//  Copyright (c) Meta Platforms, Inc. and affiliates.

//  This source code is licensed under both the GPLv2 (found in the

//  COPYING file in the root directory) and Apache 2.0 License

//  (found in the LICENSE.Apache file in the root directory).

#pragma once

#include <memory>

#include "memory/memory_allocator_impl.h"

#include "rocksdb/advanced_cache.h"

#include "rocksdb/rocksdb_namespace.h"

#include "rocksdb/slice.h"

#include "rocksdb/status.h"

namespace ROCKSDB_NAMESPACE {

// A class representing a single uncompressed value read from a blob file.

class BlobContents {

 public:

  BlobContents(CacheAllocationPtr&& allocation, size_t size)

      : allocation_(std::move(allocation)), data_(allocation_.get(), size) {}

  BlobContents(const BlobContents&) = delete;

  BlobContents& operator=(const BlobContents&) = delete;

  BlobContents(BlobContents&&) = default;

  BlobContents& operator=(BlobContents&&) = default;

  ~BlobContents() = default;

  const Slice& data() const { return data_; }

  size_t size() const { return data_.size(); }

  size_t ApproximateMemoryUsage() const;

  // For TypedCacheInterface

  const Slice& ContentSlice() const { return data_; }

  static constexpr CacheEntryRole kCacheEntryRole = CacheEntryRole::kBlobValue;

 private:

  CacheAllocationPtr allocation_;

  Slice data_;

};

class BlobContentsCreator : public Cache::CreateContext {

 public:

  static void Create(std::unique_ptr<BlobContents>* out, size_t* out_charge,

                     const Slice& contents, CompressionType /*type*/,

                     MemoryAllocator* alloc) {

    auto raw = new BlobContents(AllocateAndCopyBlock(contents, alloc),

                                contents.size());

    out->reset(raw);

    if (out_charge) {

      *out_charge = raw->ApproximateMemoryUsage();

    }

  }

};

}  // namespace ROCKSDB_NAMESPACE