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* 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).
*
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package sun.jvmstat.perfdata.monitor.protocol.rmi;
import sun.jvmstat.monitor.*;
import sun.jvmstat.monitor.event.*;
import sun.jvmstat.monitor.remote.*;
import sun.jvmstat.perfdata.monitor.*;
import java.lang.reflect.*;
import java.util.*;
import java.io.*;
import java.nio.ByteBuffer;
import java.rmi.*;
/**
* Concrete implementation of the AbstractMonitoredVm class for the
* <em>rmi:</em> protocol for the HotSpot PerfData monitoring implementation.
* <p>
* This class provides the ability to acquire to the instrumentation buffer
* of a live, remote target Java Virtual Machine through an RMI server.
*
* @author Brian Doherty
* @since 1.5
*/
public class RemoteMonitoredVm extends AbstractMonitoredVm {
private ArrayList<VmListener> listeners;
private NotifierTask notifierTask;
private SamplerTask samplerTask;
private Timer timer;
private RemoteVm rvm;
private ByteBuffer updateBuffer;
/**
* Create a RemoteMonitoredVm instance.
*
* @param rvm the proxy to the remote MonitoredVm instance.
* @param vmid the vm identifier specifying the remot target JVM
* @param timer the timer used to run polling tasks
* @param interval the sampling interval
*/
public RemoteMonitoredVm(RemoteVm rvm, VmIdentifier vmid,
Timer timer, int interval)
throws MonitorException {
super(vmid, interval);
this.rvm = rvm;
pdb = new PerfDataBuffer(rvm, vmid.getLocalVmId());
this.listeners = new ArrayList<VmListener>();
this.timer = timer;
}
/**
* Method to attach to the remote MonitoredVm.
*/
public void attach() throws MonitorException {
updateBuffer = pdb.getByteBuffer().duplicate();
// if continuous sampling is requested, register with the sampler thread
if (interval > 0) {
samplerTask = new SamplerTask();
timer.schedule(samplerTask, 0, interval);
}
}
/**
* {@inheritDoc}
*/
public void detach() {
try {
if (interval > 0) {
if (samplerTask != null) {
samplerTask.cancel();
samplerTask = null;
}
if (notifierTask != null) {
notifierTask.cancel();
notifierTask = null;
}
sample();
}
} catch (RemoteException e) {
// XXX: - use logging api? throw an exception instead?
System.err.println("Could not read data for remote JVM " + vmid);
e.printStackTrace();
} finally {
super.detach();
}
}
/**
* Get a copy of the remote instrumentation buffer.
*<p>
* The data in the remote instrumentation buffer is copied into
* a local byte buffer.
*
* @throws RemoteException Thrown on any communications errors with
* the remote system.
*/
public void sample() throws RemoteException {
assert updateBuffer != null;
((PerfDataBuffer)pdb).sample(updateBuffer);
}
/**
* Get the proxy to the remote MonitoredVm.
*
* @return RemoteVm - the proxy to the remote MonitoredVm.
*/
public RemoteVm getRemoteVm() {
return rvm;
}
/**
* {@inheritDoc}
*/
public void addVmListener(VmListener l) {
synchronized(listeners) {
listeners.add(l);
if (notifierTask == null) {
notifierTask = new NotifierTask();
timer.schedule(notifierTask, 0, interval);
}
}
}
/**
* {@inheritDoc}
*/
public void removeVmListener(VmListener l) {
synchronized(listeners) {
listeners.remove(l);
if (listeners.isEmpty() && (notifierTask != null)) {
notifierTask.cancel();
notifierTask = null;
}
}
}
/**
* {@inheritDoc}
*/
public void setInterval(int newInterval) {
synchronized(listeners) {
if (newInterval == interval) {
return;
}
int oldInterval = interval;
super.setInterval(newInterval);
if (samplerTask != null) {
samplerTask.cancel();
SamplerTask oldSamplerTask = samplerTask;
samplerTask = new SamplerTask();
CountedTimerTaskUtils.reschedule(timer, oldSamplerTask,
samplerTask, oldInterval,
newInterval);
}
if (notifierTask != null) {
notifierTask.cancel();
NotifierTask oldNotifierTask = notifierTask;
notifierTask = new NotifierTask();
CountedTimerTaskUtils.reschedule(timer, oldNotifierTask,
notifierTask, oldInterval,
newInterval);
}
}
}
/**
* Fire MonitoredVmStructureChanged events.
*
* @param inserted List of Monitor objects inserted.
* @param removed List of Monitor objects removed.
*/
@SuppressWarnings("unchecked") // Cast of result of clone
void fireMonitorStatusChangedEvents(List<Monitor> inserted, List<Monitor> removed) {
ArrayList<VmListener> registered = null;
MonitorStatusChangeEvent ev = null;
synchronized(listeners) {
registered = (ArrayList)listeners.clone();
}
for (Iterator<VmListener> i = registered.iterator(); i.hasNext(); /* empty */) {
VmListener l = i.next();
if (ev == null) {
ev = new MonitorStatusChangeEvent(this, inserted, removed);
}
l.monitorStatusChanged(ev);
}
}
/**
* Fire MonitoredVmStructureChanged events.
*/
@SuppressWarnings("unchecked") // Cast of result of clone
void fireMonitorsUpdatedEvents() {
ArrayList<VmListener> registered = null;
VmEvent ev = null;
synchronized(listeners) {
registered = (ArrayList)listeners.clone();
}
for (Iterator<VmListener> i = registered.iterator(); i.hasNext(); /* empty */) {
VmListener l = i.next();
if (ev == null) {
ev = new VmEvent(this);
}
l.monitorsUpdated(ev);
}
}
/*
* Timer Tasks. There are two separate timer tasks here. The SamplerTask
* is active whenever we are attached to the remote JVM with a periodic
* sampling interval > 0. The NotifierTask is only active if a VmListener
* has registered with this RemoteMonitoredVm instance. Also, in the future
* we may want to run these tasks at different intervals. Currently,
* they run at the same interval and some significant work may
* need to be done to complete the separation of these two intervals.
*/
/**
* Class to periodically check the state of the defined monitors
* for the remote MonitoredVm instance and to notify listeners of
* any detected changes.
*/
private class NotifierTask extends CountedTimerTask {
public void run() {
super.run();
try {
MonitorStatus status = getMonitorStatus();
List<Monitor> inserted = status.getInserted();
List<Monitor> removed = status.getRemoved();
if (!inserted.isEmpty() || !removed.isEmpty()) {
fireMonitorStatusChangedEvents(inserted, removed);
}
} catch (MonitorException e) {
// XXX: use logging api? fire disconnect events? mark errored?
// fireDisconnectedEvents();
System.err.println("Exception updating monitors for "
+ getVmIdentifier());
e.printStackTrace();
// XXX: should we cancle the notifierTask here?
// this.cancel();
}
}
}
/**
* Class to periodically sample the remote instrumentation byte buffer
* and refresh the local copy. Registered listeners are notified of
* the completion of a sampling event.
*/
private class SamplerTask extends CountedTimerTask {
public void run() {
super.run();
try {
sample();
fireMonitorsUpdatedEvents();
} catch (RemoteException e) {
// XXX: use logging api, mark vm as errored.
System.err.println("Exception taking sample for "
+ getVmIdentifier());
e.printStackTrace();
this.cancel();
}
}
}
}