defer b.Unlock()

	if b.isFull() {
		if b.store == nil {
			return ErrBatchFull
		}
		// commit batch to store
		if err := b.commit(); err != nil {
			return err
		}
	}

	b.items = append(b.items, item)
	return nil
}

// Len returns the no of items in the batch
func (b *Batch[_]) Len() int {
	b.Lock()
	defer b.Unlock()

	return len(b.items)
}

func (b *Batch[_]) isFull() bool {

    final int characteristics() {
      return spliterator.characteristics();
    }

    final long estimateSize() {
      return spliterator.estimateSize();
    }

    final Comparator<? super E> getComparator() {
      return spliterator.getComparator();
    }

    final long getExactSizeIfKnown() {
      return spliterator.getExactSizeIfKnown();
    }

    final int characteristics() {
      return spliterator.characteristics();
    }

    final long estimateSize() {
      return spliterator.estimateSize();
    }

    final Comparator<? super E> getComparator() {
      return spliterator.getComparator();
    }

    final long getExactSizeIfKnown() {
      return spliterator.getExactSizeIfKnown();
    }

    checkNotNull(function);
    return new Future<O>() {

      @Override
      public boolean cancel(boolean mayInterruptIfRunning) {
        return input.cancel(mayInterruptIfRunning);
      }

      @Override
      public boolean isCancelled() {
        return input.isCancelled();
      }

      @Override
      public boolean isDone() {
        return input.isDone();
      }

    public Authentication getAuthentication() {
        return new AuthenticationImpl(getAuthScope(), getCredentials(), getAuthScheme());
    }

    private AuthScheme getAuthScheme() {
        final String scheme = getProtocolScheme();
        if (Constants.BASIC.equals(scheme)) {
            return new BasicScheme();
        }
        if (Constants.DIGEST.equals(scheme)) {
            return new DigestScheme();
        }

    if (value == null) {
      return getWithoutCaching(key);
    } else {
      return value;
    }
  }

  @CheckForNull
  final V getWithoutCaching(Object key) {
    checkNotNull(key);
    return backingMap.get(key);
  }

  final boolean containsKey(@CheckForNull Object key) {
    return getIfCached(key) != null || backingMap.containsKey(key);
  }

          if (sourcePos < bufferPos) {
            return@synchronized SOURCE_FILE
          }

          // The buffer has the data we need. Read from there and return immediately.
          val bytesToRead = minOf(byteCount, upstreamPos - sourcePos)
          buffer.copyTo(sink, sourcePos - bufferPos, bytesToRead)
          sourcePos += bytesToRead
          return bytesToRead
        }

      // Read from the file.

        return this.isEstablished;
    }


    /**
     * @return the server's challenge
     */
    public byte[] getServerChallenge () {
        return this.serverChallenge;
    }


    @Override
    public byte[] getSigningKey () {
        return this.masterKey;
    }


    @Override
    public String getNetbiosName () {
        return this.netbiosName;
    }

    //                                                                             =======
    @Override
    public FileAuthenticationDbm asDBMeta() {
        return FileAuthenticationDbm.getInstance();
    }

    @Override
    public String asTableDbName() {
        return "file_authentication";
    }

    // ===================================================================================

  static <K, V> Map<K, V> newHashMapWithExpectedSize(int expectedSize) {
    return Maps.newHashMapWithExpectedSize(expectedSize);
  }

  static <K, V> Map<K, V> newLinkedHashMapWithExpectedSize(int expectedSize) {
    return Maps.newLinkedHashMapWithExpectedSize(expectedSize);
  }

  static <E> Set<E> newHashSetWithExpectedSize(int expectedSize) {
    return Sets.newHashSetWithExpectedSize(expectedSize);
  }