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
|
/**
* 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 <map>
#include <memory>
#include <string>
#include <utility>
#include <vector>
#include "mongo/base/string_data.h"
#include "mongo/db/update/update_leaf_node.h"
namespace mongo {
/**
* The apply() function for an update modifier must
* 1) update the element at the update path if it exists;
* 2) raise a user error, indicate a no-op, or create and initialize a new element if the update
* path does not exist, depending on the specific modifier semantics;
* 3) check for any changes that modify an immutable path;
* 4) determine whether indexes may be affected;
* 5) validate that the updated document is valid for storage; and
* 6) create an oplog entry for the update.
* ModifierNode provides a generic implementation of the apply() function that does all this heavy
* lifting and calls out to modifier-specific overrides that customize apply() behavior where
* necessary.
*/
class ModifierNode : public UpdateLeafNode {
public:
explicit ModifierNode(Context context = Context::kAll) : UpdateLeafNode(context) {}
ApplyResult apply(ApplyParams applyParams,
UpdateNodeApplyParams updateNodeApplyParams) const final;
protected:
enum class ModifyResult {
// No log entry is necessary for no-op updates.
kNoOp,
// The update can be logged as normal (usually with a $set on the entire element).
kNormalUpdate,
// The element is an array, and the update only appends new array items to the end. The
// update can be logged as a $set on each appended element, rather than including the entire
// array in the log entry.
kArrayAppendUpdate,
// The element did not exist, so it was created then populated with setValueForNewElement().
// The updateExistingElement() method should never return this value.
kCreated
};
/**
* ModifierNode::apply() calls this method when applying an update to an existing path. The
* child's implementation of this method is responsible for updating 'element' and indicating
* what kind of update was performed in its return value.
*/
virtual ModifyResult updateExistingElement(mutablebson::Element* element,
const FieldRef& elementPath) const = 0;
/**
* ModifierNode::apply() calls this method when applying an update to a path that does not yet
* exist and should be created. The child's implementation of this method is responsible for
* assigning a value to the new element, which will initially be null.
*
* This method only gets called when the child class implementation of allowCreation() returns
* true. ModiferNode child classes should override setValueForNewElement() iff allowCreation()
* returns true.
*/
virtual void setValueForNewElement(mutablebson::Element* element) const {
// Only implementations that return true for allowCreation() will override this method.
MONGO_UNREACHABLE;
};
/**
* ModifierNode::apply() calls this method after it finishes applying its update to validate
* that no changes resulted in an invalid document. See the implementation of
* storage_validation::storageValid() for more detail about document validation requirements.
* Most ModifierNode child classes can use the default implementation of this method.
*
* - 'updatedElement' is the element that was set by either updateExistingElement() or
* setValueForNewElement().
* - 'leftSibling' and 'rightSibling' are the left and right siblings of 'updatedElement' or
* are invalid if 'updatedElement' is the first or last element in its object, respectively.
* If a ModifierNode deletes an element as part of its update (as $unset does),
* 'updatedElement' will be invalid, but validateUpdate() can use the siblings to perform
* validation instead.
* - 'recursionLevel' is the document nesting depth of the 'updatedElement' field.
* - 'modifyResult' is either the value returned by updateExistingElement() or the value
* ModifyResult::kCreated.
* - If 'validateForStorage' is true, we should verify that the updated element is valid for
* storage.
* - 'containsDotsAndDollarsField' is true if 'updatedElement' contains any dots/dollars field.
*/
virtual void validateUpdate(mutablebson::ConstElement updatedElement,
mutablebson::ConstElement leftSibling,
mutablebson::ConstElement rightSibling,
std::uint32_t recursionLevel,
ModifyResult modifyResult,
const bool validateForStorage,
bool* containsDotsAndDollarsField) const;
/**
* ModifierNode::apply() calls this method after validation to create an oplog entry for the
* applied update. Most ModifierNode child classes can use the default implementation of this
* method, which creates a $set entry using 'pathTaken' for the path and 'element' for the
* value.
*
* - 'logBuilder' provides the interface for appending log entries.
* - 'pathTaken' is the path of the applied update.
* - 'element' is the element that was set by either updateExistingElement() or
* setValueForNewElement().
* - 'modifyResult' is either the value returned by updateExistingElement() or the value
* ModifyResult::kCreated.
* - 'createdFieldIdx' indicates what the first component in 'pathTaken' is that was created as
* part of this update. If the update did not add any new fields, boost::none should be
* provided.
*/
virtual void logUpdate(LogBuilderInterface* logBuilder,
const RuntimeUpdatePath& pathTaken,
mutablebson::Element element,
ModifyResult modifyResult,
boost::optional<int> createdFieldIdx) const;
/**
* ModifierNode::apply() calls this method to determine what to do when applying an update to a
* path that does not exist. If the child class overrides this method to return true,
* ModifierNode::apply() will create a new element at the path and call setValueForNewElement()
* on it. Child classes must implement setValueForNewElement() iff this function returns true.
*/
virtual bool allowCreation() const {
return false;
}
/**
* When allowCreation() returns false, ModiferNode::apply() calls this method when determining
* if an update to a non-existent path is a no-op or an error. When allowNonViablePath() is
* false, an update to a path that could be created (i.e. a "viable" path) is a no-op, and an
* update to a path that could not be created results in a PathNotViable user error. When
* allowNonViablePath() is true, there is no viabilty check, and any update to a nonexistent
* path is a no-op.
*/
virtual bool allowNonViablePath() const {
return false;
}
/**
* When it is possible for updateExistingElement to replace the element's contents with an
* object value (e.g., {$set: {a: {c: 1}}} applied to the document {a: {b:1}}),
* ModifierNode::apply() has to do extra work to determine if any immutable paths have been
* modified. Any ModifierNode child class that can perform such an update should override this
* method to return true, so that ModifierNode::apply() knows to do the extra checks.
*/
virtual bool canSetObjectValue() const {
return false;
}
void produceSerializationMap(
FieldRef* currentPath,
std::map<std::string, std::vector<std::pair<std::string, BSONObj>>>*
operatorOrientedUpdates) const override {
(*operatorOrientedUpdates)[operatorName().toString()].emplace_back(
currentPath->dottedField(), operatorValue());
}
private:
/**
* Retrieve the name of the operator this node represents in input syntax. For example, for the
* input syntax: {$set: {a: 3}}, this function would return "$set".
*/
virtual StringData operatorName() const = 0;
/**
* Retrieve the value this operator applies as a single-element BSONObj with an empty string as
* the keyname. For example, for the input syntax: {$set: {a: 3}}, this function would return:
* {"": 3} in BSON.
*/
virtual BSONObj operatorValue() const = 0;
ApplyResult applyToNonexistentElement(ApplyParams applyParams,
UpdateNodeApplyParams updateNodeApplyParams) const;
ApplyResult applyToExistingElement(ApplyParams applyParams,
UpdateNodeApplyParams updateNodeApplyParams) const;
};
} // namespace mongo
|
