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rocksdb/utilities/merge_operators/uint64add.cc

64 lines
1.6 KiB

#include <memory>
#include "leveldb/env.h"
#include "leveldb/merge_operator.h"
#include "leveldb/slice.h"
#include "util/coding.h"
#include "utilities/merge_operators.h"
using namespace leveldb;
namespace { // anonymous namespace
// A 'model' merge operator with uint64 addition semantics
class UInt64AddOperator : public MergeOperator {
public:
virtual void Merge(const Slice& key,
const Slice* existing_value,
const Slice& value,
std::string* new_value,
Logger* logger) const override {
// assuming 0 if no existing value
uint64_t existing = 0;
if (existing_value) {
if (existing_value->size() == sizeof(uint64_t)) {
existing = DecodeFixed64(existing_value->data());
} else {
// if existing_value is corrupted, treat it as 0
Log(logger, "existing value corruption, size: %zu > %zu",
existing_value->size(), sizeof(uint64_t));
existing = 0;
}
}
uint64_t operand;
if (value.size() == sizeof(uint64_t)) {
operand = DecodeFixed64(value.data());
} else {
// if operand is corrupted, treat it as 0
Log(logger, "operand value corruption, size: %zu > %zu",
value.size(), sizeof(uint64_t));
operand = 0;
}
new_value->resize(sizeof(uint64_t));
EncodeFixed64(&(*new_value)[0], existing + operand);
return;
}
virtual const char* Name() const override {
return "UInt64AddOperator";
}
};
}
namespace leveldb {
std::shared_ptr<MergeOperator> MergeOperators::CreateUInt64AddOperator() {
return std::make_shared<UInt64AddOperator>();
}
}