org.apache.cassandra.utils

Class EstimatedHistogram

java.lang.Object

org.apache.cassandra.utils.EstimatedHistogram

public class EstimatedHistogram
extends java.lang.Object

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	EstimatedHistogram.EstimatedHistogramSerializer

Field Summary

Fields

Modifier and Type	Field and Description
static EstimatedHistogram.EstimatedHistogramSerializer	serializer

Constructor Summary

Constructors

Constructor and Description
EstimatedHistogram()
EstimatedHistogram(int bucketCount)
EstimatedHistogram(int bucketCount, boolean considerZeroes)
EstimatedHistogram(long[] bucketData) Create EstimatedHistogram from only bucket data.
EstimatedHistogram(long[] offsets, long[] bucketData)

Method Summary

Modifier and Type	Method and Description
void	add(long n) Increments the count of the bucket closest to n, rounding UP.
void	add(long n, long delta) Increments the count of the bucket closest to n, rounding UP by delta
void	clearOverflow() Resets the count in the overflow bucket to zero.
long	count()
boolean	equals(java.lang.Object o)
long[]	getBucketOffsets()
long[]	getBuckets(boolean reset)
long	getLargestBucketOffset()
int	hashCode()
boolean	isOverflowed()
void	log(org.slf4j.Logger log) log.debug() every record in the histogram
long	max()
long	mean()
long	min()
static long[]	newOffsets(int size, boolean considerZeroes)
long	overflowCount()
long	percentile(double percentile)
double	rawMean()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Field Detail

serializer

public static final EstimatedHistogram.EstimatedHistogramSerializer serializer

Constructor Detail

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 Detail

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:

java.lang.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:

java.lang.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(java.lang.Object o)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object