//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.

//  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 "rocksdb/options.h"

#include "rocksdb/status.h"

namespace ROCKSDB_NAMESPACE {

class BlobFileCache;

class Version;

class Slice;

class FilePrefetchBuffer;

class PinnableSlice;

class BlobIndex;

// A thin wrapper around blob retrieval. By default it reads through Version,

// and it can optionally fall back to direct-write blob files that are not yet

// manifest-visible.

class BlobFetcher {

 public:

  BlobFetcher(const Version* version, const ReadOptions& read_options,

              BlobFileCache* blob_file_cache = nullptr,

              bool allow_write_path_fallback = false)

      : version_(version),

        read_options_(read_options),

        blob_file_cache_(blob_file_cache),

        allow_write_path_fallback_(allow_write_path_fallback) {}

  Status FetchBlob(const Slice& user_key, const Slice& blob_index_slice,

                   FilePrefetchBuffer* prefetch_buffer,

                   PinnableSlice* blob_value, uint64_t* bytes_read) const;

  Status FetchBlob(const Slice& user_key, const BlobIndex& blob_index,

                   FilePrefetchBuffer* prefetch_buffer,

                   PinnableSlice* blob_value, uint64_t* bytes_read) const;

 private:

  const Version* version_;

  ReadOptions read_options_;

  BlobFileCache* blob_file_cache_;

  bool allow_write_path_fallback_;

};

}  // namespace ROCKSDB_NAMESPACE