com.sun.enterprise.admin.monitor.stats

Class MutableCountStatisticImpl

java.lang.Object

com.sun.enterprise.admin.monitor.stats.MutableCountStatisticImpl

All Implemented Interfaces:

MutableCountStatistic, MutableStatistic, Serializable, CountStatistic, Statistic

public class MutableCountStatisticImpl
extends Object
implements CountStatistic, MutableCountStatistic

An implementation of MutableCountStatistic that provides ways to change the state externally through mutators. Convenience class that is useful for components that gather the statistical data.

Since:

S1AS8.0

Version:

1.0

Author:

Kedar Mhaswade

See Also:

for an immutable implementation, Serialized Form

Constructor Summary

Constructors

Constructor and Description
MutableCountStatisticImpl(CountStatistic initial) Constructs an instance of MutableCountStatistic that encapsulates the given Statistic.

Method Summary

Methods

Modifier and Type	Method and Description
long	getCount() The count since the last reset.
String	getDescription() A human-readable description of the Statistic.
long	getLastSampleTime() The time of the last measurement represented as a long, whose value is the number of milliseconds since January 1, 1970, 00:00:00.
String	getName() The name of this Statistic.
long	getStartTime() The time of the first measurement represented as a long, whose value is the number of milliseconds since January 1, 1970, 00:00:00.
String	getUnit() The unit of measurement for this Statistic.
Statistic	modifiableView() Returns an instance of Statistic whose state can be changed by the caller.
void	reset() Resets to the initial state.
void	setCount(long count) Changes the value of the encapsulated CountStatistic to the given value.
void	setDescription(String s)
Statistic	unmodifiableView() This method is the essence of this class.

Methods inherited from class java.lang.Object

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

Constructor Detail

MutableCountStatisticImpl

public MutableCountStatisticImpl(CountStatistic initial)

Constructs an instance of MutableCountStatistic that encapsulates the given Statistic. The only parameter denotes the initial state of this statistic. It is guaranteed that the initial state is preserved internally, so that one can reset to the initial state.

Parameters:

initial - an instance of CountStatistic that represents initial state

Method Detail

reset

public void reset()

Resets to the initial state. It is guaranteed that following changes occur to the statistic if this method is called:

• The current value is reset to its initial value.
• The lastSampleTime is reset to current time in milliseconds.
• The startTime is reset to lastSampleTime.

The remaining meta data in the statistic is unchanged.

Specified by:

reset in interface MutableStatistic

setCount

public void setCount(long count)

Changes the value of the encapsulated CountStatistic to the given value. Since this is the only mutator exposed here, here are the other side effects of calling this method:

• lastSampleTime is set to current time in milliseconds.

In a real-time system with actual probes for measurement, the lastSampleTime could be different from the instant when this method is called, but that is deemed insignificant.

Specified by:

setCount in interface MutableCountStatistic

Parameters:

count - long that represents the current value of the Statistic.

unmodifiableView

public Statistic unmodifiableView()

This method is the essence of this class. It provides the read-only view of encapsulated Statistic. If the clients have to know the Statistic, this is what should be called by actual data collecting component to return the value to them. The principle advantage is from the data collecting component's standpoint, in that it does not have to create instances of CountStatistic when its current value is queried/measured.

Specified by:

unmodifiableView in interface MutableStatistic

Returns:

instance of CountStatistic

See Also:

reset(), setCount(long)

getLastSampleTime

public long getLastSampleTime()

Description copied from interface: Statistic

The time of the last measurement represented as a long, whose value is the number of milliseconds since January 1, 1970, 00:00:00.

Specified by:

getLastSampleTime in interface Statistic

getStartTime

public long getStartTime()

Description copied from interface: Statistic

The time of the first measurement represented as a long, whose value is the number of milliseconds since January 1, 1970, 00:00:00.

Specified by:

getStartTime in interface Statistic

getName

public String getName()

Description copied from interface: Statistic

The name of this Statistic.

Specified by:

getName in interface Statistic

getDescription

public String getDescription()

Description copied from interface: Statistic

A human-readable description of the Statistic.

Specified by:

getDescription in interface Statistic

getUnit

public String getUnit()

Description copied from interface: Statistic

The unit of measurement for this Statistic. Valid values for TimeStatistic measurements are "HOUR", "MINUTE", "SECOND", "MILLISECOND", "MICROSECOND" and "NANOSECOND".

Specified by:

getUnit in interface Statistic

modifiableView

public Statistic modifiableView()

Description copied from interface: MutableStatistic

Returns an instance of Statistic whose state can be changed by the caller. It is important to know that caller should not cache the return value from this method. In general, there is a problem in this contract in that, a client would not know from a Stats.getCreateCount() method whether the return value is something that is being modified or is invariant. Hence the caller should not cache the returned value in a collection and then collectively process it. The main idea behind providing this method is to control the number of instances created (per Mahesh's Suggestion).

Specified by:

modifiableView in interface MutableStatistic

Returns:

an instance of Statistic interface that should not be cached.

getCount

public long getCount()

Description copied from interface: CountStatistic

The count since the last reset.

Specified by:

getCount in interface CountStatistic

setDescription

public void setDescription(String s)