/Users/deen/code/yugabyte-db/src/yb/rocksdb/utilities/merge_operators/put.cc
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1 | | // Copyright (c) 2011-present, Facebook, Inc. All rights reserved. |
2 | | // This source code is licensed under the BSD-style license found in the |
3 | | // LICENSE file in the root directory of this source tree. An additional grant |
4 | | // of patent rights can be found in the PATENTS file in the same directory. |
5 | | // |
6 | | // The following only applies to changes made to this file as part of YugaByte development. |
7 | | // |
8 | | // Portions Copyright (c) YugaByte, Inc. |
9 | | // |
10 | | // Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except |
11 | | // in compliance with the License. You may obtain a copy of the License at |
12 | | // |
13 | | // http://www.apache.org/licenses/LICENSE-2.0 |
14 | | // |
15 | | // Unless required by applicable law or agreed to in writing, software distributed under the License |
16 | | // is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express |
17 | | // or implied. See the License for the specific language governing permissions and limitations |
18 | | // under the License. |
19 | | // |
20 | | |
21 | | #include <memory> |
22 | | #include "yb/util/slice.h" |
23 | | #include "yb/rocksdb/merge_operator.h" |
24 | | #include "yb/rocksdb/utilities/merge_operators.h" |
25 | | |
26 | | namespace rocksdb { |
27 | | |
28 | | namespace { // anonymous namespace |
29 | | |
30 | | // A merge operator that mimics Put semantics |
31 | | // Since this merge-operator will not be used in production, |
32 | | // it is implemented as a non-associative merge operator to illustrate the |
33 | | // new interface and for testing purposes. (That is, we inherit from |
34 | | // the MergeOperator class rather than the AssociativeMergeOperator |
35 | | // which would be simpler in this case). |
36 | | // |
37 | | // From the client-perspective, semantics are the same. |
38 | | class PutOperator : public MergeOperator { |
39 | | public: |
40 | | virtual bool FullMerge(const Slice& key, |
41 | | const Slice* existing_value, |
42 | | const std::deque<std::string>& operand_sequence, |
43 | | std::string* new_value, |
44 | 75.2k | Logger* logger) const override { |
45 | | // Put basically only looks at the current/latest value |
46 | 75.2k | assert(!operand_sequence.empty()); |
47 | 75.2k | assert(new_value != nullptr); |
48 | 75.2k | new_value->assign(operand_sequence.back()); |
49 | 75.2k | return true; |
50 | 75.2k | } |
51 | | |
52 | | virtual bool PartialMerge(const Slice& key, |
53 | | const Slice& left_operand, |
54 | | const Slice& right_operand, |
55 | | std::string* new_value, |
56 | 0 | Logger* logger) const override { |
57 | 0 | new_value->assign(right_operand.cdata(), right_operand.size()); |
58 | 0 | return true; |
59 | 0 | } |
60 | | |
61 | | using MergeOperator::PartialMergeMulti; |
62 | | virtual bool PartialMergeMulti(const Slice& key, |
63 | | const std::deque<Slice>& operand_list, |
64 | | std::string* new_value, |
65 | 1.07k | Logger* logger) const override { |
66 | 1.07k | new_value->assign(operand_list.back().cdata(), operand_list.back().size()); |
67 | 1.07k | return true; |
68 | 1.07k | } |
69 | | |
70 | 1.07k | const char* Name() const override { |
71 | 1.07k | return "PutOperator"; |
72 | 1.07k | } |
73 | | }; |
74 | | |
75 | | } // end of anonymous namespace |
76 | | |
77 | 98 | std::shared_ptr<MergeOperator> MergeOperators::CreatePutOperator() { |
78 | 98 | return std::make_shared<PutOperator>(); |
79 | 98 | } |
80 | | |
81 | | } // namespace rocksdb |