com.facebook.battery.metrics.api

Class StatefulSystemMetricsCollector<R extends SystemMetrics<R>,S extends SystemMetricsCollector<R>>

java.lang.Object

com.facebook.battery.metrics.api.StatefulSystemMetricsCollector<R,S>

public class StatefulSystemMetricsCollector<R extends SystemMetrics<R>,S extends SystemMetricsCollector<R>>
extends java.lang.Object

A utility class that composes collectors to reduce boilerplate for collectors that are used to collect consecutive values: the most common use case for Battery Metrics.

Using this class makes it simple to share a single underlying collector instance, and manage state externally.

SystemMetricsCollector collector = ...; StatefulSystemMetricsCollector collector = new StatefulSystemMetricsCollector(collector); <p><p>// Every call gets the difference from the last call SystemMetrics metrics = collector.getLatestDiffAndReset();

Note - creating a Stateful collector immediately takes an initial snapshot. - this class is _not_ thread safe.

Constructor Summary

Constructors

Constructor and Description
StatefulSystemMetricsCollector(S collector) Wrap the underlying collector to maintain external state: automatically takes a snapshot to override the initial values.
StatefulSystemMetricsCollector(S collector, R curr, R prev, R diff) Wraps the underlying collector, but with custom metrics objects: useful for passing in custom metrics objects, such as WakeLockMetrics.

Method Summary

Modifier and Type	Method and Description
S	getCollector() Access the underlying collector.
R	getLatestDiff() Get a diff form the previous baseline.
R	getLatestDiffAndReset() Get a diff from the previous baseline and update it.

Methods inherited from class java.lang.Object

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

Constructor Detail

StatefulSystemMetricsCollector

public StatefulSystemMetricsCollector(S collector)

Wrap the underlying collector to maintain external state: automatically takes a snapshot to override the initial values.

StatefulSystemMetricsCollector

public StatefulSystemMetricsCollector(S collector,
                                      R curr,
                                      R prev,
                                      R diff)

Wraps the underlying collector, but with custom metrics objects: useful for passing in custom metrics objects, such as WakeLockMetrics.

Method Detail

getCollector

public S getCollector()

Access the underlying collector.

getLatestDiffAndReset

@Nullable
public R getLatestDiffAndReset()

Get a diff from the previous baseline and update it.

getLatestDiff

@Nullable
public R getLatestDiff()

Get a diff form the previous baseline.