ceph/src/rocksdb/table/block_based/uncompression_dict_reader.h

   1 //  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
   2 //  This source code is licensed under both the GPLv2 (found in the
   3 //  COPYING file in the root directory) and Apache 2.0 License
   4 //  (found in the LICENSE.Apache file in the root directory).
   5 //
   6
   7 #pragma once
   8
   9 #include <cassert>
  10 #include "table/block_based/cachable_entry.h"
  11 #include "table/format.h"
  12
  13 namespace ROCKSDB_NAMESPACE {
  14
  15 class BlockBasedTable;
  16 struct BlockCacheLookupContext;
  17 class FilePrefetchBuffer;
  18 class GetContext;
  19 struct ReadOptions;
  20 struct UncompressionDict;
  21
  22 // Provides access to the uncompression dictionary regardless of whether
  23 // it is owned by the reader or stored in the cache, or whether it is pinned
  24 // in the cache or not.
  25 class UncompressionDictReader {
  26  public:
  27   static Status Create(
  28       const BlockBasedTable* table, const ReadOptions& ro,
  29       FilePrefetchBuffer* prefetch_buffer, bool use_cache, bool prefetch,
  30       bool pin, BlockCacheLookupContext* lookup_context,
  31       std::unique_ptr<UncompressionDictReader>* uncompression_dict_reader);
  32
  33   Status GetOrReadUncompressionDictionary(
  34       FilePrefetchBuffer* prefetch_buffer, bool no_io, GetContext* get_context,
  35       BlockCacheLookupContext* lookup_context,
  36       CachableEntry<UncompressionDict>* uncompression_dict) const;
  37
  38   size_t ApproximateMemoryUsage() const;
  39
  40  private:
  41   UncompressionDictReader(const BlockBasedTable* t,
  42                           CachableEntry<UncompressionDict>&& uncompression_dict)
  43       : table_(t), uncompression_dict_(std::move(uncompression_dict)) {
  44     assert(table_);
  45   }
  46
  47   bool cache_dictionary_blocks() const;
  48
  49   static Status ReadUncompressionDictionary(
  50       const BlockBasedTable* table, FilePrefetchBuffer* prefetch_buffer,
  51       const ReadOptions& read_options, bool use_cache, GetContext* get_context,
  52       BlockCacheLookupContext* lookup_context,
  53       CachableEntry<UncompressionDict>* uncompression_dict);
  54
  55   const BlockBasedTable* table_;
  56   CachableEntry<UncompressionDict> uncompression_dict_;
  57 };
  58
  59 }  // namespace ROCKSDB_NAMESPACE