mirror of https://github.com/facebook/rocksdb.git
74 lines
2.1 KiB
C++
74 lines
2.1 KiB
C++
// Copyright (c) 2011-present, 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.
|
|
|
|
#include <memory>
|
|
|
|
#include "rocksdb/env.h"
|
|
#include "rocksdb/merge_operator.h"
|
|
#include "rocksdb/slice.h"
|
|
#include "util/coding.h"
|
|
#include "util/logging.h"
|
|
#include "utilities/merge_operators.h"
|
|
|
|
using namespace rocksdb;
|
|
|
|
namespace { // anonymous namespace
|
|
|
|
// A 'model' merge operator with uint64 addition semantics
|
|
// Implemented as an AssociativeMergeOperator for simplicity and example.
|
|
class UInt64AddOperator : public AssociativeMergeOperator {
|
|
public:
|
|
virtual 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
|
|
}
|
|
|
|
virtual 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 {
|
|
|
|
std::shared_ptr<MergeOperator> MergeOperators::CreateUInt64AddOperator() {
|
|
return std::make_shared<UInt64AddOperator>();
|
|
}
|
|
|
|
}
|