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- /*
- * Copyright 2016-present Facebook, Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- #include <folly/detail/StaticSingletonManager.h>
- #include <mutex>
- #include <typeindex>
- #include <unordered_map>
- namespace folly {
- namespace detail {
- namespace {
- class StaticSingletonManagerImpl {
- public:
- void* create(std::type_info const& key, void* (*make)(void*), void* ctx) {
- auto& e = entry(key);
- std::lock_guard<std::mutex> lock(e.mutex);
- return e.ptr ? e.ptr : (e.ptr = make(ctx));
- }
- private:
- struct Entry {
- void* ptr{};
- std::mutex mutex;
- };
- Entry& entry(std::type_info const& key) {
- std::lock_guard<std::mutex> lock(mutex_);
- auto& e = map_[key];
- return e ? *e : *(e = new Entry());
- }
- std::unordered_map<std::type_index, Entry*> map_;
- std::mutex mutex_;
- };
- } // namespace
- void* StaticSingletonManager::create_(Key const& key, Make* make, void* ctx) {
- // This Leaky Meyers Singleton must always live in the .cpp file.
- static auto& instance = *new StaticSingletonManagerImpl();
- return instance.create(key, make, ctx);
- }
- } // namespace detail
- } // namespace folly
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