| // 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 "rocksdb/merge_operator.h" |
| #include "rocksdb/slice.h" |
| #include "utilities/merge_operators.h" |
| |
| using rocksdb::Slice; |
| using rocksdb::Logger; |
| using rocksdb::MergeOperator; |
| |
| namespace { // anonymous namespace |
| |
| // Merge operator that picks the maximum operand, Comparison is based on |
| // Slice::compare |
| class MaxOperator : public MergeOperator { |
| public: |
| virtual bool FullMergeV2(const MergeOperationInput& merge_in, |
| MergeOperationOutput* merge_out) const override { |
| Slice& max = merge_out->existing_operand; |
| if (merge_in.existing_value) { |
| max = Slice(merge_in.existing_value->data(), |
| merge_in.existing_value->size()); |
| } else if (max.data() == nullptr) { |
| max = Slice(); |
| } |
| |
| for (const auto& op : merge_in.operand_list) { |
| if (max.compare(op) < 0) { |
| max = op; |
| } |
| } |
| |
| return true; |
| } |
| |
| virtual bool PartialMerge(const Slice& key, const Slice& left_operand, |
| const Slice& right_operand, std::string* new_value, |
| Logger* logger) const override { |
| if (left_operand.compare(right_operand) >= 0) { |
| new_value->assign(left_operand.data(), left_operand.size()); |
| } else { |
| new_value->assign(right_operand.data(), right_operand.size()); |
| } |
| return true; |
| } |
| |
| virtual bool PartialMergeMulti(const Slice& key, |
| const std::deque<Slice>& operand_list, |
| std::string* new_value, |
| Logger* logger) const override { |
| Slice max; |
| for (const auto& operand : operand_list) { |
| if (max.compare(operand) < 0) { |
| max = operand; |
| } |
| } |
| |
| new_value->assign(max.data(), max.size()); |
| return true; |
| } |
| |
| virtual const char* Name() const override { return "MaxOperator"; } |
| }; |
| |
| } // end of anonymous namespace |
| |
| namespace rocksdb { |
| |
| std::shared_ptr<MergeOperator> MergeOperators::CreateMaxOperator() { |
| return std::make_shared<MaxOperator>(); |
| } |
| } |