| // Copyright 2021 gRPC 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 |
| // |
| // http://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 GRPC_CORE_LIB_SLICE_SLICE_REFCOUNT_BASE_H |
| #define GRPC_CORE_LIB_SLICE_SLICE_REFCOUNT_BASE_H |
| |
| #include <grpc/support/port_platform.h> |
| |
| #include <stddef.h> |
| |
| #include <atomic> |
| |
| // grpc_slice_refcount : A reference count for grpc_slice. |
| struct grpc_slice_refcount { |
| public: |
| typedef void (*DestroyerFn)(grpc_slice_refcount*); |
| |
| static grpc_slice_refcount* NoopRefcount() { |
| return reinterpret_cast<grpc_slice_refcount*>(1); |
| } |
| |
| grpc_slice_refcount() = default; |
| |
| // Regular constructor for grpc_slice_refcount. |
| // |
| // Parameters: |
| // 1. DestroyerFn destroyer_fn |
| // Called when the refcount goes to 0, with 'this' as parameter. |
| explicit grpc_slice_refcount(DestroyerFn destroyer_fn) |
| : destroyer_fn_(destroyer_fn) {} |
| |
| void Ref() { ref_.fetch_add(1, std::memory_order_relaxed); } |
| void Unref() { |
| if (ref_.fetch_sub(1, std::memory_order_acq_rel) == 1) { |
| destroyer_fn_(this); |
| } |
| } |
| |
| // Is this the only instance? |
| // For this to be useful the caller needs to ensure that if this is the only |
| // instance, no other instance could be created during this call. |
| bool IsUnique() const { return ref_.load(std::memory_order_relaxed) == 1; } |
| |
| private: |
| std::atomic<size_t> ref_{1}; |
| DestroyerFn destroyer_fn_ = nullptr; |
| }; |
| |
| #endif // GRPC_CORE_LIB_SLICE_SLICE_REFCOUNT_BASE_H |