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* as indicated by the @author tags. See the copyright.txt file in the
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*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.mx.interceptor;
import javax.management.Attribute;
import javax.management.Descriptor;
import javax.management.InvalidAttributeValueException;
import javax.management.ObjectName;
import org.jboss.logging.Logger;
import org.jboss.mx.modelmbean.ModelMBeanConstants;
import org.jboss.mx.modelmbean.ModelMBeanInvoker;
import org.jboss.mx.server.Invocation;
import org.jboss.util.UnreachableStatementException;
/** This interceptor handles the ModelMBean attribute caching and setter
* and getter dispatches.
*
* @author Juha Lindfors.
* @author [email protected]
* @author Dimitris Andreadis.
* @version $Revision: 81026 $
*/
public class ModelMBeanAttributeInterceptor
extends AbstractInterceptor
implements ModelMBeanConstants
{
// Constants -----------------------------------------------------
private static final Logger log = Logger.getLogger(ModelMBeanAttributeInterceptor.class);
// Attributes ----------------------------------------------------
private boolean trace = log.isTraceEnabled();
// Constructors --------------------------------------------------
public ModelMBeanAttributeInterceptor()
{
super("ModelMBean Attribute Interceptor");
}
// Public --------------------------------------------------------
public Object invoke(Invocation invocation) throws Throwable
{
// get the attribute's descriptor
Descriptor d = invocation.getDescriptor();
Class clazz = invocation.getAttributeTypeClass();
String name = null;
ObjectName objectName = null;
if (trace)
{
name = (String) d.getFieldValue(NAME);
objectName = invocation.getInvoker().getObjectName();
}
// check the invocation access point: setAttribute()
if (invocation.getType().equals(Invocation.OP_SETATTRIBUTE))
{
// setAttribute always contains one arg
Object value = invocation.getArgs() [0];
if (trace)
log.trace("Setting objectName=" + objectName + " attr=" + name + " value=" + value);
checkAssignable("Set attribute ", clazz, value);
// remember the old value of this attribute for AVC notification
Object oldValue = d.getFieldValue(ATTRIBUTE_VALUE);
if (trace)
log.trace("Setting objectName=" + objectName + " attr=" + name + " oldValue=" + value);
// check if the attribute maps to a setter
String setMethod = (String) d.getFieldValue(SET_METHOD);
if (trace)
log.trace("Setting objectName=" + objectName + " attr=" + name + " setMethod=" + setMethod);
if (setMethod != null)
{
// if setter was found, invoke the corresponding setter operation
invocation.invoke();
}
// Don't cache the value or last update when not caching
String timeLimit = (String) d.getFieldValue(CURRENCY_TIME_LIMIT);
long limit = (timeLimit == null) ? CACHE_NEVER_LIMIT : Long.parseLong(timeLimit);
String timestamp = Long.toString(System.currentTimeMillis()/1000);
if (limit != CACHE_NEVER_LIMIT)
{
if (trace)
log.trace("Setting objectName=" + objectName + " attr=" + name + " value=" + value + " timestamp=" + timestamp);
d.setField(CACHED_VALUE, value);
d.setField(LAST_UPDATED_TIME_STAMP, timestamp);
}
// Always store the attribute value set, for persistence and AVC purposes mainly
// independent of whether caching is enabled or not.
// Note that if the resource updates its internal attribute value
// we will not know, unless set is performed through the ModelMBean
// interface, or the following descriptor gets updated somehow.
d.setField(ATTRIBUTE_VALUE, value);
d.setField(LAST_UPDATED_TIME_STAMP2, timestamp);
// send AVC notification
ModelMBeanInvoker invoker = (ModelMBeanInvoker) invocation.getInvoker();
invoker.sendAttributeChangeNotification(
new Attribute(invocation.getName(), oldValue),
new Attribute(invocation.getName(), value)
);
return null;
}
else if (invocation.getType().equals(Invocation.OP_GETATTRIBUTE))
{
if (trace)
log.trace("Getting objectName=" + objectName + " attr=" + name);
String timeLimit = (String)d.getFieldValue(CURRENCY_TIME_LIMIT);
long limit = (timeLimit == null) ? CACHE_NEVER_LIMIT : Long.parseLong(timeLimit);
// We are never stale
if (limit == CACHE_ALWAYS_LIMIT)
{
String timeStamp = (String)d.getFieldValue(LAST_UPDATED_TIME_STAMP);
if (timeStamp != null)
{
Object value = d.getFieldValue(CACHED_VALUE);
if (trace)
log.trace("Always cache objectName=" + objectName + " attr=" + name + " value=" + value);
checkAssignable("Cached value in descriptor ", clazz, value);
return value;
}
}
// is caching enabled
if (limit != CACHE_NEVER_LIMIT)
{
String timeStamp = (String)d.getFieldValue(LAST_UPDATED_TIME_STAMP);
long lastUpdate = (timeStamp == null) ? 0 : Long.parseLong(timeStamp);
// if the value hasn't gone stale, return from the descriptor
long now = System.currentTimeMillis();
long expires = lastUpdate * 1000 + limit * 1000;
if (now < expires)
{
Object value = d.getFieldValue(CACHED_VALUE);
if (trace)
log.trace("Using cache objectName=" + objectName + " attr=" + name + " value=" + value + " now=" + now + " expires=" + expires);
checkAssignable("Cached value in descriptor ", clazz, value);
return value;
}
else
{
if (trace)
log.trace("Cache expired objectName=" + objectName + " attr=" + name + " now=" + now + " expires=" + expires);
d.removeField(CACHED_VALUE);
}
}
else
{
// Unfortunatley we have to cope with stupid users
if (trace)
log.trace("Removing any cached value objectName=" + objectName + " attr=" + name + " descriptor=" + d);
d.removeField(CACHED_VALUE);
}
// get the attribute's descriptor
String getMethod = (String)d.getFieldValue(GET_METHOD);
if (trace)
log.trace("Get attribute objectName=" + objectName + " attr=" + name + " getMethod=" + getMethod);
if (getMethod != null)
{
// we got here means either stale value in descriptior, or no caching
Object value = invocation.invoke();
if (trace)
log.trace("Got attribute objectName=" + objectName + " attr=" + name + " value=" + value);
// update the descriptor (unless not caching)
if (limit != CACHE_NEVER_LIMIT)
{
String timestamp = Long.toString(System.currentTimeMillis()/1000);
if (trace)
log.trace("Cache attribute objectName=" + objectName + " attr=" + name + " value=" + value + " timestamp=" + timestamp);
d.setField(CACHED_VALUE, value);
d.setField(LAST_UPDATED_TIME_STAMP, timestamp);
}
return value;
}
else
{
// There is no instance accessor so check for a default value
Object value = d.getFieldValue(DEFAULT);
if (trace)
log.trace("Get attribute use default objectName=" + objectName + " attr=" + name + " default=" + value);
checkAssignable("Default value ", clazz, value);
return value;
}
}
else
throw new UnreachableStatementException(invocation.getType());
}
protected void checkAssignable(String context, Class clazz, Object value) throws InvalidAttributeValueException, ClassNotFoundException
{
if (value != null && clazz.isAssignableFrom(value.getClass()) == false)
throw new InvalidAttributeValueException(context + " has class " + value.getClass() + " loaded from " + value.getClass().getClassLoader() +
" that is not assignable to attribute class " + clazz + " loaded from " + clazz.getClassLoader());
}
}
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