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
|
/**
* 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 "pch.h"
#include "pdfile.h"
#include "curop.h"
namespace mongo {
bool BasicCursor::advance() {
killCurrentOp.checkForInterrupt();
if ( eof() ) {
if ( tailable_ && !last.isNull() ) {
curr = s->next( last );
} else {
return false;
}
} else {
last = curr;
curr = s->next( curr );
}
return ok();
}
/* these will be used outside of mutexes - really functors - thus the const */
class Forward : public AdvanceStrategy {
virtual DiskLoc next( const DiskLoc &prev ) const {
return prev.rec()->getNext( prev );
}
} _forward;
class Reverse : public AdvanceStrategy {
virtual DiskLoc next( const DiskLoc &prev ) const {
return prev.rec()->getPrev( prev );
}
} _reverse;
const AdvanceStrategy *forward() {
return &_forward;
}
const AdvanceStrategy *reverse() {
return &_reverse;
}
DiskLoc nextLoop( NamespaceDetails *nsd, const DiskLoc &prev ) {
assert( nsd->capLooped() );
DiskLoc next = forward()->next( prev );
if ( !next.isNull() )
return next;
return nsd->firstRecord();
}
DiskLoc prevLoop( NamespaceDetails *nsd, const DiskLoc &curr ) {
assert( nsd->capLooped() );
DiskLoc prev = reverse()->next( curr );
if ( !prev.isNull() )
return prev;
return nsd->lastRecord();
}
ForwardCappedCursor::ForwardCappedCursor( NamespaceDetails *_nsd, const DiskLoc &startLoc ) :
nsd( _nsd ) {
if ( !nsd )
return;
DiskLoc start = startLoc;
if ( start.isNull() ) {
if ( !nsd->capLooped() )
start = nsd->firstRecord();
else {
start = nsd->capExtent.ext()->firstRecord;
if ( !start.isNull() && start == nsd->capFirstNewRecord ) {
start = nsd->capExtent.ext()->lastRecord;
start = nextLoop( nsd, start );
}
}
}
curr = start;
s = this;
}
DiskLoc ForwardCappedCursor::next( const DiskLoc &prev ) const {
assert( nsd );
if ( !nsd->capLooped() )
return forward()->next( prev );
DiskLoc i = prev;
// Last record
if ( i == nsd->capExtent.ext()->lastRecord )
return DiskLoc();
i = nextLoop( nsd, i );
// If we become capFirstNewRecord from same extent, advance to next extent.
if ( i == nsd->capFirstNewRecord &&
i != nsd->capExtent.ext()->firstRecord )
i = nextLoop( nsd, nsd->capExtent.ext()->lastRecord );
// If we have just gotten to beginning of capExtent, skip to capFirstNewRecord
if ( i == nsd->capExtent.ext()->firstRecord )
i = nsd->capFirstNewRecord;
return i;
}
ReverseCappedCursor::ReverseCappedCursor( NamespaceDetails *_nsd, const DiskLoc &startLoc ) :
nsd( _nsd ) {
if ( !nsd )
return;
DiskLoc start = startLoc;
if ( start.isNull() ) {
if ( !nsd->capLooped() ) {
start = nsd->lastRecord();
} else {
start = nsd->capExtent.ext()->lastRecord;
}
}
curr = start;
s = this;
}
DiskLoc ReverseCappedCursor::next( const DiskLoc &prev ) const {
assert( nsd );
if ( !nsd->capLooped() )
return reverse()->next( prev );
DiskLoc i = prev;
// Last record
if ( nsd->capFirstNewRecord == nsd->capExtent.ext()->firstRecord ) {
if ( i == nextLoop( nsd, nsd->capExtent.ext()->lastRecord ) ) {
return DiskLoc();
}
} else {
if ( i == nsd->capExtent.ext()->firstRecord ) {
return DiskLoc();
}
}
// If we are capFirstNewRecord, advance to prev extent, otherwise just get prev.
if ( i == nsd->capFirstNewRecord )
i = prevLoop( nsd, nsd->capExtent.ext()->firstRecord );
else
i = prevLoop( nsd, i );
// If we just became last in cap extent, advance past capFirstNewRecord
// (We know capExtent.ext()->firstRecord != capFirstNewRecord, since would
// have returned DiskLoc() earlier otherwise.)
if ( i == nsd->capExtent.ext()->lastRecord )
i = reverse()->next( nsd->capFirstNewRecord );
return i;
}
} // namespace mongo
|
