[HADOOP-15423] Merge fileCache and dirCache into one single cache in LocalMetadataStore

• Type: Sub-task
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 3.2.0
• Assignee: Gabor Bota
• Reporter: Gabor Bota
• Created: 27/Apr/18 13:58
• Updated: 25/Jun/18 21:22
• Resolved: 25/Jun/18 21:01

Description

Right now the s3guard.LocalMetadataStore uses two HashMap in the implementation - one for the file and one for the dir hash.

  /** Contains directories and files. */
  private Cache<Path, PathMetadata> fileCache;

  /** Contains directory listings. */
  private Cache<Path, DirListingMetadata> dirCache;

It would be nice to have only one hash instead of these two for storing the values. An idea for the implementation would be to have a class with nullable fields:

  static class LocalMetaEntry {
    @Nullable
    public PathMetadata pathMetadata;
    @Nullable
    public DirListingMetadata dirListingMetadata;
  }

or a Pair (tuple):

Pair<PathMetadata, DirListingMetadata> metaEntry;

And only one hash/cache for these elements.

Issue Links

• is related to: HADOOP-13649 s3guard: implement time-based (TTL) expiry for LocalMetadataStore