b5c48b97f6
Ongoing fixes and improvements, transient suppressor is gone. Also, dropping isac because it doesn't seem to be useful, and is just build system deadweight now. Upstream references: Version: 131.0.6778.200 WebRTC: 79aff54b0fa9238ce3518dd9eaf9610cd6f22e82 Chromium: 2a19506ad24af755f2a215a4c61f775393e0db42
131 lines
4.7 KiB
C++
131 lines
4.7 KiB
C++
/*
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* Copyright 2022 The WebRTC Project Authors. All rights reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef API_MAKE_REF_COUNTED_H_
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#define API_MAKE_REF_COUNTED_H_
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#include <type_traits>
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#include <utility>
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#include "absl/base/nullability.h"
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#include "api/ref_count.h"
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#include "api/scoped_refptr.h"
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#include "rtc_base/ref_counted_object.h"
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namespace webrtc {
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namespace webrtc_make_ref_counted_internal {
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// Determines if the given class has AddRef and Release methods.
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template <typename T>
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class HasAddRefAndRelease {
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private:
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template <typename C,
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decltype(std::declval<C>().AddRef())* = nullptr,
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decltype(std::declval<C>().Release())* = nullptr>
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static int Test(int);
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template <typename>
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static char Test(...);
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public:
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static constexpr bool value = std::is_same_v<decltype(Test<T>(0)), int>;
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};
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} // namespace webrtc_make_ref_counted_internal
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// General utilities for constructing a reference counted class and the
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// appropriate reference count implementation for that class.
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//
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// These utilities select either the `RefCountedObject` implementation or
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// `FinalRefCountedObject` depending on whether the to-be-shared class is
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// derived from the RefCountInterface interface or not (respectively).
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// `make_ref_counted`:
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//
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// Use this when you want to construct a reference counted object of type T and
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// get a `scoped_refptr<>` back. Example:
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//
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// auto p = make_ref_counted<Foo>("bar", 123);
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//
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// For a class that inherits from RefCountInterface, this is equivalent to:
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//
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// auto p = scoped_refptr<Foo>(new RefCountedObject<Foo>("bar", 123));
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//
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// If the class does not inherit from RefCountInterface, but does have
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// AddRef/Release methods (so a T* is convertible to rtc::scoped_refptr), this
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// is equivalent to just
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//
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// auto p = scoped_refptr<Foo>(new Foo("bar", 123));
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//
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// Otherwise, the example is equivalent to:
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//
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// auto p = scoped_refptr<FinalRefCountedObject<Foo>>(
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// new FinalRefCountedObject<Foo>("bar", 123));
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//
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// In these cases, `make_ref_counted` reduces the amount of boilerplate code but
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// also helps with the most commonly intended usage of RefCountedObject whereby
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// methods for reference counting, are virtual and designed to satisfy the need
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// of an interface. When such a need does not exist, it is more efficient to use
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// the `FinalRefCountedObject` template, which does not add the vtable overhead.
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//
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// Note that in some cases, using RefCountedObject directly may still be what's
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// needed.
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// `make_ref_counted` for abstract classes that are convertible to
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// RefCountInterface. The is_abstract requirement rejects classes that inherit
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// both RefCountInterface and RefCounted object, which is a a discouraged
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// pattern, and would result in double inheritance of RefCountedObject if this
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// template was applied.
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template <
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typename T,
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typename... Args,
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typename std::enable_if<std::is_convertible_v<T*, RefCountInterface*> &&
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std::is_abstract_v<T>,
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T>::type* = nullptr>
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absl::Nonnull<scoped_refptr<T>> make_ref_counted(Args&&... args) {
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return scoped_refptr<T>(new RefCountedObject<T>(std::forward<Args>(args)...));
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}
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// `make_ref_counted` for complete classes that are not convertible to
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// RefCountInterface and already carry a ref count.
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template <
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typename T,
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typename... Args,
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typename std::enable_if<
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!std::is_convertible_v<T*, RefCountInterface*> &&
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webrtc_make_ref_counted_internal::HasAddRefAndRelease<T>::value,
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T>::type* = nullptr>
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absl::Nonnull<scoped_refptr<T>> make_ref_counted(Args&&... args) {
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return scoped_refptr<T>(new T(std::forward<Args>(args)...));
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}
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// `make_ref_counted` for complete classes that are not convertible to
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// RefCountInterface and have no ref count of their own.
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template <
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typename T,
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typename... Args,
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typename std::enable_if<
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!std::is_convertible_v<T*, RefCountInterface*> &&
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!webrtc_make_ref_counted_internal::HasAddRefAndRelease<T>::value,
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T>::type* = nullptr>
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absl::Nonnull<scoped_refptr<FinalRefCountedObject<T>>> make_ref_counted(
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Args&&... args) {
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return scoped_refptr<FinalRefCountedObject<T>>(
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new FinalRefCountedObject<T>(std::forward<Args>(args)...));
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}
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} // namespace webrtc
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namespace rtc {
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// Backwards compatibe alias.
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// TODO: bugs.webrtc.org/42225969 - deprecate and remove.
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using ::webrtc::make_ref_counted;
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} // namespace rtc
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#endif // API_MAKE_REF_COUNTED_H_
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