1 | /* |
2 | * Copyright 2018-present Facebook, Inc. |
3 | * |
4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
5 | * you may not use this file except in compliance with the License. |
6 | * You may obtain a copy of the License at |
7 | * |
8 | * http://www.apache.org/licenses/LICENSE-2.0 |
9 | * |
10 | * Unless required by applicable law or agreed to in writing, software |
11 | * distributed under the License is distributed on an "AS IS" BASIS, |
12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
13 | * See the License for the specific language governing permissions and |
14 | * limitations under the License. |
15 | */ |
16 | #include <folly/experimental/settings/Settings.h> |
17 | |
18 | #include <map> |
19 | |
20 | #include <folly/Synchronized.h> |
21 | |
22 | namespace folly { |
23 | namespace settings { |
24 | namespace detail { |
25 | namespace { |
26 | using SettingsMap = std::map<std::string, SettingCoreBase*>; |
27 | Synchronized<SettingsMap>& settingsMap() { |
28 | static Indestructible<Synchronized<SettingsMap>> map; |
29 | return *map; |
30 | } |
31 | } // namespace |
32 | |
33 | void registerSetting(SettingCoreBase& core) { |
34 | if (core.meta().project.empty() || |
35 | core.meta().project.find('_') != std::string::npos) { |
36 | throw std::logic_error( |
37 | "Setting project must be nonempty and cannot contain underscores: " + |
38 | core.meta().project.str()); |
39 | } |
40 | |
41 | auto fullname = core.meta().project.str() + "_" + core.meta().name.str(); |
42 | |
43 | auto mapPtr = settingsMap().wlock(); |
44 | auto it = mapPtr->find(fullname); |
45 | if (it != mapPtr->end()) { |
46 | throw std::logic_error("FOLLY_SETTING already exists: " + fullname); |
47 | } |
48 | mapPtr->emplace(std::move(fullname), &core); |
49 | } |
50 | |
51 | } // namespace detail |
52 | |
53 | Optional<SettingMetadata> getSettingsMeta(StringPiece settingName) { |
54 | auto mapPtr = detail::settingsMap().rlock(); |
55 | auto it = mapPtr->find(settingName.str()); |
56 | if (it == mapPtr->end()) { |
57 | return none; |
58 | } |
59 | return it->second->meta(); |
60 | } |
61 | |
62 | bool Snapshot::setFromString( |
63 | StringPiece settingName, |
64 | StringPiece newValue, |
65 | StringPiece reason) { |
66 | auto mapPtr = detail::settingsMap().rlock(); |
67 | auto it = mapPtr->find(settingName.str()); |
68 | if (it == mapPtr->end()) { |
69 | return false; |
70 | } |
71 | it->second->setFromString(newValue, reason, this); |
72 | return true; |
73 | } |
74 | |
75 | Optional<Snapshot::SettingsInfo> Snapshot::getAsString( |
76 | StringPiece settingName) const { |
77 | auto mapPtr = detail::settingsMap().rlock(); |
78 | auto it = mapPtr->find(settingName.str()); |
79 | if (it == mapPtr->end()) { |
80 | return none; |
81 | } |
82 | return it->second->getAsString(this); |
83 | } |
84 | |
85 | bool Snapshot::resetToDefault(StringPiece settingName) { |
86 | auto mapPtr = detail::settingsMap().rlock(); |
87 | auto it = mapPtr->find(settingName.str()); |
88 | if (it == mapPtr->end()) { |
89 | return false; |
90 | } |
91 | it->second->resetToDefault(this); |
92 | return true; |
93 | } |
94 | |
95 | void Snapshot::forEachSetting( |
96 | const std::function<void(const SettingMetadata&, StringPiece, StringPiece)>& |
97 | func) const { |
98 | detail::SettingsMap map; |
99 | /* Note that this won't hold the lock over the callback, which is |
100 | what we want since the user might call other settings:: APIs */ |
101 | map = *detail::settingsMap().rlock(); |
102 | for (const auto& kv : map) { |
103 | auto value = kv.second->getAsString(this); |
104 | func(kv.second->meta(), value.first, value.second); |
105 | } |
106 | } |
107 | |
108 | namespace detail { |
109 | std::atomic<SettingCoreBase::Version> gGlobalVersion_; |
110 | |
111 | auto& getSavedValuesMutex() { |
112 | static SharedMutex gSavedValuesMutex; |
113 | return gSavedValuesMutex; |
114 | } |
115 | |
116 | /* Version -> (count of outstanding snapshots, saved setting values) */ |
117 | auto& getSavedValues() { |
118 | static std::unordered_map< |
119 | SettingCoreBase::Version, |
120 | std::pair<size_t, std::unordered_map<SettingCoreBase::Key, BoxedValue>>> |
121 | gSavedValues; |
122 | return gSavedValues; |
123 | } |
124 | |
125 | SettingCoreBase::Version nextGlobalVersion() { |
126 | return gGlobalVersion_.fetch_add(1) + 1; |
127 | } |
128 | |
129 | void saveValueForOutstandingSnapshots( |
130 | SettingCoreBase::Key settingKey, |
131 | SettingCoreBase::Version version, |
132 | const BoxedValue& value) { |
133 | SharedMutex::WriteHolder lg(getSavedValuesMutex()); |
134 | for (auto& it : getSavedValues()) { |
135 | if (version <= it.first) { |
136 | it.second.second[settingKey] = value; |
137 | } |
138 | } |
139 | } |
140 | |
141 | const BoxedValue* FOLLY_NULLABLE |
142 | getSavedValue(SettingCoreBase::Key settingKey, SettingCoreBase::Version at) { |
143 | SharedMutex::ReadHolder lg(getSavedValuesMutex()); |
144 | auto it = getSavedValues().find(at); |
145 | if (it != getSavedValues().end()) { |
146 | auto jt = it->second.second.find(settingKey); |
147 | if (jt != it->second.second.end()) { |
148 | return &jt->second; |
149 | } |
150 | } |
151 | return nullptr; |
152 | } |
153 | |
154 | SnapshotBase::SnapshotBase() { |
155 | SharedMutex::WriteHolder lg(detail::getSavedValuesMutex()); |
156 | at_ = detail::gGlobalVersion_.load(); |
157 | auto it = detail::getSavedValues().emplace( |
158 | std::piecewise_construct, |
159 | std::forward_as_tuple(at_), |
160 | std::forward_as_tuple()); |
161 | ++it.first->second.first; |
162 | } |
163 | |
164 | SnapshotBase::~SnapshotBase() { |
165 | SharedMutex::WriteHolder lg(detail::getSavedValuesMutex()); |
166 | auto it = detail::getSavedValues().find(at_); |
167 | assert(it != detail::getSavedValues().end()); |
168 | --it->second.first; |
169 | if (!it->second.first) { |
170 | detail::getSavedValues().erase(at_); |
171 | } |
172 | } |
173 | |
174 | } // namespace detail |
175 | |
176 | void Snapshot::publish() { |
177 | for (auto& it : snapshotValues_) { |
178 | it.second.publish(); |
179 | } |
180 | } |
181 | |
182 | } // namespace settings |
183 | } // namespace folly |
184 | |