Package org.apache.cassandra.utils

Class EstimatedHistogram

java.lang.Object
org.apache.cassandra.utils.EstimatedHistogram
All Implemented Interfaces:
DoubleToLongFunction
public class EstimatedHistogram extends Object implements DoubleToLongFunction

  • Field Details

  • Constructor Details

    • EstimatedHistogram

      public EstimatedHistogram()

    • EstimatedHistogram

      public EstimatedHistogram(int bucketCount)

    • EstimatedHistogram

      public EstimatedHistogram(int bucketCount, boolean considerZeroes)

    • EstimatedHistogram

      public EstimatedHistogram(long[] bucketData)
      Create EstimatedHistogram from only bucket data.
      Parameters:
      bucketData - bucket data

    • EstimatedHistogram

      public EstimatedHistogram(long[] offsets, long[] bucketData)

  • Method Details

    • newOffsets

      public static long[] newOffsets(int size, boolean considerZeroes)

    • getBucketOffsets

      public long[] getBucketOffsets()
      Returns:
      the histogram values corresponding to each bucket index

    • add

      public void add(long n)
      Increments the count of the bucket closest to n, rounding UP.
      Parameters:
      n -

    • add

      public void add(long n, long delta)
      Increments the count of the bucket closest to n, rounding UP by delta
      Parameters:
      n -

    • getBuckets

      public long[] getBuckets(boolean reset)
      Parameters:
      reset - zero out buckets afterwards if true
      Returns:
      a long[] containing the current histogram buckets

    • min

      public long min()
      Returns:
      the smallest value that could have been added to this histogram

    • max

      public long max()
      Returns:
      the largest value that could have been added to this histogram. If the histogram overflowed, returns Long.MAX_VALUE.

    • percentile

      public long percentile(double percentile)
      Parameters:
      percentile -
      Returns:
      estimated value at given percentile

    • mean

      public long mean()
      Returns:
      the ceil of mean histogram value (average of bucket offsets, weighted by count)
      Throws:
      IllegalStateException - if any values were greater than the largest bucket threshold

    • rawMean

      public double rawMean()
      Returns:
      the mean histogram value (average of bucket offsets, weighted by count)
      Throws:
      IllegalStateException - if any values were greater than the largest bucket threshold

    • count

      public long count()
      Returns:
      the total number of non-zero values

    • getLargestBucketOffset

      public long getLargestBucketOffset()
      Returns:
      the largest bucket offset

    • isOverflowed

      public boolean isOverflowed()
      Returns:
      true if a value larger than our largest bucket offset has been recorded, and false otherwise

    • overflowCount

      public long overflowCount()
      Returns:
      the number of recorded values larger than the largest bucket offset

    • clearOverflow

      public void clearOverflow()
      Resets the count in the overflow bucket to zero. Subsequent calls to isOverflowed() will return false.

    • log

      public void log(org.slf4j.Logger log)
      log.debug() every record in the histogram
      Parameters:
      log -

    • equals

      public boolean equals(Object o)
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • applyAsLong

      public long applyAsLong(double value)
      Specified by:
      applyAsLong in interface DoubleToLongFunction