com.kdgregory.logging.common.jmx.AbstractJMXManager Maven / Gradle / Ivy
// Copyright (c) Keith D Gregory
//
// 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 com.kdgregory.logging.common.jmx;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.IdentityHashMap;
import java.util.List;
import java.util.Map;
import javax.management.MBeanServer;
import javax.management.MalformedObjectNameException;
import javax.management.ObjectName;
import javax.management.StandardMBean;
import com.kdgregory.logging.aws.internal.AbstractWriterStatistics;
import com.kdgregory.logging.common.util.InternalLogger;
/**
* This class manages the relationships between the writer statistics beans
* and the JMX server(s) where they should be registered. Servers and beans
* may be added or removed in any order; this class ensures that beans will
* be registered with any new servers, and any new beans will be registered
* with all existing servers.
*
* This works by using a "marker bean" that is registered with an MBean server
* and also with the singleton instance of this class. Statistics beans are
* added to the singleton instance by their appender. Either type of addition
* is a trigger to ensure that the statistics beans are registered with all
* known servers.
*
* The object name used to register the marker bean is retained, and used as
* the base for the object name(s) used to register the statistics bean(s):
* the stats bean name will append ",appender=X", where X is the appender name.
*
* Subclasses are expected to manage the singleton instance.
*/
public abstract class AbstractJMXManager
{
// all members are marked protected so that they can be inspected by tests
protected InternalLogger logger;
protected Map> regisrations
= new IdentityHashMap>();
// note: we only allow one registration per server
protected Map registrationNames
= new IdentityHashMap();
protected Map statsBeans
= new HashMap();
protected Map> statsBeanTypes
= new HashMap>();
protected AbstractJMXManager(InternalLogger logger)
{
this.logger = logger;
}
//----------------------------------------------------------------------------
// Methods called by StatisticsMBean
//----------------------------------------------------------------------------
/**
* Adds relationship between a marker bean and an MBeanServer. If any
* writer beans are known, they will be registered with the server at
* this time.
*
* Attempting to add the same bean/server more than once is silently
* ignored (it should never happen in the real world, so does not rate
* a check).
*/
public synchronized void addMarkerBean(Object bean, MBeanServer server, ObjectName registrationName)
{
if (registrationNames.containsKey(server))
{
logger.warn("server already registered with name " + registrationNames.get(server)
+ " ignoring " + registrationName);
return;
}
registrationNames.put(server, registrationName.getCanonicalName());
List servers = regisrations.get(bean);
if (servers == null)
{
servers = new ArrayList();
regisrations.put(bean, servers);
}
servers.add(server);
for (String appenderName : statsBeans.keySet())
{
registerAppenderBean(appenderName, server);
}
}
/**
* Will deregister a StatisticsMBean instance from all known servers.
*/
public synchronized void removeMarkerBean(Object bean)
{
List servers = regisrations.remove(bean);
if (servers == null)
{
logger.warn("JMXManager: attempt to remove unregistered StatisticsMBean");
return;
}
for (MBeanServer server : servers)
{
for (String appenderName : statsBeans.keySet())
{
unregisterAppenderBean(appenderName, server);
}
registrationNames.remove(server);
}
}
//----------------------------------------------------------------------------
// Methods called by appender
//----------------------------------------------------------------------------
/**
* Adds a writer's statsbean and its class to the internal tracking tables.
* If there are known StatisticsMBean/MBeanServer associations, the stats
* bean will also be registered with those servers.
*
* These tables are managed by appender name. Calling with the same name and
* same appender bean is silently ignored. Calling with the same name but a
* different appender bean is an error. In the real world, neither of these
* cases should happen, because the appender is registered during initialization.
*/
public synchronized void addStatsBean(String appenderName, AbstractWriterStatistics statsBean, Class statsBeanClass)
{
statsBeans.put(appenderName, statsBean);
statsBeanTypes.put(appenderName, statsBeanClass);
for (List servers : regisrations.values())
{
for (MBeanServer server : servers)
{
registerAppenderBean(appenderName, server);
}
}
}
/**
* Removes information about a stats bean from the internal tables and deregisters
* it from any MBeanServers. This is normally called when the appender is closed.
*/
public synchronized void removeStatsBean(String appenderName)
{
statsBeans.remove(appenderName);
statsBeanTypes.remove(appenderName);
for (List servers : regisrations.values())
{
for (MBeanServer server : servers)
{
unregisterAppenderBean(appenderName, server);
}
}
}
//----------------------------------------------------------------------------
// Internals -- protected so they can be overridden
//----------------------------------------------------------------------------
/**
* Registers an appender's stats bean with a server.
*/
@SuppressWarnings("rawtypes")
protected void registerAppenderBean(String appenderName, MBeanServer mbeanServer)
{
if (appenderName == null)
{
logger.error("JMXManager: attempted to register null appender", null);
return;
}
if (mbeanServer == null)
{
logger.error("log4j-aws-appenders JMXManager: attempted to register null server", null);
return;
}
Object statsBean = statsBeans.get(appenderName);
Class statsBeanClass = statsBeanTypes.get(appenderName);
if ((statsBean == null) || (statsBeanClass == null))
{
logger.error("JMXManager: don't know bean or class for appender: " + appenderName, null);
return;
}
try
{
StandardMBean mbean = new StandardMBean(statsBeanClass.cast(statsBean), statsBeanClass, false);
mbeanServer.registerMBean(mbean, toObjectName(mbeanServer, appenderName));
}
catch (Exception ex)
{
logger.error("JMXManager: failed to register appender statistics with JMX", ex);
}
}
/**
* Deregisters an appender's stats bean from a server.
*/
protected void unregisterAppenderBean(String appenderName, MBeanServer mbeanServer)
{
try
{
mbeanServer.unregisterMBean(toObjectName(mbeanServer, appenderName));
}
catch (Exception ex)
{
logger.error("JMXManager: failed to unregister appender statistics with JMX", ex);
}
}
private ObjectName toObjectName(MBeanServer mbeanServer, String appenderName)
throws MalformedObjectNameException
{
String nameForServer = registrationNames.get(mbeanServer);
if (nameForServer == null)
throw new IllegalStateException("attempted to register with unrecorded MBeanServer; should never happen");
return new ObjectName(nameForServer + ",appender=" + appenderName);
}
}