// 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.

#include "dawn_native/PooledResourceMemoryAllocator.h"
#include "dawn_native/Device.h"

namespace dawn_native {

    PooledResourceMemoryAllocator::PooledResourceMemoryAllocator(
        ResourceHeapAllocator* heapAllocator)
        : mHeapAllocator(heapAllocator) {
    }

    void PooledResourceMemoryAllocator::DestroyPool() {
        for (auto& resourceHeap : mPool) {
            ASSERT(resourceHeap != nullptr);
            mHeapAllocator->DeallocateResourceHeap(std::move(resourceHeap));
        }

        mPool.clear();
    }

    ResultOrError<std::unique_ptr<ResourceHeapBase>>
    PooledResourceMemoryAllocator::AllocateResourceHeap(uint64_t size) {
        // Pooled memory is LIFO because memory can be evicted by LRU. However, this means
        // pooling is disabled in-frame when the memory is still pending. For high in-frame
        // memory users, FIFO might be preferable when memory consumption is a higher priority.
        std::unique_ptr<ResourceHeapBase> memory;
        if (!mPool.empty()) {
            memory = std::move(mPool.front());
            mPool.pop_front();
        }

        if (memory == nullptr) {
            DAWN_TRY_ASSIGN(memory, mHeapAllocator->AllocateResourceHeap(size));
        }

        return std::move(memory);
    }

    void PooledResourceMemoryAllocator::DeallocateResourceHeap(
        std::unique_ptr<ResourceHeapBase> allocation) {
        mPool.push_front(std::move(allocation));
    }

    uint64_t PooledResourceMemoryAllocator::GetPoolSizeForTesting() const {
        return mPool.size();
    }
}  // namespace dawn_native