/*
* Copyright (c) 2005, 2006, 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
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package com.sun.jmx.mbeanserver;
import static com.sun.jmx.mbeanserver.Util.*;
import javax.management.Attribute;
import javax.management.AttributeList;
import javax.management.AttributeNotFoundException;
import javax.management.InvalidAttributeValueException;
import javax.management.MBeanException;
import javax.management.MBeanInfo;
import javax.management.MBeanRegistration;
import javax.management.MBeanServer;
import javax.management.NotCompliantMBeanException;
import javax.management.ObjectName;
import javax.management.ReflectionException;
/**
* Base class for MBeans. There is one instance of this class for
* every Standard MBean and every MXBean. We try to limit the amount
* of information per instance so we can handle very large numbers of
* MBeans comfortably.
*
* @param <M> either Method or ConvertingMethod, for Standard MBeans
* and MXBeans respectively.
*
* @since 1.6
*/
/*
* We maintain a couple of caches to increase sharing between
* different MBeans of the same type and also to reduce creation time
* for the second and subsequent instances of the same type.
*
* The first cache maps from an MBean interface to a PerInterface
* object containing information parsed out of the interface. The
* interface is either a Standard MBean interface or an MXBean
* interface, and there is one cache for each case.
*
* The PerInterface includes an MBeanInfo. This contains the
* attributes and operations parsed out of the interface's methods,
* plus a basic Descriptor for the interface containing at least the
* interfaceClassName field and any fields derived from annotations on
* the interface. This MBeanInfo can never be the MBeanInfo for any
* actual MBean, because an MBeanInfo's getClassName() is the name of
* a concrete class and we don't know what the class will be.
* Furthermore a real MBeanInfo may need to add constructors and/or
* notifications to the MBeanInfo.
*
* The PerInterface also contains an MBeanDispatcher which is able to
* route getAttribute, setAttribute, and invoke to the appropriate
* method of the interface, including doing any necessary translation
* of parameters and return values for MXBeans.
*
* The PerInterface also contains the original Class for the interface.
*
* We need to be careful about references. When there are no MBeans
* with a given interface, there must not be any strong references to
* the interface Class. Otherwise it could never be garbage collected,
* and neither could its ClassLoader or any other classes loaded by
* its ClassLoader. Therefore the cache must wrap the PerInterface
* in a WeakReference. Each instance of MBeanSupport has a strong
* reference to its PerInterface, which prevents PerInterface instances
* from being garbage-collected prematurely.
*
* The second cache maps from a concrete class and an MBean interface
* that that class implements to the MBeanInfo for that class and
* interface. (The ability to specify an interface separately comes
* from the class StandardMBean. MBeans registered directly in the
* MBean Server will always have the same interface here.)
*
* The MBeanInfo in this second cache will be the MBeanInfo from the
* PerInterface cache for the given itnerface, but with the
* getClassName() having the concrete class's name, and the public
* constructors based on the concrete class's constructors. This
* MBeanInfo can be shared between all instances of the concrete class
* specifying the same interface, except instances that are
* NotificationBroadcasters. NotificationBroadcasters supply the
* MBeanNotificationInfo[] in the MBeanInfo based on the instance
* method NotificationBroadcaster.getNotificationInfo(), so two
* instances of the same concrete class do not necessarily have the
* same MBeanNotificationInfo[]. Currently we do not try to detect
* when they do, although it would probably be worthwhile doing that
* since it is a very common case.
*
* Standard MBeans additionally have the property that
* getNotificationInfo() must in principle be called every time
* getMBeanInfo() is called for the MBean, since the returned array is
* allowed to change over time. We attempt to reduce the cost of
* doing this by detecting when the Standard MBean is a subclass of
* NotificationBroadcasterSupport that does not override
* getNotificationInfo(), meaning that the MBeanNotificationInfo[] is
* the one that was supplied to the constructor. MXBeans do not have
* this problem because their getNotificationInfo() method is called
* only once.
*
*/
public abstract class MBeanSupport<M>
implements DynamicMBean2, MBeanRegistration {
<T> MBeanSupport(T resource, Class<T> mbeanInterface)
throws NotCompliantMBeanException {
if (mbeanInterface == null)
throw new NotCompliantMBeanException("Null MBean interface");
if (!mbeanInterface.isInstance(resource)) {
final String msg =
"Resource class " + resource.getClass().getName() +
" is not an instance of " + mbeanInterface.getName();
throw new NotCompliantMBeanException(msg);
}
this.resource = resource;
MBeanIntrospector<M> introspector = getMBeanIntrospector();
this.perInterface = introspector.getPerInterface(mbeanInterface);
this.mbeanInfo = introspector.getMBeanInfo(resource, perInterface);
}
/** Return the appropriate introspector for this type of MBean. */
abstract MBeanIntrospector<M> getMBeanIntrospector();
/**
* Return a cookie for this MBean. This cookie will be passed to
* MBean method invocations where it can supply additional information
* to the invocation. For example, with MXBeans it can be used to
* supply the MXBeanLookup context for resolving inter-MXBean references.
*/
abstract Object getCookie();
public final boolean isMXBean() {
return perInterface.isMXBean();
}
// Methods that javax.management.StandardMBean should call from its
// preRegister and postRegister, given that it is not supposed to
// call the contained object's preRegister etc methods even if it has them
public abstract void register(MBeanServer mbs, ObjectName name)
throws Exception;
public abstract void unregister();
public final ObjectName preRegister(MBeanServer server, ObjectName name)
throws Exception {
if (resource instanceof MBeanRegistration)
return ((MBeanRegistration) resource).preRegister(server, name);
else
return name;
}
public final void preRegister2(MBeanServer server, ObjectName name)
throws Exception {
register(server, name);
}
public final void registerFailed() {
unregister();
}
public final void postRegister(Boolean registrationDone) {
if (resource instanceof MBeanRegistration)
((MBeanRegistration) resource).postRegister(registrationDone);
}
public final void preDeregister() throws Exception {
if (resource instanceof MBeanRegistration)
((MBeanRegistration) resource).preDeregister();
}
public final void postDeregister() {
// Undo any work from registration. We do this in postDeregister
// not preDeregister, because if the user preDeregister throws an
// exception then the MBean is not unregistered.
try {
unregister();
} finally {
if (resource instanceof MBeanRegistration)
((MBeanRegistration) resource).postDeregister();
}
}
public final Object getAttribute(String attribute)
throws AttributeNotFoundException,
MBeanException,
ReflectionException {
return perInterface.getAttribute(resource, attribute, getCookie());
}
public final AttributeList getAttributes(String[] attributes) {
final AttributeList result = new AttributeList(attributes.length);
for (String attrName : attributes) {
try {
final Object attrValue = getAttribute(attrName);
result.add(new Attribute(attrName, attrValue));
} catch (Exception e) {
// OK: attribute is not included in returned list, per spec
// XXX: log the exception
}
}
return result;
}
public final void setAttribute(Attribute attribute)
throws AttributeNotFoundException,
InvalidAttributeValueException,
MBeanException,
ReflectionException {
final String name = attribute.getName();
final Object value = attribute.getValue();
perInterface.setAttribute(resource, name, value, getCookie());
}
public final AttributeList setAttributes(AttributeList attributes) {
final AttributeList result = new AttributeList(attributes.size());
for (Object attrObj : attributes) {
// We can't use AttributeList.asList because it has side-effects
Attribute attr = (Attribute) attrObj;
try {
setAttribute(attr);
result.add(new Attribute(attr.getName(), attr.getValue()));
} catch (Exception e) {
// OK: attribute is not included in returned list, per spec
// XXX: log the exception
}
}
return result;
}
public final Object invoke(String operation, Object[] params,
String[] signature)
throws MBeanException, ReflectionException {
return perInterface.invoke(resource, operation, params, signature,
getCookie());
}
// Overridden by StandardMBeanSupport
public MBeanInfo getMBeanInfo() {
return mbeanInfo;
}
public final String getClassName() {
return resource.getClass().getName();
}
public final Object getResource() {
return resource;
}
public final Class<?> getMBeanInterface() {
return perInterface.getMBeanInterface();
}
private final MBeanInfo mbeanInfo;
private final Object resource;
private final PerInterface<M> perInterface;
}