folly/folly/detail/StaticSingletonManager.h

/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * 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 <atomic>
#include <typeinfo>

#include <folly/CPortability.h>
#include <folly/Indestructible.h>
#include <folly/Likely.h>
#include <folly/Utility.h>
#include <folly/detail/Singleton.h>
#include <folly/lang/Thunk.h>
#include <folly/lang/TypeInfo.h>

namespace folly {
namespace detail {

// Does not support dynamic loading but works without rtti.
class StaticSingletonManagerSansRtti { … };

debug;

// 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.
//
// Supports dynamic loading but requires rtti.
class StaticSingletonManagerWithRtti { … };

debug;

StaticSingletonManager;

template <typename T, typename Tag>
FOLLY_ERASE T& createGlobal() { … }

} // namespace detail
} // namespace folly