BUG-7407: Introduce API to request shard leader movement

[controller.git] / opendaylight / md-sal / cds-dom-api / src / main / java / org / opendaylight / controller / cluster / dom / api / CDSShardAccess.java

diff --git a/opendaylight/md-sal/cds-dom-api/src/main/java/org/opendaylight/controller/cluster/dom/api/CDSShardAccess.java b/opendaylight/md-sal/cds-dom-api/src/main/java/org/opendaylight/controller/cluster/dom/api/CDSShardAccess.java
new file mode 100644 (file)
index 0000000..d08b99a
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+++ b/opendaylight/md-sal/cds-dom-api/src/main/java/org/opendaylight/controller/cluster/dom/api/CDSShardAccess.java
@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2016 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.dom.api;
+
+import com.google.common.annotations.Beta;
+import java.util.concurrent.CompletionStage;
+import javax.annotation.Nonnull;
+import org.opendaylight.mdsal.dom.api.DOMDataTreeIdentifier;
+
+/**
+ * Unprivileged access interface to shard information. Provides read-only access to operational details about a CDS
+ * shard.
+ *
+ * @author Robert Varga
+ */
+@Beta
+public interface CDSShardAccess {
+    /**
+     * Return the shard identifier.
+     *
+     * @return Shard identifier.
+     * @throws IllegalStateException if the {@link CDSDataTreeProducer} from which the associated
+     *         {@link CDSDataTreeProducer} is no longer valid.
+     */
+    @Nonnull DOMDataTreeIdentifier getShardIdentifier();
+
+    /**
+     * Return the shard leader location relative to the local node.
+     *
+     * @return Shard leader location.
+     * @throws IllegalStateException if the {@link CDSDataTreeProducer} from which the associated
+     *         {@link CDSDataTreeProducer} is no longer valid.
+     */
+    @Nonnull LeaderLocation getLeaderLocation();
+
+    /**
+     * Request the shard leader to be moved to the local node. The request will be evaluated against shard state and
+     * satisfied if leader movement is possible. If current shard policy or state prevents the movement from happening,
+     * the returned {@link CompletionStage} will report an exception.
+     *
+     * <p>
+     * This is a one-time operation, which does not prevent further movement happening in future. Even if this request
+     * succeeds, there is no guarantee that the leader will remain local in face of failures, shutdown or any future
+     * movement requests from other nodes.
+     *
+     * <p>
+     * Note that due to asynchronous nature of CDS, the leader may no longer be local by the time the returned
+     * {@link CompletionStage} reports success.
+     *
+     * @return A {@link CompletionStage} representing the request.
+     * @throws IllegalStateException if the {@link CDSDataTreeProducer} from which the associated
+     *         {@link CDSDataTreeProducer} is no longer valid.
+     */
+    @Nonnull CompletionStage<Void> makeLeaderLocal();
+
+    /**
+     * Register a listener to shard location changes. Each listener object can be registered at most once.
+     *
+     * @param listener Listener object
+     * @return A {@link LeaderLocationListenerRegistration} for the listener.
+     * @throws IllegalArgumentException if the specified listener is already registered.
+     * @throws IllegalStateException if the {@link CDSDataTreeProducer} from which the associated
+     *         {@link CDSDataTreeProducer} is no longer valid.
+     * @throws NullPointerException if listener is null.
+     */
+    @Nonnull <L extends LeaderLocationListener> LeaderLocationListenerRegistration<L> registerLeaderLocationListener(
+            @Nonnull L listener);
+}