| // Copyright 2023 The Dawn & Tint Authors |
| // |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are met: |
| // |
| // 1. Redistributions of source code must retain the above copyright notice, this |
| // list of conditions and the following disclaimer. |
| // |
| // 2. Redistributions in binary form must reproduce the above copyright notice, |
| // this list of conditions and the following disclaimer in the documentation |
| // and/or other materials provided with the distribution. |
| // |
| // 3. Neither the name of the copyright holder nor the names of its |
| // contributors may be used to endorse or promote products derived from |
| // this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
| // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE |
| // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR |
| // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
| // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| #ifndef SRC_DAWN_COMMON_WEAKREFSUPPORT_H_ |
| #define SRC_DAWN_COMMON_WEAKREFSUPPORT_H_ |
| |
| #include "dawn/common/Compiler.h" |
| #include "dawn/common/Ref.h" |
| #include "partition_alloc/pointers/raw_ptr.h" |
| |
| namespace dawn { |
| |
| template <typename T> |
| class WeakRef; |
| |
| namespace detail { |
| |
| // Indirection layer to provide external ref-counting for WeakRefs. |
| class WeakRefData : public RefCounted { |
| public: |
| explicit WeakRefData(RefCounted* value); |
| void Invalidate(); |
| |
| // Tries to return a valid Ref to `mValue` if it's internal refcount is not already 0. If the |
| // internal refcount has already reached 0, returns nullptr instead. |
| Ref<RefCounted> TryGetRef(); |
| |
| // Returns the raw pointer to the RefCounted. In general, this is an unsafe operation because |
| // the RefCounted can become invalid after being retrieved. |
| RefCounted* UnsafeGet() const; |
| |
| private: |
| std::mutex mMutex; |
| raw_ptr<RefCounted> mValue = nullptr; |
| }; |
| |
| // Interface base class used to enable compile-time verification of WeakRefSupport functions. |
| class WeakRefSupportBase { |
| protected: |
| explicit WeakRefSupportBase(Ref<detail::WeakRefData> data); |
| virtual ~WeakRefSupportBase(); |
| |
| private: |
| template <typename T> |
| friend class ::dawn::WeakRef; |
| |
| Ref<detail::WeakRefData> mData; |
| }; |
| |
| } // namespace detail |
| |
| // Class that should be extended to enable WeakRefs for the type. |
| template <typename T> |
| class WeakRefSupport : public detail::WeakRefSupportBase { |
| public: |
| #if DAWN_COMPILER_IS(CLANG) |
| // Note that the static cast below fails CFI builds due to the cast. The cast itself is |
| // safe so we suppress the failure. See the following link regarding the cast: |
| // https://stackoverflow.com/questions/73172193/can-you-static-cast-this-to-a-derived-class-in-a-base-class-constructor-then-u, |
| DAWN_NO_SANITIZE("cfi-derived-cast") |
| #endif |
| WeakRefSupport() |
| : WeakRefSupportBase(AcquireRef(new detail::WeakRefData(static_cast<T*>(this)))) {} |
| }; |
| |
| } // namespace dawn |
| |
| #endif // SRC_DAWN_COMMON_WEAKREFSUPPORT_H_ |