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
  11 #include "table/block_based/cachable_entry.h"
  12 #include "table/format.h"
  13
  14 namespace ROCKSDB_NAMESPACE {
  15
  16 class BlockBasedTable;
  17 struct BlockCacheLookupContext;
  18 class FilePrefetchBuffer;
  19 class GetContext;
  20 struct ReadOptions;
  21 struct UncompressionDict;
  22
  23 // Provides access to the uncompression dictionary regardless of whether
  24 // it is owned by the reader or stored in the cache, or whether it is pinned
  25 // in the cache or not.
  26 class UncompressionDictReader {
  27  public:
  28   static Status Create(
  29       const BlockBasedTable* table, const ReadOptions& ro,
  30       FilePrefetchBuffer* prefetch_buffer, bool use_cache, bool prefetch,
  31       bool pin, BlockCacheLookupContext* lookup_context,
  32       std::unique_ptr<UncompressionDictReader>* uncompression_dict_reader);
  33
  34   Status GetOrReadUncompressionDictionary(
  35       FilePrefetchBuffer* prefetch_buffer, bool no_io, bool verify_checksums,
  36       GetContext* get_context, BlockCacheLookupContext* lookup_context,
  37       CachableEntry<UncompressionDict>* uncompression_dict) const;
  38
  39   size_t ApproximateMemoryUsage() const;
  40
  41  private:
  42   UncompressionDictReader(const BlockBasedTable* t,
  43                           CachableEntry<UncompressionDict>&& uncompression_dict)
  44       : table_(t), uncompression_dict_(std::move(uncompression_dict)) {
  45     assert(table_);
  46   }
  47
  48   bool cache_dictionary_blocks() const;
  49
  50   static Status ReadUncompressionDictionary(
  51       const BlockBasedTable* table, FilePrefetchBuffer* prefetch_buffer,
  52       const ReadOptions& read_options, bool use_cache, GetContext* get_context,
  53       BlockCacheLookupContext* lookup_context,
  54       CachableEntry<UncompressionDict>* uncompression_dict);
  55
  56   const BlockBasedTable* table_;
  57   CachableEntry<UncompressionDict> uncompression_dict_;
  58 };
  59
  60 }  // namespace ROCKSDB_NAMESPACE