org.apache.hadoop.fs.statistics

Class IOStatisticsSupport

java.lang.Object

org.apache.hadoop.fs.statistics.IOStatisticsSupport

@InterfaceAudience.Public
 @InterfaceStability.Unstable
public final class IOStatisticsSupport
extends Object

Support for working with IOStatistics.

Method Summary

Modifier and Type	Method and Description
static IOStatistics	retrieveIOStatistics(Object source) Get the IOStatistics of the source, casting it if it is of the relevant type, otherwise, if it implements IOStatisticsSource extracting the value.
static IOStatisticsSnapshot	snapshotIOStatistics() Create a snapshot statistics instance ready to aggregate data.
static IOStatisticsSnapshot	snapshotIOStatistics(IOStatistics statistics) Take a snapshot of the current statistics state.
static org.apache.hadoop.fs.statistics.DurationTracker	stubDurationTracker() Get a stub duration tracker.
static org.apache.hadoop.fs.statistics.DurationTrackerFactory	stubDurationTrackerFactory() Return a stub duration tracker factory whose returned trackers are always no-ops.

Methods inherited from class java.lang.Object

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

Method Detail

snapshotIOStatistics

public static IOStatisticsSnapshot snapshotIOStatistics(IOStatistics statistics)

Take a snapshot of the current statistics state.

This is not an atomic option.

The instance can be serialized, and its toString() method lists all the values.

Parameters:

statistics - statistics

Returns:

a snapshot of the current values.

snapshotIOStatistics

public static IOStatisticsSnapshot snapshotIOStatistics()

Create a snapshot statistics instance ready to aggregate data. The instance can be serialized, and its toString() method lists all the values.

Returns:

an empty snapshot

retrieveIOStatistics

public static IOStatistics retrieveIOStatistics(Object source)

Get the IOStatistics of the source, casting it if it is of the relevant type, otherwise, if it implements IOStatisticsSource extracting the value. Returns null if the source isn't of the write type or the return value of IOStatisticsSource.getIOStatistics() was null.

Parameters:

source - source.

Returns:

an IOStatistics instance or null

stubDurationTrackerFactory

public static org.apache.hadoop.fs.statistics.DurationTrackerFactory stubDurationTrackerFactory()

Return a stub duration tracker factory whose returned trackers are always no-ops. As singletons are returned, this is very low-cost to use.

Returns:

a duration tracker factory.

stubDurationTracker

public static org.apache.hadoop.fs.statistics.DurationTracker stubDurationTracker()

Get a stub duration tracker.

Returns:

a stub tracker.