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
|
/**
* 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 "mongo/base/disallow_copying.h"
#include "mongo/util/time_support.h"
namespace mongo {
class ConnectionString;
class OperationContext;
struct ReadPreferenceSetting;
struct HostAndPort;
template <typename T>
class StatusWith;
/**
* Interface encapsulating the targeting logic for a given replica set or a standalone host.
*/
class RemoteCommandTargeter {
MONGO_DISALLOW_COPYING(RemoteCommandTargeter);
public:
virtual ~RemoteCommandTargeter() = default;
/**
* Retrieves the full connection string for the replica set or standalone host which are
* represented by this targeter. This value is always constant for a standalone host and may
* vary for replica sets as hosts are added, discovered and removed during the lifetime of the
* set.
*/
virtual ConnectionString connectionString() = 0;
/**
* Obtains a host, which matches the read preferences specified by readPref, blocking for the
* specified maxWait milliseconds, if a match cannot be found immediately.
*
* Specifying a maxWait of zero means non-blocking. I.e., the call will just check the in-memory
* cached view of the replica set's host state and won't wait for it to be refreshed if it is
* found to be stale.
*
* Returns OK and a host and port to use for the specified read preference or an ErrorCode.
* Known error codes are:
* All error codes which can be returned by ReplicaSetMonitor::getHostOrRefresh.
*/
virtual StatusWith<HostAndPort> findHost(const ReadPreferenceSetting& readPref,
Milliseconds maxWait = Milliseconds(0)) = 0;
/**
* Reports to the targeter that a NotMaster response was received when communicating with
* "host', and so it should update its bookkeeping to avoid giving out the host again on a
* subsequent request for the primary.
*/
virtual void markHostNotMaster(const HostAndPort& host) = 0;
/**
* Similar to markHostNotMaster(). Reports to the targeter that a HostUnreachable response was
* received when communicating with "host". The targeter should update its bookkeeping to avoid
* giving out the same host on a subsequent request.
*/
virtual void markHostUnreachable(const HostAndPort& host) = 0;
/**
* Based on the remaining time of the operation and the default max wait time for findHost,
* selects an appropriate value to pass to the maxWait argument of the findHost method, so it
* has high likelyhood in returning on time and also leaving time for the rest of the call to
* complete.
*/
static Milliseconds selectFindHostMaxWaitTime(OperationContext* txn);
protected:
RemoteCommandTargeter() = default;
};
} // namespace mongo
|
