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
|
/**
* 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 <vector>
#include "mongo/db/logical_time.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/s/scoped_collection_metadata.h"
namespace mongo {
/**
* Each collection on a MongoD instance is assigned an instance of CollectionShardingState for the
* duration of its lifetime, which represents the shard's knowledge of that collection's shard
* version and the set of chunks that it owns, as well as functions for tracking this state.
*
* This is the only interface that non-sharding consumers should be interfacing with.
*
* On shard servers, the implementation used is CollectionShardingRuntime.
*
* On embedded or non-shard servers, the implementation used is CollectionShardingStateStandalone,
* which is a mostly empty implementation.
*
* The CollectionShardingStateFactory class below is used to instantiate the correct subclass of
* CollectionShardingState at runtime.
*
* Synchronization rule: In order to obtain an instance of this object, the caller must have some
* lock on the respective collection. Different functions require different lock levels though, so
* be sure to check the function-level comments for details.
*/
class CollectionShardingState {
public:
CollectionShardingState() = default;
virtual ~CollectionShardingState() = default;
CollectionShardingState(const CollectionShardingState&) = delete;
CollectionShardingState& operator=(const CollectionShardingState&) = delete;
/**
* Obtains the sharding state for the specified collection. If it does not exist, it will be
* created and will remain in memory until the collection is dropped.
*
* Must be called with some lock held on the specific collection being looked up and the
* returned pointer must not be stored.
*/
static CollectionShardingState* get(OperationContext* opCtx, const NamespaceString& nss);
/**
* Returns the names of the collections that have a CollectionShardingState.
*/
static std::vector<NamespaceString> getCollectionNames(OperationContext* opCtx);
/**
* Obtain a pointer to the CollectionShardingState that remains safe to access without holding
* a collection lock. Should be called instead of the regular get() if no collection lock is
* held. The returned CollectionShardingState instance should not be modified!
*/
static std::shared_ptr<CollectionShardingState> getSharedForLockFreeReads(
OperationContext* opCtx, const NamespaceString& nss);
/**
* Reports all collections which have filtering information associated.
*/
static void appendInfoForShardingStateCommand(OperationContext* opCtx, BSONObjBuilder* builder);
/**
* Attaches info for server status.
*/
static void appendInfoForServerStatus(OperationContext* opCtx, BSONObjBuilder* builder);
/**
* If the shard currently doesn't know whether the collection is sharded or not, it will throw
* StaleShardVersion.
*
* If the request doesn't have a shard version all collections will be treated as UNSHARDED.
*
* The returned object *is not safe* to access after the collection lock has been dropped.
*/
virtual ScopedCollectionDescription getCollectionDescription(OperationContext* opCtx) = 0;
/**
* This method must be called with an OperationShardingState, which specifies an expected shard
* version for the collection and it will invariant otherwise.
*
* If the shard currently doesn't know whether the collection is sharded or not, or if the
* expected shard version doesn't match with the one in the OperationShardingState, it will
* throw StaleShardVersion.
*
* If the operation context contains an 'atClusterTime', the returned filtering object will be
* tied to a specific point in time. Otherwise, it will reference the latest cluster time
* available.
*
* If 'kDisallowOrphanCleanup' is passed as 'OrphanCleanupPolicy', the range deleter won't
* delete any orphan chunk associated with this ScopedCollectionFilter until the object is
* destroyed. The intended users of this mode are read operations, which need to yield the
* collection lock, but still perform filtering.
*
* The 'supportNonVersionedOperations' parameter states whether this function should consider
* operations that don't have a shard version.
* If the request doesn't have a shard version:
* - this function will invariant if !supportNonVersionedOperations (default value)
* - the collection will be treated as UNSHARDED otherwise.
*
* Use 'getCollectionDescription' for other cases, like obtaining information about
* sharding-related properties of the collection are necessary that won't change under
* collection IX/IS lock (e.g., isSharded or the shard key).
*
* The returned object *is safe* to access even after the collection lock has been dropped.
*/
enum class OrphanCleanupPolicy { kDisallowOrphanCleanup, kAllowOrphanCleanup };
virtual ScopedCollectionFilter getOwnershipFilter(
OperationContext* opCtx,
OrphanCleanupPolicy orphanCleanupPolicy,
bool supportNonVersionedOperations = false) = 0;
/**
* Checks whether the shard version in the operation context is compatible with the shard
* version of the collection and if not, throws StaleConfigException populated with the received
* and wanted versions.
*
* If the request is not versioned all collections will be treated as UNSHARDED.
*/
virtual void checkShardVersionOrThrow(OperationContext* opCtx) = 0;
/**
* Appends information about the shard version of the collection.
*/
virtual void appendShardVersion(BSONObjBuilder* builder) = 0;
/**
* Returns the number of ranges scheduled for deletion on the collection.
*/
virtual size_t numberOfRangesScheduledForDeletion() const = 0;
};
/**
* Singleton factory to instantiate CollectionShardingState objects specific to the type of instance
* which is running.
*/
class CollectionShardingStateFactory {
CollectionShardingStateFactory(const CollectionShardingStateFactory&) = delete;
CollectionShardingStateFactory& operator=(const CollectionShardingStateFactory&) = delete;
public:
static void set(ServiceContext* service,
std::unique_ptr<CollectionShardingStateFactory> factory);
static void clear(ServiceContext* service);
virtual ~CollectionShardingStateFactory() = default;
/**
* Must be called prior to destruction to wait for any ongoing work to complete.
*/
virtual void join() = 0;
/**
* Called by the CollectionShardingState::get method once per newly cached namespace. It is
* invoked under a mutex and must not acquire any locks or do blocking work.
*
* Implementations must be thread-safe when called from multiple threads.
*/
virtual std::unique_ptr<CollectionShardingState> make(const NamespaceString& nss) = 0;
protected:
CollectionShardingStateFactory(ServiceContext* serviceContext)
: _serviceContext(serviceContext) {}
// The service context which owns this factory
ServiceContext* const _serviceContext;
};
} // namespace mongo
|
