// Copyright 2021 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_CONCURRENTCACHE_H_
#define SRC_DAWN_COMMON_CONCURRENTCACHE_H_

#include <mutex>
#include <unordered_set>
#include <utility>

#include "dawn/common/NonCopyable.h"

namespace dawn {

template <typename T>
class ConcurrentCache : public NonMovable {
  public:
    ConcurrentCache() = default;

    T* Find(T* object) {
        std::lock_guard<std::mutex> lock(mMutex);
        auto iter = mCache.find(object);
        if (iter == mCache.end()) {
            return nullptr;
        }
        return *iter;
    }

    std::pair<T*, bool> Insert(T* object) {
        std::lock_guard<std::mutex> lock(mMutex);
        auto [value, inserted] = mCache.insert(object);
        return {*value, inserted};
    }

    size_t Erase(T* object) {
        std::lock_guard<std::mutex> lock(mMutex);
        return mCache.erase(object);
    }

  private:
    std::mutex mMutex;
    std::unordered_set<T*, typename T::HashFunc, typename T::EqualityFunc> mCache;
};

}  // namespace dawn

#endif  // SRC_DAWN_COMMON_CONCURRENTCACHE_H_
