;
// No copying allowed
DBImplSecondary(const DBImplSecondary&);
void operator=(const DBImplSecondary&);
using DBImpl::Recover;
std::unique_ptr<log::FragmentBufferedReader> manifest_reader_;
std::unique_ptr<log::Reader::Reporter> manifest_reporter_;
std::unique_ptr<Status> manifest_reader_status_;
};
} // namespace rocksdb
#endif // !ROCKSDB_LITE
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