Monitoring.java

/*
 * Copyright (c) 2019 Matthias Sohn <matthias.sohn@sap.com>
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0 which is available at
 * https://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */
package org.eclipse.jgit.util;

import java.io.IOException;
import java.lang.management.ManagementFactory;

import javax.management.InstanceAlreadyExistsException;
import javax.management.InstanceNotFoundException;
import javax.management.MBeanRegistrationException;
import javax.management.MBeanServer;
import javax.management.MalformedObjectNameException;
import javax.management.NotCompliantMBeanException;
import javax.management.ObjectInstance;
import javax.management.ObjectName;

import org.eclipse.jgit.annotations.Nullable;
import org.eclipse.jgit.errors.ConfigInvalidException;
import org.eclipse.jgit.lib.ConfigConstants;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Enables monitoring JGit via JMX
 *
 * @since 5.1.13
 */
public class Monitoring {
    private static final Logger LOG = LoggerFactory.getLogger(Monitoring.class);

    /**
     * Register a MBean with the platform MBean server
     *
     * @param mbean
     *            the mbean object to register
     * @param metricName
     *            name of the JGit metric, will be prefixed with
     *            "org.eclipse.jgit/"
     * @return the registered mbean's object instance
     */
    public static @Nullable ObjectInstance registerMBean(Object mbean,
            String metricName) {
        boolean register = false;
        try {
            Class<?>[] interfaces = mbean.getClass().getInterfaces();
            for (Class<?> i : interfaces) {
                register = SystemReader.getInstance().getUserConfig()
                        .getBoolean(
                    ConfigConstants.CONFIG_JMX_SECTION,
                                i.getSimpleName(), false);
                if (register) {
                    break;
                }
            }
        } catch (IOException | ConfigInvalidException e) {
            LOG.error(e.getMessage(), e);
            return null;
        }
        if (!register) {
            return null;
        }
        MBeanServer server = ManagementFactory.getPlatformMBeanServer();
        try {
            ObjectName mbeanName = objectName(mbean.getClass(), metricName);
            if (server.isRegistered(mbeanName)) {
                server.unregisterMBean(mbeanName);
            }
            return server.registerMBean(mbean, mbeanName);
        } catch (MalformedObjectNameException | InstanceAlreadyExistsException
                | MBeanRegistrationException | NotCompliantMBeanException
                | InstanceNotFoundException e) {
            LOG.error(e.getMessage(), e);
            return null;
        }
    }

    private static ObjectName objectName(Class mbean, String metricName)
            throws MalformedObjectNameException {
        return new ObjectName(String.format("org.eclipse.jgit/%s:type=%s", //$NON-NLS-1$
                metricName, mbean.getSimpleName()));
    }
}