org.jboss.mx.persistence.DelegatingPersistenceManager Maven / Gradle / Ivy
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* Lesser General Public License for more details.
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package org.jboss.mx.persistence;
import javax.management.Attribute;
import javax.management.AttributeList;
import javax.management.Descriptor;
import javax.management.InstanceNotFoundException;
import javax.management.MBeanAttributeInfo;
import javax.management.MBeanException;
import javax.management.MBeanInfo;
import javax.management.MBeanServer;
import javax.management.MalformedObjectNameException;
import javax.management.ObjectName;
import javax.management.ReflectionException;
import javax.management.modelmbean.ModelMBeanAttributeInfo;
import javax.management.modelmbean.ModelMBeanInfo;
import org.jboss.logging.Logger;
import org.jboss.mx.modelmbean.ModelMBeanConstants;
import org.jboss.mx.modelmbean.ModelMBeanInvoker;
/**
* DelegatingPersistenceManager.
*
* An XMBean Persistence Manager that delegates to an external
* MBean-controlled implementation the actual persistence of
* MBean attributes.
*
* @author Dimitris Andreadis
* @version $Revision: 81026 $
*/
public class DelegatingPersistenceManager
implements PersistenceManager
{
// Private Data --------------------------------------------------
private static Logger log = Logger.getLogger(DelegatingPersistenceManager.class);
/** where calls are delegated */
private AttributePersistenceManager persistor;
/** the associated name to use at load/store */
private String persistName;
/** load operation triggers save, so we want to prevent this */
private boolean isLoading;
// Constructors --------------------------------------------------
public DelegatingPersistenceManager()
{
// emtpy
}
// PersistenceManager overrides ----------------------------------
/**
* Called initialy when the XMBean is constructed in order
* to load and set the attributes of the MBean,
* if their persistent image exists.
*/
public void load(ModelMBeanInvoker invoker, MBeanInfo metadata)
throws MBeanException
{
if (this.persistor == null) {
// lazy initialization on first load - couldn't do
// otherwise with this PersistenceManager interface
init(invoker, metadata);
}
if (log.isDebugEnabled())
log.debug("load() called for: '" + this.persistName + "'");
AttributeList attrs = null;
// load from the persistor
try {
attrs = this.persistor.load(this.persistName);
}
catch (Exception e) {
// problem while loading
log.warn("Caught exception while loading", e);
throw new MBeanException(e);
}
if (attrs != null) {
// a persistent attribute list image was found so restore it
try {
// need to mark we are loading because setting the attributes
// will triger a store() that should be ignored
setIsLoading(true);
if (log.isDebugEnabled())
log.debug("loading attributes: " + attrs);
invoker.setAttributes(attrs);
}
finally {
setIsLoading(false);
}
}
else {
if (log.isDebugEnabled())
log.debug("No attributes to load");
}
}
/**
* store() is triggered by the PersistenceInterceptor based
* on the persistence policy.
*
* In the simple case, it will be called for every attribute set.
*
* store() will save *all* attributes that:
* (a) are writable (so we can re-load them later on)
* (b) their value exists in the ATTRIBUTE_VALUE descriptor
* (c) are not marked as PM_NEVER
*/
public void store(MBeanInfo metadata)
throws MBeanException
{
if (this.persistor == null) {
// shouln't happen
throw new MBeanException(new Exception("store() called before instance initialized"));
}
// while loading store() is triggered
if (isLoading()) {
return; // ignore call
}
else {
if (log.isDebugEnabled())
log.debug("store() called for: '" + this.persistName + "'");
// placehold for attributes to be persisted
AttributeList attributes = new AttributeList();
// iterate over all attributes in metadata
MBeanAttributeInfo[] attrs = metadata.getAttributes();
if (log.isDebugEnabled() && attrs.length > 0)
log.debug("store() --- ModelMBeanAttributeInfo[] ---");
for (int i = 0; i < attrs.length; i++)
{
/// for each (a) writable attribute (b) in the model cache,
// create a new Attribute object and add it to the collection.
ModelMBeanAttributeInfo attributeInfo = (ModelMBeanAttributeInfo)attrs[i];
if (log.isDebugEnabled())
log.debug(" attr (#" + i + ") - " + attributeInfo);
if (attributeInfo.isWritable()) {
Descriptor attrDesc = attributeInfo.getDescriptor();
Object name = attrDesc.getFieldValue(ModelMBeanConstants.NAME);
Object value = attrDesc.getFieldValue(ModelMBeanConstants.ATTRIBUTE_VALUE);
Object updated = attrDesc.getFieldValue(ModelMBeanConstants.LAST_UPDATED_TIME_STAMP2);
Object pPolicy = attrDesc.getFieldValue(ModelMBeanConstants.PERSIST_POLICY);
boolean noPersistPolicy =
pPolicy != null &&
((String)pPolicy).equalsIgnoreCase(ModelMBeanConstants.PP_NEVER) ? true : false;
// to persist the attribute:
//
// (a) must be writable (so we can re-load it later on)
// (b) its value must be set in the ATTRIBUTE_VALUE descriptor
// (c) must not be marked as PM_NEVER
if (updated != null && noPersistPolicy == false) {
attributes.add(new Attribute(name.toString(), value));
}
}
}
try {
if (!attributes.isEmpty()) {
if (log.isDebugEnabled())
log.debug("calling persistor.store(" + this.persistName + ") attrs=" + attributes);
persistor.store(this.persistName, attributes);
}
else {
if (log.isDebugEnabled())
log.debug("nothing to persist");
}
}
catch (Exception e) {
log.warn("cought exception during store()", e);
}
}
}
// Protected -----------------------------------------------------
/**
* Lazy initialization
*
* Gets the external persistor to use and decides on the
* persistName to use for this MBean load()/store() calls.
*/
protected void init(ModelMBeanInvoker invoker, MBeanInfo metadata)
throws MBeanException
{
Descriptor desc = ((ModelMBeanInfo)metadata).getMBeanDescriptor();
if (log.isDebugEnabled()) {
log.debug("init() --- ModelMBeanInfo Descriptor --- ");
log.debug(desc);
}
// Decide what to use as a persistent name (id) for this MBean
// If the user has explicitly specified a "persistName", use it
String name = (String)desc.getFieldValue(ModelMBeanConstants.PERSIST_NAME);
if (name != null) {
this.persistName = name;
}
else {
// Try to find ObjectName stored (or lets say hidden) there by ModelMBeanInvoker
ObjectName objectName = (ObjectName)desc.getFieldValue(ModelMBeanConstants.OBJECT_NAME);
if (objectName != null) {
this.persistName = objectName.toString();
}
else {
throw new MBeanException(new Exception("must specify a value for: " + ModelMBeanConstants.PERSIST_NAME));
}
}
if (log.isDebugEnabled())
log.debug("chosen persistent id: '" + this.persistName + "'");
// get the name of the MBean factory service that creates
// the AttributePersistenceManager implementation
String service = (String)desc.getFieldValue(ModelMBeanConstants.DELEGATING_PM_SERVICE_DESCRIPTOR);
if (service == null)
{
// use default
service = ModelMBeanConstants.DELEGATING_PM_SERVICE_DEFAULT_VALUE;
}
// get the name of the operation to call on the MBean service
String operation = (String)desc.getFieldValue(ModelMBeanConstants.DELEGATING_PM_OPERATION_DESCRIPTOR);
if (operation == null)
{
// use default
operation = ModelMBeanConstants.DELEGATING_PM_OPERATION_DEFAULT_VALUE;
}
// Create the AttributePersistenceManager
try {
ObjectName objName = new ObjectName(service);
MBeanServer server = invoker.getServer();
this.persistor = (AttributePersistenceManager)server.invoke(objName,
operation,
new Object[] {},
new String[] {});
if (this.persistor == null) {
throw new MBeanException(new NullPointerException("null AttributePersistenceManager from: " + service));
}
}
catch (MalformedObjectNameException e) {
throw new MBeanException(e, "not a valid ObjectName: " + service);
}
catch (InstanceNotFoundException e) {
throw new MBeanException(e, "service not registered: " + service);
}
catch (ReflectionException e) {
throw new MBeanException(e);
}
if (log.isDebugEnabled())
log.debug("using AttributePersistenceManager: " + this.persistor.getClass().getName());
}
/**
* Check if we are loading state
*/
protected boolean isLoading()
{
return isLoading;
}
/**
* Set the loading status
*
* @param newIsLoading
*/
protected void setIsLoading(boolean newIsLoading)
{
isLoading = newIsLoading;
}
}
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