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// 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 "rocksdb/options.h"
#include "rocksdb/table.h"
#include "util/murmurhash.h"
namespace ROCKSDB_NAMESPACE {
const uint32_t kCuckooMurmurSeedMultiplier = 816922183;
static inline uint64_t CuckooHash(
const Slice& user_key, uint32_t hash_cnt, bool use_module_hash,
uint64_t table_size_, bool identity_as_first_hash,
uint64_t (*get_slice_hash)(const Slice&, uint32_t, uint64_t)) {
#if !defined NDEBUG || defined OS_WIN
// This part is used only in unit tests but we have to keep it for Windows
// build as we run test in both debug and release modes under Windows.
if (get_slice_hash != nullptr) {
return get_slice_hash(user_key, hash_cnt, table_size_);
}
#else
(void)get_slice_hash;
#endif
uint64_t value = 0;
if (hash_cnt == 0 && identity_as_first_hash) {
value = (*reinterpret_cast<const int64_t*>(user_key.data()));
} else {
value = MurmurHash(user_key.data(), static_cast<int>(user_key.size()),
kCuckooMurmurSeedMultiplier * hash_cnt);
}
if (use_module_hash) {
return value % table_size_;
} else {
return value & (table_size_ - 1);
}
}
// 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.
// - Does not support prefix bloom filters.
class CuckooTableFactory : public TableFactory {
public:
explicit CuckooTableFactory(
const CuckooTableOptions& table_option = CuckooTableOptions());
~CuckooTableFactory() {}
// Method to allow CheckedCast to work for this class
static const char* kClassName() { return kCuckooTableName(); }
const char* Name() const override { return kCuckooTableName(); }
using TableFactory::NewTableReader;
Status NewTableReader(
const ReadOptions& ro, const TableReaderOptions& table_reader_options,
std::unique_ptr<RandomAccessFileReader>&& file, uint64_t file_size,
std::unique_ptr<TableReader>* table,
bool prefetch_index_and_filter_in_cache = true) const override;
TableBuilder* NewTableBuilder(
const TableBuilderOptions& table_builder_options,
WritableFileWriter* file) const override;
std::string GetPrintableOptions() const override;
private:
CuckooTableOptions table_options_;
};
} // namespace ROCKSDB_NAMESPACE
#endif // ROCKSDB_LITE
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