mirror of
https://github.com/ecency/ecency-mobile.git
synced 2024-12-23 13:22:02 +03:00
88 lines
2.2 KiB
C++
88 lines
2.2 KiB
C++
/*
|
|
* Copyright 2016 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.
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include <mutex>
|
|
#include <typeindex>
|
|
#include <unordered_map>
|
|
|
|
namespace folly {
|
|
namespace detail {
|
|
|
|
// This internal-use-only class is used to create all leaked Meyers singletons.
|
|
// It guarantees that only one instance of every such singleton will ever be
|
|
// created, even when requested from different compilation units linked
|
|
// dynamically.
|
|
class StaticSingletonManager {
|
|
public:
|
|
static StaticSingletonManager& instance();
|
|
|
|
template <typename T, typename Tag, typename F>
|
|
inline T* create(F&& creator) {
|
|
auto& entry = [&]() mutable -> Entry<T>& {
|
|
std::lock_guard<std::mutex> lg(mutex_);
|
|
|
|
auto& id = typeid(TypePair<T, Tag>);
|
|
auto& entryPtr = map_[id];
|
|
if (!entryPtr) {
|
|
entryPtr = new Entry<T>();
|
|
}
|
|
assert(dynamic_cast<Entry<T>*>(entryPtr) != nullptr);
|
|
return *static_cast<Entry<T>*>(entryPtr);
|
|
}();
|
|
|
|
std::lock_guard<std::mutex> lg(entry.mutex);
|
|
|
|
if (!entry.ptr) {
|
|
entry.ptr = creator();
|
|
}
|
|
return entry.ptr;
|
|
}
|
|
|
|
private:
|
|
template <typename A, typename B>
|
|
class TypePair {};
|
|
|
|
StaticSingletonManager() {}
|
|
|
|
struct EntryIf {
|
|
virtual ~EntryIf() {}
|
|
};
|
|
|
|
template <typename T>
|
|
struct Entry : public EntryIf {
|
|
T* ptr{nullptr};
|
|
std::mutex mutex;
|
|
};
|
|
|
|
std::unordered_map<std::type_index, EntryIf*> map_;
|
|
std::mutex mutex_;
|
|
};
|
|
|
|
template <typename T, typename Tag, typename F>
|
|
inline T* createGlobal(F&& creator) {
|
|
return StaticSingletonManager::instance().create<T, Tag>(
|
|
std::forward<F>(creator));
|
|
}
|
|
|
|
template <typename T, typename Tag>
|
|
inline T* createGlobal() {
|
|
return createGlobal<T, Tag>([]() { return new T(); });
|
|
}
|
|
}
|
|
}
|