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
|
// btreecursor.cpp
/**
* Copyright (C) 2008 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/>.
*/
#include "stdafx.h"
#include "btree.h"
#include "pdfile.h"
#include "jsobj.h"
#include "curop.h"
namespace mongo {
extern int otherTraceLevel;
BtreeCursor::BtreeCursor( NamespaceDetails *_d, int _idxNo, const IndexDetails &_id,
const BSONObj &_startKey, const BSONObj &_endKey, bool endKeyInclusive, int _direction ) :
d(_d), idxNo(_idxNo),
startKey( _startKey ),
endKey( _endKey ),
endKeyInclusive_( endKeyInclusive ),
multikey( d->isMultikey( idxNo ) ),
indexDetails( _id ),
order( _id.keyPattern() ),
direction( _direction ),
boundIndex_(),
_spec( _id.getSpec() )
{
audit();
init();
}
BtreeCursor::BtreeCursor( NamespaceDetails *_d, int _idxNo, const IndexDetails& _id, const vector< pair< BSONObj, BSONObj > > &_bounds, int _direction )
:
d(_d), idxNo(_idxNo),
endKeyInclusive_( true ),
multikey( d->isMultikey( idxNo ) ),
indexDetails( _id ),
order( _id.keyPattern() ),
direction( _direction ),
bounds_( _bounds ),
boundIndex_(),
_spec( _id.getSpec() )
{
assert( !bounds_.empty() );
audit();
initInterval();
}
void BtreeCursor::audit() {
dassert( d->idxNo((IndexDetails&) indexDetails) == idxNo );
if ( otherTraceLevel >= 12 ) {
if ( otherTraceLevel >= 200 ) {
out() << "::BtreeCursor() qtl>200. validating entire index." << endl;
indexDetails.head.btree()->fullValidate(indexDetails.head, order);
}
else {
out() << "BTreeCursor(). dumping head bucket" << endl;
indexDetails.head.btree()->dump();
}
}
}
void BtreeCursor::init() {
if ( _spec.getType() ){
startKey = _spec.getType()->fixKey( startKey );
endKey = _spec.getType()->fixKey( endKey );
}
bool found;
bucket = indexDetails.head.btree()->
locate(indexDetails, indexDetails.head, startKey, order, keyOfs, found, direction > 0 ? minDiskLoc : maxDiskLoc, direction);
skipUnusedKeys();
checkEnd();
}
void BtreeCursor::initInterval() {
do {
startKey = bounds_[ boundIndex_ ].first;
endKey = bounds_[ boundIndex_ ].second;
init();
} while ( !ok() && ++boundIndex_ < bounds_.size() );
}
/* skip unused keys. */
void BtreeCursor::skipUnusedKeys() {
int u = 0;
while ( 1 ) {
if ( !ok() )
break;
BtreeBucket *b = bucket.btree();
_KeyNode& kn = b->k(keyOfs);
if ( kn.isUsed() )
break;
bucket = b->advance(bucket, keyOfs, direction, "skipUnusedKeys");
u++;
}
if ( u > 10 )
OCCASIONALLY log() << "btree unused skipped:" << u << '\n';
}
// 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;
}
// Check if the current key is beyond endKey.
void BtreeCursor::checkEnd() {
if ( bucket.isNull() )
return;
if ( !endKey.isEmpty() ) {
int cmp = sgn( endKey.woCompare( currKey(), order ) );
if ( ( cmp != 0 && cmp != direction ) ||
( cmp == 0 && !endKeyInclusive_ ) )
bucket = DiskLoc();
}
}
bool BtreeCursor::advance() {
killCurrentOp.checkForInterrupt();
if ( bucket.isNull() )
return false;
bucket = bucket.btree()->advance(bucket, keyOfs, direction, "BtreeCursor::advance");
skipUnusedKeys();
checkEnd();
if( !ok() && ++boundIndex_ < bounds_.size() )
initInterval();
return !bucket.isNull();
}
void BtreeCursor::noteLocation() {
if ( !eof() ) {
BSONObj o = bucket.btree()->keyAt(keyOfs).copy();
keyAtKeyOfs = o;
locAtKeyOfs = bucket.btree()->k(keyOfs).recordLoc;
}
}
/* Since the last noteLocation(), our key may have moved around, and that old cached
information may thus be stale and wrong (although often it is right). We check
that here; if we have moved, we have to search back for where we were at.
i.e., after operations on the index, the BtreeCursor's cached location info may
be invalid. This function ensures validity, so you should call it before using
the cursor if other writers have used the database since the last noteLocation
call.
*/
void BtreeCursor::checkLocation() {
if ( eof() )
return;
multikey = d->isMultikey(idxNo);
if ( keyOfs >= 0 ) {
BtreeBucket *b = bucket.btree();
assert( !keyAtKeyOfs.isEmpty() );
// Note keyAt() returns an empty BSONObj if keyOfs is now out of range,
// which is possible as keys may have been deleted.
if ( b->keyAt(keyOfs).woEqual(keyAtKeyOfs) &&
b->k(keyOfs).recordLoc == locAtKeyOfs ) {
if ( !b->k(keyOfs).isUsed() ) {
/* we were deleted but still exist as an unused
marker key. advance.
*/
skipUnusedKeys();
}
return;
}
}
/* normally we don't get to here. when we do, old position is no longer
valid and we must refind where we left off (which is expensive)
*/
bool found;
/* TODO: Switch to keep indexdetails and do idx.head! */
bucket = indexDetails.head.btree()->locate(indexDetails, indexDetails.head, keyAtKeyOfs, order, keyOfs, found, locAtKeyOfs, direction);
RARELY log() << " key seems to have moved in the index, refinding. found:" << found << endl;
if ( ! bucket.isNull() )
skipUnusedKeys();
}
/* ----------------------------------------------------------------------------- */
struct BtreeCursorUnitTest {
BtreeCursorUnitTest() {
assert( minDiskLoc.compare(maxDiskLoc) < 0 );
}
} btut;
} // namespace mongo
|
