//  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 <cassert>

#include "table/block_based/cachable_entry.h"

#include "table/format.h"

namespace ROCKSDB_NAMESPACE {

class BlockBasedTable;

struct BlockCacheLookupContext;

class FilePrefetchBuffer;

class GetContext;

struct ReadOptions;

struct UncompressionDict;

// Provides access to the uncompression dictionary regardless of whether

// it is owned by the reader or stored in the cache, or whether it is pinned

// in the cache or not.

class UncompressionDictReader {

 public:

  static Status Create(

      const BlockBasedTable* table, const ReadOptions& ro,

      FilePrefetchBuffer* prefetch_buffer, bool use_cache, bool prefetch,

      bool pin, BlockCacheLookupContext* lookup_context,

      std::unique_ptr<UncompressionDictReader>* uncompression_dict_reader);

  Status GetOrReadUncompressionDictionary(

      FilePrefetchBuffer* prefetch_buffer, const ReadOptions& ro,

      GetContext* get_context, BlockCacheLookupContext* lookup_context,

      CachableEntry<UncompressionDict>* uncompression_dict) const;

  size_t ApproximateMemoryUsage() const;

 private:

  UncompressionDictReader(const BlockBasedTable* t,

                          CachableEntry<UncompressionDict>&& uncompression_dict)

      : table_(t), uncompression_dict_(std::move(uncompression_dict)) {

    assert(table_);

  }

  bool cache_dictionary_blocks() const;

  static Status ReadUncompressionDictionary(

      const BlockBasedTable* table, FilePrefetchBuffer* prefetch_buffer,

      const ReadOptions& read_options, bool use_cache, GetContext* get_context,

      BlockCacheLookupContext* lookup_context,

      CachableEntry<UncompressionDict>* uncompression_dict);

  const BlockBasedTable* table_;

  CachableEntry<UncompressionDict> uncompression_dict_;

};

}  // namespace ROCKSDB_NAMESPACE