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/*
* Copyright 2017 The WebRTC Project Authors. All rights reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef API_REF_COUNTED_BASE_H_
#define API_REF_COUNTED_BASE_H_
#include <type_traits>
#include "api/ref_count.h"
#include "rtc_base/ref_counter.h"
namespace webrtc {
class RefCountedBase {
public:
RefCountedBase() = default;
RefCountedBase(const RefCountedBase&) = delete;
RefCountedBase& operator=(const RefCountedBase&) = delete;
void AddRef() const { ref_count_.IncRef(); }
RefCountReleaseStatus Release() const {
const auto status = ref_count_.DecRef();
if (status == RefCountReleaseStatus::kDroppedLastRef) {
delete this;
}
return status;
}
protected:
// Provided for internal webrtc subclasses for corner cases where it's
// necessary to know whether or not a reference is exclusively held.
bool HasOneRef() const { return ref_count_.HasOneRef(); }
virtual ~RefCountedBase() = default;
private:
mutable webrtc_impl::RefCounter ref_count_{0};
};
// Template based version of `RefCountedBase` for simple implementations that do
// not need (or want) destruction via virtual destructor or the overhead of a
// vtable.
//
// To use:
// struct MyInt : public RefCountedNonVirtual<MyInt> {
// int foo_ = 0;
// };
//
// scoped_refptr<MyInt> my_int(new MyInt());
//
// sizeof(MyInt) on a 32 bit system would then be 8, int + refcount and no
// vtable generated.
template <typename T>
class RefCountedNonVirtual {
public:
RefCountedNonVirtual() = default;
RefCountedNonVirtual(const RefCountedNonVirtual&) = delete;
RefCountedNonVirtual& operator=(const RefCountedNonVirtual&) = delete;
void AddRef() const { ref_count_.IncRef(); }
RefCountReleaseStatus Release() const {
// If you run into this assert, T has virtual methods. There are two
// options:
// 1) The class doesn't actually need virtual methods, the type is complete
// so the virtual attribute(s) can be removed.
// 2) The virtual methods are a part of the design of the class. In this
// case you can consider using `RefCountedBase` instead or alternatively
// use `RefCountedObject`.
static_assert(!std::is_polymorphic<T>::value,
"T has virtual methods. RefCountedBase is a better fit.");
const auto status = ref_count_.DecRef();
if (status == RefCountReleaseStatus::kDroppedLastRef) {
delete static_cast<const T*>(this);
}
return status;
}
protected:
// Provided for internal webrtc subclasses for corner cases where it's
// necessary to know whether or not a reference is exclusively held.
bool HasOneRef() const { return ref_count_.HasOneRef(); }
~RefCountedNonVirtual() = default;
private:
mutable webrtc_impl::RefCounter ref_count_{0};
};
} // namespace webrtc
// Backwards compatibe aliases.
// TODO: https://issues.webrtc.org/42225969 - deprecate and remove.
#ifdef WEBRTC_ALLOW_DEPRECATED_NAMESPACES
namespace rtc {
using RefCountedBase = webrtc::RefCountedBase;
template <typename T>
using RefCountedNonVirtual = webrtc::RefCountedNonVirtual<T>;
} // namespace rtc
#endif // WEBRTC_ALLOW_DEPRECATED_NAMESPACES
#endif // API_REF_COUNTED_BASE_H_
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