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From d..@apache.org
Subject svn commit: r628585 - /db/derby/code/trunk/java/engine/org/apache/derby/impl/services/jmx/JMXManagementService.java
Date Mon, 18 Feb 2008 00:31:02 GMT
Author: djd
Date: Sun Feb 17 16:31:01 2008
New Revision: 628585

URL: http://svn.apache.org/viewvc?rev=628585&view=rev
Log:
DERBY-3424 (partial) Improve JMXManagementService to spearate registering of mbeans with Derby's
management service from registering with the JMX service. This allows the ManagementMBEan
to correctly implement the stop and start management service to unregister (from the platform
mbean server) Derby's MBean when the stopManagement() is called and then re-register them
when startManagement() is called.

Modified:
    db/derby/code/trunk/java/engine/org/apache/derby/impl/services/jmx/JMXManagementService.java

Modified: db/derby/code/trunk/java/engine/org/apache/derby/impl/services/jmx/JMXManagementService.java
URL: http://svn.apache.org/viewvc/db/derby/code/trunk/java/engine/org/apache/derby/impl/services/jmx/JMXManagementService.java?rev=628585&r1=628584&r2=628585&view=diff
==============================================================================
--- db/derby/code/trunk/java/engine/org/apache/derby/impl/services/jmx/JMXManagementService.java
(original)
+++ db/derby/code/trunk/java/engine/org/apache/derby/impl/services/jmx/JMXManagementService.java
Sun Feb 17 16:31:01 2008
@@ -22,12 +22,11 @@
 import java.security.PrivilegedAction;
 import java.security.PrivilegedActionException;
 import java.security.PrivilegedExceptionAction;
-import java.util.Collections;
+import java.util.HashMap;
 import java.util.HashSet;
+import java.util.Map;
 import java.util.Properties;
-import java.util.Set;
 
-import javax.management.InstanceNotFoundException;
 import javax.management.JMException;
 import javax.management.MBeanServer;
 import javax.management.ObjectName;
@@ -40,27 +39,45 @@
 import org.apache.derby.iapi.services.monitor.ModuleControl;
 import org.apache.derby.iapi.services.monitor.Monitor;
 import org.apache.derby.iapi.services.property.PropertyUtil;
-import org.apache.derby.mbeans.Management;
 import org.apache.derby.mbeans.ManagementMBean;
 import org.apache.derby.mbeans.VersionMBean;
 
 /** 
  * This class implements the ManagementService interface and provides a simple
  * management and monitoring service.
+ * 
+ * An mbean registered with this service remains until it is unregistered.
+ * While registered with this service it may be registered and unregistered
+ * with the jmx service a number of times.
  *
  * @see org.apache.derby.iapi.services.jmx.ManagementService
  */
-public class JMXManagementService implements ManagementService, ModuleControl {
+public final class JMXManagementService implements ManagementService, ModuleControl {
 
     /**
-     * Platfrom MBean server, from ManagementFactory.getPlatformMBeanServer().
+     * Platform MBean server, from ManagementFactory.getPlatformMBeanServer().
+     * If not null then this service has registered mbeans with the
+     * plaform MBean server.
+     * If null then this service either has no mbeans registered
+     * or one mbean registered (representing itself).
      */
     private MBeanServer mbeanServer;
    
     /**
-     * The set of mbeans registered by this service.
+     * The set of mbeans registered to this service by
+     * Derby's code. These beans are registered with
+     * the platform mbean server if mbeanServer is not null.
      */
-    private Set<ObjectName> registeredMbeans;
+    private Map<ObjectName,StandardMBean> registeredMbeans;
+    
+    /**
+     * If this object is registered as a management mbean
+     * then myManagementBean represents its name. This will
+     * be non-null when derby.system.jmx is true.
+     */
+    private ObjectName myManagementBean;
+    
+    private MBeanServer myManagementServer;
 
     public JMXManagementService() {
 
@@ -77,22 +94,50 @@
      */
     public void boot(boolean create, Properties properties)
             throws StandardException {
-
-        if (PropertyUtil.getSystemBoolean(Property.JMX))
-            initialize();
+        
+        registeredMbeans = new HashMap<ObjectName,StandardMBean>();
+        
+        if (PropertyUtil.getSystemBoolean(Property.JMX)) {
+            findServer();
+             
+            myManagementBean = (ObjectName) registerMBean(this,
+                ManagementMBean.class,
+                "type=Management");
+            myManagementServer = mbeanServer;
+        }
+        
+        registerMBean(new Version(Monitor.getMonitor().getEngineVersion()),
+                VersionMBean.class,
+                "type=Version,jar=derby.jar");
     }
-
+    
     public synchronized void stop() {
-        if (mbeanServer == null)
-            return;
+        
+        // If we are currently not registering any mbeans
+        // then we might still have this registered as
+        // a management mbean. Need to explicitly remove this
+        // using the mbean server that created it, which
+        // possibly could not be the same as the current server.
+        if (mbeanServer == null && myManagementBean != null)
+        {
+            mbeanServer = myManagementServer;
+            unregisterMBean(myManagementBean);
+            mbeanServer = null;
+        }
 
         // Need a copy of registeredMbeans since unregisterMBean will remove
         // items from registeredMbeans and thus invalidate any iterator
         // on it directly.
-        for (ObjectName mbeanName : new HashSet<ObjectName>(registeredMbeans))
+        for (ObjectName mbeanName :
+                new HashSet<ObjectName>(registeredMbeans.keySet()))
             unregisterMBean(mbeanName);
         
         mbeanServer = null;
+        
+        // registeredMbeans == null indicates service is not active
+        registeredMbeans = null;
+        
+        myManagementServer = null;
     }
 
     /**
@@ -103,9 +148,8 @@
      * 
      * @throws StandardException
      */
-    private synchronized void initialize() throws StandardException {
+    private synchronized void findServer() {
         
-        registeredMbeans = new HashSet<ObjectName>();
         try {
             mbeanServer = AccessController
                     .doPrivileged(new PrivilegedAction<MBeanServer>() {
@@ -113,17 +157,10 @@
                             return ManagementFactory.getPlatformMBeanServer();
                         }
                     });
-
-            registerMBean(new Version(Monitor.getMonitor().getEngineVersion()),
-                    VersionMBean.class,
-                    "type=Version,jar=derby.jar");
-            
-            registerMBean(this,
-                    ManagementMBean.class,
-                    "type=Management");
             
         } catch (SecurityException se) {
-            // TODO: just ignoring inability to create the mbean server.
+            // TODO: just ignoring inability to create or
+            // find the mbean server.
             // or should an error or warning be raised?
         }
     }
@@ -148,40 +185,48 @@
             final String nameAttributes)
             throws StandardException {
 
-        if (mbeanServer == null)
-            return null;
-
         try {
             final ObjectName beanName = new ObjectName(
                     DERBY_JMX_DOMAIN + ":" + nameAttributes);
             final StandardMBean standardMBean =
                 new StandardMBean(bean, beanInterface);
-            try {
+            
+            registeredMbeans.put(beanName, standardMBean);
+            if (mbeanServer != null)
+                jmxRegister(standardMBean, beanName);
+            
+            return beanName;
+        
+        } catch (JMException jme) {
+            throw StandardException.plainWrapException(jme);
+        }
+    }
+    
+    /**
+     * Register an mbean with the platform mbean server.
+     */
+    private void jmxRegister(final StandardMBean standardMBean,
+            final ObjectName beanName) throws JMException
+    {
+        try {
 
-                AccessController
-                        .doPrivileged(new PrivilegedExceptionAction<Object>() {
+            AccessController
+               .doPrivileged(new PrivilegedExceptionAction<Object>() {
 
-                            public Object run() throws JMException {
-                                mbeanServer.registerMBean(standardMBean, beanName);
-                                return null;
-                            }
-
-                        });
-                
-                registeredMbeans.add(beanName);
-                return beanName;
+                    public Object run() throws JMException {
+                        mbeanServer.registerMBean(standardMBean, beanName);
+                        return null;
+                    }
 
-            } catch (PrivilegedActionException pae) {
-                throw (JMException) pae.getException();
-            }
-        } catch (JMException jme) {
-            throw StandardException.plainWrapException(jme);
+                });
+
+        } catch (PrivilegedActionException pae) {
+            throw (JMException) pae.getException();
         }
     }
     
     /**
-     * Unregister an mbean using an object previous returned
-     * from registerMBean.
+     * Unregister an mbean using an object previous returned from registerMBean.
      */
     public void unregisterMBean(Object mbeanIdentifier)
     {
@@ -191,13 +236,28 @@
     }
     
     /**
-     * Unregisters an mbean that was registered  by this service.
+     * Unregisters an mbean from this service and JMX plaform server
      * @param mbeanName Bean to unregister.
      */
     private synchronized void unregisterMBean(final ObjectName mbeanName)
     {
-        if (!registeredMbeans.remove(mbeanName))
+        if (registeredMbeans.remove(mbeanName) == null)
             return;
+        
+        if (mbeanServer == null)
+            return;
+        
+        jmxUnregister(mbeanName);
+    }
+    
+    /**
+     * Unregister an mbean from the JMX plaform server
+     * but leave it registered to this service. This
+     * is so that if jmx is reenabled we can reestablish
+     * all vaid mbeans (that are still registered with this service).
+     * @param mbeanName
+     */
+    private void jmxUnregister(final ObjectName mbeanName) {
 
         if (!mbeanServer.isRegistered(mbeanName))
             return;
@@ -228,10 +288,54 @@
     }
 
     public synchronized void startManagement() {
-        // TODO:
+        
+        //Has this service been shut down?
+        if (registeredMbeans == null)
+            return;
+        
+        // Already active?
+        if (isManagementActive())
+            return;
+        
+        findServer();
+        
+        // If we can't find the server then we can't register.
+        if (mbeanServer == null)
+            return;
+        
+        for (ObjectName mbeanName : registeredMbeans.keySet())
+        {
+            // If we registered this as a management bean
+            // then leave it registered to allow the mbeans
+            // to be re-registered with JMX
+            if (mbeanName.equals(myManagementBean))
+                continue;
+            
+            try {
+                jmxRegister(registeredMbeans.get(mbeanName), mbeanName);
+            } catch (JMException e) {
+                // TODO - what to do here?
+            }
+        }
     }
 
     public synchronized void stopManagement() {
-        // TODO:
+        
+        // Has this service been shut down?
+        if (registeredMbeans == null)
+            return;
+        
+        if (isManagementActive()) {
+            for (ObjectName mbeanName : registeredMbeans.keySet())
+            {
+                // If we registered this as a management bean
+                // then leave it registered to allow the mbeans
+                // to be re-registered with JMX
+                if (mbeanName.equals(myManagementBean))
+                    continue;
+                jmxUnregister(mbeanName);
+            }
+            mbeanServer = null;
+        }
     }
 }



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