// Copyright 2020 The Dawn 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 SRC_DAWN_NATIVE_POOLEDRESOURCEMEMORYALLOCATOR_H_
#define SRC_DAWN_NATIVE_POOLEDRESOURCEMEMORYALLOCATOR_H_

#include <deque>
#include <memory>

#include "dawn/common/SerialQueue.h"
#include "dawn/native/ResourceHeapAllocator.h"

namespace dawn::native {

class DeviceBase;

// |PooledResourceMemoryAllocator| allocates a fixed-size resource memory from a resource memory
// pool. Internally, it manages a list of heaps using LIFO (newest heaps are recycled first).
// The heap is in one of two states: AVAILABLE or not. Upon de-allocate, the heap is returned
// the pool and made AVAILABLE.
class PooledResourceMemoryAllocator : public ResourceHeapAllocator {
  public:
    explicit PooledResourceMemoryAllocator(ResourceHeapAllocator* heapAllocator);
    ~PooledResourceMemoryAllocator() override;

    ResultOrError<std::unique_ptr<ResourceHeapBase>> AllocateResourceHeap(uint64_t size) override;
    void DeallocateResourceHeap(std::unique_ptr<ResourceHeapBase> allocation) override;

    void DestroyPool();

    // For testing purposes.
    uint64_t GetPoolSizeForTesting() const;

  private:
    ResourceHeapAllocator* mHeapAllocator = nullptr;

    std::deque<std::unique_ptr<ResourceHeapBase>> mPool;
};

}  // namespace dawn::native

#endif  // SRC_DAWN_NATIVE_POOLEDRESOURCEMEMORYALLOCATOR_H_