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
210
211
212
213
214
215
216
|
/**
* 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 <functional>
#include <map>
#include <memory>
#include <string>
#include <tuple>
#include <vector>
#include "mongo/base/status.h"
#include "mongo/base/status_with.h"
#include "mongo/base/string_data.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/views/durable_view_catalog.h"
#include "mongo/db/views/resolved_view.h"
#include "mongo/db/views/view.h"
#include "mongo/db/views/view_graph.h"
#include "mongo/platform/mutex.h"
#include "mongo/util/concurrency/with_lock.h"
#include "mongo/util/string_map.h"
namespace mongo {
class OperationContext;
class Database;
/**
* In-memory data structure for view definitions. Instances returned by get() are immutable,
* modifications through the static functions copy the existing instance and perform the
* modification on the copy. A new call to get() is necessary to observe the modification.
*
* Writes via the static functions are thread-safe and serialized with a mutex per Database -- this
* is needed as concurrent updates may happen through direct writes to the views catalog collection.
*
* The static methods refresh the in-memory map with the views catalog collection if necessary,
* throwing if the refresh fails.
*/
class ViewCatalog {
public:
using ViewMap = StringMap<std::shared_ptr<ViewDefinition>>;
using ViewIteratorCallback = std::function<bool(const ViewDefinition& view)>;
static std::shared_ptr<const ViewCatalog> get(const Database* db);
static void set(Database* db, std::unique_ptr<ViewCatalog> catalog);
explicit ViewCatalog(std::unique_ptr<DurableViewCatalog> durable)
: _durable(std::move(durable)), _valid(false), _viewGraphNeedsRefresh(true) {}
/**
* Iterates through the catalog, applying 'callback' to each view. This callback function
* executes under the catalog's mutex, so it must not access other methods of the catalog,
* acquire locks or run for a long time. If the 'callback' returns false, the iterator exists
* early.
*/
void iterate(ViewIteratorCallback callback) const;
/**
* Create a new view 'viewName' with contents defined by running the specified aggregation
* 'pipeline' with collation 'collation' on a collection or view 'viewOn'. This method will
* check correctness with respect to the view catalog, but will not check for conflicts with the
* database's catalog, so the check for an existing collection with the same name must be done
* before calling createView.
*
* Must be in WriteUnitOfWork. View creation rolls back if the unit of work aborts.
*/
static Status createView(OperationContext* opCtx,
const Database* db,
const NamespaceString& viewName,
const NamespaceString& viewOn,
const BSONArray& pipeline,
const BSONObj& collation);
/**
* Drop the view named 'viewName'.
*
* Must be in WriteUnitOfWork. The drop rolls back if the unit of work aborts.
*/
static Status dropView(OperationContext* opCtx,
const Database* db,
const NamespaceString& viewName);
/**
* Modify the view named 'viewName' to have the new 'viewOn' and 'pipeline'.
*
* Must be in WriteUnitOfWork. The modification rolls back if the unit of work aborts.
*/
static Status modifyView(OperationContext* opCtx,
const Database* db,
const NamespaceString& viewName,
const NamespaceString& viewOn,
const BSONArray& pipeline);
/**
* Look up the 'nss' in the view catalog, returning a shared pointer to a View definition, or
* nullptr if it doesn't exist.
*/
std::shared_ptr<const ViewDefinition> lookup(OperationContext* opCtx, StringData nss) const;
/**
* Same functionality as above, except this function skips validating durable views in the view
* catalog.
*/
std::shared_ptr<const ViewDefinition> lookupWithoutValidatingDurableViews(
OperationContext* opCtx, StringData nss) const;
/**
* Resolve the views on 'nss', transforming the pipeline appropriately. This function returns a
* fully-resolved view definition containing the backing namespace, the resolved pipeline and
* the collation to use for the operation.
*/
StatusWith<ResolvedView> resolveView(OperationContext* opCtx, const NamespaceString& nss) const;
/**
* Returns Status::OK with the set of involved namespaces if the given pipeline is eligible to
* act as a view definition. Otherwise, returns ErrorCodes::OptionNotSupportedOnView.
*/
static StatusWith<stdx::unordered_set<NamespaceString>> validatePipeline(
OperationContext* opCtx, const ViewDefinition& viewDef);
/**
* Reloads the in-memory state of the view catalog from the 'system.views' collection catalog.
* If the 'lookupBehavior' is 'kValidateDurableViews', then the durable view definitions will be
* validated. Reading stops on the first invalid entry with errors logged and returned. Performs
* no cycle detection, etc.
* This is implicitly called by other methods when write operations are performed on the view
* catalog, on external changes to the 'system.views' collection and on the first opening of a
* database.
*/
static Status reload(OperationContext* opCtx,
const Database* db,
ViewCatalogLookupBehavior lookupBehavior);
/**
* Clears the in-memory state of the view catalog.
*/
static void clear(const Database* db);
/**
* The view catalog needs to ignore external changes for its own modifications.
*/
static bool shouldIgnoreExternalChange(OperationContext* opCtx,
const Database* db,
const NamespaceString& name);
private:
Status _createOrUpdateView(OperationContext* opCtx,
const NamespaceString& viewName,
const NamespaceString& viewOn,
const BSONArray& pipeline,
std::unique_ptr<CollatorInterface> collator);
/**
* Parses the view definition pipeline, attempts to upsert into the view graph, and refreshes
* the graph if necessary. Returns an error status if the resulting graph would be invalid.
*/
Status _upsertIntoGraph(OperationContext* opCtx, const ViewDefinition& viewDef);
/**
* Returns Status::OK if each view namespace in 'refs' has the same default collation as 'view'.
* Otherwise, returns ErrorCodes::OptionNotSupportedOnView.
*/
Status _validateCollation(OperationContext* opCtx,
const ViewDefinition& view,
const std::vector<NamespaceString>& refs) const;
std::shared_ptr<const ViewDefinition> _lookup(OperationContext* opCtx,
StringData ns,
ViewCatalogLookupBehavior lookupBehavior) const;
std::shared_ptr<ViewDefinition> _lookup(OperationContext* opCtx,
StringData ns,
ViewCatalogLookupBehavior lookupBehavior);
Status _reload(OperationContext* opCtx, ViewCatalogLookupBehavior lookupBehavior);
/**
* uasserts with the InvalidViewDefinition error if the current in-memory state of the view
* catalog is invalid. This ensures that calling into the view catalog while it is invalid
* renders it inoperable.
*/
void _requireValidCatalog() const;
ViewMap _viewMap;
ViewMap _viewMapBackup;
std::shared_ptr<DurableViewCatalog> _durable;
bool _valid;
ViewGraph _viewGraph;
bool _viewGraphNeedsRefresh;
};
} // namespace mongo
|