ceph/src/rocksdb/table/block_based/index_reader_common.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 // Copyright (c) 2011 The LevelDB Authors. All rights reserved.
   7 // Use of this source code is governed by a BSD-style license that can be
   8 // found in the LICENSE file. See the AUTHORS file for names of contributors.
   9 #pragma once
  10
  11 #include "table/block_based/block_based_table_reader.h"
  12
  13 #include "table/block_based/reader_common.h"
  14
  15 namespace ROCKSDB_NAMESPACE {
  16 // Encapsulates common functionality for the various index reader
  17 // implementations. Provides access to the index block regardless of whether
  18 // it is owned by the reader or stored in the cache, or whether it is pinned
  19 // in the cache or not.
  20 class BlockBasedTable::IndexReaderCommon : public BlockBasedTable::IndexReader {
  21  public:
  22   IndexReaderCommon(const BlockBasedTable* t,
  23                     CachableEntry<Block>&& index_block)
  24       : table_(t), index_block_(std::move(index_block)) {
  25     assert(table_ != nullptr);
  26   }
  27
  28  protected:
  29   static Status ReadIndexBlock(const BlockBasedTable* table,
  30                                FilePrefetchBuffer* prefetch_buffer,
  31                                const ReadOptions& read_options, bool use_cache,
  32                                GetContext* get_context,
  33                                BlockCacheLookupContext* lookup_context,
  34                                CachableEntry<Block>* index_block);
  35
  36   const BlockBasedTable* table() const { return table_; }
  37
  38   const InternalKeyComparator* internal_comparator() const {
  39     assert(table_ != nullptr);
  40     assert(table_->get_rep() != nullptr);
  41
  42     return &table_->get_rep()->internal_comparator;
  43   }
  44
  45   bool index_has_first_key() const {
  46     assert(table_ != nullptr);
  47     assert(table_->get_rep() != nullptr);
  48     return table_->get_rep()->index_has_first_key;
  49   }
  50
  51   bool index_key_includes_seq() const {
  52     assert(table_ != nullptr);
  53     assert(table_->get_rep() != nullptr);
  54     return table_->get_rep()->index_key_includes_seq;
  55   }
  56
  57   bool index_value_is_full() const {
  58     assert(table_ != nullptr);
  59     assert(table_->get_rep() != nullptr);
  60     return table_->get_rep()->index_value_is_full;
  61   }
  62
  63   bool cache_index_blocks() const {
  64     assert(table_ != nullptr);
  65     assert(table_->get_rep() != nullptr);
  66     return table_->get_rep()->table_options.cache_index_and_filter_blocks;
  67   }
  68
  69   Status GetOrReadIndexBlock(bool no_io, GetContext* get_context,
  70                              BlockCacheLookupContext* lookup_context,
  71                              CachableEntry<Block>* index_block) const;
  72
  73   size_t ApproximateIndexBlockMemoryUsage() const {
  74     assert(!index_block_.GetOwnValue() || index_block_.GetValue() != nullptr);
  75     return index_block_.GetOwnValue()
  76                ? index_block_.GetValue()->ApproximateMemoryUsage()
  77                : 0;
  78   }
  79
  80  private:
  81   const BlockBasedTable* table_;
  82   CachableEntry<Block> index_block_;
  83 };
  84
  85 }  // namespace ROCKSDB_NAMESPACE