com.bigdata.counters
Class Instrument<T>

java.lang.Object
  com.bigdata.counters.Instrument<T>

All Implemented Interfaces:

IInstrument<T>

public abstract class Instrument<T>
extends Object
implements IInstrument<T>

Abstract class for reporting instrumented values supporting some useful conversions.

Version:

$Id: Instrument.java 2265 2009-10-26 12:51:06Z thompsonbry $

Author:

Bryan Thompson

Field Summary

protected long	lastModified The timestamp associated with value.
protected static org.apache.log4j.Logger	log
protected static String	NA N/A
protected T	value The current value -or- null if there is no current value.

Constructor Summary

Instrument()

Method Summary

T	getCurrentValue() Return the current value without taking another sample()
T	getValue() Obtain a sample.
long	lastModified() Obtain the timestamp for the last collected sample.
String	nanosToPerSec(long counter, long nanos) Converts an event count whose durations were measured in elapsed nanoseconds to an event rate per second.
protected abstract void	sample() Take a sample, setting the current value and timestamp using either setValue(Object) or setValue(Object, long).
void	setValue(T value) Set the value.
void	setValue(T value, long timestamp) Set the value.

Methods inherited from class java.lang.Object

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

Field Detail

log

protected static org.apache.log4j.Logger log

NA

protected static final transient String NA

N/A

See Also:

Constant Field Values

value

protected T value

The current value -or- null if there is no current value.

lastModified

protected long lastModified

The timestamp associated with value.

Constructor Detail

Instrument

public Instrument()

Method Detail

nanosToPerSec

public final String nanosToPerSec(long counter,
                                  long nanos)

Converts an event count whose durations were measured in elapsed nanoseconds to an event rate per second.

Parameters:

counter - The event count.

nanos - The elapsed nanoseconds for the events.

Returns:

Either "N/A" if nanos is ZERO (0) or the rate per second for the event.

TODO:

move to a util class? deprecate and remove in favor of Double counters?

sample

protected abstract void sample()

Take a sample, setting the current value and timestamp using either setValue(Object) or setValue(Object, long).

setValue

public final void setValue(T value)

Set the value.

Parameters:

value - The value, which will be associated with the current time as reported by System.currentTimeMillis().

setValue

public final void setValue(T value,
                           long timestamp)

Set the value.

Specified by:

setValue in interface IInstrument<T>

Parameters:

value - The value.

timestamp - The timestamp for that value.

getValue

public final T getValue()

Description copied from interface: IInstrument

Obtain a sample.

Specified by:

getValue in interface IInstrument<T>

getCurrentValue

public T getCurrentValue()

Return the current value without taking another sample()

lastModified

public final long lastModified()

Description copied from interface: IInstrument

Obtain the timestamp for the last collected sample.

Specified by:

lastModified in interface IInstrument<T>