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.TransactionCommand;
  47 import org.opendaylight.ovsdb.southbound.transactions.md.TransactionInvoker;
  48 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.ovsdb.rev150105.OvsdbBridgeAttributes;
  49 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.ovsdb.rev150105.OvsdbBridgeAugmentation;
  50 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.ovsdb.rev150105.OvsdbNodeAugmentation;
  51 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.ovsdb.rev150105.ovsdb.node.attributes.ConnectionInfo;
  52 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.ovsdb.rev150105.ovsdb.node.attributes.ManagedNodeEntry;
  53 import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.topology.Node;
  54 import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
  55 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  56 import org.slf4j.Logger;
  57 import org.slf4j.LoggerFactory;
  58
  59 import com.google.common.base.Optional;
  60 import com.google.common.base.Preconditions;
  61 import com.google.common.util.concurrent.CheckedFuture;
  62
  63 public class OvsdbConnectionManager implements OvsdbConnectionListener, AutoCloseable {
  64     private Map<ConnectionInfo, OvsdbConnectionInstance> clients =
  65             new ConcurrentHashMap<>();
  66     private static final Logger LOG = LoggerFactory.getLogger(OvsdbConnectionManager.class);
  67     private static final String ENTITY_TYPE = "ovsdb";
  68
  69     private DataBroker db;
  70     private TransactionInvoker txInvoker;
  71     private Map<ConnectionInfo,InstanceIdentifier<Node>> instanceIdentifiers =
  72             new ConcurrentHashMap<>();
  73     private Map<Entity, OvsdbConnectionInstance> entityConnectionMap =
  74             new ConcurrentHashMap<>();
  75     private EntityOwnershipService entityOwnershipService;
  76     private OvsdbDeviceEntityOwnershipListener ovsdbDeviceEntityOwnershipListener;
  77     private OvsdbConnection ovsdbConnection;
  78
  79     public OvsdbConnectionManager(DataBroker db,TransactionInvoker txInvoker,
  80                                   EntityOwnershipService entityOwnershipService,
  81                                   OvsdbConnection ovsdbConnection) {
  82         this.db = db;
  83         this.txInvoker = txInvoker;
  84         this.entityOwnershipService = entityOwnershipService;
  85         this.ovsdbDeviceEntityOwnershipListener = new OvsdbDeviceEntityOwnershipListener(this, entityOwnershipService);
  86         this.ovsdbConnection = ovsdbConnection;
  87     }
  88
  89     @Override
  90     public void connected(@Nonnull final OvsdbClient externalClient) {
  91         LOG.info("Library connected {} from {}:{} to {}:{}",
  92                 externalClient.getConnectionInfo().getType(),
  93                 externalClient.getConnectionInfo().getRemoteAddress(),
  94                 externalClient.getConnectionInfo().getRemotePort(),
  95                 externalClient.getConnectionInfo().getLocalAddress(),
  96                 externalClient.getConnectionInfo().getLocalPort());
  97         if(externalClient.getSchema(SouthboundConstants.OPEN_V_SWITCH) != null) {
  98             OvsdbConnectionInstance client = connectedButCallBacksNotRegistered(externalClient);
  99             // Register Cluster Ownership for ConnectionInfo
 100             registerEntityForOwnership(client);
 101         }
 102     }
 103
 104     public OvsdbConnectionInstance connectedButCallBacksNotRegistered(final OvsdbClient externalClient) {
 105         LOG.info("OVSDB Connection from {}:{}",externalClient.getConnectionInfo().getRemoteAddress(),
 106                 externalClient.getConnectionInfo().getRemotePort());
 107         ConnectionInfo key = SouthboundMapper.createConnectionInfo(externalClient);
 108         OvsdbConnectionInstance ovsdbConnectionInstance = getConnectionInstance(key);
 109
 110         // Check if existing ovsdbConnectionInstance for the OvsdbClient present.
 111         // In such cases, we will see if the ovsdbConnectionInstance has same externalClient.
 112         if (ovsdbConnectionInstance != null) {
 113             if (ovsdbConnectionInstance.hasOvsdbClient(externalClient)) {
 114                 LOG.warn("OVSDB Connection Instance {} already exists for client {}", key, externalClient);
 115                 return ovsdbConnectionInstance;
 116             }
 117             LOG.warn("OVSDB Connection Instance {} being replaced with client {}", key, externalClient);
 118
 119             // Unregister Cluster Ownership for ConnectionInfo
 120             // Because the ovsdbConnectionInstance is about to be completely replaced!
 121             unregisterEntityForOwnership(ovsdbConnectionInstance);
 122
 123             ovsdbConnectionInstance.disconnect();
 124
 125             removeConnectionInstance(key);
 126         }
 127
 128         ovsdbConnectionInstance = new OvsdbConnectionInstance(key, externalClient, txInvoker,
 129                 getInstanceIdentifier(key));
 130         ovsdbConnectionInstance.createTransactInvokers();
 131         return ovsdbConnectionInstance;
 132     }
 133
 134     @Override
 135     public void disconnected(OvsdbClient client) {
 136         LOG.info("Library disconnected {} from {}:{} to {}:{}. Cleaning up the operational data store",
 137                 client.getConnectionInfo().getType(),
 138                 client.getConnectionInfo().getRemoteAddress(),
 139                 client.getConnectionInfo().getRemotePort(),
 140                 client.getConnectionInfo().getLocalAddress(),
 141                 client.getConnectionInfo().getLocalPort());
 142         ConnectionInfo key = SouthboundMapper.createConnectionInfo(client);
 143         OvsdbConnectionInstance ovsdbConnectionInstance = getConnectionInstance(key);
 144         if (ovsdbConnectionInstance != null) {
 145             // Unregister Entity ownership as soon as possible ,so this instance should
 146             // not be used as a candidate in Entity election (given that this instance is
 147             // about to disconnect as well), if current owner get disconnected from
 148             // OVSDB device.
 149             unregisterEntityForOwnership(ovsdbConnectionInstance);
 150
 151             txInvoker.invoke(new OvsdbNodeRemoveCommand(ovsdbConnectionInstance, null, null));
 152
 153             removeConnectionInstance(key);
 154         } else {
 155             LOG.warn("disconnected : Connection instance not found for OVSDB Node {} ", key);
 156         }
 157         LOG.trace("OvsdbConnectionManager: exit disconnected client: {}", client);
 158     }
 159
 160     public OvsdbClient connect(InstanceIdentifier<Node> iid,
 161             OvsdbNodeAugmentation ovsdbNode) throws UnknownHostException {
 162         LOG.info("Connecting to {}", SouthboundUtil.connectionInfoToString(ovsdbNode.getConnectionInfo()));
 163
 164         // TODO handle case where we already have a connection
 165         // TODO use transaction chains to handle ordering issues between disconnected
 166         // TODO and connected when writing to the operational store
 167         InetAddress ip = SouthboundMapper.createInetAddress(ovsdbNode.getConnectionInfo().getRemoteIp());
 168         OvsdbClient client = ovsdbConnection.connect(ip,
 169                 ovsdbNode.getConnectionInfo().getRemotePort().getValue());
 170         // For connections from the controller to the ovs instance, the library doesn't call
 171         // this method for us
 172         if (client != null) {
 173             putInstanceIdentifier(ovsdbNode.getConnectionInfo(), iid.firstIdentifierOf(Node.class));
 174             OvsdbConnectionInstance ovsdbConnectionInstance = connectedButCallBacksNotRegistered(client);
 175             ovsdbConnectionInstance.setOvsdbNodeAugmentation(ovsdbNode);
 176
 177             // Register Cluster Ownership for ConnectionInfo
 178             registerEntityForOwnership(ovsdbConnectionInstance);
 179         } else {
 180             LOG.warn("Failed to connect to OVSDB Node {}", ovsdbNode.getConnectionInfo());
 181         }
 182         return client;
 183     }
 184
 185     public void disconnect(OvsdbNodeAugmentation ovsdbNode) throws UnknownHostException {
 186         LOG.info("Disconnecting from {}", SouthboundUtil.connectionInfoToString(ovsdbNode.getConnectionInfo()));
 187         OvsdbConnectionInstance client = getConnectionInstance(ovsdbNode.getConnectionInfo());
 188         if (client != null) {
 189             // Unregister Cluster Onwership for ConnectionInfo
 190             unregisterEntityForOwnership(client);
 191
 192             client.disconnect();
 193
 194             removeInstanceIdentifier(ovsdbNode.getConnectionInfo());
 195         } else {
 196             LOG.debug("disconnect : connection instance not found for {}",ovsdbNode.getConnectionInfo());
 197         }
 198     }
 199
 200 /*    public void init(ConnectionInfo key) {
 201         OvsdbConnectionInstance client = getConnectionInstance(key);
 202
 203         // TODO (FF): make sure that this cluster instance is the 'entity owner' fo the given OvsdbConnectionInstance ?
 204
 205         if (client != null) {
 206
 207              *  Note: registerCallbacks() is idemPotent... so if you call it repeatedly all is safe,
 208              *  it only registersCallbacks on the *first* call.
 209
 210             client.registerCallbacks();
 211         }
 212     }
 213 */
 214     @Override
 215     public void close() {
 216         if (ovsdbDeviceEntityOwnershipListener != null) {
 217             ovsdbDeviceEntityOwnershipListener.close();
 218         }
 219
 220         for (OvsdbClient client: clients.values()) {
 221             client.disconnect();
 222         }
 223     }
 224
 225     private void putConnectionInstance(ConnectionInfo key,OvsdbConnectionInstance instance) {
 226         ConnectionInfo connectionInfo = SouthboundMapper.suppressLocalIpPort(key);
 227         clients.put(connectionInfo, instance);
 228     }
 229
 230     private void removeConnectionInstance(ConnectionInfo key) {
 231         ConnectionInfo connectionInfo = SouthboundMapper.suppressLocalIpPort(key);
 232         clients.remove(connectionInfo);
 233     }
 234
 235     private void putInstanceIdentifier(ConnectionInfo key,InstanceIdentifier<Node> iid) {
 236         ConnectionInfo connectionInfo = SouthboundMapper.suppressLocalIpPort(key);
 237         instanceIdentifiers.put(connectionInfo, iid);
 238     }
 239
 240     private void removeInstanceIdentifier(ConnectionInfo key) {
 241         ConnectionInfo connectionInfo = SouthboundMapper.suppressLocalIpPort(key);
 242         instanceIdentifiers.remove(connectionInfo);
 243     }
 244
 245     public OvsdbConnectionInstance getConnectionInstance(ConnectionInfo key) {
 246         ConnectionInfo connectionInfo = SouthboundMapper.suppressLocalIpPort(key);
 247         return clients.get(connectionInfo);
 248     }
 249
 250     public InstanceIdentifier<Node> getInstanceIdentifier(ConnectionInfo key) {
 251         ConnectionInfo connectionInfo = SouthboundMapper.suppressLocalIpPort(key);
 252         return instanceIdentifiers.get(connectionInfo);
 253     }
 254
 255     public OvsdbConnectionInstance getConnectionInstance(OvsdbBridgeAttributes mn) {
 256         Optional<OvsdbNodeAugmentation> optional = SouthboundUtil.getManagingNode(db, mn);
 257         if (optional.isPresent()) {
 258             return getConnectionInstance(optional.get().getConnectionInfo());
 259         } else {
 260             return null;
 261         }
 262     }
 263
 264     public OvsdbConnectionInstance getConnectionInstance(Node node) {
 265         Preconditions.checkNotNull(node);
 266         OvsdbNodeAugmentation ovsdbNode = node.getAugmentation(OvsdbNodeAugmentation.class);
 267         OvsdbBridgeAugmentation ovsdbManagedNode = node.getAugmentation(OvsdbBridgeAugmentation.class);
 268         if (ovsdbNode != null) {
 269             return getConnectionInstance(ovsdbNode.getConnectionInfo());
 270         } else if (ovsdbManagedNode != null) {
 271             return getConnectionInstance(ovsdbManagedNode);
 272         } else {
 273             LOG.warn("This is not a node that gives any hint how to find its OVSDB Manager: {}",node);
 274             return null;
 275         }
 276     }
 277
 278     public OvsdbConnectionInstance getConnectionInstance(InstanceIdentifier<Node> nodePath) {
 279         try {
 280             ReadOnlyTransaction transaction = db.newReadOnlyTransaction();
 281             CheckedFuture<Optional<Node>, ReadFailedException> nodeFuture = transaction.read(
 282                     LogicalDatastoreType.OPERATIONAL, nodePath);
 283             transaction.close();
 284             Optional<Node> optional = nodeFuture.get();
 285             if (optional != null && optional.isPresent() && optional.get() != null) {
 286                 return this.getConnectionInstance(optional.get());
 287             } else {
 288                 LOG.warn("Found non-topological node {} on path {}",optional);
 289                 return null;
 290             }
 291         } catch (Exception e) {
 292             LOG.warn("Failed to get Ovsdb Node {}",nodePath, e);
 293             return null;
 294         }
 295     }
 296
 297     public OvsdbClient getClient(ConnectionInfo connectionInfo) {
 298         return getConnectionInstance(connectionInfo);
 299     }
 300
 301     public OvsdbClient getClient(OvsdbBridgeAttributes mn) {
 302         return getConnectionInstance(mn);
 303     }
 304
 305     public OvsdbClient getClient(Node node) {
 306         return getConnectionInstance(node);
 307     }
 308
 309     public Boolean getHasDeviceOwnership(ConnectionInfo connectionInfo) {
 310         OvsdbConnectionInstance ovsdbConnectionInstance = getConnectionInstance(connectionInfo);
 311         if (ovsdbConnectionInstance == null) {
 312             return Boolean.FALSE;
 313         }
 314         return ovsdbConnectionInstance.getHasDeviceOwnership();
 315     }
 316
 317     private void handleOwnershipChanged(EntityOwnershipChange ownershipChange) {
 318         OvsdbConnectionInstance ovsdbConnectionInstance = getConnectionInstanceFromEntity(ownershipChange.getEntity());
 319         LOG.debug("handleOwnershipChanged: {} event received for device {}",
 320                 ownershipChange, ovsdbConnectionInstance != null ? ovsdbConnectionInstance.getConnectionInfo()
 321                         : "that's currently NOT registered by *this* southbound plugin instance");
 322
 323         if (ovsdbConnectionInstance == null) {
 324             if (ownershipChange.isOwner()) {
 325                 LOG.warn("handleOwnershipChanged: *this* instance is elected as an owner of the device {} but it "
 326                         + "is NOT registered for ownership", ownershipChange.getEntity());
 327             } else {
 328                 // EntityOwnershipService sends notification to all the nodes, irrespective of whether
 329                 // that instance registered for the device ownership or not. It is to make sure that
 330                 // If all the controller instance that was connected to the device are down, so the
 331                 // running instance can clear up the operational data store even though it was not
 332                 // connected to the device.
 333                 LOG.debug("handleOwnershipChanged: No connection instance found for {}", ownershipChange.getEntity());
 334             }
 335
 336             // If entity has no owner, clean up the operational data store (it's possible because owner controller
 337             // might went down abruptly and didn't get a chance to clean up the operational data store.
 338             if (!ownershipChange.hasOwner()) {
 339                 LOG.info("{} has no owner, cleaning up the operational data store", ownershipChange.getEntity());
 340                 cleanEntityOperationalData(ownershipChange.getEntity());
 341             }
 342             return;
 343         }
 344         //Connection detail need to be cached, irrespective of ownership result.
 345         putConnectionInstance(ovsdbConnectionInstance.getMDConnectionInfo(),ovsdbConnectionInstance);
 346
 347         if (ownershipChange.isOwner() == ovsdbConnectionInstance.getHasDeviceOwnership()) {
 348             LOG.info("handleOwnershipChanged: no change in ownership for {}. Ownership status is : {}",
 349                     ovsdbConnectionInstance.getConnectionInfo(), ovsdbConnectionInstance.getHasDeviceOwnership()
 350                             ? SouthboundConstants.OWNERSHIPSTATES.OWNER.getState()
 351                             : SouthboundConstants.OWNERSHIPSTATES.NONOWNER.getState());
 352             return;
 353         }
 354
 355         ovsdbConnectionInstance.setHasDeviceOwnership(ownershipChange.isOwner());
 356         // You were not an owner, but now you are
 357         if (ownershipChange.isOwner()) {
 358             LOG.info("handleOwnershipChanged: *this* southbound plugin instance is an OWNER of the device {}",
 359                     ovsdbConnectionInstance.getConnectionInfo());
 360
 361             //*this* instance of southbound plugin is owner of the device,
 362             //so register for monitor callbacks
 363             ovsdbConnectionInstance.registerCallbacks();
 364
 365         } else {
 366             //You were owner of the device, but now you are not. With the current ownership
 367             //grant mechanism, this scenario should not occur. Because this scenario will occur
 368             //when this controller went down or switch flap the connection, but in both the case
 369             //it will go through the re-registration process. We need to implement this condition
 370             //when clustering service implement a ownership grant strategy which can revoke the
 371             //device ownership for load balancing the devices across the instances.
 372             //Once this condition occur, we should unregister the callback.
 373             LOG.error("handleOwnershipChanged: *this* southbound plugin instance is no longer the owner of device {}."
 374                     + "This should NOT happen.",
 375                     ovsdbConnectionInstance.getNodeId().getValue());
 376         }
 377     }
 378
 379     private void cleanEntityOperationalData(Entity entity) {
 380
 381         //Do explicit cleanup rather than using OvsdbNodeRemoveCommand, because there
 382         // are chances that other controller instance went down abruptly and it does
 383         // not clear manager entry, which OvsdbNodeRemoveCommand look for before cleanup.
 384
 385         @SuppressWarnings("unchecked") final InstanceIdentifier<Node> nodeIid =
 386                 (InstanceIdentifier<Node>) SouthboundUtil
 387                         .getInstanceIdentifierCodec().bindingDeserializer(entity.getId());
 388
 389         txInvoker.invoke(new TransactionCommand() {
 390             @Override
 391             public void execute(ReadWriteTransaction transaction) {
 392                 Optional<Node> ovsdbNodeOpt = SouthboundUtil.readNode(transaction, nodeIid);
 393                 if (ovsdbNodeOpt.isPresent()) {
 394                     Node ovsdbNode = ovsdbNodeOpt.get();
 395                     OvsdbNodeAugmentation nodeAugmentation = ovsdbNode.getAugmentation(OvsdbNodeAugmentation.class);
 396                     if (nodeAugmentation != null) {
 397                         if (nodeAugmentation.getManagedNodeEntry() != null) {
 398                             for (ManagedNodeEntry managedNode : nodeAugmentation.getManagedNodeEntry()) {
 399                                 transaction.delete(
 400                                         LogicalDatastoreType.OPERATIONAL, managedNode.getBridgeRef().getValue());
 401                             }
 402                         } else {
 403                             LOG.debug("{} had no managed nodes", ovsdbNode.getNodeId().getValue());
 404                         }
 405                     }
 406                     transaction.delete(LogicalDatastoreType.OPERATIONAL, nodeIid);
 407                 }
 408             }
 409         });
 410
 411     }
 412
 413     private OpenVSwitch getOpenVswitchTableEntry(OvsdbConnectionInstance connectionInstance) {
 414         DatabaseSchema dbSchema = null;
 415         OpenVSwitch openVSwitchRow = null;
 416         try {
 417             dbSchema = connectionInstance.getSchema(OvsdbSchemaContants.databaseName).get();
 418         } catch (InterruptedException | ExecutionException e) {
 419             LOG.warn("Not able to fetch schema for database {} from device {}",
 420                     OvsdbSchemaContants.databaseName,connectionInstance.getConnectionInfo(),e);
 421         }
 422         if (dbSchema != null) {
 423             GenericTableSchema openVSwitchSchema = TyperUtils.getTableSchema(dbSchema, OpenVSwitch.class);
 424
 425             List<String> openVSwitchTableColumn = new ArrayList<>();
 426             openVSwitchTableColumn.addAll(openVSwitchSchema.getColumns());
 427             Select<GenericTableSchema> selectOperation = op.select(openVSwitchSchema);
 428             selectOperation.setColumns(openVSwitchTableColumn);
 429
 430             List<Operation> operations = new ArrayList<>();
 431             operations.add(selectOperation);
 432             operations.add(op.comment("Fetching Open_VSwitch table rows"));
 433             try {
 434                 List<OperationResult> results = connectionInstance.transact(dbSchema, operations).get();
 435                 if (results != null ) {
 436                     OperationResult selectResult = results.get(0);
 437                     openVSwitchRow = TyperUtils.getTypedRowWrapper(
 438                             dbSchema,OpenVSwitch.class,selectResult.getRows().get(0));
 439
 440                 }
 441             } catch (InterruptedException | ExecutionException e) {
 442                 LOG.warn("Not able to fetch OpenVswitch table row from device {}",
 443                         connectionInstance.getConnectionInfo(),e);
 444             }
 445         }
 446         return openVSwitchRow;
 447     }
 448     private Entity getEntityFromConnectionInstance(@Nonnull OvsdbConnectionInstance ovsdbConnectionInstance) {
 449         InstanceIdentifier<Node> iid = ovsdbConnectionInstance.getInstanceIdentifier();
 450         if ( iid == null ) {
 451             /* Switch initiated connection won't have iid, till it gets OpenVSwitch
 452              * table update but update callback is always registered after ownership
 453              * is granted. So we are explicitly fetch the row here to get the iid.
 454              */
 455             OpenVSwitch openvswitchRow = getOpenVswitchTableEntry(ovsdbConnectionInstance);
 456             iid = SouthboundMapper.getInstanceIdentifier(openvswitchRow);
 457             LOG.info("InstanceIdentifier {} generated for device "
 458                     + "connection {}",iid,ovsdbConnectionInstance.getConnectionInfo());
 459             ovsdbConnectionInstance.setInstanceIdentifier(iid);
 460         }
 461         YangInstanceIdentifier entityId = SouthboundUtil.getInstanceIdentifierCodec().getYangInstanceIdentifier(iid);
 462         Entity deviceEntity = new Entity(ENTITY_TYPE, entityId);
 463         LOG.debug("Entity {} created for device connection {}",
 464                 deviceEntity, ovsdbConnectionInstance.getConnectionInfo());
 465         return deviceEntity;
 466     }
 467
 468     private OvsdbConnectionInstance getConnectionInstanceFromEntity(Entity entity) {
 469         return entityConnectionMap.get(entity);
 470     }
 471
 472     private void registerEntityForOwnership(OvsdbConnectionInstance ovsdbConnectionInstance) {
 473
 474         Entity candidateEntity = getEntityFromConnectionInstance(ovsdbConnectionInstance);
 475         entityConnectionMap.put(candidateEntity, ovsdbConnectionInstance);
 476         ovsdbConnectionInstance.setConnectedEntity(candidateEntity);
 477         try {
 478             EntityOwnershipCandidateRegistration registration =
 479                     entityOwnershipService.registerCandidate(candidateEntity);
 480             ovsdbConnectionInstance.setDeviceOwnershipCandidateRegistration(registration);
 481             LOG.info("OVSDB entity {} is registered for ownership.", candidateEntity);
 482
 483             //If entity already has owner, it won't get notification from EntityOwnershipService
 484             //so cache the connection instances.
 485             Optional<EntityOwnershipState> ownershipStateOpt =
 486                     entityOwnershipService.getOwnershipState(candidateEntity);
 487             if (ownershipStateOpt.isPresent()) {
 488                 EntityOwnershipState ownershipState = ownershipStateOpt.get();
 489                 if (ownershipState.hasOwner() && !ownershipState.isOwner()) {
 490                     LOG.info("OVSDB entity {} is already owned by other southbound plugin "
 491                                     + "instance, so *this* instance is NOT an OWNER of the device",
 492                             ovsdbConnectionInstance.getConnectionInfo());
 493                     putConnectionInstance(ovsdbConnectionInstance.getMDConnectionInfo(),ovsdbConnectionInstance);
 494                 }
 495             }
 496         } catch (CandidateAlreadyRegisteredException e) {
 497             LOG.warn("OVSDB entity {} was already registered for ownership", candidateEntity, e);
 498         }
 499
 500     }
 501
 502     private void unregisterEntityForOwnership(OvsdbConnectionInstance ovsdbConnectionInstance) {
 503         ovsdbConnectionInstance.closeDeviceOwnershipCandidateRegistration();
 504         entityConnectionMap.remove(ovsdbConnectionInstance.getConnectedEntity());
 505     }
 506
 507     private class OvsdbDeviceEntityOwnershipListener implements EntityOwnershipListener {
 508         private OvsdbConnectionManager cm;
 509         private EntityOwnershipListenerRegistration listenerRegistration;
 510
 511         OvsdbDeviceEntityOwnershipListener(OvsdbConnectionManager cm, EntityOwnershipService entityOwnershipService) {
 512             this.cm = cm;
 513             listenerRegistration = entityOwnershipService.registerListener(ENTITY_TYPE, this);
 514         }
 515         public void close() {
 516             listenerRegistration.close();
 517         }
 518         @Override
 519         public void ownershipChanged(EntityOwnershipChange ownershipChange) {
 520             cm.handleOwnershipChanged(ownershipChange);
 521         }
 522     }
 523 }