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
|
/**
* Copyright (C) 2015 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.
*/
#pragma once
#include <tuple>
#include "mongo/bson/timestamp.h"
namespace mongo {
class BSONObj;
class BSONObjBuilder;
class BSONObjBuilderValueStream;
template <typename T>
class StatusWith;
namespace repl {
/**
* OpTime encompasses a Timestamp (which itself is composed of two 32-bit integers, which can
* represent a time_t and a counter), and a 64-bit Term number. OpTime can be used to
* label every op in an oplog with a unique identifier.
*/
class OpTime {
public:
static const char kTimestampFieldName[];
static const char kTermFieldName[];
// The term of an OpTime generated by old protocol version.
static const long long kUninitializedTerm = -1;
// The initial term after the first time upgrading from protocol version 0.
//
// This is also the initial term for nodes that were recently started up but have not
// yet joined the cluster, all in protocol version 1.
static const long long kInitialTerm;
/**
* Returns maximum OpTime value.
*/
static OpTime max();
// Default OpTime, also the smallest one.
OpTime() : _timestamp(Timestamp(0, 0)), _term(kUninitializedTerm) {}
OpTime(Timestamp ts, long long term) : _timestamp(std::move(ts)), _term(term) {}
Timestamp getTimestamp() const {
return _timestamp;
}
long long getSecs() const {
return _timestamp.getSecs();
}
long long getTerm() const {
return _term;
}
/**
* Serializes the contents of this optime to the specified builder in the form:
* subObjName : { ts: <timestamp>, t: <term> }
*/
void append(BSONObjBuilder* builder, const std::string& subObjName) const;
BSONObj toBSON() const;
static StatusWith<OpTime> parseFromOplogEntry(const BSONObj& obj);
/**
* Parses OpTime from a document in the form:
* { ts: <timestamp>, t: <term> }
*
* Throws an exception on error.
*/
static OpTime parse(const BSONObj& obj);
std::string toString() const;
// Returns true when this OpTime is not yet initialized.
bool isNull() const {
return _timestamp.isNull();
}
inline bool operator==(const OpTime& rhs) const {
// Only compare timestamp if either of the two OpTimes is generated by old protocol,
// so that (Timestamp(), 0) == (Timestamp(), -1)
if (_term == kUninitializedTerm || rhs._term == kUninitializedTerm) {
return _timestamp == rhs._timestamp;
}
// Compare term first, then the timestamps.
return std::tie(_term, _timestamp) == std::tie(rhs._term, rhs._timestamp);
}
// Since the term will be reset to 0 after upgrade protocol version -> downgrade
// -> upgrade again, comparison of arbitrary OpTimes may not be safe. However it's safe
// to compare OpTimes generated in same or successive replset configs.
// Upgrade / downgrade process will make sure the last oplog entries on all nodes are from
// the same protocol version to avoid problematic scenarios.
inline bool operator<(const OpTime& rhs) const {
// Only compare timestamp if either of the two OpTimes is generated by old protocol.
if (_term == kUninitializedTerm || rhs._term == kUninitializedTerm) {
return _timestamp < rhs._timestamp;
}
// Compare term first, then the timestamps.
return std::tie(_term, _timestamp) < std::tie(rhs._term, rhs._timestamp);
}
inline bool operator!=(const OpTime& rhs) const {
return !(*this == rhs);
}
inline bool operator<=(const OpTime& rhs) const {
return *this < rhs || *this == rhs;
}
inline bool operator>(const OpTime& rhs) const {
return !(*this <= rhs);
}
inline bool operator>=(const OpTime& rhs) const {
return !(*this < rhs);
}
friend std::ostream& operator<<(std::ostream& out, const OpTime& opTime);
void appendAsQuery(BSONObjBuilder* builder) const;
BSONObj asQuery() const;
private:
Timestamp _timestamp;
long long _term = kInitialTerm;
};
} // namespace repl
/**
* Support BSONObjBuilder and BSONArrayBuilder "stream" API.
*/
BSONObjBuilder& operator<<(BSONObjBuilderValueStream& builder, const repl::OpTime& value);
} // namespace mongo
|
