Bug 4105: Choose Owner for an Entity based on first come first served basis

[controller.git] / opendaylight / md-sal / sal-distributed-datastore / src / main / java / org / opendaylight / controller / cluster / datastore / entityownership / CandidateListChangeListener.java

diff --git a/opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/entityownership/CandidateListChangeListener.java b/opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/entityownership/CandidateListChangeListener.java
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@@ -0,0 +1,125 @@
+/*
+ * 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.datastore.entityownership;
+
+import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.CANDIDATE_NAME_QNAME;
+import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_ID_QNAME;
+import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_OWNERS_PATH;
+import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_QNAME;
+import akka.actor.ActorRef;
+import com.google.common.base.Preconditions;
+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.Map.Entry;
+import org.opendaylight.controller.cluster.datastore.ShardDataTree;
+import org.opendaylight.controller.cluster.datastore.entityownership.messages.CandidateAdded;
+import org.opendaylight.controller.cluster.datastore.entityownership.messages.CandidateRemoved;
+import org.opendaylight.controller.md.sal.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.common.QName;
+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
+ */
+public class CandidateListChangeListener implements DOMDataTreeChangeListener {
+    private static final Logger LOG = LoggerFactory.getLogger(CandidateListChangeListener.class);
+
+    private final ActorRef shard;
+    private final Map<YangInstanceIdentifier, Collection<String>> currentCandidates = new HashMap<>();
+
+    public CandidateListChangeListener(ActorRef shard, ShardDataTree shardDataTree) {
+        this.shard = Preconditions.checkNotNull(shard, "shard should not be null");
+
+        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);
+    }
+
+    @Override
+    public void onDataTreeChanged(Collection<DataTreeCandidate> changes) {
+        for(DataTreeCandidate change: changes) {
+            DataTreeCandidateNode changeRoot = change.getRootNode();
+
+            LOG.debug("Candidate node changed: {}, {}", changeRoot.getModificationType(), change.getRootPath());
+
+            NodeIdentifierWithPredicates candidateKey =
+                    (NodeIdentifierWithPredicates) change.getRootPath().getLastPathArgument();
+            String candidate = candidateKey.getKeyValues().get(CANDIDATE_NAME_QNAME).toString();
+
+            YangInstanceIdentifier entityId = extractEntityPath(change.getRootPath());
+
+            if(changeRoot.getModificationType() == ModificationType.WRITE) {
+                LOG.debug("Candidate {} was added for entity {}", candidate, entityId);
+
+                Collection<String> currentCandidates = addToCurrentCandidates(entityId, candidate);
+                shard.tell(new CandidateAdded(entityId, candidate, new ArrayList<>(currentCandidates)), shard);
+            } else if(changeRoot.getModificationType() == ModificationType.DELETE) {
+                LOG.debug("Candidate {} was removed for entity {}", candidate, entityId);
+
+                Collection<String> currentCandidates = removeFromCurrentCandidates(entityId, candidate);
+                shard.tell(new CandidateRemoved(entityId, candidate, new ArrayList<>(currentCandidates)), shard);
+            }
+        }
+    }
+
+    private Collection<String> addToCurrentCandidates(YangInstanceIdentifier entityId, String newCandidate) {
+        Collection<String> candidates = currentCandidates.get(entityId);
+        if(candidates == null) {
+            candidates = new LinkedHashSet<>();
+            currentCandidates.put(entityId, candidates);
+        }
+
+        candidates.add(newCandidate);
+        return candidates;
+    }
+
+    private Collection<String> removeFromCurrentCandidates(YangInstanceIdentifier entityId, String candidateToRemove) {
+        Collection<String> candidates = currentCandidates.get(entityId);
+        if(candidates != null) {
+            candidates.remove(candidateToRemove);
+            return candidates;
+        }
+
+        // Shouldn't happen
+        return Collections.emptyList();
+    }
+
+    private YangInstanceIdentifier extractEntityPath(YangInstanceIdentifier candidatePath) {
+        List<PathArgument> newPathArgs = new ArrayList<>();
+        for(PathArgument pathArg: candidatePath.getPathArguments()) {
+            newPathArgs.add(pathArg);
+            if(pathArg instanceof NodeIdentifierWithPredicates) {
+                NodeIdentifierWithPredicates nodeKey = (NodeIdentifierWithPredicates) pathArg;
+                Entry<QName, Object> key = nodeKey.getKeyValues().entrySet().iterator().next();
+                if(ENTITY_ID_QNAME.equals(key.getKey())) {
+                    break;
+                }
+            }
+        }
+
+        return YangInstanceIdentifier.create(newPathArgs);
+    }
+}
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