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
|
/**
* 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.
*/
#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kSharding
#include "mongo/platform/basic.h"
#include "mongo/db/s/implicit_create_collection.h"
#include <map>
#include <memory>
#include <string>
#include "mongo/db/catalog/database_holder.h"
#include "mongo/db/catalog_raii.h"
#include "mongo/db/commands.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/service_context.h"
#include "mongo/s/grid.h"
#include "mongo/s/request_types/create_collection_gen.h"
#include "mongo/platform/mutex.h"
#include "mongo/stdx/condition_variable.h"
#include "mongo/util/scopeguard.h"
namespace mongo {
namespace {
/**
* Responsible for explicitly creating collections in the sharding catalog. Also takes care of
* making sure that concurrent attempts to create a collection for the same ns will be
* synchronized and avoid duplicate work as much as possible.
*/
class CreateCollectionSerializer {
public:
explicit CreateCollectionSerializer(NamespaceString ns) : _ns(std::move(ns)) {}
/**
* Initialize this collection so it will be officially tracked in a sharded environment
* by sending the command to the config server to create an entry for this collection in
* the sharding catalog.
*/
Status onCannotImplicitlyCreateCollection(OperationContext* opCtx) noexcept {
invariant(!opCtx->lockState()->isLocked());
try {
stdx::unique_lock<Latch> lg(_mutex);
opCtx->waitForConditionOrInterrupt(_cvIsInProgress, lg, [&] { return !_isInProgress; });
_isInProgress = true;
} catch (const DBException& e) {
return e.toStatus();
}
ON_BLOCK_EXIT([&] {
stdx::lock_guard<Latch> lg(_mutex);
_isInProgress = false;
_cvIsInProgress.notify_one();
});
try {
// Take the DBLock and CollectionLock directly rather than using AutoGetCollection
// (which calls AutoGetDb) to avoid doing database and shard version checks.
Lock::DBLock dbLock(opCtx, _ns.db(), MODE_IS);
auto databaseHolder = DatabaseHolder::get(opCtx);
auto db = databaseHolder->getDb(opCtx, _ns.db());
if (db) {
Lock::CollectionLock collLock(opCtx, _ns, MODE_IS);
if (CollectionCatalog::get(opCtx).lookupCollectionByNamespace(opCtx, _ns)) {
// Collection already created, no more work needs to be done.
return Status::OK();
}
}
} catch (const DBException& ex) {
return ex.toStatus();
}
ConfigsvrCreateCollection configCreateCmd(_ns);
configCreateCmd.setDbName(NamespaceString::kAdminDb);
auto statusWith =
Grid::get(opCtx)->shardRegistry()->getConfigShard()->runCommandWithFixedRetryAttempts(
opCtx,
ReadPreferenceSetting{ReadPreference::PrimaryOnly},
NamespaceString::kAdminDb.toString(),
CommandHelpers::appendMajorityWriteConcern(configCreateCmd.toBSON({})),
Shard::RetryPolicy::kIdempotent);
if (!statusWith.isOK()) {
return statusWith.getStatus();
}
return Shard::CommandResponse::getEffectiveStatus(statusWith.getValue());
}
private:
const NamespaceString _ns;
Mutex _mutex = MONGO_MAKE_LATCH("CreateCollectionSerializer::_mutex");
stdx::condition_variable _cvIsInProgress;
bool _isInProgress = false;
};
class CreateCollectionSerializerMap {
public:
std::shared_ptr<CreateCollectionSerializer> getForNs(const NamespaceString& ns) {
stdx::lock_guard<Latch> lg(_mutex);
auto iter = _inProgressMap.find(ns.ns());
if (iter == _inProgressMap.end()) {
std::tie(iter, std::ignore) =
_inProgressMap.emplace(ns.ns(), std::make_shared<CreateCollectionSerializer>(ns));
}
return iter->second;
}
void cleanupNs(const NamespaceString& ns) {
stdx::lock_guard<Latch> lg(_mutex);
_inProgressMap.erase(ns.ns());
}
private:
Mutex _mutex = MONGO_MAKE_LATCH("CreateCollectionSerializerMap::_mutex");
std::map<std::string, std::shared_ptr<CreateCollectionSerializer>> _inProgressMap;
};
const auto createCollectionSerializerMap =
ServiceContext::declareDecoration<CreateCollectionSerializerMap>();
} // unnamed namespace
Status onCannotImplicitlyCreateCollection(OperationContext* opCtx,
const NamespaceString& ns) noexcept {
auto& handlerMap = createCollectionSerializerMap(opCtx->getServiceContext());
auto status = handlerMap.getForNs(ns)->onCannotImplicitlyCreateCollection(opCtx);
if (status.isOK()) {
handlerMap.cleanupNs(ns);
} else {
// We only cleanup on success because that is our last chance for us to do so. This avoids
// the scenario with multiple handlers for the same ns to exist at the same time if we
// cleanup regardless of success or failure. On the other hand, cleaning it up only on
// success can cause the handler to never get cleaned up when the collection was
// successfully created, but this shard got an error response from the config
// server.
}
return status;
}
} // namespace mongo
|