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
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
|
/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* 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 Server Side 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 <set>
#include <vector>
#include "mongo/db/exec/plan_stage.h"
#include "mongo/db/exec/sort_executor.h"
#include "mongo/db/exec/sort_key_comparator.h"
#include "mongo/db/exec/sort_key_generator.h"
#include "mongo/db/exec/working_set.h"
#include "mongo/db/record_id.h"
namespace mongo {
/**
* Sorts the input received from the child according to the sort pattern provided. If
* 'addSortKeyMetadata' is true, then also attaches the sort key as metadata. This could be consumed
* downstream for a sort-merge on a merging node, or by a $meta:"sortKey" expression.
*
* Concrete implementations derive from this abstract base class by implementing methods for
* spooling and unspooling.
*/
class SortStage : public PlanStage {
public:
static constexpr StringData kStageType = "SORT"_sd;
SortStage(boost::intrusive_ptr<ExpressionContext> expCtx,
WorkingSet* ws,
SortPattern sortPattern,
bool addSortKeyMetadata,
std::unique_ptr<PlanStage> child);
/**
* Loads the WorkingSetMember pointed to by 'wsid' into the set of objects being sorted. This
* should be called repeatedly until all documents are loaded, followed by a single call to
* 'loadingDone()'. Illegal to call after 'loadingDone()' has been called.
*/
virtual void spool(WorkingSetID wsid) = 0;
/**
* Indicates that all documents to be sorted have been loaded via 'spool()'. This method must
* not be called more than once.
*/
virtual void loadingDone() = 0;
/**
* Returns an id referring to the next WorkingSetMember in the sorted stream of results.
*
* If there is another WSM, the id is returned via the out-parameter and the return value is
* PlanStage::ADVANCED. If there are no more documents remaining in the sorted stream, returns
* PlanStage::IS_EOF, and 'out' is left unmodified.
*
* Illegal to call before 'loadingDone()' has been called.
*/
virtual StageState unspool(WorkingSetID* out) = 0;
StageState doWork(WorkingSetID* out) final;
std::unique_ptr<PlanStageStats> getStats() override final;
protected:
// Not owned by us.
WorkingSet* _ws;
const SortKeyGenerator _sortKeyGen;
const bool _addSortKeyMetadata;
private:
// Whether or not we have finished loading data into '_sortExecutor'.
bool _populated = false;
};
/**
* Generic sorting implementation which can handle sorting any WorkingSetMember, including those
* that have RecordIds, metadata, or which represent index keys.
*/
class SortStageDefault final : public SortStage {
public:
SortStageDefault(boost::intrusive_ptr<ExpressionContext> expCtx,
WorkingSet* ws,
SortPattern sortPattern,
uint64_t limit,
uint64_t maxMemoryUsageBytes,
bool addSortKeyMetadata,
std::unique_ptr<PlanStage> child);
void spool(WorkingSetID wsid) override final;
void loadingDone() override final;
StageState unspool(WorkingSetID* out) override final;
StageType stageType() const final {
return STAGE_SORT_DEFAULT;
}
bool isEOF() final {
return _sortExecutor.isEOF();
}
const SpecificStats* getSpecificStats() const final {
return &_sortExecutor.stats();
}
private:
SortExecutor<SortableWorkingSetMember> _sortExecutor;
};
/**
* Optimized sorting implementation which can be used for WorkingSetMembers in a fetched state that
* have no metadata. This implementation is faster but less general than WorkingSetMemberSortStage.
*
* For performance, this implementation discards record ids and returns WorkingSetMembers in the
* OWNED_OBJ state. Therefore, this sort implementation cannot be used if the plan requires the
* record id to be preserved (e.g. for update or delete plans, where an ancestor stage needs to
* refer to the record in order to perform a write).
*/
class SortStageSimple final : public SortStage {
public:
SortStageSimple(boost::intrusive_ptr<ExpressionContext> expCtx,
WorkingSet* ws,
SortPattern sortPattern,
uint64_t limit,
uint64_t maxMemoryUsageBytes,
bool addSortKeyMetadata,
std::unique_ptr<PlanStage> child);
virtual void spool(WorkingSetID wsid) override final;
void loadingDone() override final;
virtual StageState unspool(WorkingSetID* out) override final;
StageType stageType() const final {
return STAGE_SORT_SIMPLE;
}
bool isEOF() final {
return _sortExecutor.isEOF();
}
const SpecificStats* getSpecificStats() const final {
return &_sortExecutor.stats();
}
private:
SortExecutor<BSONObj> _sortExecutor;
};
} // namespace mongo
|
