com.datastax.driver.core

Class ClusterWidePercentileTracker

java.lang.Object

com.datastax.driver.core.PercentileTracker

com.datastax.driver.core.ClusterWidePercentileTracker

All Implemented Interfaces:

LatencyTracker, LifecycleAwareLatencyTracker

public class ClusterWidePercentileTracker
extends PercentileTracker

A PercentileTracker that aggregates all measurements into a single histogram.

This gives you global latency percentiles for the whole cluster, meaning that latencies of slower hosts will tend to appear in higher percentiles.

Nested Class Summary

Nested Classes

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

Method Summary

Modifier and Type	Method and Description
static ClusterWidePercentileTracker.Builder	builder(long highestTrackableLatencyMillis) Returns a builder to create a new instance.
protected Cluster	computeKey(Host host, Statement statement, Exception exception) Computes a key used to categorize measurements.
void	onRegister(Cluster cluster) Gets invoked when the tracker is registered with a cluster, or at cluster startup if the tracker was registered at initialization with Cluster.register(LatencyTracker).

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

getLatencyAtPercentile, include, onUnregister, update

Methods inherited from class java.lang.Object

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

Method Detail

onRegister

public void onRegister(Cluster cluster)

Description copied from interface: LifecycleAwareLatencyTracker

Gets invoked when the tracker is registered with a cluster, or at cluster startup if the tracker was registered at initialization with Cluster.register(LatencyTracker).

Specified by:

onRegister in interface LifecycleAwareLatencyTracker

Overrides:

onRegister in class PercentileTracker

Parameters:

cluster - the cluster that this tracker is registered with.

computeKey

protected Cluster 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 ClusterWidePercentileTracker.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.