lib/AtomicSharedPtr.h

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */
#pragma once

#include <memory>
namespace pulsar {

// C++17 does not have std::atomic<std::shared_ptr<T>>, so we have to manually implement it.
template <typename T>
class AtomicSharedPtr {
   public:
    using Pointer = std::shared_ptr<const T>;

    AtomicSharedPtr() = default;
    explicit AtomicSharedPtr(T value) : ptr_(std::make_shared<const T>(std::move(value))) {}

    auto load() const { return std::atomic_load(&ptr_); }

    void store(Pointer&& newPtr) { std::atomic_store(&ptr_, std::move(newPtr)); }

   private:
    std::shared_ptr<const T> ptr_;
};

}  // namespace pulsar