Module org.elasticsearch.exponentialhistogram
Package org.elasticsearch.exponentialhistogram

Interface BucketIterator

All Known Subinterfaces:
CopyableBucketIterator
public interface BucketIterator
An iterator over the non-empty buckets of the histogram for either the positive or negative range.
  • The iterator always iterates from the lowest bucket index to the highest.
  • The iterator never returns duplicate buckets (buckets with the same index).
  • The iterator never returns empty buckets (peekCount() is never zero).

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    advance()
    Moves the iterator to the next, non-empty bucket.
    boolean
    hasNext()
    Checks if there are any buckets remaining to be visited by this iterator.
    long
    peekCount()
    The number of items in the bucket at the current iterator position.
    long
    peekIndex()
    The index of the bucket at the current iterator position.
    int
    scale()
    Provides the scale that can be used to convert indices returned by peekIndex() to the bucket boundaries, e.g., via ExponentialScaleUtils.getLowerBucketBoundary(long, int).

  • Method Details

    • hasNext

      boolean hasNext()
      Checks if there are any buckets remaining to be visited by this iterator. If the end has been reached, it is illegal to call peekCount(), peekIndex(), or advance().
      Returns:
      true if the iterator has more elements, false otherwise

    • peekCount

      long peekCount()
      The number of items in the bucket at the current iterator position. Does not advance the iterator. Must not be called if hasNext() returns false.
      Returns:
      the number of items in the bucket, always greater than zero

    • peekIndex

      long peekIndex()
      The index of the bucket at the current iterator position. Does not advance the iterator. Must not be called if hasNext() returns false.
      Returns:
      the index of the bucket, guaranteed to be in the range [ExponentialHistogram.MIN_INDEX, ExponentialHistogram.MAX_INDEX]

    • advance

      void advance()
      Moves the iterator to the next, non-empty bucket. If hasNext() is true after calling advance(), peekIndex() is guaranteed to return a value greater than the value returned prior to the advance() call.

    • scale

      int scale()
      Provides the scale that can be used to convert indices returned by peekIndex() to the bucket boundaries, e.g., via ExponentialScaleUtils.getLowerBucketBoundary(long, int).
      Returns:
      the scale, which is guaranteed to be constant over the lifetime of this iterator