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
|
// Copyright (C) 2018-2019,2021 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
#ifndef SERVER_SELECTOR_H
#define SERVER_SELECTOR_H
#include <cc/server_tag.h>
#include <set>
#include <string>
namespace isc {
namespace db {
/// @brief Server selector for associating objects in a database with
/// specific servers.
///
/// Configuration information stored in the configuration backends can be
/// associated with selected servers, all servers or no particular server.
/// For example: a particular subnet definition in the database may be
/// associated with one server or can be shared by multiple servers.
/// In the latter case, a subnet may be associated with a subset of
/// servers or all servers. An administrator may also add the
/// configuration data into the database and do not associate this data
/// with any particular server.
///
/// When fetching the configuration data from a database or when storing
/// data in the database there is a need to specify which servers this
/// data is associated with. The @c ServerSelector class represents
/// such associations.
///
/// It includes three modes of selection: UNASSIGNED, ALL and SUBSET and
/// several factory functions making associations described above.
///
/// The @c ServerSelector class should be used in objects derived from
/// @c BaseConfigBackendPool and in objects derived from
/// @c BaseConfigBackend to indicate which servers the specific calls
/// exposed by these objects refer to.
///
/// @todo Add server selector for selecting only those configuration
/// elements that are associated with all servers (and not with any
/// particular server tags). Translating this to SQL queries it would
/// probably be an empty or non-existing server tag.
class ServerSelector {
public:
/// @brief Type of the server selection.
enum class Type {
UNASSIGNED,
ALL,
SUBSET,
ANY
};
/// @brief Factory returning "unassigned" server selector.
static ServerSelector UNASSIGNED() {
ServerSelector selector(Type::UNASSIGNED);
return (selector);
}
/// @brief Factory returning "all servers" selector.
static ServerSelector ALL() {
ServerSelector selector(Type::ALL);
return (selector);
}
/// @brief Factory returning selector of one server.
///
/// @param server_tag tag of the single server to be selected.
static ServerSelector ONE(const std::string& server_tag) {
ServerSelector selector((data::ServerTag(server_tag)));
return (selector);
}
/// @brief Factory returning "multiple servers" selector.
///
/// @param server_tags set of server tags to be selected.
/// @throw InvalidOperation if no server tags provided.
static ServerSelector MULTIPLE(const std::set<std::string>& server_tags);
/// @brief Factory returning "any server" selector.
static ServerSelector ANY() {
ServerSelector selector(Type::ANY);
return (selector);
}
/// @brief Returns type of the selector.
Type getType() const {
return (type_);
}
/// @brief Returns tags associated with the selector.
///
/// @return server tags for multiple selections and for one server,
/// empty set for all servers and and unassigned.
std::set<data::ServerTag> getTags() const {
return (tags_);
}
/// @brief Convenience method checking if the server selector has no tags.
///
/// @return true when the server selector has no tags, false otherwise.
bool hasNoTags() const {
return (tags_.empty());
}
/// @brief Convenience method checking if the server selector is "unassigned".
///
/// @return true if the selector is "unassigned", false otherwise.
bool amUnassigned() const {
return (getType() == Type::UNASSIGNED);
}
/// @brief Convenience method checking if the server selector is "all".
///
/// @return true if the selector is "all", false otherwise.
bool amAll() const {
return (getType() == Type::ALL);
}
/// @brief Convenience method checking if the server selector is "any".
///
/// @return true if the selector is "any", false otherwise.
bool amAny() const {
return (getType() == Type::ANY);
}
/// @brief Convenience method checking if the server selector has multiple tags.
///
/// @return true if it has multiple tags, false otherwise.
bool hasMultipleTags() const {
return (tags_.size() > 1);
}
private:
/// @brief Constructor used for "unassigned" and "all" selection types.
///
/// @param type selector type.
explicit ServerSelector(const Type& type);
/// @brief Constructor used for selecting a single server.
///
/// @param server_tag tag of the server to be selected.
explicit ServerSelector(const data::ServerTag& server_tag);
/// @brief Constructor used for selecting multiple servers.
///
/// @param server_tags set of server tags.
explicit ServerSelector(const std::set<data::ServerTag>& server_tags);
/// @brief Selection type used.
Type type_;
/// @brief Holds tags of explicitly selected servers.
std::set<data::ServerTag> tags_;
};
} // end of namespace isc::db
} // end of namespace isc
#endif
|
