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
|
/**
* Copyright (C) 2020-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* 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 Server Side 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 "mongo/base/status.h"
#include "mongo/base/string_data.h"
#include "mongo/bson/bsonelement.h"
#include "mongo/bson/bsonobjbuilder.h"
#include "mongo/db/read_write_concern_provenance_base_gen.h"
#include "mongo/idl/basic_types_gen.h"
namespace mongo {
/**
* This class represents the "provenance" (ie. original source) of a read or write concern.
*
* This information is serialized as a 'provenance' field inside readConcern/writeConcern objects,
* which is parsed, stored, and forwarded, but has no other effect on the meaning of the read or
* write concern (RWC). This means it is possible to see (in logs, currentOp, profiling, etc) where
* a given RWC has come from. It also makes it possible for the server to adjust its behavior based
* on the origin of the RWC (even though the semantics of the RWC itself have not changed), for
* example, by having special metrics that only apply to RWC from certain sources.
*
* Possible sources are:
*
* - unset (ie. the 'provenance' field was absent):
* Implicitly means "clientSupplied" (so drivers do not need to send a 'provenance' field).
*
* - "clientSupplied":
* The RWC was originally explicitly passed to a mongos or plain replica set member by the
* driver.
*
* - "implicitDefault":
* The client did not supply an explicit RWC, and there was no RWC default, so this RWC
* represents the corresponding implicit server default, ie. read concern of "local" (except
* "available" on sharded secondaries) and {w: 1, wtimeout: 0}.
*
* - "customDefault":
* Represents an admin-defined cluster-wide RWC default that was applied to the operation
* because no explicit RWC was provided, and there was a custom RWC default defined at the time.
*
* - "getLastErrorDefaults":
* Only applicable to write concern, and indicates that it originated from the (deprecated)
* 'settings.getLastErrorDefaults' field of the replica set configuration.
*
* - "internalWriteDefault":
* Only applicable to write concern on internal writes, and indicates that the internal client
* did not supply an explicit write concern, so this write concern represents the corresponding
* server default for internal writes, ie. {w: 1, wtimeout: 0}.
*
* A ReadWriteConcernProvenance object may only have a single Source value throughout its lifetime;
* once the Source has been set, attempting to change it will trigger an invariant. This ensures
* the integrity of the provenance value as the operation makes its way through the server (and
* through the overall cluster).
*/
class ReadWriteConcernProvenance : public ReadWriteConcernProvenanceBase {
public:
using Source = ReadWriteConcernProvenanceSourceEnum;
static constexpr StringData kClientSupplied = "clientSupplied"_sd;
static constexpr StringData kImplicitDefault = "implicitDefault"_sd;
static constexpr StringData kCustomDefault = "customDefault"_sd;
static constexpr StringData kGetLastErrorDefaults = "getLastErrorDefaults"_sd;
static constexpr StringData kInternalWriteDefault = "internalWriteDefault"_sd;
ReadWriteConcernProvenance() = default;
ReadWriteConcernProvenance(Source source) {
setSource(source);
}
ReadWriteConcernProvenance(ReadWriteConcernProvenanceBase&& base)
: ReadWriteConcernProvenanceBase(base) {}
/**
* Returns true if this provenance has been set to an actual source, or false if it is unset.
*/
const bool hasSource() const {
return static_cast<bool>(getSource());
}
/**
* Returns true if the RWC has been supplied by the client, ie. if this provenance's source is
* either unset (the client specified RWC but without provenance) or explicitly the
* "clientSupplied" source.
*/
const bool isClientSupplied() const {
return !hasSource() || *getSource() == Source::clientSupplied;
}
/**
* Returns true if the RWC was an implicit default.
*/
const bool isImplicitDefault() const {
return hasSource() && *getSource() == Source::implicitDefault;
}
/**
* Sets the source of this provenance. In order to prevent accidental clobbering of provenance
* with incorrect values, a source cannot change during the provenance's lifetime, except for
* the initial transition from kUnset to some other Source value.
*
* Apart from the initial transition from kUnset to some other Source value, the source of a
* provenance must not be changed during its lifetime, and this function enforces that property
* with an invariant. This is to prevent provenances from being accidentally clobbered with
* incorrect values.
*/
void setSource(boost::optional<Source> source) &;
/**
* Creates a provenance with source according to the given object's 'provenance' field.
*/
static ReadWriteConcernProvenance parse(const IDLParserErrorContext& ctxt,
const BSONObj& bsonObject);
/**
* Convenience functions.
*/
static StringData sourceToString(boost::optional<Source> source);
bool operator==(const ReadWriteConcernProvenance& other) const {
return getSource() == other.getSource();
}
bool operator!=(const ReadWriteConcernProvenance& other) const {
return !operator==(other);
}
};
} // namespace mongo
|
