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
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
|
/* Copyright 2014 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.
*/
/**
* This is an internal header.
* This should only be included by replica_set_monitor.cpp and replica_set_monitor_test.cpp.
* This should never be included by any header.
*/
#pragma once
#include <cstdint>
#include <deque>
#include <set>
#include <string>
#include <vector>
#include "mongo/base/disallow_copying.h"
#include "mongo/client/read_preference.h"
#include "mongo/client/replica_set_monitor.h"
#include "mongo/db/jsobj.h"
#include "mongo/platform/random.h"
#include "mongo/stdx/condition_variable.h"
#include "mongo/util/net/hostandport.h"
namespace mongo {
struct ReplicaSetMonitor::IsMasterReply {
IsMasterReply() : ok(false) {}
IsMasterReply(const HostAndPort& host, int64_t latencyMicros, const BSONObj& reply)
: ok(false), host(host), latencyMicros(latencyMicros) {
parse(reply);
}
/**
* Never throws. If parsing fails for any reason, sets ok to false.
*/
void parse(const BSONObj& obj);
bool ok; // if false, ignore all other fields
BSONObj raw; // Always owned. Other fields are allowed to be a view into this.
std::string setName;
bool isMaster;
bool secondary;
bool hidden;
int configVersion{0};
OID electionId; // Set if this isMaster reply is from the primary
HostAndPort primary; // empty if not present
std::set<HostAndPort> normalHosts; // both "hosts" and "passives"
BSONObj tags;
int minWireVersion{0};
int maxWireVersion{0};
// remaining fields aren't in isMaster reply, but are known to caller.
HostAndPort host;
int64_t latencyMicros; // ignored if negative
};
struct ReplicaSetMonitor::SetState {
MONGO_DISALLOW_COPYING(SetState);
public:
/**
* Holds the state of a single node in the replicaSet
*/
struct Node {
explicit Node(const HostAndPort& host);
void markFailed(const Status& status);
bool matches(const ReadPreference pref) const;
/**
* Checks if the given tag matches the tag attached to this node.
*
* Example:
*
* Tag of this node: { "dc": "nyc", "region": "na", "rack": "4" }
*
* match: {}
* match: { "dc": "nyc", "rack": 4 }
* match: { "region": "na", "dc": "nyc" }
* not match: { "dc": "nyc", "rack": 2 }
* not match: { "dc": "sf" }
*/
bool matches(const BSONObj& tag) const;
/**
* Updates this Node based on information in reply. The reply must be from this host.
*/
void update(const IsMasterReply& reply);
HostAndPort host;
bool isUp{false};
bool isMaster{false}; // implies isUp
int64_t latencyMicros; // unknownLatency if unknown
BSONObj tags; // owned
int minWireVersion{0};
int maxWireVersion{0};
};
typedef std::vector<Node> Nodes;
/**
* seedNodes must not be empty
*/
SetState(StringData name, const std::set<HostAndPort>& seedNodes);
bool isUsable() const;
/**
* Returns a host matching criteria or an empty host if no known host matches.
*
* Note: Uses only local data and does not go over the network.
*/
HostAndPort getMatchingHost(const ReadPreferenceSetting& criteria) const;
/**
* Returns the Node with the given host, or NULL if no Node has that host.
*/
Node* findNode(const HostAndPort& host);
/**
* Returns the Node with the given host, or creates one if no Node has that host.
* Maintains the sorted order of nodes.
*/
Node* findOrCreateNode(const HostAndPort& host);
void updateNodeIfInNodes(const IsMasterReply& reply);
/**
* Returns the connection string of the nodes that are known the be in the set because we've
* seen them in the isMaster reply of a PRIMARY.
*/
std::string getConfirmedServerAddress() const;
/**
* Returns the connection string of the nodes that are believed to be in the set because we've
* seen them in the isMaster reply of non-PRIMARY nodes in our seed list.
*/
std::string getUnconfirmedServerAddress() const;
/**
* Before unlocking, do DEV checkInvariants();
*/
void checkInvariants() const;
stdx::mutex mutex; // must hold this to access any other member or method (except name).
// If Refresher::getNextStep returns WAIT, you should wait on the condition_variable,
// releasing mutex. It will be notified when either getNextStep will return something other
// than WAIT, or a new host is available for consideration by getMatchingHost. Essentially,
// this will be hit whenever the _refreshUntilMatches loop has the potential to make
// progress.
// TODO consider splitting cv into two: one for when looking for a master, one for all other
// cases.
stdx::condition_variable cv;
const std::string name; // safe to read outside lock since it is const
int consecutiveFailedScans;
std::set<HostAndPort> seedNodes; // updated whenever a master reports set membership changes
OID maxElectionId; // largest election id observed by this ReplicaSetMonitor
int configVersion{0}; // version number of the replica set config.
HostAndPort lastSeenMaster; // empty if we have never seen a master. can be same as current
Nodes nodes; // maintained sorted and unique by host
ScanStatePtr currentScan; // NULL if no scan in progress
int64_t latencyThresholdMicros;
mutable PseudoRandom rand; // only used for host selection to balance load
mutable int roundRobin; // used when useDeterministicHostSelection is true
};
struct ReplicaSetMonitor::ScanState {
MONGO_DISALLOW_COPYING(ScanState);
public:
ScanState() : foundUpMaster(false), foundAnyUpNodes(false) {}
/**
* Adds all hosts in container that aren't in triedHosts to hostsToScan, then shuffles the
* queue.
*/
template <typename Container>
void enqueAllUntriedHosts(const Container& container, PseudoRandom& rand);
// Access to fields is guarded by associated SetState's mutex.
bool foundUpMaster;
bool foundAnyUpNodes;
std::deque<HostAndPort> hostsToScan; // Work queue.
std::set<HostAndPort> possibleNodes; // Nodes reported by non-primary hosts.
std::set<HostAndPort> waitingFor; // Hosts we have dispatched but haven't replied yet.
std::set<HostAndPort> triedHosts; // Hosts that have been returned from getNextStep.
// All responses go here until we find a master.
typedef std::vector<IsMasterReply> UnconfirmedReplies;
UnconfirmedReplies unconfirmedReplies;
};
} // namespace mongo
|
