com.datastax.driver.core

Class Metrics

java.lang.Object

com.datastax.driver.core.Metrics

public class Metrics
extends Object

Metrics exposed by the driver.

The metrics exposed by this class use the Metrics library and you should refer its documentation for details on how to handle the exposed metric objects.

By default, metrics are exposed through JMX, which is very useful for development and browsing, but for production environments you may want to have a look at the reporters provided by the Metrics library which could be more efficient/adapted.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	Metrics.Errors Metrics on errors encountered.

Method Summary

Methods

Modifier and Type	Method and Description
com.yammer.metrics.core.Gauge<Integer>	getConnectedToHosts() Returns the number of Cassandra hosts the driver is currently connected to (that is have at least one connection opened to).
Metrics.Errors	getErrorMetrics() Returns an object regrouping metrics related to the errors encountered.
com.yammer.metrics.core.Gauge<Integer>	getKnownHosts() Returns the number of Cassandra hosts currently known by the driver (that is whether they are currently considered up or down).
com.yammer.metrics.core.Gauge<Integer>	getOpenConnections() Returns the total number of currently opened connections to Cassandra hosts.
com.yammer.metrics.core.MetricsRegistry	getRegistry() Returns the registry containing all metrics.
com.yammer.metrics.core.Timer	getRequestsTimer() Returns metrics on the user requests performed on the Cluster.

Methods inherited from class java.lang.Object

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

Method Detail

getRegistry

public com.yammer.metrics.core.MetricsRegistry getRegistry()

Returns the registry containing all metrics.

The metrics registry allows you to easily use the reporters that ships with Metrics or a custom written one. For instance, if metrics is this object, you can easily export the metrics to csv files using:

     com.yammer.metrics.reporting.CsvReporter.enable(metrics.getRegistry(), new File("measurements/"), 1, TimeUnit.SECONDS);
 

Returns:

the registry containing all metrics.

getRequestsTimer

public com.yammer.metrics.core.Timer getRequestsTimer()

Returns metrics on the user requests performed on the Cluster.

This metric exposes

• the total number of requests.
• the requests rate (in requests per seconds), including 1, 5 and 15 minute rates.
• the mean, min and max latencies, as well as latency at a given percentile.

Returns:

a Timer metric object exposing the rate and latency for user requests.

getErrorMetrics

public Metrics.Errors getErrorMetrics()

Returns an object regrouping metrics related to the errors encountered.

Returns:

an object regrouping metrics related to the errors encountered.

getKnownHosts

public com.yammer.metrics.core.Gauge<Integer> getKnownHosts()

Returns the number of Cassandra hosts currently known by the driver (that is whether they are currently considered up or down).

Returns:

the number of Cassandra hosts currently known by the driver.

getConnectedToHosts

public com.yammer.metrics.core.Gauge<Integer> getConnectedToHosts()

Returns the number of Cassandra hosts the driver is currently connected to (that is have at least one connection opened to).

Returns:

the number of Cassandra hosts the driver is currently connected to.

getOpenConnections

public com.yammer.metrics.core.Gauge<Integer> getOpenConnections()

Returns the total number of currently opened connections to Cassandra hosts.

Returns:

The total number of currently opened connections to Cassandra hosts.