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
|
/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* 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 Server Side 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/db/catalog/database.h"
#include "mongo/db/s/sharding_migration_critical_section.h"
#include "mongo/db/s/sharding_state_lock.h"
#include "mongo/s/database_version_gen.h"
namespace mongo {
class MovePrimarySourceManager;
class OperationContext;
/**
* Synchronizes access to this shard server's cached database version for Database.
*/
class DatabaseShardingState {
DatabaseShardingState(const DatabaseShardingState&) = delete;
DatabaseShardingState& operator=(const DatabaseShardingState&) = delete;
public:
/**
* A ShardingStateLock is used on DatabaseShardingState operations in order to ensure
* synchronization across operations.
*/
using DSSLock = ShardingStateLock<DatabaseShardingState>;
DatabaseShardingState(const StringData dbName);
~DatabaseShardingState() = default;
/**
* Obtains the sharding state for the specified database. If it does not exist, it will be
* created and will remain in memory until the database is dropped.
*
* Must be called with some lock held on the database being looked up and the returned
* pointer must not be stored.
*/
static DatabaseShardingState* get(OperationContext* opCtx, const StringData dbName);
/**
* Methods to control the databases's critical section. Must be called with the database X lock
* held.
*/
void enterCriticalSectionCatchUpPhase(OperationContext* opCtx, DSSLock&);
void enterCriticalSectionCommitPhase(OperationContext* opCtx, DSSLock&);
void exitCriticalSection(OperationContext* opCtx,
boost::optional<DatabaseVersion> newDbVersion,
DSSLock&);
auto getCriticalSectionSignal(ShardingMigrationCriticalSection::Operation op, DSSLock&) const {
return _critSec.getSignal(op);
}
/**
* Returns this shard server's cached dbVersion, if one is cached.
*
* Invariants that the caller holds the DBLock in X or IS.
*/
boost::optional<DatabaseVersion> getDbVersion(OperationContext* opCtx, DSSLock&) const;
/**
* Sets this shard server's cached dbVersion to newVersion.
*
* Invariants that the caller holds the DBLock in X mode.
*/
void setDbVersion(OperationContext* opCtx,
boost::optional<DatabaseVersion> newVersion,
DSSLock&);
/**
* If _critSecSignal is non-null, always throws StaleDbVersion.
* Otherwise, if there is a client dbVersion on the OperationContext, compares it with this
* shard server's cached dbVersion and throws StaleDbVersion if they do not match.
*/
void checkDbVersion(OperationContext* opCtx, DSSLock&) const;
/**
* Returns the active movePrimary source manager, if one is available.
*/
MovePrimarySourceManager* getMovePrimarySourceManager(DSSLock&);
/**
* Attaches a movePrimary source manager to this database's sharding state. Must be called with
* the database lock in X mode. May not be called if there is a movePrimary source manager
* already installed. Must be followed by a call to clearMovePrimarySourceManager.
*/
void setMovePrimarySourceManager(OperationContext* opCtx,
MovePrimarySourceManager* sourceMgr,
DSSLock&);
/**
* Removes a movePrimary source manager from this database's sharding state. Must be called with
* with the database lock in X mode. May not be called if there isn't a movePrimary source
* manager installed already through a previous call to setMovePrimarySourceManager.
*/
void clearMovePrimarySourceManager(OperationContext* opCtx, DSSLock&);
private:
friend DSSLock;
// Object-wide ResourceMutex to protect changes to the DatabaseShardingState or objects held
// within.
Lock::ResourceMutex _stateChangeMutex{"DatabaseShardingState"};
const std::string _dbName;
// Modifying the state below requires holding the DBLock in X mode; holding the DBLock in any
// mode is acceptable for reading it. (Note: accessing this class at all requires holding the
// DBLock in some mode).
ShardingMigrationCriticalSection _critSec;
// This shard server's cached dbVersion. If boost::none, indicates this shard server does not
// know the dbVersion.
boost::optional<DatabaseVersion> _dbVersion = boost::none;
// If this database is serving as a source shard for a movePrimary, the source manager will be
// non-null. To write this value, there needs to be X-lock on the database in order to
// synchronize with other callers which will read the source manager.
//
// NOTE: The source manager is not owned by this class.
MovePrimarySourceManager* _sourceMgr{nullptr};
};
} // namespace mongo
|
