1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
|
/**
* Copyright (C) 2018 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects
* for all of the code used other than as permitted herein. If you modify
* file(s) with this exception, you may extend this exception to your
* version of the file(s), but you are not obligated to do so. If you do not
* wish to do so, delete this exception statement from your version. If you
* delete this exception statement from all source files in the program,
* then also delete it in the license file.
*/
#pragma once
#include "mongo/db/pipeline/change_stream_constants.h"
#include "mongo/db/pipeline/document_source.h"
#include "mongo/db/pipeline/document_source_change_stream.h"
#include "mongo/db/pipeline/document_source_sort.h"
namespace mongo {
/**
* This stage is used internally for change notifications to close cursor after returning
* "invalidate" entries.
* It is not intended to be created by the user.
*/
class DocumentSourceCloseCursor final : public DocumentSource, public NeedsMergerDocumentSource {
public:
GetNextResult getNext() final;
const char* getSourceName() const final {
// This is used in error reporting.
return "$changeStream";
}
StageConstraints constraints(Pipeline::SplitState pipeState) const final {
// This stage should never be in the shards part of a split pipeline.
invariant(pipeState != Pipeline::SplitState::kSplitForShards);
return {StreamType::kStreaming,
PositionRequirement::kNone,
// If this is parsed on mongos it should stay on mongos. If we're not in a sharded
// cluster then it's okay to run on mongod.
HostTypeRequirement::kLocalOnly,
DiskUseRequirement::kNoDiskUse,
FacetRequirement::kNotAllowed,
TransactionRequirement::kNotAllowed,
ChangeStreamRequirement::kChangeStreamStage};
}
Value serialize(boost::optional<ExplainOptions::Verbosity> explain = boost::none) const final {
// This stage is created by the DocumentSourceChangeStream stage, so serializing it
// here would result in it being created twice.
return Value();
}
static boost::intrusive_ptr<DocumentSourceCloseCursor> create(
const boost::intrusive_ptr<ExpressionContext>& expCtx) {
return new DocumentSourceCloseCursor(expCtx);
}
boost::intrusive_ptr<DocumentSource> getShardSource() final {
return nullptr;
}
MergingLogic mergingLogic() final {
// This stage must run on mongos to ensure it sees any invalidation in the correct order,
// and to ensure that all remote cursors are cleaned up properly.
return {this, change_stream_constants::kSortSpec};
}
private:
/**
* Use the create static method to create a DocumentSourceCloseCursor.
*/
DocumentSourceCloseCursor(const boost::intrusive_ptr<ExpressionContext>& expCtx)
: DocumentSource(expCtx) {}
bool _shouldCloseCursor = false;
};
} // namespace mongo
|