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
|
/**
* Copyright (C) 2014 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.
*/
#include "mongo/platform/basic.h"
#include "mongo/db/exec/multi_iterator.h"
#include "mongo/db/exec/working_set_common.h"
#include "mongo/db/storage/record_fetcher.h"
namespace mongo {
MultiIteratorStage::MultiIteratorStage(OperationContext* txn,
WorkingSet* ws,
Collection* collection)
: _txn(txn),
_collection(collection),
_ws(ws),
_wsidForFetch(_ws->allocate()) {
// We pre-allocate a WSM and use it to pass up fetch requests. This should never be used
// for anything other than passing up NEED_FETCH. We use the loc and unowned obj state, but
// the loc isn't really pointing at any obj. The obj field of the WSM should never be used.
WorkingSetMember* member = _ws->get(_wsidForFetch);
member->state = WorkingSetMember::LOC_AND_UNOWNED_OBJ;
}
void MultiIteratorStage::addIterator(RecordIterator* it) {
_iterators.push_back(it);
}
PlanStage::StageState MultiIteratorStage::work(WorkingSetID* out) {
if ( _collection == NULL )
return PlanStage::DEAD;
// The DiskLoc we're about to look at it might not be in memory. In this case
// we request a yield while we fetch the document.
if (!_iterators.empty()) {
DiskLoc curr = _iterators.back()->curr();
if (!curr.isNull()) {
std::auto_ptr<RecordFetcher> fetcher(_collection->documentNeedsFetch(_txn, curr));
if (NULL != fetcher.get()) {
WorkingSetMember* member = _ws->get(_wsidForFetch);
member->loc = curr;
// Pass the RecordFetcher off to the WSM on which we're performing the fetch.
member->setFetcher(fetcher.release());
*out = _wsidForFetch;
return NEED_FETCH;
}
}
}
DiskLoc next = _advance();
if (next.isNull())
return PlanStage::IS_EOF;
*out = _ws->allocate();
WorkingSetMember* member = _ws->get(*out);
member->loc = next;
member->obj = _collection->docFor(_txn, next);
member->state = WorkingSetMember::LOC_AND_UNOWNED_OBJ;
return PlanStage::ADVANCED;
}
bool MultiIteratorStage::isEOF() {
return _collection == NULL || _iterators.empty();
}
void MultiIteratorStage::kill() {
_collection = NULL;
_iterators.clear();
}
void MultiIteratorStage::saveState() {
for (size_t i = 0; i < _iterators.size(); i++) {
_iterators[i]->saveState();
}
}
void MultiIteratorStage::restoreState(OperationContext* opCtx) {
_txn = opCtx;
for (size_t i = 0; i < _iterators.size(); i++) {
if (!_iterators[i]->restoreState(opCtx)) {
kill();
}
}
}
void MultiIteratorStage::invalidate(const DiskLoc& dl, InvalidationType type) {
switch ( type ) {
case INVALIDATION_DELETION:
for (size_t i = 0; i < _iterators.size(); i++) {
_iterators[i]->invalidate(dl);
}
break;
case INVALIDATION_MUTATION:
// no-op
break;
}
}
vector<PlanStage*> MultiIteratorStage::getChildren() const {
vector<PlanStage*> empty;
return empty;
}
DiskLoc MultiIteratorStage::_advance() {
while (!_iterators.empty()) {
DiskLoc out = _iterators.back()->getNext();
if (!out.isNull())
return out;
_iterators.popAndDeleteBack();
}
return DiskLoc();
}
} // namespace mongo
|
