1 /* -*- Mode: C++; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
2 /*
3  *     Copyright 2017 Couchbase, Inc
4  *
5  *   Licensed under the Apache License, Version 2.0 (the "License");
6  *   you may not use this file except in compliance with the License.
7  *   You may obtain a copy of the License at
8  *
9  *       http://www.apache.org/licenses/LICENSE-2.0
10  *
11  *   Unless required by applicable law or agreed to in writing, software
12  *   distributed under the License is distributed on an "AS IS" BASIS,
13  *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  *   See the License for the specific language governing permissions and
15  *   limitations under the License.
16  */
17 
18 #include "collections/collections_types.h"
19 #include "collections/scan_context.h"
20 #include "storeddockey.h"
21 
22 #include <vector>
23 
24 class VBucket;
25 
26 #pragma once
27 
28 namespace Collections {
29 namespace VB {
30 
31 /**
32  * The EraserContext holds important data that the erasing process requires
33  * as it visits all of the keys of a vbucket (as part of compaction).
34  * For example it tracks defunct collection separator keys (so the can be
35  * purged).
36  */
37 class EraserContext : public ScanContext {
38 public:
EraserContext()39     EraserContext() : staleSeparatorChangeKeys(0), lastSeparatorChangeKey() {
40     }
41 
42     /**
43      * Manage the context's separator. If the DocKey is a system event for a
44      * changed separator, then we will update the context and return true.
45      *
46      * @return true if the separator was updated
47      */
48     bool manageSeparator(const ::DocKey& key);
49 
50     /**
51      * Function used to delete the staleSeparatorKeys.
52      * @param vb The vbucket to issue deletes against for each key in
53      *        staleSeparatorKeys
54      */
55     void processKeys(VBucket& vb);
56 
57 private:
58     /// A list of separator change keys which can be deleted
59     std::vector<StoredDocKey> staleSeparatorChangeKeys;
60     StoredDocKey lastSeparatorChangeKey;
61 };
62 } // end VB
63 } // end Collections