-
Notifications
You must be signed in to change notification settings - Fork 140
/
keypattern.cpp
executable file
·158 lines (139 loc) · 6.04 KB
/
keypattern.cpp
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
// @file keypattern.cpp
/**
* Copyright (C) 2012 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/keypattern.h"
#include "mongo/db/index_names.h"
namespace mongo {
KeyPattern::KeyPattern(const BSONObj& pattern) : _pattern(pattern) {}
//判断是否id范围索引
bool KeyPattern::isIdKeyPattern(const BSONObj& pattern) {
BSONObjIterator i(pattern);
BSONElement e = i.next();
// _id index must have form exactly {_id : 1} or {_id : -1}.
// Allows an index of form {_id : "hashed"} to exist but
// do not consider it to be the primary _id index
return (0 == strcmp(e.fieldName(), "_id")) && (e.numberInt() == 1 || e.numberInt() == -1) &&
i.next().eoo();
}
//是否为普通索引,如"xx":1
bool KeyPattern::isOrderedKeyPattern(const BSONObj& pattern) {
return IndexNames::BTREE == IndexNames::findPluginName(pattern);
}
//是否为hash索引
bool KeyPattern::isHashedKeyPattern(const BSONObj& pattern) {
return IndexNames::HASHED == IndexNames::findPluginName(pattern);
}
//获取所有字符串 例如: {"AA":1, "BB":-1} {"AA":"hashed"}
StringBuilder& operator<<(StringBuilder& sb, const KeyPattern& keyPattern) {
// Rather than return BSONObj::toString() we construct a keyPattern string manually. This allows
// us to avoid the cost of writing numeric direction to the str::stream which will then undergo
// expensive number to string conversion.
sb << "{ ";
bool first = true;
for (auto&& elem : keyPattern._pattern) {
if (first) {
first = false;
} else {
sb << ", ";
}
if (mongo::String == elem.type()) { //说明是字符串,例如hash 2d text索引都是字符串
sb << elem;
} else if (elem.number() >= 0) {
// The canonical check as to whether a key pattern element is "ascending" or
// "descending" is (elem.number() >= 0). This is defined by the Ordering class.
sb << elem.fieldNameStringData() << ": 1";
} else {
sb << elem.fieldNameStringData() << ": -1";
}
}
sb << " }";
return sb;
}
/* Takes a BSONObj whose field names are a prefix of the fields in this keyPattern, and
* outputs a new bound with MinKey values appended to match the fields in this keyPattern
* (or MaxKey values for descending -1 fields). This is useful in sharding for
* calculating chunk boundaries when tag ranges are specified on a prefix of the actual
* shard key, or for calculating index bounds when the shard key is a prefix of the actual
* index used.
*
* @param makeUpperInclusive If true, then MaxKeys instead of MinKeys will be appended, so
* that the output bound will compare *greater* than the bound being extended (note that
* -1's in the keyPattern will swap MinKey/MaxKey vals. See examples).
*
* Examples:
* If this keyPattern is {a : 1}
* extendRangeBound( {a : 55}, false) --> {a : 55}
*
* If this keyPattern is {a : 1, b : 1}
* extendRangeBound( {a : 55}, false) --> {a : 55, b : MinKey}
* extendRangeBound( {a : 55}, true ) --> {a : 55, b : MaxKey}
*
* If this keyPattern is {a : 1, b : -1}
* extendRangeBound( {a : 55}, false) --> {a : 55, b : MaxKey}
* extendRangeBound( {a : 55}, true ) --> {a : 55, b : MinKey}
*/
//bound做转换,如上备注
BSONObj KeyPattern::extendRangeBound(const BSONObj& bound, bool makeUpperInclusive) const {
BSONObjBuilder newBound(bound.objsize());
BSONObjIterator src(bound);
BSONObjIterator pat(_pattern);
while (src.more()) {
massert(16649,
str::stream() << "keyPattern " << _pattern << " shorter than bound " << bound,
pat.more());
BSONElement srcElt = src.next();
BSONElement patElt = pat.next();
massert(16634,
str::stream() << "field names of bound " << bound
<< " do not match those of keyPattern "
<< _pattern,
str::equals(srcElt.fieldName(), patElt.fieldName()));
newBound.append(srcElt);
}
while (pat.more()) {
BSONElement patElt = pat.next();
// for non 1/-1 field values, like {a : "hashed"}, treat order as ascending
int order = patElt.isNumber() ? patElt.numberInt() : 1;
// flip the order semantics if this is an upper bound
if (makeUpperInclusive)
order *= -1;
if (order > 0) {
newBound.appendMinKey(patElt.fieldName());
} else {
newBound.appendMaxKey(patElt.fieldName());
}
}
return newBound.obj();
}
BSONObj KeyPattern::globalMin() const {
return extendRangeBound(BSONObj(), false);
}
BSONObj KeyPattern::globalMax() const {
return extendRangeBound(BSONObj(), true);
}
} // namespace mongo