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rocksdb/table/cuckoo_table_factory.h

71 lines
2.3 KiB

// Copyright (c) 2014, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
#pragma once
#ifndef ROCKSDB_LITE
#include <string>
#include "rocksdb/table.h"
#include "util/murmurhash.h"
namespace rocksdb {
const uint32_t kCuckooMurmurSeedMultiplier = 816922183;
static inline uint64_t CuckooHash(
const Slice& user_key, uint32_t hash_cnt, uint64_t table_size_minus_one,
uint64_t (*get_slice_hash)(const Slice&, uint32_t, uint64_t)) {
#ifndef NDEBUG
// This part is used only in unit tests.
if (get_slice_hash != nullptr) {
return get_slice_hash(user_key, hash_cnt, table_size_minus_one + 1);
}
#endif
return MurmurHash(user_key.data(), user_key.size(),
kCuckooMurmurSeedMultiplier * hash_cnt) & table_size_minus_one;
}
// Cuckoo Table is designed for applications that require fast point lookups
// but not fast range scans.
//
// Some assumptions:
// - Key length and Value length are fixed.
// - Does not support Snapshot.
// - Does not support Merge operations.
class CuckooTableFactory : public TableFactory {
public:
CuckooTableFactory(double hash_table_ratio, uint32_t max_search_depth,
uint32_t cuckoo_block_size)
: hash_table_ratio_(hash_table_ratio),
max_search_depth_(max_search_depth),
cuckoo_block_size_(cuckoo_block_size) {}
~CuckooTableFactory() {}
const char* Name() const override { return "CuckooTable"; }
Status NewTableReader(
const Options& options, const EnvOptions& soptions,
const InternalKeyComparator& internal_comparator,
unique_ptr<RandomAccessFile>&& file, uint64_t file_size,
unique_ptr<TableReader>* table) const override;
TableBuilder* NewTableBuilder(const Options& options,
const InternalKeyComparator& icomparator, WritableFile* file,
CompressionType compression_type) const override;
// Sanitizes the specified DB Options.
Status SanitizeDBOptions(const DBOptions* db_opts) const override {
return Status::OK();
}
std::string GetPrintableTableOptions() const override;
private:
const double hash_table_ratio_;
const uint32_t max_search_depth_;
const uint32_t cuckoo_block_size_;
};
} // namespace rocksdb
#endif // ROCKSDB_LITE