com.datastax.driver.core

Class PercentileTracker.Builder<B,T>

java.lang.Object

com.datastax.driver.core.PercentileTracker.Builder<B,T>

Type Parameters:

B - the type of the concrete builder implementation.

T - the type of the object to build.

Direct Known Subclasses:

ClusterWidePercentileTracker.Builder, PerHostPercentileTracker.Builder

Enclosing class:

PercentileTracker

public abstract static class PercentileTracker.Builder<B,T>
extends Object

Base class for PercentileTracker implementation builders.

Field Summary

Fields

Modifier and Type	Field and Description
protected long	highestTrackableLatencyMillis
protected long	intervalMs
protected int	minRecordedValues
protected int	numberOfSignificantValueDigits

Method Summary

Modifier and Type	Method and Description
abstract T	build() Builds the PercentileTracker instance configured with this builder.
protected abstract B	self()
B	withInterval(long interval, TimeUnit unit) Sets the time interval over which samples are recorded.
B	withMinRecordedValues(int minRecordedValues) Sets the minimum number of values that must be recorded for a host before we consider the sample size significant.
B	withNumberOfSignificantValueDigits(int numberOfSignificantValueDigits) Sets the number of significant decimal digits to which histograms will maintain value resolution and separation.

Methods inherited from class java.lang.Object

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

Field Detail

highestTrackableLatencyMillis

protected final long highestTrackableLatencyMillis

numberOfSignificantValueDigits

protected int numberOfSignificantValueDigits

minRecordedValues

protected int minRecordedValues

intervalMs

protected long intervalMs

Method Detail

self

protected abstract B self()

withNumberOfSignificantValueDigits

public B withNumberOfSignificantValueDigits(int numberOfSignificantValueDigits)

Sets the number of significant decimal digits to which histograms will maintain value resolution and separation. This must be an integer between 0 and 5.

If not set explicitly, this value defaults to 3.

See the HdrHistogram Javadocs for a more detailed explanation on how this parameter affects the resolution of recorded samples.

Parameters:

numberOfSignificantValueDigits - the new value.

Returns:

this builder.

withMinRecordedValues

public B withMinRecordedValues(int minRecordedValues)

Sets the minimum number of values that must be recorded for a host before we consider the sample size significant.

If this count is not reached during a given interval, PercentileTracker.getLatencyAtPercentile(Host, Statement, Exception, double) will return a negative value, indicating that statistics are not available. In particular, this is true during the first interval.

If not set explicitly, this value default to 1000.

Parameters:

minRecordedValues - the new value.

Returns:

this builder.

withInterval

public B withInterval(long interval,
                      TimeUnit unit)

Sets the time interval over which samples are recorded.

For each host, there is a "live" histogram where current latencies are recorded, and a "cached", read-only histogram that is used when clients call PercentileTracker.getLatencyAtPercentile(Host, Statement, Exception, double). Each time the cached histogram becomes older than the interval, the two histograms are switched. Note that statistics will not be available during the first interval at cluster startup, since we don't have a cached histogram yet.

If not set explicitly, this value defaults to 5 minutes.

Parameters:

interval - the new interval.

unit - the unit that the interval is expressed in.

Returns:

this builder.

build

public abstract T build()

Builds the PercentileTracker instance configured with this builder.

Returns:

the instance.