Method Create

table/block_based_table_reader.cc:469–551

class HashIndexReader : public IndexReader {
 public:
  static Status Create(
      const SliceTransform* hash_key_extractor, const Footer& footer,
      RandomAccessFileReader* file, FilePrefetchBuffer* prefetch_buffer,
      const ImmutableCFOptions& ioptions,
      const InternalKeyComparator* icomparator, const BlockHandle& index_handle,
      InternalIteratorBase<Slice>* meta_index_iter, IndexReader** index_reader,
      bool /*hash_index_allow_collision*/,
      const PersistentCacheOptions& cache_options,
      const bool index_key_includes_seq, const bool index_value_is_full,
      MemoryAllocator* memory_allocator) {
    std::unique_ptr<Block> index_block;
    auto s = ReadBlockFromFile(
        file, prefetch_buffer, footer, ReadOptions(), index_handle,
        &index_block, ioptions, true /* decompress */,
        true /*maybe_compressed*/, Slice() /*compression dict*/, cache_options,
        kDisableGlobalSequenceNumber, 0 /* read_amp_bytes_per_bit */,
        memory_allocator);

    if (!s.ok()) {
      return s;
    }

    // Note, failure to create prefix hash index does not need to be a
    // hard error. We can still fall back to the original binary search index.
    // So, Create will succeed regardless, from this point on.

    auto new_index_reader = new HashIndexReader(
        icomparator, std::move(index_block), ioptions.statistics,
        index_key_includes_seq, index_value_is_full);
    *index_reader = new_index_reader;

    // Get prefixes block
    BlockHandle prefixes_handle;
    s = FindMetaBlock(meta_index_iter, kHashIndexPrefixesBlock,
                      &prefixes_handle);
    if (!s.ok()) {
      // TODO: log error
      return Status::OK();
    }

    // Get index metadata block
    BlockHandle prefixes_meta_handle;
    s = FindMetaBlock(meta_index_iter, kHashIndexPrefixesMetadataBlock,
                      &prefixes_meta_handle);
    if (!s.ok()) {
      // TODO: log error
      return Status::OK();
    }

    Slice dummy_comp_dict;
    // Read contents for the blocks
    BlockContents prefixes_contents;
    BlockFetcher prefixes_block_fetcher(
        file, prefetch_buffer, footer, ReadOptions(), prefixes_handle,
        &prefixes_contents, ioptions, true /*decompress*/,
        true /*maybe_compressed*/, dummy_comp_dict /*compression dict*/,
        cache_options, memory_allocator);
    s = prefixes_block_fetcher.ReadBlockContents();