Abseil Common Libraries (C++) (grcp 依赖)
https://abseil.io/
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
100 lines
2.7 KiB
100 lines
2.7 KiB
// Copyright 2021 The Abseil Authors. |
|
// |
|
// 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 |
|
// |
|
// https://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. |
|
|
|
#ifndef ABSL_CLEANUP_INTERNAL_CLEANUP_H_ |
|
#define ABSL_CLEANUP_INTERNAL_CLEANUP_H_ |
|
|
|
#include <new> |
|
#include <type_traits> |
|
#include <utility> |
|
|
|
#include "absl/base/internal/invoke.h" |
|
#include "absl/base/macros.h" |
|
#include "absl/base/thread_annotations.h" |
|
#include "absl/utility/utility.h" |
|
|
|
namespace absl { |
|
ABSL_NAMESPACE_BEGIN |
|
|
|
namespace cleanup_internal { |
|
|
|
struct Tag {}; |
|
|
|
template <typename Arg, typename... Args> |
|
constexpr bool WasDeduced() { |
|
return (std::is_same<cleanup_internal::Tag, Arg>::value) && |
|
(sizeof...(Args) == 0); |
|
} |
|
|
|
template <typename Callback> |
|
constexpr bool ReturnsVoid() { |
|
return (std::is_same<base_internal::invoke_result_t<Callback>, void>::value); |
|
} |
|
|
|
template <typename Callback> |
|
class Storage { |
|
public: |
|
Storage() = delete; |
|
|
|
explicit Storage(Callback callback) { |
|
// Placement-new into a character buffer is used for eager destruction when |
|
// the cleanup is invoked or cancelled. To ensure this optimizes well, the |
|
// behavior is implemented locally instead of using an absl::optional. |
|
::new (GetCallbackBuffer()) Callback(std::move(callback)); |
|
is_callback_engaged_ = true; |
|
} |
|
|
|
Storage(Storage&& other) { |
|
ABSL_HARDENING_ASSERT(other.IsCallbackEngaged()); |
|
|
|
::new (GetCallbackBuffer()) Callback(std::move(other.GetCallback())); |
|
is_callback_engaged_ = true; |
|
|
|
other.DestroyCallback(); |
|
} |
|
|
|
Storage(const Storage& other) = delete; |
|
|
|
Storage& operator=(Storage&& other) = delete; |
|
|
|
Storage& operator=(const Storage& other) = delete; |
|
|
|
void* GetCallbackBuffer() { return static_cast<void*>(+callback_buffer_); } |
|
|
|
Callback& GetCallback() { |
|
return *reinterpret_cast<Callback*>(GetCallbackBuffer()); |
|
} |
|
|
|
bool IsCallbackEngaged() const { return is_callback_engaged_; } |
|
|
|
void DestroyCallback() { |
|
is_callback_engaged_ = false; |
|
GetCallback().~Callback(); |
|
} |
|
|
|
void InvokeCallback() ABSL_NO_THREAD_SAFETY_ANALYSIS { |
|
std::move(GetCallback())(); |
|
} |
|
|
|
private: |
|
bool is_callback_engaged_; |
|
alignas(Callback) char callback_buffer_[sizeof(Callback)]; |
|
}; |
|
|
|
} // namespace cleanup_internal |
|
|
|
ABSL_NAMESPACE_END |
|
} // namespace absl |
|
|
|
#endif // ABSL_CLEANUP_INTERNAL_CLEANUP_H_
|
|
|