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
|
/**
* Copyright (C) 2016 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/bson/bsonobj.h"
#include "mongo/client/connection_string.h"
#include "mongo/client/read_preference.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/repl/optime.h"
namespace mongo {
class OperationContext;
class RemoteCommandTargeter;
using ShardId = std::string;
/**
* Presents an interface for talking to shards, regardless of whether that shard is remote or is
* the current (local) shard.
*/
class Shard {
public:
struct CommandResponse {
CommandResponse(BSONObj _response,
BSONObj _metadata,
Status _commandStatus,
Status _writeConcernStatus)
: response(std::move(_response)),
metadata(std::move(_metadata)),
commandStatus(std::move(_commandStatus)),
writeConcernStatus(std::move(_writeConcernStatus)) {}
BSONObj response;
BSONObj metadata;
Status commandStatus;
Status writeConcernStatus;
};
struct QueryResponse {
std::vector<BSONObj> docs;
repl::OpTime opTime;
};
enum class RetryPolicy {
kIdempotent,
kNotIdempotent,
kNoRetry,
};
virtual ~Shard() = default;
const ShardId getId() const;
/**
* Returns true if this shard object represents the config server.
*/
bool isConfig() const;
/**
* Returns the current connection string for the shard.
*
* This is only valid to call on ShardRemote instances.
*/
virtual const ConnectionString getConnString() const = 0;
/**
* Returns the connection string that was used when the shard was added. The current connection
* string may be different for shards that are replica sets.
*
* This is only valid to call on ShardRemote instances.
*/
virtual const ConnectionString originalConnString() const = 0;
/**
* Returns the RemoteCommandTargeter for the hosts in this shard.
*
* This is only valid to call on ShardRemote instances.
*/
virtual std::shared_ptr<RemoteCommandTargeter> getTargeter() const = 0;
/**
* Notifies the RemoteCommandTargeter owned by the shard of a particular mode of failure for
* the specified host.
*
* This is only valid to call on ShardRemote instances.
*/
virtual void updateReplSetMonitor(const HostAndPort& remoteHost,
const Status& remoteCommandStatus) = 0;
/**
* Returns a string description of this shard entry.
*/
virtual std::string toString() const = 0;
/**
* Returns whether a server operation which failed with the given error code should be retried
* (i.e. is safe to retry and has the potential to succeed next time). The 'options' argument
* describes whether the operation that generated the given code was idempotent, which affects
* which codes are safe to retry on.
*/
virtual bool isRetriableError(ErrorCodes::Error code, RetryPolicy options) = 0;
/**
* Runs a command against this shard and returns the BSON command response, as well as the
* already-parsed out Status of the command response and write concern error (if present).
* Retries failed operations according to the given "retryPolicy".
*/
StatusWith<CommandResponse> runCommand(OperationContext* txn,
const ReadPreferenceSetting& readPref,
const std::string& dbName,
const BSONObj& cmdObj,
RetryPolicy retryPolicy);
/**
* Warning: This method exhausts the cursor and pulls all data into memory.
* Do not use other than for very small (i.e., admin or metadata) collections.
* Performs retries if the query fails in accordance with the kIdempotent RetryPolicy.
*/
StatusWith<QueryResponse> exhaustiveFindOnConfig(OperationContext* txn,
const ReadPreferenceSetting& readPref,
const NamespaceString& nss,
const BSONObj& query,
const BSONObj& sort,
const boost::optional<long long> limit);
protected:
Shard(const ShardId& id);
private:
virtual StatusWith<CommandResponse> _runCommand(OperationContext* txn,
const ReadPreferenceSetting& readPref,
const std::string& dbname,
const BSONObj& cmdObj) = 0;
virtual StatusWith<QueryResponse> _exhaustiveFindOnConfig(OperationContext* txn,
const ReadPreferenceSetting& readPref,
const NamespaceString& nss,
const BSONObj& query,
const BSONObj& sort,
boost::optional<long long> limit) = 0;
/**
* Identifier of the shard as obtained from the configuration data (i.e. shard0000).
*/
const ShardId _id;
};
} // namespace mongo
|
