/Users/deen/code/yugabyte-db/src/yb/rocksdb/wal_filter.h
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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 | | #pragma once |
22 | | |
23 | | namespace rocksdb { |
24 | | |
25 | | class WriteBatch; |
26 | | |
27 | | // WALFilter allows an application to inspect write-ahead-log (WAL) |
28 | | // records or modify their processing on recovery. |
29 | | // Please see the details below. |
30 | | class WalFilter { |
31 | | public: |
32 | | enum class WalProcessingOption { |
33 | | // Continue processing as usual |
34 | | kContinueProcessing = 0, |
35 | | // Ignore the current record but continue processing of log(s) |
36 | | kIgnoreCurrentRecord = 1, |
37 | | // Stop replay of logs and discard logs |
38 | | // Logs won't be replayed on subsequent recovery |
39 | | kStopReplay = 2, |
40 | | // Corrupted record detected by filter |
41 | | kCorruptedRecord = 3, |
42 | | // Marker for enum count |
43 | | kWalProcessingOptionMax = 4 |
44 | | }; |
45 | | |
46 | 6 | virtual ~WalFilter() {} |
47 | | |
48 | | // LogRecord is invoked for each log record encountered for all the logs |
49 | | // during replay on logs on recovery. This method can be used to: |
50 | | // * inspect the record (using the batch parameter) |
51 | | // * ignoring current record |
52 | | // (by returning WalProcessingOption::kIgnoreCurrentRecord) |
53 | | // * reporting corrupted record |
54 | | // (by returning WalProcessingOption::kCorruptedRecord) |
55 | | // * stop log replay |
56 | | // (by returning kStop replay) - please note that this implies |
57 | | // discarding the logs from current record onwards. |
58 | | // |
59 | | // @params batch batch encountered in the log during recovery |
60 | | // @params new_batch new_batch to populate if filter wants to change |
61 | | // the batch (for example to filter some records out, |
62 | | // or alter some records). |
63 | | // Please note that the new batch MUST NOT contain |
64 | | // more records than original, else recovery would |
65 | | // be failed. |
66 | | // @params batch_changed Whether batch was changed by the filter. |
67 | | // It must be set to true if new_batch was populated, |
68 | | // else new_batch has no effect. |
69 | | // @returns Processing option for the current record. |
70 | | // Please see WalProcessingOption enum above for |
71 | | // details. |
72 | | virtual WalProcessingOption LogRecord(const WriteBatch& batch, |
73 | | WriteBatch* new_batch, |
74 | | bool* batch_changed) const = 0; |
75 | | |
76 | | // Returns a name that identifies this WAL filter. |
77 | | // The name will be printed to LOG file on start up for diagnosis. |
78 | | virtual const char* Name() const = 0; |
79 | | }; |
80 | | |
81 | | } // namespace rocksdb |