com.datastax.driver.core

Class PerHostPercentileTracker

java.lang.Object

com.datastax.driver.core.PercentileTracker

com.datastax.driver.core.PerHostPercentileTracker

All Implemented Interfaces:

LatencyTracker, LifecycleAwareLatencyTracker

public class PerHostPercentileTracker
extends PercentileTracker

A PercentileTracker that maintains a separate histogram for each host.

This gives you per-host latency percentiles, meaning that each host will only be compared to itself.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	PerHostPercentileTracker.Builder Helper class to build PerHostPercentileTracker instances with a fluent interface.

Method Summary

Modifier and Type	Method and Description
static PerHostPercentileTracker.Builder	builder(long highestTrackableLatencyMillis) Returns a builder to create a new instance.
protected Host	computeKey(Host host, Statement statement, Exception exception) Computes a key used to categorize measurements.

Methods inherited from class com.datastax.driver.core.PercentileTracker

getLatencyAtPercentile, include, onRegister, onUnregister, update

Methods inherited from class java.lang.Object

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

Method Detail

computeKey

protected Host computeKey(Host host,
                          Statement statement,
                          Exception exception)

Description copied from class: PercentileTracker

Computes a key used to categorize measurements. Measurements with the same key will be recorded in the same histogram.

It's recommended to keep the number of distinct keys low, in order to limit the memory footprint of the histograms.

Specified by:

computeKey in class PercentileTracker

Parameters:

host - the host that was queried.

statement - the statement that was executed.

exception - if the query failed, the corresponding exception.

Returns:

the key.

builder

public static PerHostPercentileTracker.Builder builder(long highestTrackableLatencyMillis)

Returns a builder to create a new instance.

Parameters:

highestTrackableLatencyMillis - the highest expected latency. If a higher value is reported, it will be ignored and a warning will be logged. A good rule of thumb is to set it slightly higher than SocketOptions.getReadTimeoutMillis().

Returns:

the builder.