com.sleepycat.je.jmx

Class JEMonitor

java.lang.Object

com.sleepycat.je.jmx.JEMonitor

All Implemented Interfaces:

javax.management.DynamicMBean

public class JEMonitor
extends java.lang.Object
implements javax.management.DynamicMBean

JEMonitor is a JMX MBean which manages a JE environment. The MBean may be installed as is, or used as a starting point for building a MBean which includes JE support. JEMonitor expects another component in the JVM to configure and open the JE environment; it will only access a JE environment that is already active. It is intended for these use cases:

• The application wants to add database monitoring with minimal effort and little knowledge of JMX. Configuring JEMonitor within the JMX container provides monitoring without requiring application code changes.
• An application already supports JMX and wants to add database monitoring without modifying its existing MBean. The user can configure JEMonitor in the JMX container in conjunction with other application MBeans that are non-overlapping with JE monitoring. No application code changes are required.

In this MBean, JE management is divided between the JEMonitor class and JEMBeanHelper class. JEMonitor contains an instance of JEMBeanHelper, which knows about JE attributes, operations and notifications. JEMonitor itself has the responsibility of obtaining a temporary handle for the JE environment.

The key implementation choice for a JE MBean is the approach taken for accessing the JE environment. Some of the salient considerations are:

• Applications may open one or many Environment objects per process against a given environment.
• All Environment handles reference the same underlying JE environment implementation object.
• The first Environment object instantiated in the process does the real work of configuring and opening the environment. Follow-on instantiations of Environment merely increment a reference count. Likewise, Environment.close() only does real work when it's called by the last Environment object in the process.

Because of these considerations, JEMonitor avoids holding a JE environment handle in order to not impact the environment lifetime. Any environment handles used are held temporarily.

Constructor Summary

Constructors

Constructor and Description
JEMonitor(java.lang.String environmentHome) Instantiate a JEMonitor

Method Summary

Methods

Modifier and Type	Method and Description
protected void	closeEnvironment(Environment targetEnv) Be sure to close Environments when they are no longer used, because they pin down resources.
java.lang.Object	getAttribute(java.lang.String attributeName)
javax.management.AttributeList	getAttributes(java.lang.String[] attributes)
protected Environment	getEnvironmentIfOpen() This MBean has the policy of only accessing an environment when it has already been configured and opened by other application threads.
javax.management.MBeanInfo	getMBeanInfo()
java.lang.Object	invoke(java.lang.String actionName, java.lang.Object[] params, java.lang.String[] signature)
void	setAttribute(javax.management.Attribute attribute)
javax.management.AttributeList	setAttributes(javax.management.AttributeList attributes)

Methods inherited from class java.lang.Object

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

Constructor Detail

JEMonitor

public JEMonitor(java.lang.String environmentHome)
          throws javax.management.MBeanException

Instantiate a JEMonitor

Parameters:

environmentHome - home directory of the target JE environment.

Throws:

javax.management.MBeanException

Method Detail

getAttribute

public java.lang.Object getAttribute(java.lang.String attributeName)
                              throws javax.management.AttributeNotFoundException,
                                     javax.management.MBeanException

Specified by:

getAttribute in interface javax.management.DynamicMBean

Throws:

javax.management.AttributeNotFoundException

javax.management.MBeanException

See Also:

DynamicMBean.getAttribute(java.lang.String)

setAttribute

public void setAttribute(javax.management.Attribute attribute)
                  throws javax.management.AttributeNotFoundException,
                         javax.management.InvalidAttributeValueException,
                         javax.management.MBeanException

Specified by:

setAttribute in interface javax.management.DynamicMBean

Throws:

javax.management.AttributeNotFoundException

javax.management.InvalidAttributeValueException

javax.management.MBeanException

See Also:

DynamicMBean.setAttribute(javax.management.Attribute)

getAttributes

public javax.management.AttributeList getAttributes(java.lang.String[] attributes)

Specified by:

getAttributes in interface javax.management.DynamicMBean

See Also:

DynamicMBean.getAttributes(java.lang.String[])

setAttributes

public javax.management.AttributeList setAttributes(javax.management.AttributeList attributes)

Specified by:

setAttributes in interface javax.management.DynamicMBean

See Also:

DynamicMBean.setAttributes(javax.management.AttributeList)

invoke

public java.lang.Object invoke(java.lang.String actionName,
                      java.lang.Object[] params,
                      java.lang.String[] signature)
                        throws javax.management.MBeanException

Specified by:

invoke in interface javax.management.DynamicMBean

Throws:

javax.management.MBeanException

See Also:

DynamicMBean.invoke(java.lang.String, java.lang.Object[], java.lang.String[])

getMBeanInfo

public javax.management.MBeanInfo getMBeanInfo()

Specified by:

getMBeanInfo in interface javax.management.DynamicMBean

See Also:

DynamicMBean.getMBeanInfo()

getEnvironmentIfOpen

protected Environment getEnvironmentIfOpen()

This MBean has the policy of only accessing an environment when it has already been configured and opened by other application threads.

Returns:

a valid Environment or null if the environment is not open

closeEnvironment

protected void closeEnvironment(Environment targetEnv)
                         throws javax.management.MBeanException

Be sure to close Environments when they are no longer used, because they pin down resources.

Parameters:

targetEnv - the open environment. May be null.

Throws:

javax.management.MBeanException