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
|
/**
* Copyright (C) 2012 10gen 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 <boost/optional.hpp>
#include <string>
#include "mongo/base/disallow_copying.h"
#include "mongo/bson/bsonobj.h"
#include "mongo/client/connection_string.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/write_concern_options.h"
#include "mongo/s/catalog/forwarding_catalog_manager.h"
#include "mongo/s/chunk_version.h"
namespace mongo {
class CollectionMetadata;
class OperationContext;
template <typename T>
class StatusWith;
/**
* Returns the default write concern for migration cleanup on the donor shard and for cloning
* documents on the destination shard.
*/
class ChunkMoveWriteConcernOptions {
public:
/**
* Parses the chunk move options from a command object.
*/
static StatusWith<ChunkMoveWriteConcernOptions> initFromCommand(const BSONObj& cmdObj);
/**
* Returns the throttle options to be used when committing migrated documents on the recipient
* shard's seconary.
*/
const BSONObj& getSecThrottle() const {
return _secThrottleObj;
}
/**
* Returns the write concern options.
*/
const WriteConcernOptions& getWriteConcern() const {
return _writeConcernOptions;
}
private:
ChunkMoveWriteConcernOptions(BSONObj secThrottleObj, WriteConcernOptions writeConcernOptions);
const BSONObj _secThrottleObj;
const WriteConcernOptions _writeConcernOptions;
};
/**
* Contains all the runtime state for an active move operation and allows persistence of this state
* to BSON, so it can be resumed. Intended to be used from within a single thread of execution
* (single OperationContext) at a time and should not be moved between threads.
*/
class ChunkMoveOperationState {
MONGO_DISALLOW_COPYING(ChunkMoveOperationState);
public:
ChunkMoveOperationState(OperationContext* txn, NamespaceString ns);
~ChunkMoveOperationState();
/**
* Extracts and validates the move chunk parameters from the given cmdObj.
*/
Status initialize(const BSONObj& cmdObj);
/**
* Acquires the distributed lock for the collection, whose chunk is being moved and fetches the
* latest metadata as of the time of the call. The fetched metadata will be cached on the
* operation state until the entire operation completes. Also, because of the distributed lock
* being held, other processes should not change it on the config servers.
*
* Returns a pointer to the distributed lock acquired by the operation so it can be periodically
* checked for liveness. The returned value is owned by the move operation state and should not
* be accessed after it completes.
*
* TODO: Once the entire chunk move process is moved to be inside this state machine, there
* will not be any need to expose the distributed lock.
*/
StatusWith<ForwardingCatalogManager::ScopedDistLock*> acquireMoveMetadata();
/**
* Starts the move chunk operation.
*/
Status start(BSONObj shardKeyPattern);
/**
* Implements the migration critical section. Needs to be invoked after all data has been moved
* after which it will enter the migration critical section, move the remaining batch and then
* donate the chunk.
*
* Returns OK if the migration commits successfully or a status describing the error otherwise.
* Since some migration failures are non-recoverable, it may also shut down the server on
* certain errors.
*/
Status commitMigration();
const NamespaceString& getNss() const {
return _nss;
}
const std::string& getFromShard() const {
return _fromShard;
}
const ConnectionString& getFromShardCS() const {
return _fromShardCS;
}
const std::string& getToShard() const {
return _toShard;
}
const ConnectionString& getToShardCS() const {
return _toShardCS;
}
const BSONObj& getMinKey() const {
return _minKey;
}
const BSONObj& getMaxKey() const {
return _maxKey;
}
/**
* Retrieves the highest chunk version on this shard of the collection being moved as of the
* time the distributed lock was acquired. It is illegal to call this method before
* acquireMoveMetadata has been called and succeeded.
*/
ChunkVersion getShardVersion() const;
/**
* Retrieves the snapshotted collection metadata as of the time the distributed lock was
* acquired. It is illegal to call this method before acquireMoveMetadata has been called and
* succeeded.
*/
std::shared_ptr<CollectionMetadata> getCollMetadata() const;
private:
// The context of which the migration is running on.
OperationContext* const _txn = nullptr;
const NamespaceString _nss;
// The source and recipient shard ids
std::string _fromShard;
std::string _toShard;
// Resolved shard connection strings for the above shards
ConnectionString _fromShardCS;
ConnectionString _toShardCS;
// Epoch for the collection sent along with the command
// TODO(SERVER-20742): remove this after 3.2, now that we're sending version it is redundant
OID _collectionEpoch;
// ChunkVersion for the collection sent along with the command
ChunkVersion _collectionVersion;
// Min and max key of the chunk being moved
BSONObj _minKey;
BSONObj _maxKey;
// The distributed lock, which protects other migrations from happening on the same collection
boost::optional<StatusWith<ForwardingCatalogManager::ScopedDistLock>> _distLockStatus;
// The cached collection metadata and the shard version from the time the migration process
// started. This metadata is guaranteed to not change until either failure or successful
// completion, because the distributed lock is being held.
ChunkVersion _shardVersion;
std::shared_ptr<CollectionMetadata> _collMetadata;
// True if this migration is running.
bool _isRunning = false;
};
} // namespace mongo
|
