1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
|
// 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/table.h"
#include "util/murmurhash.h"
#include "rocksdb/options.h"
namespace rocksdb {
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_options)
: table_options_(table_options) {}
~CuckooTableFactory() {}
const char* Name() const override { return "CuckooTable"; }
Status NewTableReader(
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,
uint32_t column_family_id, WritableFileWriter* file) const override;
// Sanitizes the specified DB Options.
Status SanitizeOptions(
const DBOptions& /*db_opts*/,
const ColumnFamilyOptions& /*cf_opts*/) const override {
return Status::OK();
}
std::string GetPrintableTableOptions() const override;
void* GetOptions() override { return &table_options_; }
Status GetOptionString(std::string* /*opt_string*/,
const std::string& /*delimiter*/) const override {
return Status::OK();
}
private:
CuckooTableOptions table_options_;
};
} // namespace rocksdb
#endif // ROCKSDB_LITE
|
