+/*
+ * Copyright (c) 2015 Cisco Systems, Inc. and others. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.opendaylight.controller.cluster.entityownership;
+
+import static java.util.Objects.requireNonNull;
+import static org.opendaylight.controller.cluster.entityownership.EntityOwnersModel.CANDIDATE_NAME_QNAME;
+import static org.opendaylight.controller.cluster.entityownership.EntityOwnersModel.ENTITY_ID_QNAME;
+import static org.opendaylight.controller.cluster.entityownership.EntityOwnersModel.ENTITY_OWNERS_PATH;
+import static org.opendaylight.controller.cluster.entityownership.EntityOwnersModel.ENTITY_QNAME;
+
+import akka.actor.ActorRef;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import org.opendaylight.controller.cluster.datastore.ShardDataTree;
+import org.opendaylight.controller.cluster.entityownership.messages.CandidateAdded;
+import org.opendaylight.controller.cluster.entityownership.messages.CandidateRemoved;
+import org.opendaylight.mdsal.dom.api.DOMDataTreeChangeListener;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.controller.md.sal.clustering.entity.owners.rev150804.entity.owners.EntityType;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.controller.md.sal.clustering.entity.owners.rev150804.entity.owners.entity.type.entity.Candidate;
+import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
+import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.NodeIdentifierWithPredicates;
+import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.PathArgument;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidate;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidateNode;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.ModificationType;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Listens for candidate entries added/removed and notifies the EntityOwnershipShard appropriately.
+ *
+ * @author Moiz Raja
+ * @author Thomas Pantelis
+ */
+class CandidateListChangeListener implements DOMDataTreeChangeListener {
+ private static final Logger LOG = LoggerFactory.getLogger(CandidateListChangeListener.class);
+
+ private final String logId;
+ private final ActorRef shard;
+ private final Map<YangInstanceIdentifier, Collection<String>> currentCandidates = new HashMap<>();
+
+ CandidateListChangeListener(final ActorRef shard, final String logId) {
+ this.shard = requireNonNull(shard, "shard should not be null");
+ this.logId = logId;
+ }
+
+ void init(final ShardDataTree shardDataTree) {
+ shardDataTree.registerTreeChangeListener(YangInstanceIdentifier.builder(ENTITY_OWNERS_PATH)
+ .node(EntityType.QNAME).node(EntityType.QNAME).node(ENTITY_QNAME).node(ENTITY_QNAME)
+ .node(Candidate.QNAME).node(Candidate.QNAME).build(), this, Optional.empty(), noop -> { /* NOOP */ });
+ }
+
+ @Override
+ public void onDataTreeChanged(final Collection<DataTreeCandidate> changes) {
+ for (DataTreeCandidate change: changes) {
+ DataTreeCandidateNode changeRoot = change.getRootNode();
+ ModificationType type = changeRoot.getModificationType();
+
+ LOG.debug("{}: Candidate node changed: {}, {}", logId, type, change.getRootPath());
+
+ NodeIdentifierWithPredicates candidateKey =
+ (NodeIdentifierWithPredicates) change.getRootPath().getLastPathArgument();
+ String candidate = candidateKey.getValue(CANDIDATE_NAME_QNAME).toString();
+
+ YangInstanceIdentifier entityId = extractEntityPath(change.getRootPath());
+
+ if (type == ModificationType.WRITE || type == ModificationType.APPEARED) {
+ LOG.debug("{}: Candidate {} was added for entity {}", logId, candidate, entityId);
+
+ Collection<String> newCandidates = addToCurrentCandidates(entityId, candidate);
+ shard.tell(new CandidateAdded(entityId, candidate, new ArrayList<>(newCandidates)), shard);
+ } else if (type == ModificationType.DELETE || type == ModificationType.DISAPPEARED) {
+ LOG.debug("{}: Candidate {} was removed for entity {}", logId, candidate, entityId);
+
+ Collection<String> newCandidates = removeFromCurrentCandidates(entityId, candidate);
+ shard.tell(new CandidateRemoved(entityId, candidate, new ArrayList<>(newCandidates)), shard);
+ }
+ }
+ }
+
+ private Collection<String> addToCurrentCandidates(final YangInstanceIdentifier entityId,
+ final String newCandidate) {
+ Collection<String> candidates = currentCandidates.computeIfAbsent(entityId, k -> new LinkedHashSet<>());
+ candidates.add(newCandidate);
+ return candidates;
+ }
+
+ private Collection<String> removeFromCurrentCandidates(final YangInstanceIdentifier entityId,
+ final String candidateToRemove) {
+ Collection<String> candidates = currentCandidates.get(entityId);
+ if (candidates != null) {
+ candidates.remove(candidateToRemove);
+ return candidates;
+ }
+
+ // Shouldn't happen
+ return Collections.emptyList();
+ }
+
+ private static YangInstanceIdentifier extractEntityPath(final YangInstanceIdentifier candidatePath) {
+ List<PathArgument> newPathArgs = new ArrayList<>();
+ for (PathArgument pathArg: candidatePath.getPathArguments()) {
+ newPathArgs.add(pathArg);
+ if (pathArg instanceof NodeIdentifierWithPredicates
+ && ENTITY_ID_QNAME.equals(((NodeIdentifierWithPredicates) pathArg).keySet().iterator().next())) {
+ break;
+ }
+ }
+
+ return YangInstanceIdentifier.create(newPathArgs);
+ }
+}