rocksdb/utilities/cassandra/merge_operator.h

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// Copyright (c) 2017-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
#include "rocksdb/merge_operator.h"
#include "rocksdb/slice.h"
namespace rocksdb {
namespace cassandra {
/**
* A MergeOperator for rocksdb that implements Cassandra row value merge.
*/
class CassandraValueMergeOperator : public MergeOperator {
public:
explicit CassandraValueMergeOperator(int32_t gc_grace_period_in_seconds,
size_t operands_limit = 0)
: gc_grace_period_in_seconds_(gc_grace_period_in_seconds),
operands_limit_(operands_limit) {}
virtual bool FullMergeV2(const MergeOperationInput& merge_in,
MergeOperationOutput* merge_out) const override;
virtual bool PartialMergeMulti(const Slice& key,
const std::deque<Slice>& operand_list,
std::string* new_value,
Logger* logger) const override;
virtual const char* Name() const override;
virtual bool AllowSingleOperand() const override { return true; }
virtual bool ShouldMerge(const std::vector<Slice>& operands) const override {
return operands_limit_ > 0 && operands.size() >= operands_limit_;
}
private:
int32_t gc_grace_period_in_seconds_;
size_t operands_limit_;
};
} // namespace cassandra
} // namespace rocksdb