com.berryworks.jquantify

Class Metric

java.lang.Object

com.berryworks.jquantify.Metric

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

EventCounter, VMUsage

public abstract class Metric
extends Object
implements Serializable

Abstract superclass for EventCounter, SessionCounter, and other metric classes.

Each Metric is associated with a descriptive label that is used in reporting to suggest what is being counted.

A Metric views time as a series of non-overlapping time intervals. The duration of an interval is a number of seconds and does not vary for the intervals within a given Metric. At any point in time, a Metric maintains knowledge of the current interval, as an Interval object, as well as one or more Intervals that have were noted in the history of this metric.

Choosing the duration of an interval. Each instance of a Metric has a fixed duration for each interval. The choice of duration makes no difference in the actual count of event occurrences. It may, however, influence other calculations relevant to a particular subclass of Metric. For example, an EventCounter is able to report the peak frequency of events. If you are counting train departures from a station, it may be reasonable to configure the interval duration at one hour, and learn the peak frequency rate in departures/hour. If you used the default duration of one second, the peak frequency would probably never exceed 1.0 per second during even the busiest part of the day. If, on the other hand, you are counting database commits, then a one second interval may be appropriate, since detecting a spike at 100 per second might be very helpful and could go unnoticed in a commits per hour rate.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected int	intervalSeconds How many seconds are in each interval
protected long	startTime When the Metric was constructed or reset
protected long	totalIntervals Number of intervals that have occurred so far during the life of this Metric

Constructor Summary

Constructors

Constructor and Description
Metric() No-arg constructor necessary for serialization.
Metric(String label) Constructs a new Metric with an interval duration of 1 second.
Metric(String label, int intervalDurationInSeconds) Constructs a new Metric.

Method Summary

Methods

Modifier and Type	Method and Description
void	add() Adds a single event.
abstract void	add(int count) Adds a number of events.
float	getAge() Gets the age of this metric in seconds.
long	getAgeMillis() Gets the age of this metric in milliseconds.
abstract long	getCount() Gets the total count of events.
int	getIntervalSeconds() Gets the number of seconds in each interval.
String	getLabel() Gets the descriptive label associated with this Metric instance.
long	getTotalIntervals() Gets number of intervals that have occurred during the life of this Metric.
void	reset() Reset this Metric to its "zero" condition.
void	setLabel(String label) Sets the descriptive label associated with this Metric instance.
static float	uptime() Return the uptime in hours, measured from when the Metric class was loaded into the VM by the classloader.

Methods inherited from class java.lang.Object

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

Field Detail

startTime

protected long startTime

When the Metric was constructed or reset

intervalSeconds

protected int intervalSeconds

How many seconds are in each interval

totalIntervals

protected long totalIntervals

Number of intervals that have occurred so far during the life of this Metric

Constructor Detail

Metric

public Metric(String label,
      int intervalDurationInSeconds)

Constructs a new Metric.

Parameters:

label - descriptive label for this Metric

intervalDurationInSeconds - number of seconds in each interval

Metric

public Metric(String label)

Constructs a new Metric with an interval duration of 1 second.

Parameters:

label - - descriptive label for this Metric

Metric

public Metric()

No-arg constructor necessary for serialization.

Method Detail

getIntervalSeconds

public int getIntervalSeconds()

Gets the number of seconds in each interval.

Returns:

number of seconds in each interval

getLabel

public String getLabel()

Gets the descriptive label associated with this Metric instance.

Returns:

descriptive label for this Metric

setLabel

public void setLabel(String label)

Sets the descriptive label associated with this Metric instance.

Parameters:

label - descriptive label for this Metric

getAgeMillis

public long getAgeMillis()

Gets the age of this metric in milliseconds.

Returns:

age in milliseconds of this Metric

getAge

public float getAge()

Gets the age of this metric in seconds.

Returns:

age of this Metric in seconds

add

public void add()

Adds a single event.

Equivalent to add(1).

add

public abstract void add(int count)

Adds a number of events.

All events are considered to have happened simultaneously.

Parameters:

count - number of events counted by this call

getCount

public abstract long getCount()

Gets the total count of events.

Returns:

count

getTotalIntervals

public long getTotalIntervals()

Gets number of intervals that have occurred during the life of this Metric.

Returns:

number of intervals

reset

public void reset()

Reset this Metric to its "zero" condition.

uptime

public static float uptime()

Return the uptime in hours, measured from when the Metric class was loaded into the VM by the classloader.

Returns:

Description of the Return Value