code: public TempBlockMeta getTempBlockMetaOrNull(long blockId) {
      for (StorageTier tier : mTiers) {
        for (StorageDir dir : tier.getStorageDirs()) {
          if (dir.hasTempBlockMeta(blockId)) {
            return dir.getTempBlockMeta(blockId);
          }
        }
      }
      return null;
    }
docs: Gets the metadata of a temp block.
  
  @param blockId the id of the temp block
  @return metadata of the block or null