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
|
/**
* 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 <boost/optional.hpp>
#include <memory>
#include "mongo/platform/mutex.h"
#include "mongo/s/request_types/shard_collection_gen.h"
#include "mongo/util/concurrency/notification.h"
#include "mongo/util/string_map.h"
namespace mongo {
class OperationContext;
class ScopedShardCollection;
template <typename T>
class StatusWith;
/**
* Thread-safe object that keeps track of any active shardCollection commands running. There is only
* one instance of this object per shard.
*/
class ActiveShardCollectionRegistry {
ActiveShardCollectionRegistry(const ActiveShardCollectionRegistry&) = delete;
ActiveShardCollectionRegistry& operator=(const ActiveShardCollectionRegistry&) = delete;
public:
ActiveShardCollectionRegistry();
~ActiveShardCollectionRegistry();
static ActiveShardCollectionRegistry& get(ServiceContext* service);
static ActiveShardCollectionRegistry& get(OperationContext* opCtx);
/**
* If the collection being requested to shard is not already being sharded on this shard,
* registers an active shardCollection with the specified arguments. Returns a
* ScopedShardCollection object, which must be signaled by the caller before it goes out of
* scope.
*
* If this collection is already being sharded on this shard and it has the exact same
* arguments, returns a ScopedShardCollection. The ScopedShardCollection can be used to join the
* already running shard collection.
*
* Otherwise returns a ConflictingOperationInProgress error.
*/
StatusWith<ScopedShardCollection> registerShardCollection(
const ShardsvrShardCollection& request);
/**
* Takes a snapshot of all currently active shard collections and synchronously waits for each
* to complete.
*
* TODO SERVER-44034: Remove this method.
*/
void waitForActiveShardCollectionsToComplete(OperationContext* opCtx);
private:
friend class ScopedShardCollection;
// Describes the state of a currently active shardCollection operation
struct ActiveShardCollectionState {
ActiveShardCollectionState(ShardsvrShardCollection inRequest)
: activeRequest(std::move(inRequest)) {}
/**
* Constructs an error status to return in the case of conflicting operations.
*/
Status constructErrorStatus(const ShardsvrShardCollection& request) const;
// Exact arguments of the currently active operation
ShardsvrShardCollection activeRequest;
/**
* Promise that contains the uuid for this collection so that a shardCollection object
* that is in 'join' mode has access to the collection uuid.
*/
SharedPromise<boost::optional<UUID>> _uuidPromise;
};
/**
* Unregisters a previously registered namespace with an ongoing shardCollection. Must only be
* called if a previous call to registerShardCollection has succeeded.
*/
void _clearShardCollection(std::string nss);
// Fulfills the promise and stores the uuid for the collection if the status is OK or sets an
// error on the promise if it is not.
void _setUUIDOrError(std::string nss, StatusWith<boost::optional<UUID>> swUUID);
// Protects the state below
Mutex _mutex = MONGO_MAKE_LATCH("ActiveShardCollectionRegistry::_mutex");
// Map containing any collections currently being sharded
StringMap<std::shared_ptr<ActiveShardCollectionState>> _activeShardCollectionMap;
};
/**
* Object of this class is returned from the registerShardCollection call of the active shard
* collection registry. It can exist in two modes - 'execute' and 'join'. See the comments for
* registerShardCollection method for more details.
*/
class ScopedShardCollection {
ScopedShardCollection(const ScopedShardCollection&) = delete;
ScopedShardCollection& operator=(const ScopedShardCollection&) = delete;
public:
ScopedShardCollection(std::string nss,
ActiveShardCollectionRegistry* registry,
bool shouldExecute,
SharedSemiFuture<boost::optional<UUID>> uuidFuture);
~ScopedShardCollection();
ScopedShardCollection(ScopedShardCollection&&);
ScopedShardCollection& operator=(ScopedShardCollection&&);
/**
* Returns true if the shardCollection object is in the 'execute' mode. This means that the
* caller can execute the shardCollection command. The holder must execute the command and call
* signalComplete with a status.
*/
bool mustExecute() const {
return _shouldExecute;
}
/**
* Must only be called if the object is in the 'execute' mode when the shardCollection command
* was invoked (the command immediately executed). Will either emplace the uuid on the promise
* stored in the ActiveShardCollectionRegistry for this nss if status is OK or sets an error if
* it is not.
*/
void emplaceUUID(StatusWith<boost::optional<UUID>> swUUID);
/**
* Must only be called if the object is in the 'join' mode. Gets a future that contains the uuid
* for the collection.
*/
SharedSemiFuture<boost::optional<UUID>> getUUID();
private:
// Namespace of collection being sharded
std::string _nss;
// Registry from which to unregister the migration. Not owned.
ActiveShardCollectionRegistry* _registry;
/**
* Whether the holder is the first in line for a newly started shardCollection (in which case
* the destructor must unregister) or the caller is joining on an already-running
* shardCollection (in which case the caller must block and wait for completion).
*/
bool _shouldExecute;
// Future that will be signaled at the end of shardCollection, contains the uuid for the
// collection
SharedSemiFuture<boost::optional<UUID>> _uuidFuture;
};
} // namespace mongo
|
