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Java example source code file (GaugeMonitor.java)
This example Java source code file (GaugeMonitor.java) is included in the alvinalexander.com
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The GaugeMonitor.java Java example source code
/*
* Copyright (c) 1999, 2008, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package javax.management.monitor;
import static com.sun.jmx.defaults.JmxProperties.MONITOR_LOGGER;
import java.util.logging.Level;
import javax.management.MBeanNotificationInfo;
import javax.management.ObjectName;
import static javax.management.monitor.Monitor.NumericalType.*;
import static javax.management.monitor.MonitorNotification.*;
/**
* Defines a monitor MBean designed to observe the values of a gauge attribute.
*
* <P> A gauge monitor observes an attribute that is continuously
* variable with time. A gauge monitor sends notifications as
* follows:
*
* <UL>
*
* <LI> if the attribute value is increasing and becomes equal to or
* greater than the high threshold value, a {@link
* MonitorNotification#THRESHOLD_HIGH_VALUE_EXCEEDED threshold high
* notification} is sent. The notify high flag must be set to
* <CODE>true.
*
* <BR>Subsequent crossings of the high threshold value do not cause
* further notifications unless the attribute value becomes equal to
* or less than the low threshold value.</LI>
*
* <LI> if the attribute value is decreasing and becomes equal to or
* less than the low threshold value, a {@link
* MonitorNotification#THRESHOLD_LOW_VALUE_EXCEEDED threshold low
* notification} is sent. The notify low flag must be set to
* <CODE>true.
*
* <BR>Subsequent crossings of the low threshold value do not cause
* further notifications unless the attribute value becomes equal to
* or greater than the high threshold value.</LI>
*
* </UL>
*
* This provides a hysteresis mechanism to avoid repeated triggering
* of notifications when the attribute value makes small oscillations
* around the high or low threshold value.
*
* <P> If the gauge difference mode is used, the value of the derived
* gauge is calculated as the difference between the observed gauge
* values for two successive observations.
*
* <BR>The derived gauge value (V[t]) is calculated using the following method:
* <UL>
* <LI>V[t] = gauge[t] - gauge[t-GP]
* </UL>
*
* This implementation of the gauge monitor requires the observed
* attribute to be of the type integer or floating-point
* (<CODE>Byte, Integer, Short,
* <CODE>Long, Float, Double).
*
*
* @since 1.5
*/
public class GaugeMonitor extends Monitor implements GaugeMonitorMBean {
/*
* ------------------------------------------
* PACKAGE CLASSES
* ------------------------------------------
*/
static class GaugeMonitorObservedObject extends ObservedObject {
public GaugeMonitorObservedObject(ObjectName observedObject) {
super(observedObject);
}
public final synchronized boolean getDerivedGaugeValid() {
return derivedGaugeValid;
}
public final synchronized void setDerivedGaugeValid(
boolean derivedGaugeValid) {
this.derivedGaugeValid = derivedGaugeValid;
}
public final synchronized NumericalType getType() {
return type;
}
public final synchronized void setType(NumericalType type) {
this.type = type;
}
public final synchronized Number getPreviousScanGauge() {
return previousScanGauge;
}
public final synchronized void setPreviousScanGauge(
Number previousScanGauge) {
this.previousScanGauge = previousScanGauge;
}
public final synchronized int getStatus() {
return status;
}
public final synchronized void setStatus(int status) {
this.status = status;
}
private boolean derivedGaugeValid;
private NumericalType type;
private Number previousScanGauge;
private int status;
}
/*
* ------------------------------------------
* PRIVATE VARIABLES
* ------------------------------------------
*/
/**
* Gauge high threshold.
*
* <BR>The default value is a null Integer object.
*/
private Number highThreshold = INTEGER_ZERO;
/**
* Gauge low threshold.
*
* <BR>The default value is a null Integer object.
*/
private Number lowThreshold = INTEGER_ZERO;
/**
* Flag indicating if the gauge monitor notifies when exceeding
* the high threshold.
*
* <BR>The default value is false.
*/
private boolean notifyHigh = false;
/**
* Flag indicating if the gauge monitor notifies when exceeding
* the low threshold.
*
* <BR>The default value is false.
*/
private boolean notifyLow = false;
/**
* Flag indicating if the gauge difference mode is used. If the
* gauge difference mode is used, the derived gauge is the
* difference between two consecutive observed values. Otherwise,
* the derived gauge is directly the value of the observed
* attribute.
*
* <BR>The default value is set to false.
*/
private boolean differenceMode = false;
private static final String[] types = {
RUNTIME_ERROR,
OBSERVED_OBJECT_ERROR,
OBSERVED_ATTRIBUTE_ERROR,
OBSERVED_ATTRIBUTE_TYPE_ERROR,
THRESHOLD_ERROR,
THRESHOLD_HIGH_VALUE_EXCEEDED,
THRESHOLD_LOW_VALUE_EXCEEDED
};
private static final MBeanNotificationInfo[] notifsInfo = {
new MBeanNotificationInfo(
types,
"javax.management.monitor.MonitorNotification",
"Notifications sent by the GaugeMonitor MBean")
};
// Flags needed to implement the hysteresis mechanism.
//
private static final int RISING = 0;
private static final int FALLING = 1;
private static final int RISING_OR_FALLING = 2;
/*
* ------------------------------------------
* CONSTRUCTORS
* ------------------------------------------
*/
/**
* Default constructor.
*/
public GaugeMonitor() {
}
/*
* ------------------------------------------
* PUBLIC METHODS
* ------------------------------------------
*/
/**
* Starts the gauge monitor.
*/
public synchronized void start() {
if (isActive()) {
MONITOR_LOGGER.logp(Level.FINER, GaugeMonitor.class.getName(),
"start", "the monitor is already active");
return;
}
// Reset values.
//
for (ObservedObject o : observedObjects) {
final GaugeMonitorObservedObject gmo =
(GaugeMonitorObservedObject) o;
gmo.setStatus(RISING_OR_FALLING);
gmo.setPreviousScanGauge(null);
}
doStart();
}
/**
* Stops the gauge monitor.
*/
public synchronized void stop() {
doStop();
}
// GETTERS AND SETTERS
//--------------------
/**
* Gets the derived gauge of the specified object, if this object is
* contained in the set of observed MBeans, or <code>null otherwise.
*
* @param object the name of the MBean.
*
* @return The derived gauge of the specified object.
*
*/
@Override
public synchronized Number getDerivedGauge(ObjectName object) {
return (Number) super.getDerivedGauge(object);
}
/**
* Gets the derived gauge timestamp of the specified object, if
* this object is contained in the set of observed MBeans, or
* <code>0 otherwise.
*
* @param object the name of the object whose derived gauge
* timestamp is to be returned.
*
* @return The derived gauge timestamp of the specified object.
*
*/
@Override
public synchronized long getDerivedGaugeTimeStamp(ObjectName object) {
return super.getDerivedGaugeTimeStamp(object);
}
/**
* Returns the derived gauge of the first object in the set of
* observed MBeans.
*
* @return The derived gauge.
*
* @deprecated As of JMX 1.2, replaced by
* {@link #getDerivedGauge(ObjectName)}
*/
@Deprecated
public synchronized Number getDerivedGauge() {
if (observedObjects.isEmpty()) {
return null;
} else {
return (Number) observedObjects.get(0).getDerivedGauge();
}
}
/**
* Gets the derived gauge timestamp of the first object in the set
* of observed MBeans.
*
* @return The derived gauge timestamp.
*
* @deprecated As of JMX 1.2, replaced by
* {@link #getDerivedGaugeTimeStamp(ObjectName)}
*/
@Deprecated
public synchronized long getDerivedGaugeTimeStamp() {
if (observedObjects.isEmpty()) {
return 0;
} else {
return observedObjects.get(0).getDerivedGaugeTimeStamp();
}
}
/**
* Gets the high threshold value common to all observed MBeans.
*
* @return The high threshold value.
*
* @see #setThresholds
*/
public synchronized Number getHighThreshold() {
return highThreshold;
}
/**
* Gets the low threshold value common to all observed MBeans.
*
* @return The low threshold value.
*
* @see #setThresholds
*/
public synchronized Number getLowThreshold() {
return lowThreshold;
}
/**
* Sets the high and the low threshold values common to all
* observed MBeans.
*
* @param highValue The high threshold value.
* @param lowValue The low threshold value.
*
* @exception IllegalArgumentException The specified high/low
* threshold is null or the low threshold is greater than the high
* threshold or the high threshold and the low threshold are not
* of the same type.
*
* @see #getHighThreshold
* @see #getLowThreshold
*/
public synchronized void setThresholds(Number highValue, Number lowValue)
throws IllegalArgumentException {
if ((highValue == null) || (lowValue == null)) {
throw new IllegalArgumentException("Null threshold value");
}
if (highValue.getClass() != lowValue.getClass()) {
throw new IllegalArgumentException("Different type " +
"threshold values");
}
if (isFirstStrictlyGreaterThanLast(lowValue, highValue,
highValue.getClass().getName())) {
throw new IllegalArgumentException("High threshold less than " +
"low threshold");
}
if (highThreshold.equals(highValue) && lowThreshold.equals(lowValue))
return;
highThreshold = highValue;
lowThreshold = lowValue;
// Reset values.
//
int index = 0;
for (ObservedObject o : observedObjects) {
resetAlreadyNotified(o, index++, THRESHOLD_ERROR_NOTIFIED);
final GaugeMonitorObservedObject gmo =
(GaugeMonitorObservedObject) o;
gmo.setStatus(RISING_OR_FALLING);
}
}
/**
* Gets the high notification's on/off switch value common to all
* observed MBeans.
*
* @return <CODE>true if the gauge monitor notifies when
* exceeding the high threshold, <CODE>false otherwise.
*
* @see #setNotifyHigh
*/
public synchronized boolean getNotifyHigh() {
return notifyHigh;
}
/**
* Sets the high notification's on/off switch value common to all
* observed MBeans.
*
* @param value The high notification's on/off switch value.
*
* @see #getNotifyHigh
*/
public synchronized void setNotifyHigh(boolean value) {
if (notifyHigh == value)
return;
notifyHigh = value;
}
/**
* Gets the low notification's on/off switch value common to all
* observed MBeans.
*
* @return <CODE>true if the gauge monitor notifies when
* exceeding the low threshold, <CODE>false otherwise.
*
* @see #setNotifyLow
*/
public synchronized boolean getNotifyLow() {
return notifyLow;
}
/**
* Sets the low notification's on/off switch value common to all
* observed MBeans.
*
* @param value The low notification's on/off switch value.
*
* @see #getNotifyLow
*/
public synchronized void setNotifyLow(boolean value) {
if (notifyLow == value)
return;
notifyLow = value;
}
/**
* Gets the difference mode flag value common to all observed MBeans.
*
* @return <CODE>true if the difference mode is used,
* <CODE>false otherwise.
*
* @see #setDifferenceMode
*/
public synchronized boolean getDifferenceMode() {
return differenceMode;
}
/**
* Sets the difference mode flag value common to all observed MBeans.
*
* @param value The difference mode flag value.
*
* @see #getDifferenceMode
*/
public synchronized void setDifferenceMode(boolean value) {
if (differenceMode == value)
return;
differenceMode = value;
// Reset values.
//
for (ObservedObject o : observedObjects) {
final GaugeMonitorObservedObject gmo =
(GaugeMonitorObservedObject) o;
gmo.setStatus(RISING_OR_FALLING);
gmo.setPreviousScanGauge(null);
}
}
/**
* Returns a <CODE>NotificationInfo object containing the
* name of the Java class of the notification and the notification
* types sent by the gauge monitor.
*/
@Override
public MBeanNotificationInfo[] getNotificationInfo() {
return notifsInfo.clone();
}
/*
* ------------------------------------------
* PRIVATE METHODS
* ------------------------------------------
*/
/**
* Updates the derived gauge attribute of the observed object.
*
* @param scanGauge The value of the observed attribute.
* @param o The observed object.
* @return <CODE>true if the derived gauge value is valid,
* <CODE>false otherwise. The derived gauge value is
* invalid when the differenceMode flag is set to
* <CODE>true and it is the first notification (so we
* haven't 2 consecutive values to update the derived gauge).
*/
private synchronized boolean updateDerivedGauge(
Object scanGauge, GaugeMonitorObservedObject o) {
boolean is_derived_gauge_valid;
// The gauge difference mode is used.
//
if (differenceMode) {
// The previous scan gauge has been initialized.
//
if (o.getPreviousScanGauge() != null) {
setDerivedGaugeWithDifference((Number)scanGauge, o);
is_derived_gauge_valid = true;
}
// The previous scan gauge has not been initialized.
// We cannot update the derived gauge...
//
else {
is_derived_gauge_valid = false;
}
o.setPreviousScanGauge((Number)scanGauge);
}
// The gauge difference mode is not used.
//
else {
o.setDerivedGauge((Number)scanGauge);
is_derived_gauge_valid = true;
}
return is_derived_gauge_valid;
}
/**
* Updates the notification attribute of the observed object
* and notifies the listeners only once if the notify flag
* is set to <CODE>true.
* @param o The observed object.
*/
private synchronized MonitorNotification updateNotifications(
GaugeMonitorObservedObject o) {
MonitorNotification n = null;
// Send high notification if notifyHigh is true.
// Send low notification if notifyLow is true.
//
if (o.getStatus() == RISING_OR_FALLING) {
if (isFirstGreaterThanLast((Number)o.getDerivedGauge(),
highThreshold,
o.getType())) {
if (notifyHigh) {
n = new MonitorNotification(
THRESHOLD_HIGH_VALUE_EXCEEDED,
this,
0,
0,
"",
null,
null,
null,
highThreshold);
}
o.setStatus(FALLING);
} else if (isFirstGreaterThanLast(lowThreshold,
(Number)o.getDerivedGauge(),
o.getType())) {
if (notifyLow) {
n = new MonitorNotification(
THRESHOLD_LOW_VALUE_EXCEEDED,
this,
0,
0,
"",
null,
null,
null,
lowThreshold);
}
o.setStatus(RISING);
}
} else {
if (o.getStatus() == RISING) {
if (isFirstGreaterThanLast((Number)o.getDerivedGauge(),
highThreshold,
o.getType())) {
if (notifyHigh) {
n = new MonitorNotification(
THRESHOLD_HIGH_VALUE_EXCEEDED,
this,
0,
0,
"",
null,
null,
null,
highThreshold);
}
o.setStatus(FALLING);
}
} else if (o.getStatus() == FALLING) {
if (isFirstGreaterThanLast(lowThreshold,
(Number)o.getDerivedGauge(),
o.getType())) {
if (notifyLow) {
n = new MonitorNotification(
THRESHOLD_LOW_VALUE_EXCEEDED,
this,
0,
0,
"",
null,
null,
null,
lowThreshold);
}
o.setStatus(RISING);
}
}
}
return n;
}
/**
* Sets the derived gauge when the differenceMode flag is set to
* <CODE>true. Both integer and floating-point types are
* allowed.
*
* @param scanGauge The value of the observed attribute.
* @param o The observed object.
*/
private synchronized void setDerivedGaugeWithDifference(
Number scanGauge, GaugeMonitorObservedObject o) {
Number prev = o.getPreviousScanGauge();
Number der;
switch (o.getType()) {
case INTEGER:
der = Integer.valueOf(((Integer)scanGauge).intValue() -
((Integer)prev).intValue());
break;
case BYTE:
der = Byte.valueOf((byte)(((Byte)scanGauge).byteValue() -
((Byte)prev).byteValue()));
break;
case SHORT:
der = Short.valueOf((short)(((Short)scanGauge).shortValue() -
((Short)prev).shortValue()));
break;
case LONG:
der = Long.valueOf(((Long)scanGauge).longValue() -
((Long)prev).longValue());
break;
case FLOAT:
der = Float.valueOf(((Float)scanGauge).floatValue() -
((Float)prev).floatValue());
break;
case DOUBLE:
der = Double.valueOf(((Double)scanGauge).doubleValue() -
((Double)prev).doubleValue());
break;
default:
// Should never occur...
MONITOR_LOGGER.logp(Level.FINEST, GaugeMonitor.class.getName(),
"setDerivedGaugeWithDifference",
"the threshold type is invalid");
return;
}
o.setDerivedGauge(der);
}
/**
* Tests if the first specified Number is greater than or equal to
* the last. Both integer and floating-point types are allowed.
*
* @param greater The first Number to compare with the second.
* @param less The second Number to compare with the first.
* @param type The number type.
* @return <CODE>true if the first specified Number is
* greater than or equal to the last, <CODE>false
* otherwise.
*/
private boolean isFirstGreaterThanLast(Number greater,
Number less,
NumericalType type) {
switch (type) {
case INTEGER:
case BYTE:
case SHORT:
case LONG:
return (greater.longValue() >= less.longValue());
case FLOAT:
case DOUBLE:
return (greater.doubleValue() >= less.doubleValue());
default:
// Should never occur...
MONITOR_LOGGER.logp(Level.FINEST, GaugeMonitor.class.getName(),
"isFirstGreaterThanLast",
"the threshold type is invalid");
return false;
}
}
/**
* Tests if the first specified Number is strictly greater than the last.
* Both integer and floating-point types are allowed.
*
* @param greater The first Number to compare with the second.
* @param less The second Number to compare with the first.
* @param className The number class name.
* @return <CODE>true if the first specified Number is
* strictly greater than the last, <CODE>false otherwise.
*/
private boolean isFirstStrictlyGreaterThanLast(Number greater,
Number less,
String className) {
if (className.equals("java.lang.Integer") ||
className.equals("java.lang.Byte") ||
className.equals("java.lang.Short") ||
className.equals("java.lang.Long")) {
return (greater.longValue() > less.longValue());
}
else if (className.equals("java.lang.Float") ||
className.equals("java.lang.Double")) {
return (greater.doubleValue() > less.doubleValue());
}
else {
// Should never occur...
MONITOR_LOGGER.logp(Level.FINEST, GaugeMonitor.class.getName(),
"isFirstStrictlyGreaterThanLast",
"the threshold type is invalid");
return false;
}
}
/*
* ------------------------------------------
* PACKAGE METHODS
* ------------------------------------------
*/
/**
* Factory method for ObservedObject creation.
*
* @since 1.6
*/
@Override
ObservedObject createObservedObject(ObjectName object) {
final GaugeMonitorObservedObject gmo =
new GaugeMonitorObservedObject(object);
gmo.setStatus(RISING_OR_FALLING);
gmo.setPreviousScanGauge(null);
return gmo;
}
/**
* This method globally sets the derived gauge type for the given
* "object" and "attribute" after checking that the type of the
* supplied observed attribute value is one of the value types
* supported by this monitor.
*/
@Override
synchronized boolean isComparableTypeValid(ObjectName object,
String attribute,
Comparable<?> value) {
final GaugeMonitorObservedObject o =
(GaugeMonitorObservedObject) getObservedObject(object);
if (o == null)
return false;
// Check that the observed attribute is either of type
// "Integer" or "Float".
//
if (value instanceof Integer) {
o.setType(INTEGER);
} else if (value instanceof Byte) {
o.setType(BYTE);
} else if (value instanceof Short) {
o.setType(SHORT);
} else if (value instanceof Long) {
o.setType(LONG);
} else if (value instanceof Float) {
o.setType(FLOAT);
} else if (value instanceof Double) {
o.setType(DOUBLE);
} else {
return false;
}
return true;
}
@Override
synchronized Comparable<?> getDerivedGaugeFromComparable(
ObjectName object,
String attribute,
Comparable<?> value) {
final GaugeMonitorObservedObject o =
(GaugeMonitorObservedObject) getObservedObject(object);
if (o == null)
return null;
// Update the derived gauge attributes and check the
// validity of the new value. The derived gauge value
// is invalid when the differenceMode flag is set to
// true and it is the first notification, i.e. we
// haven't got 2 consecutive values to update the
// derived gauge.
//
o.setDerivedGaugeValid(updateDerivedGauge(value, o));
return (Comparable<?>) o.getDerivedGauge();
}
@Override
synchronized void onErrorNotification(MonitorNotification notification) {
final GaugeMonitorObservedObject o = (GaugeMonitorObservedObject)
getObservedObject(notification.getObservedObject());
if (o == null)
return;
// Reset values.
//
o.setStatus(RISING_OR_FALLING);
o.setPreviousScanGauge(null);
}
@Override
synchronized MonitorNotification buildAlarmNotification(
ObjectName object,
String attribute,
Comparable<?> value) {
final GaugeMonitorObservedObject o =
(GaugeMonitorObservedObject) getObservedObject(object);
if (o == null)
return null;
// Notify the listeners if the updated derived
// gauge value is valid.
//
final MonitorNotification alarm;
if (o.getDerivedGaugeValid())
alarm = updateNotifications(o);
else
alarm = null;
return alarm;
}
/**
* Tests if the threshold high and threshold low are both of the
* same type as the gauge. Both integer and floating-point types
* are allowed.
*
* Note:
* If the optional lowThreshold or highThreshold have not been
* initialized, their default value is an Integer object with
* a value equal to zero.
*
* @param object The observed object.
* @param attribute The observed attribute.
* @param value The sample value.
* @return <CODE>true if type is the same,
* <CODE>false otherwise.
*/
@Override
synchronized boolean isThresholdTypeValid(ObjectName object,
String attribute,
Comparable<?> value) {
final GaugeMonitorObservedObject o =
(GaugeMonitorObservedObject) getObservedObject(object);
if (o == null)
return false;
Class<? extends Number> c = classForType(o.getType());
return (isValidForType(highThreshold, c) &&
isValidForType(lowThreshold, c));
}
}
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