org.apache.hadoop.metrics.spi

Class AbstractMetricsContext

java.lang.Object

org.apache.hadoop.metrics.spi.AbstractMetricsContext

All Implemented Interfaces:

org.apache.hadoop.metrics.MetricsContext

Direct Known Subclasses:

Log4JMetricsContext

public abstract class AbstractMetricsContext
extends Object
implements org.apache.hadoop.metrics.MetricsContext

The main class of the Service Provider Interface. This class should be extended in order to integrate the Metrics API with a specific metrics client library. This class implements the internal table of metric data, and the timer on which data is to be sent to the metrics system. Subclasses must override the abstract emitRecord method in order to transmit the data.

Field Summary

Fields inherited from interface org.apache.hadoop.metrics.MetricsContext

DEFAULT_PERIOD

Method Summary

Modifier and Type	Method and Description
void	close() Stops monitoring and frees buffered data, returning this object to its initial state.
org.apache.hadoop.metrics.MetricsRecord	createRecord(String recordName) Creates a new AbstractMetricsRecord instance with the given recordName.
org.apache.hadoop.metrics.ContextFactory	getContextFactory() Returns the factory by which this context was created.
String	getContextName() Returns the context name.
int	getPeriod() Returns the timer period.
void	init(String contextName, org.apache.hadoop.metrics.ContextFactory factory) Initializes the context.
boolean	isMonitoring() Returns true if monitoring is currently in progress.
void	registerUpdater(org.apache.hadoop.metrics.Updater updater) Registers a callback to be called at time intervals determined by the configuration.
void	startMonitoring() Starts or restarts monitoring, the emitting of metrics records.
void	stopMonitoring() Stops monitoring.
void	unregisterUpdater(org.apache.hadoop.metrics.Updater updater) Removes a callback, if it exists.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.hadoop.metrics.MetricsContext

getAllRecords

Method Detail

init

public void init(String contextName,
                 org.apache.hadoop.metrics.ContextFactory factory)

Initializes the context.

Specified by:

init in interface org.apache.hadoop.metrics.MetricsContext

getContextName

public String getContextName()

Returns the context name.

Specified by:

getContextName in interface org.apache.hadoop.metrics.MetricsContext

getContextFactory

public org.apache.hadoop.metrics.ContextFactory getContextFactory()

Returns the factory by which this context was created.

Returns:

the factory by which the context was created

startMonitoring

public void startMonitoring()
                     throws IOException

Starts or restarts monitoring, the emitting of metrics records.

Specified by:

startMonitoring in interface org.apache.hadoop.metrics.MetricsContext

Throws:

IOException

stopMonitoring

public void stopMonitoring()

Stops monitoring. This does not free buffered data.

Specified by:

stopMonitoring in interface org.apache.hadoop.metrics.MetricsContext

See Also:

close()

isMonitoring

public boolean isMonitoring()

Returns true if monitoring is currently in progress.

Specified by:

isMonitoring in interface org.apache.hadoop.metrics.MetricsContext

close

public void close()

Stops monitoring and frees buffered data, returning this object to its initial state.

Specified by:

close in interface org.apache.hadoop.metrics.MetricsContext

createRecord

public final org.apache.hadoop.metrics.MetricsRecord createRecord(String recordName)

Creates a new AbstractMetricsRecord instance with the given recordName. Throws an exception if the metrics implementation is configured with a fixed set of record names and recordName is not in that set.

Specified by:

createRecord in interface org.apache.hadoop.metrics.MetricsContext

Parameters:

recordName - the name of the record

Throws:

org.apache.hadoop.metrics.MetricsException - if recordName conflicts with configuration data

registerUpdater

public void registerUpdater(org.apache.hadoop.metrics.Updater updater)

Registers a callback to be called at time intervals determined by the configuration.

Specified by:

registerUpdater in interface org.apache.hadoop.metrics.MetricsContext

Parameters:

updater - object to be run periodically; it should update some metrics records

unregisterUpdater

public void unregisterUpdater(org.apache.hadoop.metrics.Updater updater)

Removes a callback, if it exists.

Specified by:

unregisterUpdater in interface org.apache.hadoop.metrics.MetricsContext

Parameters:

updater - object to be removed from the callback list

getPeriod

public int getPeriod()

Returns the timer period.

Specified by:

getPeriod in interface org.apache.hadoop.metrics.MetricsContext