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
|
/**
* 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.
*/
#include "mongo/base/initializer_dependency_graph.h"
#include <algorithm>
#include <iterator>
#include <sstream>
namespace mongo {
InitializerDependencyGraph::InitializerDependencyGraph() {}
InitializerDependencyGraph::~InitializerDependencyGraph() {}
Status InitializerDependencyGraph::addInitializer(std::string name,
InitializerFunction initFn,
DeinitializerFunction deinitFn,
std::vector<std::string> prerequisites,
std::vector<std::string> dependents) {
if (!initFn)
return Status(ErrorCodes::BadValue, "Illegal to supply a NULL function");
InitializerDependencyNode& newNode = _nodes[name];
if (newNode.initFn) {
return Status(ErrorCodes::DuplicateKey, name);
}
newNode.initFn = std::move(initFn);
newNode.deinitFn = std::move(deinitFn);
for (size_t i = 0; i < prerequisites.size(); ++i) {
newNode.prerequisites.insert(prerequisites[i]);
}
for (size_t i = 0; i < dependents.size(); ++i) {
_nodes[dependents[i]].prerequisites.insert(name);
}
return Status::OK();
}
InitializerDependencyNode* InitializerDependencyGraph::getInitializerNode(const std::string& name) {
NodeMap::iterator iter = _nodes.find(name);
if (iter == _nodes.end())
return nullptr;
return &iter->second;
}
Status InitializerDependencyGraph::topSort(std::vector<std::string>* sortedNames) const {
/*
* This top-sort is implemented by performing a depth-first traversal of the dependency
* graph, once for each node. "visitedNodeNames" tracks the set of node names ever visited,
* and it is used to prune each DFS. A node that has been visited once on any DFS is never
* visited again. Complexity of this implementation is O(n+m) where "n" is the number of
* nodes and "m" is the number of prerequisite edges. Space complexity is O(n), in both
* stack space and size of the "visitedNodeNames" set.
*
* "inProgressNodeNames" is used to detect and report cycles.
*/
std::vector<std::string> inProgressNodeNames;
stdx::unordered_set<std::string> visitedNodeNames;
sortedNames->clear();
for (const auto& node : _nodes) {
Status status =
recursiveTopSort(_nodes, node, &inProgressNodeNames, &visitedNodeNames, sortedNames);
if (Status::OK() != status)
return status;
}
for (const auto& node : _nodes) {
if (!node.second.initFn) {
std::ostringstream os;
os << "No implementation provided for initializer " << node.first;
return {ErrorCodes::BadValue, os.str()};
}
}
return Status::OK();
}
Status InitializerDependencyGraph::recursiveTopSort(
const NodeMap& nodeMap,
const Node& currentNode,
std::vector<std::string>* inProgressNodeNames,
stdx::unordered_set<std::string>* visitedNodeNames,
std::vector<std::string>* sortedNames) {
/*
* The top sort is performed by depth-first traversal starting at each node in the
* dependency graph, short-circuited any time a node is seen that has already been visited
* in any traversal. "visitedNodeNames" is the set of nodes that have been successfully
* visited, while "inProgressNodeNames" are nodes currently in the exploration chain. This
* structure is kept explicitly to facilitate cycle detection.
*
* This function implements a depth-first traversal, and is called once for each node in the
* graph by topSort(), above.
*/
if ((*visitedNodeNames).count(currentNode.first))
return Status::OK();
inProgressNodeNames->push_back(currentNode.first);
auto firstOccurence =
std::find(inProgressNodeNames->begin(), inProgressNodeNames->end(), currentNode.first);
if (std::next(firstOccurence) != inProgressNodeNames->end()) {
sortedNames->clear();
std::copy(firstOccurence, inProgressNodeNames->end(), std::back_inserter(*sortedNames));
std::ostringstream os;
os << "Cycle in dependendcy graph: " << sortedNames->at(0);
for (size_t i = 1; i < sortedNames->size(); ++i)
os << " -> " << sortedNames->at(i);
return Status(ErrorCodes::GraphContainsCycle, os.str());
}
for (const auto& prereq : currentNode.second.prerequisites) {
auto nextNode = nodeMap.find(prereq);
if (nextNode == nodeMap.end()) {
std::ostringstream os;
os << "Initializer " << currentNode.first << " depends on missing initializer "
<< prereq;
return {ErrorCodes::BadValue, os.str()};
}
Status status = recursiveTopSort(
nodeMap, *nextNode, inProgressNodeNames, visitedNodeNames, sortedNames);
if (Status::OK() != status)
return status;
}
sortedNames->push_back(currentNode.first);
if (inProgressNodeNames->back() != currentNode.first)
return Status(ErrorCodes::InternalError, "inProgressNodeNames stack corrupt");
inProgressNodeNames->pop_back();
visitedNodeNames->insert(currentNode.first);
return Status::OK();
}
} // namespace mongo
|
