/**
*
* Copyright 2003-2004 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.geronimo.gbean.jmx;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import javax.management.JMException;
import javax.management.MBeanRegistration;
import javax.management.MBeanServer;
import javax.management.MBeanServerNotification;
import javax.management.Notification;
import javax.management.NotificationFilterSupport;
import javax.management.NotificationListener;
import javax.management.ObjectName;
import org.apache.geronimo.kernel.jmx.JMXUtil;
/**
* DependencyService is the record keeper of the dependencies in Geronimo. The DependencyService
* does not enforce any dependencies, it is simply a place where components can register their intent
* to be dependent on another component. Since a JMX Component can pretty much do whatever it wants
* a component must watch the components it depends on to assure that they are following the
* J2EE-Management state machine.
*
* The DependencyService uses the nomenclature of parent-child where a child is dependent on a parent.
* The names parent and child have no other meaning are just a convience to make the code readable.
*
* @jmx:mbean
*
* @version $Revision: 1.3 $ $Date: 2004/03/10 09:59:00 $
*/
public class DependencyService implements MBeanRegistration, NotificationListener, DependencyServiceMBean {
/**
* The mbean server we are registered with.
*/
private MBeanServer server;
/**
* A map from child names to a list of parents.
*/
private final Map childToParentMap = new HashMap();
/**
* A map from parent back to a list of its children.
*/
private final Map parentToChildMap = new HashMap();
/**
* A map from a component's ObjectName to the list of ObjectPatterns that the component is blocking
* from starting.
*/
private final Map startHoldsMap = new HashMap();
public ObjectName preRegister(MBeanServer server, ObjectName objectName) throws Exception {
if (objectName == null) {
objectName = JMXUtil.DEPENDENCY_SERVICE_NAME;
}
this.server = server;
NotificationFilterSupport mbeanServerFilter = new NotificationFilterSupport();
mbeanServerFilter.enableType(MBeanServerNotification.UNREGISTRATION_NOTIFICATION);
server.addNotificationListener(JMXUtil.DELEGATE_NAME, this, mbeanServerFilter, null);
return objectName;
}
public void postRegister(Boolean aBoolean) {
}
public void preDeregister() throws Exception {
}
public void postDeregister() {
try {
server.removeNotificationListener(JMXUtil.DELEGATE_NAME, this);
} catch (JMException ignored) {
// no big deal... just good citizen clean up code
}
synchronized(this) {
server = null;
childToParentMap.clear();
parentToChildMap.clear();
startHoldsMap.clear();
}
}
/**
* Declares a dependency from a child to a parent.
* @param child the dependent component
* @param parent the component the child is depending on
*
* @jmx:managed-operation
*/
public synchronized void addDependency(ObjectName child, ObjectName parent) {
Set parents = (Set) childToParentMap.get(child);
if (parents == null) {
parents = new HashSet();
childToParentMap.put(child, parents);
}
parents.add(parent);
Set children = (Set) parentToChildMap.get(parent);
if (children == null) {
children = new HashSet();
parentToChildMap.put(parent, children);
}
children.add(child);
}
/**
* Removes a dependency from a child to a parent
* @param child the dependnet component
* @param parent the component that the child wil no longer depend on
*
* @jmx:managed-operation
*/
public synchronized void removeDependency(ObjectName child, ObjectName parent) {
Set parents = (Set) childToParentMap.get(child);
if (parents != null) {
parents.remove(parent);
}
Set children = (Set) parentToChildMap.get(parent);
if (children != null) {
children.remove(child);
}
}
/**
* Removes all dependencies for a child
* @param child the component that will no longer depend on anything
*
* @jmx:managed-operation
*/
public synchronized void removeAllDependencies(ObjectName child) {
Set parents = (Set) childToParentMap.remove(child);
if(parents == null) {
return;
}
for (Iterator iterator = parents.iterator(); iterator.hasNext();) {
ObjectName parent = (ObjectName) iterator.next();
Set children = (Set) parentToChildMap.get(parent);
if (children != null) {
children.remove(child);
}
}
}
/**
* Adds dependencies from the child to every parent in the parents set
*
* @param child the dependent component
* @param parents the set of components the child is depending on
*
* @jmx:managed-operation
*/
public synchronized void addDependencies(ObjectName child, Set parents) {
Set existingParents = (Set) childToParentMap.get(child);
if (existingParents == null) {
existingParents = new HashSet(parents);
childToParentMap.put(child, existingParents);
} else {
existingParents.addAll(parents);
}
for (Iterator i = parents.iterator(); i.hasNext();) {
Object startParent = i.next();
Set children = (Set) parentToChildMap.get(startParent);
if (children == null) {
children = new HashSet();
parentToChildMap.put(startParent, children);
}
children.add(child);
}
}
/**
* Gets the set of parents that the child is depending on
*
* @param child the dependent component
* @return a collection containing all of the components the child depends on; will never be null
*
* @jmx:managed-operation
*/
public synchronized Set getParents(ObjectName child) {
Set parents = (Set) childToParentMap.get(child);
if (parents == null) {
return Collections.EMPTY_SET;
}
return parents;
}
/**
* Gets all of the MBeans that have a dependency on the specified startParent.
*
* @param parent the component the returned childen set depend on
* @return a collection containing all of the components that depend on the parent; will never be null
*
* @jmx:managed-operation
*/
public synchronized Set getChildren(ObjectName parent) {
Set children = (Set) parentToChildMap.get(parent);
if (children == null) {
return Collections.EMPTY_SET;
}
return children;
}
/**
* Adds a hold on a collection of object name patterns. If the name of a component matches an object name
* pattern in the collection, the component should not start.
* @param objectName the name of the component placing the holds
* @param holds a collection of object name patterns which should not start
*
* @jmx:managed-operation
*/
public synchronized void addStartHolds(ObjectName objectName, java.util.Collection holds) {
Collection currentHolds = (Collection)startHoldsMap.get(objectName);
if(currentHolds == null) {
currentHolds = new LinkedList(holds);
startHoldsMap.put(objectName, currentHolds);
} else {
currentHolds.addAll(holds);
}
}
/**
* Removes a collection of holds.
* @param objectName the object name of the components owning the holds
* @param holds a collection of the holds to remove
*
* @jmx:managed-operation
*/
public synchronized void removeStartHolds(ObjectName objectName, java.util.Collection holds) {
Collection currentHolds = (Collection)startHoldsMap.get(objectName);
if(currentHolds != null) {
currentHolds.removeAll(holds);
}
}
/**
* Removes all of the holds owned by a component.
* @param objectName the object name of the component that will no longer have any holds
*
* @jmx:managed-operation
*/
public synchronized void removeAllStartHolds(ObjectName objectName) {
startHoldsMap.remove(objectName);
}
/**
* Gets the object name of the mbean blocking the start specified mbean.
* @param objectName the mbean to check for blockers
* @return the mbean blocking the specified mbean, or null if there are no blockers
*
* @jmx:managed-operation
*/
public synchronized ObjectName checkBlocker(ObjectName objectName) {
// check if objectName name is on one of the hold lists
for (Iterator iterator = startHoldsMap.keySet().iterator(); iterator.hasNext();) {
ObjectName blocker = (ObjectName) iterator.next();
List holds = (List) startHoldsMap.get(blocker);
for (Iterator holdsIterator = holds.iterator(); holdsIterator.hasNext();) {
ObjectName pattern = (ObjectName) holdsIterator.next();
if(pattern.apply(objectName)) {
return blocker;
}
}
}
return null;
}
public void handleNotification(Notification n, Object handback) {
String type = n.getType();
if (MBeanServerNotification.UNREGISTRATION_NOTIFICATION.equals(type)) {
MBeanServerNotification notification = (MBeanServerNotification) n;
ObjectName source = notification.getMBeanName();
synchronized(this) {
removeAllDependencies(source);
removeAllStartHolds(source);
}
}
}
}