view system-backend/src/main/java/com/redhat/thermostat/backend/system/VmStatusChangeNotifier.java @ 1176:f7961cf1e440

Convert VM IDs to UUIDs This commit changes VM IDs used in VmRef and VmInfo to a randomly generated UUID string. The VM PIDs are still stored, but are not used to identify a specific VM. The motivation behind this change is that PIDs can be reused by the OS, thus there is a chance we could have a PID that refers to two different VMs (one alive, one dead). There are then security implications if we return the wrong VM, which the client user may not have access to. The VM's PID is still required when dealing with external interfaces like /proc and JMX, but the data collected is placed in storage using the VM's UUID. Additionally, I have cleaned up the API in VmRef. I have removed getIdString from VmRef since we already have a getStringID that does the same thing. I've also changed VmRef.getAgent to getHostRef to more accurately reflect what is returned. Reviewed-by: jerboaa Review-thread: http://icedtea.classpath.org/pipermail/thermostat/2013-July/007242.html
author Elliott Baron <ebaron@redhat.com>
date Thu, 18 Jul 2013 18:33:49 -0400
parents ccac9bcabaa0
children
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/*
 * Copyright 2012, 2013 Red Hat, Inc.
 *
 * This file is part of Thermostat.
 *
 * Thermostat is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2, or (at your
 * option) any later version.
 *
 * Thermostat is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Thermostat; see the file COPYING.  If not see
 * <http://www.gnu.org/licenses/>.
 *
 * Linking this code with other modules is making a combined work
 * based on this code.  Thus, the terms and conditions of the GNU
 * General Public License cover the whole combination.
 *
 * As a special exception, the copyright holders of this code give
 * you permission to link this code with independent modules to
 * produce an executable, regardless of the license terms of these
 * independent modules, and to copy and distribute the resulting
 * executable under terms of your choice, provided that you also
 * meet, for each linked independent module, the terms and conditions
 * of the license of that module.  An independent module is a module
 * which is not derived from or based on this code.  If you modify
 * this code, you may extend this exception to your version of the
 * library, but you are not obligated to do so.  If you do not wish
 * to do so, delete this exception statement from your version.
 */

package com.redhat.thermostat.backend.system;

import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.TreeSet;

import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import org.osgi.util.tracker.ServiceTracker;

import com.redhat.thermostat.agent.VmStatusListener;
import com.redhat.thermostat.agent.VmStatusListener.Status;

/**
 * Notifies any and all {@link VmStatusListener} registered as OSGi Services
 * about VM status changes: {@link VmStatusListener.Status#VM_STARTED} and
 * {@link VmStatusListener.Status#VM_STOPPED}.
 * <p>
 * Any listeners registered after a {@link VmStatusListener.Status#VM_STARTED}
 * was delivered receive a {@link VmStatusListener.Status#VM_ACTIVE} event
 * instead as an indication that a VM was started at some unknown point
 * previously.
 */
public class VmStatusChangeNotifier {

    private final Object listenerLock = new Object();
    private final Map<Integer, String> activePids;
    private final Map<VmStatusListener, Set<Integer>> listeners = new HashMap<>();

    private final ServiceTracker tracker;

    public VmStatusChangeNotifier(BundleContext bundleContext) {
        this.activePids = new HashMap<>();

        tracker = new ServiceTracker(bundleContext, VmStatusListener.class, null) {
            @Override
            public VmStatusListener addingService(ServiceReference reference) {
                VmStatusListener listener = (VmStatusListener) super.addingService(reference);

                synchronized (listenerLock) {
                    Set<Integer> notifiedAbout = new TreeSet<>();
                    for (Entry<Integer, String> entry : activePids.entrySet()) {
                        Integer pid = entry.getKey();
                        listener.vmStatusChanged(Status.VM_ACTIVE, entry.getValue(), pid);
                        notifiedAbout.add(pid);
                    }

                    listeners.put(listener, notifiedAbout);
                }

                return listener;
            }

            @Override
            public void removedService(ServiceReference reference,
                    Object service) {
                VmStatusListener listener = (VmStatusListener) service;
                listeners.remove(listener);
                super.removedService(reference, service);
            }
        };
    }

    public void start() {
        tracker.open();
    }

    public void stop() {
        tracker.close();
    }

    /**
     * Notify all registered listeners about a Vm status change.
     *
     * @param newStatus either {@link VmStatusListener.Status#VM_STARTED} or
     * {@link VmStatusListener.Status#VM_STOPPED}
     * @param vmId unique identifier for the VM
     * @param pid process ID for the VM
     */
    public void notifyVmStatusChange(VmStatusListener.Status newStatus, String vmId, int pid) {
        if (newStatus == Status.VM_ACTIVE) {
            throw new IllegalArgumentException("Dont pass in " + Status.VM_ACTIVE + ", that will be handled automatically");
        }

        synchronized (listenerLock) {
            for (Entry<VmStatusListener, Set<Integer>> entry : listeners.entrySet()) {
                entry.getKey().vmStatusChanged(newStatus, vmId, pid);
                entry.getValue().add(pid);
            }

            if (newStatus == Status.VM_STARTED) {
                activePids.put(pid, vmId);
            } else {
                activePids.remove(pid);
            }
        }
    }

}