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package org.graalvm.compiler.hotspot.management;

import java.lang.management.ManagementFactory;
import java.util.ArrayList;

import javax.management.InstanceAlreadyExistsException;
import javax.management.MBeanRegistrationException;
import javax.management.MBeanServer;
import javax.management.MBeanServerFactory;
import javax.management.MalformedObjectNameException;
import javax.management.NotCompliantMBeanException;
import javax.management.ObjectName;

import org.graalvm.compiler.debug.TTY;
import org.graalvm.compiler.hotspot.HotSpotGraalManagementRegistration;
import org.graalvm.compiler.hotspot.HotSpotGraalRuntime;
import org.graalvm.compiler.serviceprovider.ServiceProvider;

Dynamically registers an MBean with the ManagementFactory.getPlatformMBeanServer(). Polling for an active platform MBean server is done by calling MBeanServerFactory.findMBeanServer(String) with an argument value of null. Once this returns an non-empty list, ManagementFactory.getPlatformMBeanServer() can be called to obtain a reference to the platform MBean server instance.
/** * Dynamically registers an MBean with the {@link ManagementFactory#getPlatformMBeanServer()}. * * Polling for an active platform MBean server is done by calling * {@link MBeanServerFactory#findMBeanServer(String)} with an argument value of {@code null}. Once * this returns an non-empty list, {@link ManagementFactory#getPlatformMBeanServer()} can be called * to obtain a reference to the platform MBean server instance. */
@ServiceProvider(HotSpotGraalManagementRegistration.class) public final class HotSpotGraalManagement implements HotSpotGraalManagementRegistration { private HotSpotGraalRuntimeMBean bean; private volatile boolean needsRegistration = true; HotSpotGraalManagement nextDeferred; @Override public void initialize(HotSpotGraalRuntime runtime) { if (bean == null) { if (runtime.getManagement() != this) { throw new IllegalArgumentException("Cannot initialize a second management object for runtime " + runtime.getName()); } try { String name = runtime.getName().replace(':', '_'); ObjectName objectName = new ObjectName("org.graalvm.compiler.hotspot:type=" + name); bean = new HotSpotGraalRuntimeMBean(objectName, runtime); registration.add(this); } catch (MalformedObjectNameException err) { err.printStackTrace(TTY.out); } } else if (bean.getRuntime() != runtime) { throw new IllegalArgumentException("Cannot change the runtime a management interface is associated with"); } } static final class RegistrationThread extends Thread { private MBeanServer platformMBeanServer; private HotSpotGraalManagement deferred; RegistrationThread() { super("HotSpotGraalManagement Bean Registration"); this.setPriority(Thread.MIN_PRIORITY); this.setDaemon(true); this.start(); }
Poll for active MBean server every 2 seconds.
/** * Poll for active MBean server every 2 seconds. */
private static final int POLL_INTERVAL_MS = 2000;
Adds a HotSpotGraalManagement to register with an active MBean server when one becomes available.
/** * Adds a {@link HotSpotGraalManagement} to register with an active MBean server when one * becomes available. */
synchronized void add(HotSpotGraalManagement e) { if (deferred != null) { e.nextDeferred = deferred; } deferred = e; // Notify the registration thread that there is now // a deferred registration to process notify(); }
Processes and clears any deferred registrations.
/** * Processes and clears any deferred registrations. */
private void process() { for (HotSpotGraalManagement m = deferred; m != null; m = m.nextDeferred) { HotSpotGraalRuntimeMBean bean = m.bean; if (m.needsRegistration && bean != null) { try { platformMBeanServer.registerMBean(bean, bean.getObjectName()); } catch (InstanceAlreadyExistsException | MBeanRegistrationException | NotCompliantMBeanException e) { e.printStackTrace(TTY.out); // Registration failed - don't try again m.bean = null; } m.needsRegistration = false; } } deferred = null; } @Override public void run() { while (true) { try { synchronized (this) { // Wait until there are deferred registrations to process while (deferred == null) { wait(); } } poll(); Thread.sleep(POLL_INTERVAL_MS); } catch (InterruptedException e) { // Be verbose about unexpected interruption and then continue e.printStackTrace(TTY.out); } } }
Checks for active MBean server and if available, processes deferred registrations.
/** * Checks for active MBean server and if available, processes deferred registrations. */
synchronized void poll() { if (platformMBeanServer == null) { try { ArrayList<MBeanServer> servers = MBeanServerFactory.findMBeanServer(null); if (!servers.isEmpty()) { platformMBeanServer = ManagementFactory.getPlatformMBeanServer(); process(); } } catch (SecurityException e) { // Without permission to find or create the MBeanServer, // we cannot process any Graal mbeans. deferred = null; } } else { process(); } } } private static final RegistrationThread registration = new RegistrationThread(); @Override public ObjectName poll(boolean sync) { if (sync) { registration.poll(); } if (bean == null || needsRegistration) { // initialize() has not been called, it failed or registration failed return null; } return bean.getObjectName(); } }