southbound/southbound-impl/src/main/java/org/opendaylight/ovsdb/southbound/OvsdbConnectionManager.java

   1 /*
   2  * Copyright (c) 2014 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 package org.opendaylight.ovsdb.southbound;
   9
  10 import static org.opendaylight.ovsdb.lib.operations.Operations.op;
  11
  12 import java.net.InetAddress;
  13 import java.net.UnknownHostException;
  14 import java.util.ArrayList;
  15 import java.util.List;
  16 import java.util.Map;
  17 import java.util.concurrent.ConcurrentHashMap;
  18 import java.util.concurrent.ExecutionException;
  19
  20 import javax.annotation.Nonnull;
  21
  22 import org.opendaylight.controller.md.sal.binding.api.DataBroker;
  23 import org.opendaylight.controller.md.sal.binding.api.ReadOnlyTransaction;
  24 import org.opendaylight.controller.md.sal.binding.api.ReadWriteTransaction;
  25 import org.opendaylight.controller.md.sal.common.api.clustering.CandidateAlreadyRegisteredException;
  26 import org.opendaylight.controller.md.sal.common.api.clustering.Entity;
  27 import org.opendaylight.controller.md.sal.common.api.clustering.EntityOwnershipCandidateRegistration;
  28 import org.opendaylight.controller.md.sal.common.api.clustering.EntityOwnershipChange;
  29 import org.opendaylight.controller.md.sal.common.api.clustering.EntityOwnershipListener;
  30 import org.opendaylight.controller.md.sal.common.api.clustering.EntityOwnershipListenerRegistration;
  31 import org.opendaylight.controller.md.sal.common.api.clustering.EntityOwnershipService;
  32 import org.opendaylight.controller.md.sal.common.api.clustering.EntityOwnershipState;
  33 import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
  34 import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
  35 import org.opendaylight.ovsdb.lib.OvsdbClient;
  36 import org.opendaylight.ovsdb.lib.OvsdbConnection;
  37 import org.opendaylight.ovsdb.lib.OvsdbConnectionListener;
  38 import org.opendaylight.ovsdb.lib.operations.Operation;
  39 import org.opendaylight.ovsdb.lib.operations.OperationResult;
  40 import org.opendaylight.ovsdb.lib.operations.Select;
  41 import org.opendaylight.ovsdb.lib.schema.DatabaseSchema;
  42 import org.opendaylight.ovsdb.lib.schema.GenericTableSchema;
  43 import org.opendaylight.ovsdb.lib.schema.typed.TyperUtils;
  44 import org.opendaylight.ovsdb.schema.openvswitch.OpenVSwitch;
  45 import org.opendaylight.ovsdb.southbound.transactions.md.OvsdbNodeRemoveCommand;
  46 import org.opendaylight.ovsdb.southbound.transactions.md.TransactionInvoker;
  47 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.ovsdb.rev150105.OvsdbBridgeAttributes;
  48 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.ovsdb.rev150105.OvsdbBridgeAugmentation;
  49 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.ovsdb.rev150105.OvsdbNodeAugmentation;
  50 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.ovsdb.rev150105.ovsdb.node.attributes.ConnectionInfo;
  51 import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.topology.Node;
  52 import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
  53 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  54 import org.slf4j.Logger;
  55 import org.slf4j.LoggerFactory;
  56
  57 import com.google.common.base.Optional;
  58 import com.google.common.base.Preconditions;
  59 import com.google.common.util.concurrent.CheckedFuture;
  60
  61 public class OvsdbConnectionManager implements OvsdbConnectionListener, AutoCloseable {
  62     private Map<ConnectionInfo, OvsdbConnectionInstance> clients =
  63             new ConcurrentHashMap<>();
  64     private static final Logger LOG = LoggerFactory.getLogger(OvsdbConnectionManager.class);
  65     private static final String ENTITY_TYPE = "ovsdb";
  66
  67     private DataBroker db;
  68     private TransactionInvoker txInvoker;
  69     private Map<ConnectionInfo,InstanceIdentifier<Node>> instanceIdentifiers =
  70             new ConcurrentHashMap<>();
  71     private Map<Entity, OvsdbConnectionInstance> entityConnectionMap =
  72             new ConcurrentHashMap<>();
  73     private EntityOwnershipService entityOwnershipService;
  74     private OvsdbDeviceEntityOwnershipListener ovsdbDeviceEntityOwnershipListener;
  75     private OvsdbConnection ovsdbConnection;
  76
  77     public OvsdbConnectionManager(DataBroker db,TransactionInvoker txInvoker,
  78                                   EntityOwnershipService entityOwnershipService,
  79                                   OvsdbConnection ovsdbConnection) {
  80         this.db = db;
  81         this.txInvoker = txInvoker;
  82         this.entityOwnershipService = entityOwnershipService;
  83         this.ovsdbDeviceEntityOwnershipListener = new OvsdbDeviceEntityOwnershipListener(this, entityOwnershipService);
  84         this.ovsdbConnection = ovsdbConnection;
  85     }
  86
  87     @Override
  88     public void connected(@Nonnull final OvsdbClient externalClient) {
  89
  90         OvsdbConnectionInstance client = connectedButCallBacksNotRegistered(externalClient);
  91
  92         // Register Cluster Ownership for ConnectionInfo
  93         registerEntityForOwnership(client);
  94     }
  95
  96     public OvsdbConnectionInstance connectedButCallBacksNotRegistered(final OvsdbClient externalClient) {
  97         LOG.info("OVSDB Connection from {}:{}",externalClient.getConnectionInfo().getRemoteAddress(),
  98                 externalClient.getConnectionInfo().getRemotePort());
  99         ConnectionInfo key = SouthboundMapper.createConnectionInfo(externalClient);
 100         OvsdbConnectionInstance ovsdbConnectionInstance = getConnectionInstance(key);
 101
 102         // Check if existing ovsdbConnectionInstance for the OvsdbClient present.
 103         // In such cases, we will see if the ovsdbConnectionInstance has same externalClient.
 104         if (ovsdbConnectionInstance != null) {
 105             if (ovsdbConnectionInstance.hasOvsdbClient(externalClient)) {
 106                 LOG.warn("OVSDB Connection Instance {} already exists for client {}", key, externalClient);
 107                 return ovsdbConnectionInstance;
 108             }
 109             LOG.warn("OVSDB Connection Instance {} being replaced with client {}", key, externalClient);
 110             ovsdbConnectionInstance.disconnect();
 111
 112             // Unregister Cluster Ownership for ConnectionInfo
 113             // Because the ovsdbConnectionInstance is about to be completely replaced!
 114             unregisterEntityForOwnership(ovsdbConnectionInstance);
 115
 116             removeConnectionInstance(key);
 117         }
 118
 119         ovsdbConnectionInstance = new OvsdbConnectionInstance(key, externalClient, txInvoker,
 120                 getInstanceIdentifier(key));
 121         ovsdbConnectionInstance.createTransactInvokers();
 122         return ovsdbConnectionInstance;
 123     }
 124
 125     @Override
 126     public void disconnected(OvsdbClient client) {
 127         LOG.info("OVSDB Disconnected from {}:{}. Cleaning up the operational data store"
 128                 ,client.getConnectionInfo().getRemoteAddress(),
 129                 client.getConnectionInfo().getRemotePort());
 130         ConnectionInfo key = SouthboundMapper.createConnectionInfo(client);
 131         OvsdbConnectionInstance ovsdbConnectionInstance = getConnectionInstance(key);
 132         if (ovsdbConnectionInstance != null) {
 133             txInvoker.invoke(new OvsdbNodeRemoveCommand(ovsdbConnectionInstance, null, null));
 134             removeConnectionInstance(key);
 135
 136             // Unregister Cluster Onwership for ConnectionInfo
 137             unregisterEntityForOwnership(ovsdbConnectionInstance);
 138         } else {
 139             LOG.warn("OVSDB disconnected event did not find connection instance for {}", key);
 140         }
 141         LOG.trace("OvsdbConnectionManager: disconnected exit");
 142     }
 143
 144     public OvsdbClient connect(InstanceIdentifier<Node> iid,
 145             OvsdbNodeAugmentation ovsdbNode) throws UnknownHostException {
 146         // TODO handle case where we already have a connection
 147         // TODO use transaction chains to handle ordering issues between disconnected
 148         // TODO and connected when writing to the operational store
 149         InetAddress ip = SouthboundMapper.createInetAddress(ovsdbNode.getConnectionInfo().getRemoteIp());
 150         OvsdbClient client = ovsdbConnection.connect(ip,
 151                 ovsdbNode.getConnectionInfo().getRemotePort().getValue());
 152         // For connections from the controller to the ovs instance, the library doesn't call
 153         // this method for us
 154         if (client != null) {
 155             putInstanceIdentifier(ovsdbNode.getConnectionInfo(), iid.firstIdentifierOf(Node.class));
 156             OvsdbConnectionInstance ovsdbConnectionInstance = connectedButCallBacksNotRegistered(client);
 157             ovsdbConnectionInstance.setOvsdbNodeAugmentation(ovsdbNode);
 158
 159             // Register Cluster Ownership for ConnectionInfo
 160             registerEntityForOwnership(ovsdbConnectionInstance);
 161         } else {
 162             LOG.warn("Failed to connect to Ovsdb Node {}", ovsdbNode.getConnectionInfo());
 163         }
 164         return client;
 165     }
 166
 167     public void disconnect(OvsdbNodeAugmentation ovsdbNode) throws UnknownHostException {
 168         OvsdbConnectionInstance client = getConnectionInstance(ovsdbNode.getConnectionInfo());
 169         if (client != null) {
 170             client.disconnect();
 171
 172             // Unregister Cluster Onwership for ConnectionInfo
 173             unregisterEntityForOwnership(client);
 174
 175             removeInstanceIdentifier(ovsdbNode.getConnectionInfo());
 176         }
 177     }
 178
 179 /*    public void init(ConnectionInfo key) {
 180         OvsdbConnectionInstance client = getConnectionInstance(key);
 181
 182         // TODO (FF): make sure that this cluster instance is the 'entity owner' fo the given OvsdbConnectionInstance ?
 183
 184         if (client != null) {
 185
 186              *  Note: registerCallbacks() is idemPotent... so if you call it repeatedly all is safe,
 187              *  it only registersCallbacks on the *first* call.
 188
 189             client.registerCallbacks();
 190         }
 191     }
 192 */
 193     @Override
 194     public void close() throws Exception {
 195         if (ovsdbDeviceEntityOwnershipListener != null) {
 196             ovsdbDeviceEntityOwnershipListener.close();
 197         }
 198
 199         for (OvsdbClient client: clients.values()) {
 200             client.disconnect();
 201         }
 202     }
 203
 204     private void putConnectionInstance(ConnectionInfo key,OvsdbConnectionInstance instance) {
 205         ConnectionInfo connectionInfo = SouthboundMapper.suppressLocalIpPort(key);
 206         clients.put(connectionInfo, instance);
 207     }
 208
 209     private void removeConnectionInstance(ConnectionInfo key) {
 210         ConnectionInfo connectionInfo = SouthboundMapper.suppressLocalIpPort(key);
 211         clients.remove(connectionInfo);
 212     }
 213
 214     private void putInstanceIdentifier(ConnectionInfo key,InstanceIdentifier<Node> iid) {
 215         ConnectionInfo connectionInfo = SouthboundMapper.suppressLocalIpPort(key);
 216         instanceIdentifiers.put(connectionInfo, iid);
 217     }
 218
 219     private void removeInstanceIdentifier(ConnectionInfo key) {
 220         ConnectionInfo connectionInfo = SouthboundMapper.suppressLocalIpPort(key);
 221         instanceIdentifiers.remove(connectionInfo);
 222     }
 223
 224     public OvsdbConnectionInstance getConnectionInstance(ConnectionInfo key) {
 225         ConnectionInfo connectionInfo = SouthboundMapper.suppressLocalIpPort(key);
 226         return clients.get(connectionInfo);
 227     }
 228
 229     public InstanceIdentifier<Node> getInstanceIdentifier(ConnectionInfo key) {
 230         ConnectionInfo connectionInfo = SouthboundMapper.suppressLocalIpPort(key);
 231         InstanceIdentifier<Node> iid = instanceIdentifiers.get(connectionInfo);
 232         return iid;
 233     }
 234
 235     public OvsdbConnectionInstance getConnectionInstance(OvsdbBridgeAttributes mn) {
 236         Optional<OvsdbNodeAugmentation> optional = SouthboundUtil.getManagingNode(db, mn);
 237         if (optional.isPresent()) {
 238             return getConnectionInstance(optional.get().getConnectionInfo());
 239         } else {
 240             return null;
 241         }
 242     }
 243
 244     public OvsdbConnectionInstance getConnectionInstance(Node node) {
 245         Preconditions.checkNotNull(node);
 246         OvsdbNodeAugmentation ovsdbNode = node.getAugmentation(OvsdbNodeAugmentation.class);
 247         OvsdbBridgeAugmentation ovsdbManagedNode = node.getAugmentation(OvsdbBridgeAugmentation.class);
 248         if (ovsdbNode != null) {
 249             return getConnectionInstance(ovsdbNode.getConnectionInfo());
 250         } else if (ovsdbManagedNode != null) {
 251             return getConnectionInstance(ovsdbManagedNode);
 252         } else {
 253             LOG.warn("This is not a node that gives any hint how to find its OVSDB Manager: {}",node);
 254             return null;
 255         }
 256     }
 257
 258     public OvsdbConnectionInstance getConnectionInstance(InstanceIdentifier<Node> nodePath) {
 259         try {
 260             ReadOnlyTransaction transaction = db.newReadOnlyTransaction();
 261             CheckedFuture<Optional<Node>, ReadFailedException> nodeFuture = transaction.read(
 262                     LogicalDatastoreType.OPERATIONAL, nodePath);
 263             transaction.close();
 264             Optional<Node> optional = nodeFuture.get();
 265             if (optional != null && optional.isPresent() && optional.get() instanceof Node) {
 266                 return this.getConnectionInstance(optional.get());
 267             } else {
 268                 LOG.warn("Found non-topological node {} on path {}",optional);
 269                 return null;
 270             }
 271         } catch (Exception e) {
 272             LOG.warn("Failed to get Ovsdb Node {}",nodePath, e);
 273             return null;
 274         }
 275     }
 276
 277     public OvsdbClient getClient(ConnectionInfo connectionInfo) {
 278         return getConnectionInstance(connectionInfo);
 279     }
 280
 281     public OvsdbClient getClient(OvsdbBridgeAttributes mn) {
 282         return getConnectionInstance(mn);
 283     }
 284
 285     public OvsdbClient getClient(Node node) {
 286         return getConnectionInstance(node);
 287     }
 288
 289     public Boolean getHasDeviceOwnership(ConnectionInfo connectionInfo) {
 290         OvsdbConnectionInstance ovsdbConnectionInstance = getConnectionInstance(connectionInfo);
 291         if (ovsdbConnectionInstance == null) {
 292             return Boolean.FALSE;
 293         }
 294         return ovsdbConnectionInstance.getHasDeviceOwnership();
 295     }
 296
 297     public void setHasDeviceOwnership(ConnectionInfo connectionInfo, Boolean hasDeviceOwnership) {
 298         OvsdbConnectionInstance ovsdbConnectionInstance = getConnectionInstance(connectionInfo);
 299         if (ovsdbConnectionInstance != null) {
 300             ovsdbConnectionInstance.setHasDeviceOwnership(hasDeviceOwnership);
 301         }
 302     }
 303
 304     private void handleOwnershipChanged(EntityOwnershipChange ownershipChange) {
 305         OvsdbConnectionInstance ovsdbConnectionInstance = getConnectionInstanceFromEntity(ownershipChange.getEntity());
 306         LOG.info("handleOwnershipChanged: {} event received for device {}",
 307                 ownershipChange, ovsdbConnectionInstance != null ? ovsdbConnectionInstance.getConnectionInfo()
 308                         : "THAT'S NOT REGISTERED BY THIS SOUTHBOUND PLUGIN INSTANCE");
 309
 310         if (ovsdbConnectionInstance == null) {
 311             if (ownershipChange.isOwner()) {
 312                 LOG.warn("handleOwnershipChanged: found no connection instance for {}", ownershipChange.getEntity());
 313             } else {
 314                 // EntityOwnershipService sends notification to all the nodes, irrespective of whether
 315                 // that instance registered for the device ownership or not. It is to make sure that
 316                 // If all the controller instance that was connected to the device are down, so the
 317                 // running instance can clear up the operational data store even though it was not
 318                 // connected to the device.
 319                 LOG.debug("handleOwnershipChanged: found no connection instance for {}", ownershipChange.getEntity());
 320             }
 321
 322             // If entity has no owner, clean up the operational data store (it's possible because owner controller
 323             // might went down abruptly and didn't get a chance to clean up the operational data store.
 324             if (!ownershipChange.hasOwner()) {
 325                 LOG.debug("{} has no onwer, cleaning up the operational data store", ownershipChange.getEntity());
 326                 // Below code might look weird but it's required. We want to give first opportunity to the
 327                 // previous owner of the device to clean up the operational data store if there is no owner now.
 328                 // That way we will avoid lot of nasty md-sal exceptions because of concurrent delete.
 329                 if (ownershipChange.wasOwner()) {
 330                     cleanEntityOperationalData(ownershipChange.getEntity());
 331                 }
 332                 // If first cleanEntityOperationalData() was called, this call will be no-op.
 333                 cleanEntityOperationalData(ownershipChange.getEntity());
 334             }
 335             return;
 336         }
 337         //Connection detail need to be cached, irrespective of ownership result.
 338         putConnectionInstance(ovsdbConnectionInstance.getMDConnectionInfo(),ovsdbConnectionInstance);
 339
 340         if (ownershipChange.isOwner() == ovsdbConnectionInstance.getHasDeviceOwnership()) {
 341             LOG.debug("handleOwnershipChanged: no change in ownership for {}. Ownership status is : {}",
 342                     ovsdbConnectionInstance.getConnectionInfo(), ovsdbConnectionInstance.getHasDeviceOwnership());
 343             return;
 344         }
 345
 346         ovsdbConnectionInstance.setHasDeviceOwnership(ownershipChange.isOwner());
 347         // You were not an owner, but now you are
 348         if (ownershipChange.isOwner()) {
 349             LOG.info("handleOwnershipChanged: *this* southbound plugin instance is owner of device {}",
 350                     ovsdbConnectionInstance.getConnectionInfo());
 351
 352             //*this* instance of southbound plugin is owner of the device,
 353             //so register for monitor callbacks
 354             ovsdbConnectionInstance.registerCallbacks();
 355
 356         } else {
 357             //You were owner of the device, but now you are not. With the current ownership
 358             //grant mechanism, this scenario should not occur. Because this scenario will occur
 359             //when this controller went down or switch flap the connection, but in both the case
 360             //it will go through the re-registration process. We need to implement this condition
 361             //when clustering service implement a ownership grant strategy which can revoke the
 362             //device ownership for load balancing the devices across the instances.
 363             //Once this condition occur, we should unregister the callback.
 364             LOG.error("handleOwnershipChanged: *this* southbound plugin instance is no longer the owner of device {}",
 365                     ovsdbConnectionInstance.getNodeId().getValue());
 366         }
 367     }
 368
 369     private void cleanEntityOperationalData(Entity entity) {
 370
 371         InstanceIdentifier<Node> nodeIid = (InstanceIdentifier<Node>) SouthboundUtil
 372                 .getInstanceIdentifierCodec().bindingDeserializer(entity.getId());
 373
 374         final ReadWriteTransaction transaction = db.newReadWriteTransaction();
 375         Optional<Node> node = SouthboundUtil.readNode(transaction, nodeIid);
 376         if (node.isPresent()) {
 377             SouthboundUtil.deleteNode(transaction, nodeIid);
 378         }
 379     }
 380
 381     private OpenVSwitch getOpenVswitchTableEntry(OvsdbConnectionInstance connectionInstance) {
 382         DatabaseSchema dbSchema = null;
 383         OpenVSwitch openVSwitchRow = null;
 384         try {
 385             dbSchema = connectionInstance.getSchema(OvsdbSchemaContants.databaseName).get();
 386         } catch (InterruptedException | ExecutionException e) {
 387             LOG.warn("Not able to fetch schema for database {} from device {}",
 388                     OvsdbSchemaContants.databaseName,connectionInstance.getConnectionInfo(),e);
 389         }
 390         if (dbSchema != null) {
 391             GenericTableSchema openVSwitchSchema = TyperUtils.getTableSchema(dbSchema, OpenVSwitch.class);
 392
 393             List<String> openVSwitchTableColumn = new ArrayList<>();
 394             openVSwitchTableColumn.addAll(openVSwitchSchema.getColumns());
 395             Select<GenericTableSchema> selectOperation = op.select(openVSwitchSchema);
 396             selectOperation.setColumns(openVSwitchTableColumn);
 397
 398             List<Operation> operations = new ArrayList<>();
 399             operations.add(selectOperation);
 400             operations.add(op.comment("Fetching Open_VSwitch table rows"));
 401             try {
 402                 List<OperationResult> results = connectionInstance.transact(dbSchema, operations).get();
 403                 if (results != null ) {
 404                     OperationResult selectResult = results.get(0);
 405                     openVSwitchRow = TyperUtils.getTypedRowWrapper(
 406                             dbSchema,OpenVSwitch.class,selectResult.getRows().get(0));
 407
 408                 }
 409             } catch (InterruptedException | ExecutionException e) {
 410                 LOG.warn("Not able to fetch OpenVswitch table row from device {}",
 411                         connectionInstance.getConnectionInfo(),e);
 412             }
 413         }
 414         return openVSwitchRow;
 415     }
 416     private Entity getEntityFromConnectionInstance(@Nonnull OvsdbConnectionInstance ovsdbConnectionInstance) {
 417         InstanceIdentifier<Node> iid = ovsdbConnectionInstance.getInstanceIdentifier();;
 418         if ( iid == null ) {
 419             /* Switch initiated connection won't have iid, till it gets OpenVSwitch
 420              * table update but update callback is always registered after ownership
 421              * is granted. So we are explicitly fetch the row here to get the iid.
 422              */
 423             OpenVSwitch openvswitchRow = getOpenVswitchTableEntry(ovsdbConnectionInstance);
 424             iid = SouthboundMapper.getInstanceIdentifier(openvswitchRow);
 425             LOG.info("InstanceIdentifier {} generated for device "
 426                     + "connection {}",iid,ovsdbConnectionInstance.getConnectionInfo());
 427
 428         }
 429         YangInstanceIdentifier entityId = SouthboundUtil.getInstanceIdentifierCodec().getYangInstanceIdentifier(iid);
 430         Entity deviceEntity = new Entity(ENTITY_TYPE, entityId);
 431         LOG.debug("Entity {} created for device connection {}",
 432                 deviceEntity, ovsdbConnectionInstance.getConnectionInfo());
 433         return deviceEntity;
 434     }
 435
 436     private OvsdbConnectionInstance getConnectionInstanceFromEntity(Entity entity) {
 437         return entityConnectionMap.get(entity);
 438     }
 439
 440     private void registerEntityForOwnership(OvsdbConnectionInstance ovsdbConnectionInstance) {
 441
 442         Entity candidateEntity = getEntityFromConnectionInstance(ovsdbConnectionInstance);
 443         entityConnectionMap.put(candidateEntity, ovsdbConnectionInstance);
 444         ovsdbConnectionInstance.setConnectedEntity(candidateEntity);
 445         try {
 446             EntityOwnershipCandidateRegistration registration =
 447                     entityOwnershipService.registerCandidate(candidateEntity);
 448             ovsdbConnectionInstance.setDeviceOwnershipCandidateRegistration(registration);
 449             LOG.info("OVSDB entity {} is registred for ownership.", candidateEntity);
 450
 451             //If entity already has owner, it won't get notification from EntityOwnershipService
 452             //so cache the connection instances.
 453             Optional<EntityOwnershipState> ownershipStateOpt =
 454                     entityOwnershipService.getOwnershipState(candidateEntity);
 455             if (ownershipStateOpt.isPresent()) {
 456                 EntityOwnershipState ownershipState = ownershipStateOpt.get();
 457                 if (ownershipState.hasOwner() && !ownershipState.isOwner()) {
 458                     if (getConnectionInstance(ovsdbConnectionInstance.getMDConnectionInfo()) != null) {
 459                         LOG.info("OVSDB entity {} is already owned by other southbound plugin "
 460                                 + "instance, so *this* instance is NOT an OWNER of the device",
 461                                 ovsdbConnectionInstance.getConnectionInfo());
 462                         putConnectionInstance(ovsdbConnectionInstance.getMDConnectionInfo(),ovsdbConnectionInstance);
 463                     }
 464                 }
 465             }
 466         } catch (CandidateAlreadyRegisteredException e) {
 467             LOG.warn("OVSDB entity {} was already registered for {} ownership", candidateEntity, e);
 468         }
 469
 470     }
 471
 472     private void unregisterEntityForOwnership(OvsdbConnectionInstance ovsdbConnectionInstance) {
 473         ovsdbConnectionInstance.closeDeviceOwnershipCandidateRegistration();
 474         entityConnectionMap.remove(ovsdbConnectionInstance.getConnectedEntity());
 475     }
 476
 477     private class OvsdbDeviceEntityOwnershipListener implements EntityOwnershipListener {
 478         private OvsdbConnectionManager cm;
 479         private EntityOwnershipListenerRegistration listenerRegistration;
 480
 481         OvsdbDeviceEntityOwnershipListener(OvsdbConnectionManager cm, EntityOwnershipService entityOwnershipService) {
 482             this.cm = cm;
 483             listenerRegistration = entityOwnershipService.registerListener(ENTITY_TYPE, this);
 484         }
 485         public void close() {
 486             listenerRegistration.close();
 487         }
 488         @Override
 489         public void ownershipChanged(EntityOwnershipChange ownershipChange) {
 490             cm.handleOwnershipChanged(ownershipChange);
 491         }
 492     }
 493 }