openflowplugin-impl/src/main/java/org/opendaylight/openflowplugin/impl/device/PostHandshakeNodeProducer.java

   1 /**
   2  * Copyright (c) 2015 Cisco Systems, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8
   9 package org.opendaylight.openflowplugin.impl.device;
  10
  11 import com.google.common.base.Preconditions;
  12 import com.google.common.util.concurrent.FutureCallback;
  13 import com.google.common.util.concurrent.Futures;
  14 import com.google.common.util.concurrent.ListenableFuture;
  15 import com.google.common.util.concurrent.SettableFuture;
  16 import java.util.ArrayList;
  17 import java.util.Collection;
  18 import java.util.Collections;
  19 import java.util.List;
  20 import java.util.Map;
  21 import java.util.concurrent.ConcurrentHashMap;
  22 import java.util.concurrent.Future;
  23 import javax.annotation.Nonnull;
  24 import org.opendaylight.openflowplugin.api.openflow.connection.ConnectionContext;
  25 import org.opendaylight.openflowplugin.api.openflow.device.XidGenerator;
  26 import org.opendaylight.openflowplugin.impl.common.MultipartRequestInputFactory;
  27 import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.yang.types.rev100924.Counter32;
  28 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.inventory.rev130819.FlowCapableNode;
  29 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.inventory.rev130819.FlowCapableNodeBuilder;
  30 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.inventory.rev130819.tables.Table;
  31 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.inventory.rev130819.tables.TableBuilder;
  32 import org.opendaylight.yang.gen.v1.urn.opendaylight.flow.inventory.rev130819.tables.TableKey;
  33 import org.opendaylight.yang.gen.v1.urn.opendaylight.group.statistics.rev131111.NodeGroupFeatures;
  34 import org.opendaylight.yang.gen.v1.urn.opendaylight.group.statistics.rev131111.NodeGroupFeaturesBuilder;
  35 import org.opendaylight.yang.gen.v1.urn.opendaylight.group.statistics.rev131111.group.features.GroupFeaturesBuilder;
  36 import org.opendaylight.yang.gen.v1.urn.opendaylight.group.types.rev131018.Chaining;
  37 import org.opendaylight.yang.gen.v1.urn.opendaylight.group.types.rev131018.ChainingChecks;
  38 import org.opendaylight.yang.gen.v1.urn.opendaylight.group.types.rev131018.GroupAll;
  39 import org.opendaylight.yang.gen.v1.urn.opendaylight.group.types.rev131018.GroupCapability;
  40 import org.opendaylight.yang.gen.v1.urn.opendaylight.group.types.rev131018.GroupFf;
  41 import org.opendaylight.yang.gen.v1.urn.opendaylight.group.types.rev131018.GroupIndirect;
  42 import org.opendaylight.yang.gen.v1.urn.opendaylight.group.types.rev131018.GroupSelect;
  43 import org.opendaylight.yang.gen.v1.urn.opendaylight.group.types.rev131018.GroupType;
  44 import org.opendaylight.yang.gen.v1.urn.opendaylight.group.types.rev131018.SelectLiveness;
  45 import org.opendaylight.yang.gen.v1.urn.opendaylight.group.types.rev131018.SelectWeight;
  46 import org.opendaylight.yang.gen.v1.urn.opendaylight.inventory.rev130819.nodes.Node;
  47 import org.opendaylight.yang.gen.v1.urn.opendaylight.inventory.rev130819.nodes.NodeBuilder;
  48 import org.opendaylight.yang.gen.v1.urn.opendaylight.inventory.rev130819.nodes.NodeKey;
  49 import org.opendaylight.yang.gen.v1.urn.opendaylight.meter.statistics.rev131111.NodeMeterFeatures;
  50 import org.opendaylight.yang.gen.v1.urn.opendaylight.meter.statistics.rev131111.NodeMeterFeaturesBuilder;
  51 import org.opendaylight.yang.gen.v1.urn.opendaylight.meter.statistics.rev131111.nodes.node.MeterFeaturesBuilder;
  52 import org.opendaylight.yang.gen.v1.urn.opendaylight.meter.types.rev130918.MeterBand;
  53 import org.opendaylight.yang.gen.v1.urn.opendaylight.meter.types.rev130918.MeterBandDrop;
  54 import org.opendaylight.yang.gen.v1.urn.opendaylight.meter.types.rev130918.MeterBandDscpRemark;
  55 import org.opendaylight.yang.gen.v1.urn.opendaylight.meter.types.rev130918.MeterBurst;
  56 import org.opendaylight.yang.gen.v1.urn.opendaylight.meter.types.rev130918.MeterCapability;
  57 import org.opendaylight.yang.gen.v1.urn.opendaylight.meter.types.rev130918.MeterKbps;
  58 import org.opendaylight.yang.gen.v1.urn.opendaylight.meter.types.rev130918.MeterPktps;
  59 import org.opendaylight.yang.gen.v1.urn.opendaylight.meter.types.rev130918.MeterStats;
  60 import org.opendaylight.yang.gen.v1.urn.opendaylight.openflow.common.types.rev130731.ActionType;
  61 import org.opendaylight.yang.gen.v1.urn.opendaylight.openflow.common.types.rev130731.MultipartType;
  62 import org.opendaylight.yang.gen.v1.urn.opendaylight.openflow.protocol.rev130731.MultipartReply;
  63 import org.opendaylight.yang.gen.v1.urn.opendaylight.openflow.protocol.rev130731.multipart.reply.multipart.reply.body.MultipartReplyDescCase;
  64 import org.opendaylight.yang.gen.v1.urn.opendaylight.openflow.protocol.rev130731.multipart.reply.multipart.reply.body.MultipartReplyGroupFeaturesCase;
  65 import org.opendaylight.yang.gen.v1.urn.opendaylight.openflow.protocol.rev130731.multipart.reply.multipart.reply.body.MultipartReplyMeterFeaturesCase;
  66 import org.opendaylight.yang.gen.v1.urn.opendaylight.openflow.protocol.rev130731.multipart.reply.multipart.reply.body.MultipartReplyTableFeaturesCase;
  67 import org.opendaylight.yang.gen.v1.urn.opendaylight.openflow.protocol.rev130731.multipart.reply.multipart.reply.body.multipart.reply.desc._case.MultipartReplyDesc;
  68 import org.opendaylight.yang.gen.v1.urn.opendaylight.openflow.protocol.rev130731.multipart.reply.multipart.reply.body.multipart.reply.group.features._case.MultipartReplyGroupFeatures;
  69 import org.opendaylight.yang.gen.v1.urn.opendaylight.openflow.protocol.rev130731.multipart.reply.multipart.reply.body.multipart.reply.meter.features._case.MultipartReplyMeterFeatures;
  70 import org.opendaylight.yang.gen.v1.urn.opendaylight.openflow.protocol.rev130731.multipart.reply.multipart.reply.body.multipart.reply.table.features._case.MultipartReplyTableFeatures;
  71 import org.slf4j.Logger;
  72 import org.slf4j.LoggerFactory;
  73
  74 /**
  75  * openflowplugin-impl
  76  * org.opendaylight.openflowplugin.impl.device
  77  *
  78  * Class is a helper to prepare FlowCapableNode with whole internal future structure.
  79  * Everything is realized by {@link ListenableFuture} objects.
  80  *
  81  * @author <a href="mailto:vdemcak@cisco.com">Vaclav Demcak</a>
  82  *
  83  * Created: Mar 27, 2015
  84  */
  85 class PostHandshakeNodeProducer {
  86
  87     private static final Logger LOG = LoggerFactory.getLogger(PostHandshakeNodeProducer.class);
  88
  89     private final Map<Long, Future<?>> futures;
  90     private final XidGenerator xidGenerator;
  91     private final ConnectionContext connectionContext;
  92     private SettableFuture<Node> deviceFuture;
  93
  94     public PostHandshakeNodeProducer (@Nonnull final ConnectionContext connectionContext,
  95                                       @Nonnull final XidGenerator xidGenerator) {
  96         this.xidGenerator = Preconditions.checkNotNull(xidGenerator);
  97         this.connectionContext = Preconditions.checkNotNull(connectionContext);
  98         futures = new ConcurrentHashMap<>();
  99     }
 100
 101     public ListenableFuture<Node> prepareFlowCapabeNode() {
 102         deviceFuture = SettableFuture.create();
 103         final NodeBuilder nodeBuilder = new NodeBuilder();
 104         nodeBuilder.setId(connectionContext.getNodeId());
 105         nodeBuilder.setKey(new NodeKey(connectionContext.getNodeId()));
 106         final Short version = connectionContext.getFeatures().getVersion();
 107
 108         final long nodeDescXid = xidGenerator.generate().getValue();
 109         futures.put(nodeDescXid, queryDescription(connectionContext, nodeDescXid, nodeBuilder));
 110
 111         final long meterFutureXid = xidGenerator.generate().getValue();
 112         futures.put(meterFutureXid, queryMeterFuture(connectionContext, meterFutureXid, nodeBuilder));
 113
 114         final long groupFutureXid = xidGenerator.generate().getValue();
 115         futures.put(groupFutureXid, queryGroupFuture(connectionContext, groupFutureXid, nodeBuilder));
 116
 117         final long tableFutureXid = xidGenerator.generate().getValue();
 118         futures.put(tableFutureXid, queryTableFuture(connectionContext, tableFutureXid, nodeBuilder));
 119
 120         connectionContext.getConnectionAdapter().multipartRequest(MultipartRequestInputFactory
 121                 .makeMultipartRequestInput(nodeDescXid, version, MultipartType.OFPMPDESC));
 122         connectionContext.getConnectionAdapter().multipartRequest(MultipartRequestInputFactory
 123                 .makeMultipartRequestInput(meterFutureXid, version, MultipartType.OFPMPMETERFEATURES));
 124         connectionContext.getConnectionAdapter().multipartRequest(MultipartRequestInputFactory
 125                 .makeMultipartRequestInput(groupFutureXid, version, MultipartType.OFPMPGROUPFEATURES));
 126         connectionContext.getConnectionAdapter().multipartRequest(MultipartRequestInputFactory
 127                 .makeMultipartRequestInput(tableFutureXid, version, MultipartType.OFPMPTABLEFEATURES));
 128
 129         return deviceFuture;
 130     }
 131
 132     private ListenableFuture<Collection<MultipartReply>> queryTableFuture(final ConnectionContext connectionContext,
 133             final long tableFutureXid, final NodeBuilder nodeBuilder) {
 134         final ListenableFuture<Collection<MultipartReply>> nodeTableFuture = connectionContext.registerMultipartMsg(tableFutureXid);
 135         Futures.addCallback(nodeTableFuture, new FutureCallback<Collection<MultipartReply>>() {
 136
 137             @Override
 138             public void onSuccess(final Collection<MultipartReply> result) {
 139                 Preconditions.checkArgument(result != null && ( ! result.isEmpty()), "Node table future info result is null or empty!");
 140                 final FlowCapableNode flowCapNode = nodeBuilder.getAugmentation(FlowCapableNode.class);
 141                 final FlowCapableNodeBuilder flowCapAugBuilder = flowCapNode != null
 142                         ? new FlowCapableNodeBuilder(flowCapNode) : new FlowCapableNodeBuilder();
 143                 for (final MultipartReply reply : result) {
 144                     final MultipartReplyTableFeaturesCase replyBody = (MultipartReplyTableFeaturesCase) reply.getMultipartReplyBody();
 145                     final MultipartReplyTableFeatures tableFutures = replyBody.getMultipartReplyTableFeatures();
 146                     // FIXME : add DataStore model in future commits in this chain
 147                 }
 148                 checkForFinalization(tableFutureXid, nodeBuilder);
 149             }
 150
 151             @Override
 152             public void onFailure(final Throwable t) {
 153                 LOG.info("Failed to retrieve node table future info: {}", t.getMessage());
 154                 checkForFinalization(tableFutureXid, nodeBuilder);
 155             }
 156         });
 157
 158         return nodeTableFuture;
 159     }
 160
 161     private ListenableFuture<Collection<MultipartReply>> queryGroupFuture(final ConnectionContext connectionContext,
 162             final long groupFutureXid, final NodeBuilder nodeBuilder) {
 163         final ListenableFuture<Collection<MultipartReply>> nodeGroupFuture = connectionContext.registerMultipartMsg(groupFutureXid);
 164         Futures.addCallback(nodeGroupFuture, new FutureCallback<Collection<MultipartReply>>() {
 165
 166             @Override
 167             public void onSuccess(final Collection<MultipartReply> result) {
 168                 Preconditions.checkArgument(result != null && ( ! result.isEmpty()), "Node group future info result is null or empty!");
 169                 final NodeGroupFeaturesBuilder nodeGroupFeaturesBuilder = new NodeGroupFeaturesBuilder();
 170                 final GroupFeaturesBuilder groupFeature = new GroupFeaturesBuilder();
 171                 for (final MultipartReply reply : result) {
 172                     final MultipartReplyGroupFeaturesCase replyBody = (MultipartReplyGroupFeaturesCase) reply.getMultipartReplyBody();
 173                     final MultipartReplyGroupFeatures groupReplyFutures = replyBody.getMultipartReplyGroupFeatures();
 174                     groupFeature.setMaxGroups(groupReplyFutures.getMaxGroups());
 175                     final List<Class<? extends GroupType>> supportedGroups =  new ArrayList<>();
 176                     if(groupReplyFutures.getTypes().isOFPGTALL()){
 177                         supportedGroups.add(GroupAll.class);
 178                     }
 179                     if(groupReplyFutures.getTypes().isOFPGTSELECT()){
 180                         supportedGroups.add(GroupSelect.class);
 181                     }
 182                     if(groupReplyFutures.getTypes().isOFPGTINDIRECT()){
 183                         supportedGroups.add(GroupIndirect.class);
 184                     }
 185                     if(groupReplyFutures.getTypes().isOFPGTFF()){
 186                         supportedGroups.add(GroupFf.class);
 187                     }
 188                     groupFeature.setGroupTypesSupported(supportedGroups);
 189
 190                     final List<Class<? extends GroupCapability>> gCapability = new ArrayList<>();
 191                     if(groupReplyFutures.getCapabilities().isOFPGFCCHAINING()){
 192                         gCapability.add(Chaining.class);
 193                     }
 194                     if(groupReplyFutures.getCapabilities().isOFPGFCCHAININGCHECKS()){
 195                         gCapability.add(ChainingChecks.class);
 196                     }
 197                     if(groupReplyFutures.getCapabilities().isOFPGFCSELECTLIVENESS()){
 198                         gCapability.add(SelectLiveness.class);
 199                     }
 200                     if(groupReplyFutures.getCapabilities().isOFPGFCSELECTWEIGHT()){
 201                         gCapability.add(SelectWeight.class);
 202                     }
 203                     groupFeature.setGroupCapabilitiesSupported(gCapability);
 204                     /* TODO :
 205                      *  My recommendation would be, its good to have a respective model of
 206                      * 'type bits', which will generate a class where all these flags will eventually
 207                      * be stored as boolean. It will be convenient for application to check the
 208                      * supported action, rather then doing bitmap operation.
 209                      */
 210                     final List<Long> supportActionByGroups = new ArrayList<>();
 211                     for (final ActionType actionType : groupReplyFutures.getActionsBitmap()) {
 212                         long supportActionBitmap = 0;
 213                         supportActionBitmap |= actionType.isOFPATOUTPUT()?(1 << 0): 0;
 214                         supportActionBitmap |= actionType.isOFPATCOPYTTLOUT()?(1 << 11): 0;
 215                         supportActionBitmap |= actionType.isOFPATCOPYTTLIN()?(1 << 12): 0;
 216                         supportActionBitmap |= actionType.isOFPATSETMPLSTTL()?(1 << 15): 0;
 217                         supportActionBitmap |= actionType.isOFPATDECMPLSTTL()?(1 << 16): 0;
 218                         supportActionBitmap |= actionType.isOFPATPUSHVLAN()?(1 << 17): 0;
 219                         supportActionBitmap |= actionType.isOFPATPOPVLAN()?(1 << 18): 0;
 220                         supportActionBitmap |= actionType.isOFPATPUSHMPLS()?(1 << 19): 0;
 221                         supportActionBitmap |= actionType.isOFPATPOPMPLS()?(1 << 20): 0;
 222                         supportActionBitmap |= actionType.isOFPATSETQUEUE()?(1 << 21): 0;
 223                         supportActionBitmap |= actionType.isOFPATGROUP()?(1 << 22): 0;
 224                         supportActionBitmap |= actionType.isOFPATSETNWTTL()?(1 << 23): 0;
 225                         supportActionBitmap |= actionType.isOFPATDECNWTTL()?(1 << 24): 0;
 226                         supportActionBitmap |= actionType.isOFPATSETFIELD()?(1 << 25): 0;
 227                         supportActionBitmap |= actionType.isOFPATPUSHPBB()?(1 << 26): 0;
 228                         supportActionBitmap |= actionType.isOFPATPOPPBB()?(1 << 27): 0;
 229                         supportActionByGroups.add(Long.valueOf(supportActionBitmap));
 230                     }
 231                     groupFeature.setActions(supportActionByGroups);
 232                 }
 233                 nodeGroupFeaturesBuilder.setGroupFeatures(groupFeature.build());
 234                 nodeBuilder.addAugmentation(NodeGroupFeatures.class, nodeGroupFeaturesBuilder.build());
 235                 checkForFinalization(groupFutureXid, nodeBuilder);
 236             }
 237
 238             @Override
 239             public void onFailure(final Throwable t) {
 240                 LOG.info("Failed to retrieve node group future info: {}", t.getMessage());
 241                 checkForFinalization(groupFutureXid, nodeBuilder);
 242             }
 243         });
 244
 245         return nodeGroupFuture;
 246     }
 247
 248     private ListenableFuture<Collection<MultipartReply>> queryMeterFuture(final ConnectionContext connectionContext,
 249             final long meterFutureXid, final NodeBuilder nodeBuilder) {
 250         final ListenableFuture<Collection<MultipartReply>> nodeMeterFuture = connectionContext.registerMultipartMsg(meterFutureXid);
 251         Futures.addCallback(nodeMeterFuture, new FutureCallback<Collection<MultipartReply>>() {
 252
 253             @Override
 254             public void onSuccess(final Collection<MultipartReply> result) {
 255                 Preconditions.checkArgument(result != null && ( ! result.isEmpty()), "Node meter future info result is null or empty!");
 256                 final NodeMeterFeaturesBuilder nodeMeterFeaturesBuilder = new NodeMeterFeaturesBuilder();
 257                 final MeterFeaturesBuilder meterFeature = new MeterFeaturesBuilder();
 258                 for (final MultipartReply reply : result) {
 259                     final MultipartReplyMeterFeaturesCase replyBody = (MultipartReplyMeterFeaturesCase) reply.getMultipartReplyBody();
 260                     final MultipartReplyMeterFeatures meterReplyFutures = replyBody.getMultipartReplyMeterFeatures();
 261                     meterFeature.setMaxBands(meterReplyFutures.getMaxBands());
 262                     meterFeature.setMaxColor(meterReplyFutures.getMaxColor());
 263                     meterFeature.setMaxMeter(new Counter32(meterReplyFutures.getMaxMeter()));
 264                     final List<Class<? extends MeterBand>> meterBandTypes = new ArrayList<>();
 265                     if (meterReplyFutures.getBandTypes().isOFPMBTDROP()) {
 266                         meterBandTypes.add(MeterBandDrop.class);
 267                     }
 268                     if (meterReplyFutures.getBandTypes().isOFPMBTDSCPREMARK()) {
 269                         meterBandTypes.add(MeterBandDscpRemark.class);
 270                     }
 271                     meterFeature.setMeterBandSupported(Collections.unmodifiableList(meterBandTypes));
 272
 273                     final List<java.lang.Class<? extends MeterCapability>> mCapability = new ArrayList<>();
 274                     if (meterReplyFutures.getCapabilities().isOFPMFBURST()) {
 275                         mCapability.add(MeterBurst.class);
 276                     }
 277                     if(meterReplyFutures.getCapabilities().isOFPMFKBPS()){
 278                         mCapability.add(MeterKbps.class);
 279
 280                     }
 281                     if(meterReplyFutures.getCapabilities().isOFPMFPKTPS()){
 282                         mCapability.add(MeterPktps.class);
 283
 284                     }
 285                     if(meterReplyFutures.getCapabilities().isOFPMFSTATS()){
 286                         mCapability.add(MeterStats.class);
 287
 288                     }
 289                     meterFeature.setMeterCapabilitiesSupported(Collections.unmodifiableList(mCapability));
 290                 }
 291                 nodeMeterFeaturesBuilder.setMeterFeatures(meterFeature.build());
 292                 nodeBuilder.addAugmentation(NodeMeterFeatures.class, nodeMeterFeaturesBuilder.build());
 293                 checkForFinalization(meterFutureXid, nodeBuilder);
 294             }
 295
 296             @Override
 297             public void onFailure(final Throwable t) {
 298                 LOG.info("Failed to retrieve node meter future info: {}", t.getMessage());
 299                 checkForFinalization(meterFutureXid, nodeBuilder);
 300             }
 301         });
 302
 303         return nodeMeterFuture;
 304     }
 305
 306     private ListenableFuture<Collection<MultipartReply>> queryDescription(final ConnectionContext connectionContext,
 307             final long nodeDescXid, final NodeBuilder nodeBuilder) {
 308         final ListenableFuture<Collection<MultipartReply>> nodeDesc = connectionContext.registerMultipartMsg(nodeDescXid);
 309         final Short nrOfTables = connectionContext.getFeatures().getTables();
 310         Futures.addCallback(nodeDesc, new FutureCallback<Collection<MultipartReply>>() {
 311
 312             @Override
 313             public void onSuccess(final Collection<MultipartReply> result) {
 314                 Preconditions.checkArgument(result != null && ( ! result.isEmpty()), "Node static info result is null or empty!");
 315                 final FlowCapableNode flowCapNode = nodeBuilder.getAugmentation(FlowCapableNode.class);
 316                 final FlowCapableNodeBuilder flowCapAugBuilder = flowCapNode != null
 317                         ? new FlowCapableNodeBuilder(flowCapNode) : new FlowCapableNodeBuilder();
 318                 final List<Table> tables = flowCapAugBuilder.getTable();
 319                 for (int i = 0; i < nrOfTables.intValue(); i++) {
 320                     final Short id = Short.valueOf(((short) i));
 321                     tables.add(new TableBuilder().setId(id).setKey(new TableKey(id)).build());
 322                 }
 323                 flowCapAugBuilder.setTable(tables);
 324                 for (final MultipartReply reply : result) {
 325                     final MultipartReplyDescCase replyBody = (MultipartReplyDescCase) reply.getMultipartReplyBody();
 326                     final MultipartReplyDesc description = replyBody.getMultipartReplyDesc();
 327                     flowCapAugBuilder.setDescription(choiseValues(flowCapAugBuilder.getDescription(), description.getDpDesc()));
 328                     flowCapAugBuilder.setHardware(choiseValues(flowCapAugBuilder.getHardware(), description.getHwDesc()));
 329                     flowCapAugBuilder.setManufacturer(choiseValues(flowCapAugBuilder.getManufacturer(), description.getMfrDesc()));
 330                     flowCapAugBuilder.setSoftware(choiseValues(flowCapAugBuilder.getSoftware(), description.getSwDesc()));
 331                     flowCapAugBuilder.setSerialNumber(choiseValues(flowCapAugBuilder.getSerialNumber(), description.getSerialNum()));
 332                 }
 333                 nodeBuilder.addAugmentation(FlowCapableNode.class, flowCapAugBuilder.build());
 334                 checkForFinalization(nodeDescXid, nodeBuilder);
 335             }
 336
 337             @Override
 338             public void onFailure(final Throwable t) {
 339                 LOG.info("Failed to retrieve node static info: {}", t.getMessage());
 340                 checkForFinalization(nodeDescXid, nodeBuilder);
 341             }
 342         });
 343
 344         return nodeDesc;
 345     }
 346
 347     private void checkForFinalization(final long xid, final NodeBuilder nodeBuilder) {
 348         futures.remove(xid);
 349         if (futures.isEmpty()) {
 350             deviceFuture.set(nodeBuilder.build());
 351         }
 352     }
 353
 354     private static <T> T choiseValues(final T actual, final T newValue) {
 355         if (actual == null || newValue != null) {
 356             return newValue;
 357         } else {
 358             return actual;
 359         }
 360     }
 361
 362 }