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
|
// 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).
#include <memory>
#include "logging/logging.h"
#include "rocksdb/env.h"
#include "rocksdb/merge_operator.h"
#include "rocksdb/slice.h"
#include "util/coding.h"
#include "utilities/merge_operators.h"
using namespace ROCKSDB_NAMESPACE;
namespace { // anonymous namespace
// A 'model' merge operator with uint64 addition semantics
// Implemented as an AssociativeMergeOperator for simplicity and example.
class UInt64AddOperator : public AssociativeMergeOperator {
public:
bool Merge(const Slice& /*key*/, const Slice* existing_value,
const Slice& value, std::string* new_value,
Logger* logger) const override {
uint64_t orig_value = 0;
if (existing_value){
orig_value = DecodeInteger(*existing_value, logger);
}
uint64_t operand = DecodeInteger(value, logger);
assert(new_value);
new_value->clear();
PutFixed64(new_value, orig_value + operand);
return true; // Return true always since corruption will be treated as 0
}
const char* Name() const override { return "UInt64AddOperator"; }
private:
// Takes the string and decodes it into a uint64_t
// On error, prints a message and returns 0
uint64_t DecodeInteger(const Slice& value, Logger* logger) const {
uint64_t result = 0;
if (value.size() == sizeof(uint64_t)) {
result = DecodeFixed64(value.data());
} else if (logger != nullptr) {
// If value is corrupted, treat it as 0
ROCKS_LOG_ERROR(logger, "uint64 value corruption, size: %" ROCKSDB_PRIszt
" > %" ROCKSDB_PRIszt,
value.size(), sizeof(uint64_t));
}
return result;
}
};
}
namespace ROCKSDB_NAMESPACE {
std::shared_ptr<MergeOperator> MergeOperators::CreateUInt64AddOperator() {
return std::make_shared<UInt64AddOperator>();
}
} // namespace ROCKSDB_NAMESPACE
|
