hu.mta.sztaki.lpds.cloud.simulator.iaas.statenotifications.VMStateChangeNotificationHandler.java Source code

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Here is the source code for hu.mta.sztaki.lpds.cloud.simulator.iaas.statenotifications.VMStateChangeNotificationHandler.java

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/*
 *  ========================================================================
 *  DIScrete event baSed Energy Consumption simulaTor 
 *                                for Clouds and Federations (DISSECT-CF)
 *  ========================================================================
 *  
 *  This file is part of DISSECT-CF.
 *  
 *  DISSECT-CF is free software: you can redistribute it and/or modify it
 *  under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or (at
 *  your option) any later version.
 *  
 *  DISSECT-CF 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 Lesser
 *  General Public License for more details.
 *  
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with DISSECT-CF.  If not, see <http://www.gnu.org/licenses/>.
 *  
 *  (C) Copyright 2014, Gabor Kecskemeti (gkecskem@dps.uibk.ac.at,
 *                                kecskemeti.gabor@sztaki.mta.hu)
 */

package hu.mta.sztaki.lpds.cloud.simulator.iaas.statenotifications;

import org.apache.commons.lang3.tuple.Triple;

import hu.mta.sztaki.lpds.cloud.simulator.iaas.VirtualMachine;
import hu.mta.sztaki.lpds.cloud.simulator.iaas.VirtualMachine.State;
import hu.mta.sztaki.lpds.cloud.simulator.iaas.VirtualMachine.StateChange;
import hu.mta.sztaki.lpds.cloud.simulator.notifications.SingleNotificationHandler;
import hu.mta.sztaki.lpds.cloud.simulator.notifications.StateDependentEventHandler;

/**
 * implements a notification handler for sending out notifications about VM
 * state changes
 * 
 * @author "Gabor Kecskemeti, Laboratory of Parallel and Distributed Systems, MTA SZTAKI (c) 2015"
 *
 */
public class VMStateChangeNotificationHandler
        implements SingleNotificationHandler<StateChange, Triple<VirtualMachine, State, State>> {

    /**
     * the singleton notification sender object that will send out all
     * notifications about a VM state changes on a uniform way
     */
    private static final VMStateChangeNotificationHandler handlerSingleton = new VMStateChangeNotificationHandler();

    /**
     * disables the instantiation of the handler so we really just have a single
     * instance for all handling operations
     */
    private VMStateChangeNotificationHandler() {

    }

    /**
     * gets the event handler that will manage the subscriptions for the
     * particular VM object that asked for the handler. One should be requested for
     * every VM that expects to send out state change notifications.
     * 
     * @return the eventh handler
     */
    public static StateDependentEventHandler<StateChange, Triple<VirtualMachine, State, State>> getHandlerInstance() {
        return new StateDependentEventHandler<StateChange, Triple<VirtualMachine, State, State>>(handlerSingleton);
    }

    /**
     * The event handling mechanism for VM state change notifications
     * 
     * @param onObject
     *            The listener to send the event to
     * @param stateData
     *            a data triplet containing the VM and its the past and future
     *            states.
     */
    @Override
    public void sendNotification(final StateChange onObject, Triple<VirtualMachine, State, State> stateData) {
        onObject.stateChanged(stateData.getLeft(), stateData.getMiddle(), stateData.getRight());
    }
}