// Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
//
// 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 "paddle/fluid/memory/allocation/buffered_allocator.h"

#include <gtest/gtest.h>

#include <utility>

#include "paddle/fluid/memory/allocation/best_fit_allocator.h"
#include "paddle/fluid/memory/allocation/cpu_allocator.h"

namespace paddle {
namespace memory {
namespace allocation {

class StubAllocation : public Allocation {
 public:
  using Allocation::Allocation;
};

class StubAllocator : public Allocator {
 public:
  void ResetCounter() {
    construct_count_ = 0;
    destruct_count_ = 0;
  }

  size_t GetAllocCount() const { return construct_count_; }

  size_t GetFreeCount() const { return destruct_count_; }

 protected:
  void FreeImpl(phi::Allocation *allocation) override {
    auto *alloc = dynamic_cast<StubAllocation *>(allocation);
    PADDLE_ENFORCE_NOT_NULL(
        alloc,
        platform::errors::InvalidArgument(
            "The input allocation is not type of StubAllocation."));
    if (alloc->ptr()) delete[] static_cast<uint8_t *>(alloc->ptr());
    ++destruct_count_;
    delete allocation;
  }
  phi::Allocation *AllocateImpl(size_t size) override {
    ++construct_count_;
    if (size == 0) {
      return new StubAllocation(nullptr, 0, platform::CPUPlace());
    } else {
      return new StubAllocation(new uint8_t[size], size, platform::CPUPlace());
    }
  }

 private:
  size_t construct_count_ = 0;
  size_t destruct_count_ = 0;
};

constexpr size_t kZero = 0;
constexpr size_t kOne = 1;
constexpr size_t kTwo = 2;

TEST(buffered_allocator, lazy_free) {
  std::unique_ptr<StubAllocator> stub_allocator(new StubAllocator());
  auto *underlying_allocator = stub_allocator.get();
  std::unique_ptr<BufferedAllocator> allocator(
      new BufferedAllocator(std::move(stub_allocator)));

  {
    underlying_allocator->ResetCounter();
    auto x = allocator->Allocate(1025);
    ASSERT_EQ(underlying_allocator->GetAllocCount(), kOne);
    ASSERT_EQ(underlying_allocator->GetFreeCount(), kZero);
    x = nullptr;
    ASSERT_EQ(underlying_allocator->GetFreeCount(), kZero);
  }

  {
    underlying_allocator->ResetCounter();
    auto x = allocator->Allocate(900);
    ASSERT_EQ(underlying_allocator->GetAllocCount(), kZero);
    ASSERT_EQ(underlying_allocator->GetFreeCount(), kZero);
    auto y = allocator->Allocate(2048);
    ASSERT_EQ(underlying_allocator->GetAllocCount(), kOne);
    ASSERT_EQ(underlying_allocator->GetFreeCount(), kZero);
    x = nullptr;
    ASSERT_EQ(underlying_allocator->GetFreeCount(), kZero);
    y = nullptr;
    ASSERT_EQ(underlying_allocator->GetFreeCount(), kZero);
  }

  {
    underlying_allocator->ResetCounter();
    allocator->ClearCache();
    ASSERT_EQ(underlying_allocator->GetAllocCount(), kZero);
    ASSERT_EQ(underlying_allocator->GetFreeCount(), kTwo);
  }
}

TEST(buffered_allocator, garbage_collection) {
  std::unique_ptr<CPUAllocator> cpu_allocator(new CPUAllocator());
  auto chunk = cpu_allocator->Allocate(2048);
  std::unique_ptr<Allocator> allocator(new BestFitAllocator(chunk.get()));

  auto buffered_allocator =
      std::make_unique<BufferedAllocator>(std::move(allocator));
  auto x1 = buffered_allocator->Allocate(1600);
  auto x2 = buffered_allocator->Allocate(400);
  x1 = nullptr;
  x2 = nullptr;
  auto x3 = buffered_allocator->Allocate(1600);
  ASSERT_NE(x3, nullptr);
  ASSERT_NE(x3->ptr(), nullptr);
}

}  // namespace allocation
}  // namespace memory
}  // namespace paddle
