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
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
|
/**
* Copyright (C) 2013 10gen 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/db/exec/index_scan.h"
#include "mongo/db/exec/filter.h"
#include "mongo/db/index/catalog_hack.h"
#include "mongo/db/index/index_access_method.h"
#include "mongo/db/index/index_cursor.h"
#include "mongo/db/index/index_descriptor.h"
namespace {
// Return a value in the set {-1, 0, 1} to represent the sign of parameter i.
int sgn(int i) {
if (i == 0)
return 0;
return i > 0 ? 1 : -1;
}
} // namespace
namespace mongo {
IndexScan::IndexScan(const IndexScanParams& params, WorkingSet* workingSet,
const MatchExpression* filter)
: _workingSet(workingSet), _descriptor(params.descriptor), _hitEnd(false), _filter(filter),
_shouldDedup(params.descriptor->isMultikey()), _yieldMovedCursor(false), _params(params),
_btreeCursor(NULL) {
string amName;
// If the query is using complex bounds, we must use a Btree access method, since that's the
// only one that handles complex bounds.
if (params.forceBtreeAccessMethod || !_params.bounds.isSimpleRange) {
_iam = _descriptor->getIndexCatalog()->getBtreeIndex(_descriptor);
amName = "";
}
else {
amName = _descriptor->getIndexCatalog()->getAccessMethodName(_descriptor->keyPattern());
_iam = _descriptor->getIndexCatalog()->getIndex(_descriptor);
}
if (IndexNames::GEO_2D == amName || IndexNames::GEO_2DSPHERE == amName) {
// _endKey is meaningless for 2d and 2dsphere.
verify(_params.bounds.isSimpleRange);
verify(_params.bounds.endKey.isEmpty());
}
if (_params.doNotDedup) {
_shouldDedup = false;
}
_specificStats.indexType = "BtreeCursor"; // TODO amName;
_specificStats.indexName = _descriptor->infoObj()["name"].String();
_specificStats.indexBounds = _params.bounds.toBSON();
_specificStats.direction = _params.direction;
_specificStats.isMultiKey = _descriptor->isMultikey();
_specificStats.keyPattern = _descriptor->keyPattern();
}
PlanStage::StageState IndexScan::work(WorkingSetID* out) {
++_commonStats.works;
if (NULL == _indexCursor.get()) {
// First call to work(). Perform cursor init.
CursorOptions cursorOptions;
// The limit is *required* for 2d $near, which is the only index that pays attention to
// it anyway.
cursorOptions.numWanted = _params.limit;
if (1 == _params.direction) {
cursorOptions.direction = CursorOptions::INCREASING;
}
else {
cursorOptions.direction = CursorOptions::DECREASING;
}
IndexCursor *cursor;
Status s = _iam->newCursor(&cursor);
verify(s.isOK());
_indexCursor.reset(cursor);
_indexCursor->setOptions(cursorOptions);
if (_params.bounds.isSimpleRange) {
// Start at one key, end at another.
Status status = _indexCursor->seek(_params.bounds.startKey);
if (!status.isOK()) {
warning() << "Seek failed: " << status.toString();
_hitEnd = true;
return PlanStage::FAILURE;
}
if (!isEOF()) {
_specificStats.keysExamined = 1;
}
}
else {
// "Fast" Btree-specific navigation.
_btreeCursor = static_cast<BtreeIndexCursor*>(_indexCursor.get());
_checker.reset(new IndexBoundsChecker(&_params.bounds,
_descriptor->keyPattern(),
_params.direction));
int nFields = _descriptor->keyPattern().nFields();
vector<const BSONElement*> key;
vector<bool> inc;
key.resize(nFields);
inc.resize(nFields);
if (_checker->getStartKey(&key, &inc)) {
_btreeCursor->seek(key, inc);
_keyElts.resize(nFields);
_keyEltsInc.resize(nFields);
}
else {
_hitEnd = true;
}
}
checkEnd();
}
else if (_yieldMovedCursor) {
_yieldMovedCursor = false;
// Note that we're not calling next() here.
}
else {
// You're allowed to call work() even if the stage is EOF, but we can't call
// _indexCursor->next() if we're EOF.
if (!isEOF()) {
_indexCursor->next();
checkEnd();
}
}
if (isEOF()) { return PlanStage::IS_EOF; }
DiskLoc loc = _indexCursor->getValue();
if (_shouldDedup) {
++_specificStats.dupsTested;
if (_returned.end() != _returned.find(loc)) {
++_specificStats.dupsDropped;
++_commonStats.needTime;
return PlanStage::NEED_TIME;
}
else {
_returned.insert(loc);
}
}
WorkingSetID id = _workingSet->allocate();
WorkingSetMember* member = _workingSet->get(id);
member->loc = loc;
member->keyData.push_back(IndexKeyDatum(_descriptor->keyPattern(),
_indexCursor->getKey().getOwned()));
member->state = WorkingSetMember::LOC_AND_IDX;
if (Filter::passes(member, _filter)) {
if (NULL != _filter) {
++_specificStats.matchTested;
}
*out = id;
++_commonStats.advanced;
return PlanStage::ADVANCED;
}
_workingSet->free(id);
++_commonStats.needTime;
return PlanStage::NEED_TIME;
}
bool IndexScan::isEOF() {
if (NULL == _indexCursor.get()) {
// Have to call work() at least once.
return false;
}
// If there's a limit on how many keys we can scan, we may be EOF when we hit that.
if (0 != _params.maxScan) {
if (_specificStats.keysExamined >= _params.maxScan) {
return true;
}
}
return _hitEnd || _indexCursor->isEOF();
}
void IndexScan::prepareToYield() {
++_commonStats.yields;
if (isEOF() || (NULL == _indexCursor.get())) { return; }
_savedKey = _indexCursor->getKey().getOwned();
_savedLoc = _indexCursor->getValue();
_indexCursor->savePosition();
}
void IndexScan::recoverFromYield() {
++_commonStats.unyields;
if (isEOF() || (NULL == _indexCursor.get())) { return; }
// We can have a valid position before we check isEOF(), restore the position, and then be
// EOF upon restore.
if (!_indexCursor->restorePosition().isOK() || _indexCursor->isEOF()) {
_hitEnd = true;
return;
}
if (!_savedKey.binaryEqual(_indexCursor->getKey())
|| _savedLoc != _indexCursor->getValue()) {
// Our restored position isn't the same as the saved position. When we call work()
// again we want to return where we currently point, not past it.
_yieldMovedCursor = true;
++_specificStats.yieldMovedCursor;
// Our restored position might be past endKey, see if we've hit the end.
checkEnd();
}
}
void IndexScan::invalidate(const DiskLoc& dl) {
++_commonStats.invalidates;
// If we see this DiskLoc again, it may not be the same doc. it was before, so we want to
// return it.
unordered_set<DiskLoc, DiskLoc::Hasher>::iterator it = _returned.find(dl);
if (it != _returned.end()) {
++_specificStats.seenInvalidated;
_returned.erase(it);
}
}
void IndexScan::checkEnd() {
if (isEOF()) {
_commonStats.isEOF = true;
return;
}
if (_params.bounds.isSimpleRange) {
// "Normal" start -> end scanning.
verify(NULL == _btreeCursor);
verify(NULL == _checker.get());
// If there is an empty endKey we will scan until we run out of index to scan over.
if (_params.bounds.endKey.isEmpty()) { return; }
int cmp = sgn(_params.bounds.endKey.woCompare(_indexCursor->getKey(),
_descriptor->keyPattern()));
if ((cmp != 0 && cmp != _params.direction)
|| (cmp == 0 && !_params.bounds.endKeyInclusive)) {
_hitEnd = true;
_commonStats.isEOF = true;
}
if (!isEOF() && _params.bounds.isSimpleRange) {
++_specificStats.keysExamined;
}
}
else {
verify(NULL != _btreeCursor);
verify(NULL != _checker.get());
// Use _checker to see how things are.
for (;;) {
//cout << "current index key is " << _indexCursor->getKey().toString() << endl;
//cout << "keysExamined is " << _specificStats.keysExamined << endl;
IndexBoundsChecker::KeyState keyState;
keyState = _checker->checkKey(_indexCursor->getKey(),
&_keyEltsToUse,
&_movePastKeyElts,
&_keyElts,
&_keyEltsInc);
if (IndexBoundsChecker::DONE == keyState) {
_hitEnd = true;
break;
}
// This seems weird but it's the old definition of nscanned.
++_specificStats.keysExamined;
if (IndexBoundsChecker::VALID == keyState) {
break;
}
//cout << "skipping...\n";
verify(IndexBoundsChecker::MUST_ADVANCE == keyState);
_btreeCursor->skip(_indexCursor->getKey(), _keyEltsToUse, _movePastKeyElts,
_keyElts, _keyEltsInc);
// Must check underlying cursor EOF after every cursor movement.
if (_btreeCursor->isEOF()) {
_hitEnd = true;
break;
}
// TODO: Can we do too much scanning here? Old BtreeCursor stops scanning after a
// while and relies on a Matcher to make sure the result is ok.
}
}
}
PlanStageStats* IndexScan::getStats() {
_commonStats.isEOF = isEOF();
auto_ptr<PlanStageStats> ret(new PlanStageStats(_commonStats, STAGE_IXSCAN));
ret->specific.reset(new IndexScanStats(_specificStats));
return ret.release();
}
} // namespace mongo
|