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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 "rtc_base/ref_counter.h"
+
+namespace rtc {
+
+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::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 rtc::RefCountedNonVirtual<MyInt> {
+// int foo_ = 0;
+// };
+//
+// rtc::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 `rtc::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::webrtc_impl::RefCounter ref_count_{0};
+};
+
+} // namespace rtc
+
+#endif // API_REF_COUNTED_BASE_H_