1 //  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
2 //  This source code is licensed under both the GPLv2 (found in the
3 //  COPYING file in the root directory) and Apache 2.0 License
4 //  (found in the LICENSE.Apache file in the root directory).
5 
6 // A MergeOperator for RocksDB that implements Merge Sort.
7 // It is built using the MergeOperator interface. The operator works by taking
8 // an input which contains one or more merge operands where each operand is a
9 // list of sorted ints and merges them to form a large sorted list.
10 #pragma once
11 
12 #include "rocksdb/merge_operator.h"
13 #include "rocksdb/slice.h"
14 
15 namespace ROCKSDB_NAMESPACE {
16 
17 class SortList : public MergeOperator {
18  public:
19   bool FullMergeV2(const MergeOperationInput& merge_in,
20                    MergeOperationOutput* merge_out) const override;
21 
22   bool PartialMerge(const Slice& /*key*/, const Slice& left_operand,
23                     const Slice& right_operand, std::string* new_value,
24                     Logger* /*logger*/) const override;
25 
26   bool PartialMergeMulti(const Slice& key,
27                          const std::deque<Slice>& operand_list,
28                          std::string* new_value, Logger* logger) const override;
29 
30   const char* Name() const override;
31 
32   void MakeVector(std::vector<int>& operand, Slice slice) const;
33 
34  private:
35   std::vector<int> Merge(std::vector<int>& left, std::vector<int>& right) const;
36 };
37 
38 }  // namespace ROCKSDB_NAMESPACE
39