[ONOS-6395] (vNet) Defining mastership service

Defines the interface for mastership service for virtual networks.
This service is needed to achieve HA and load balancing.

Change-Id: I5b68511c114ebd818429f4f6eb622dff95dd8630
diff --git a/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/VirtualNetworkMastershipStore.java b/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/VirtualNetworkMastershipStore.java
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+/*
+ * Copyright 2017-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.incubator.net.virtual;
+
+import org.onosproject.cluster.NodeId;
+import org.onosproject.cluster.RoleInfo;
+import org.onosproject.mastership.MastershipEvent;
+import org.onosproject.mastership.MastershipStoreDelegate;
+import org.onosproject.mastership.MastershipTerm;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.MastershipRole;
+
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+
+/**
+ * Manages inventory of mastership roles for devices, across controller
+ * instances for virtual networks; not intended for direct use.
+ */
+public interface VirtualNetworkMastershipStore
+        extends VirtualStore<MastershipEvent, MastershipStoreDelegate> {
+
+    // three things to map: NodeId, DeviceId, MastershipRole
+
+    /**
+     * Requests role of the local node for the specified device.
+     *
+     * @param networkId the virtual network identifier
+     * @param deviceId  the device identifier
+     * @return established or newly negotiated mastership role
+     */
+    CompletableFuture<MastershipRole> requestRole(NetworkId networkId, DeviceId deviceId);
+
+    /**
+     * Returns the role of a device for a specific controller instance.
+     *
+     * @param networkId virtual network identifier
+     * @param nodeId    the instance identifier
+     * @param deviceId  the device identifiers
+     * @return the role
+     */
+    MastershipRole getRole(NetworkId networkId, NodeId nodeId, DeviceId deviceId);
+
+    /**
+     * Returns the master for a device.
+     *
+     * @param networkId virtual network identifier
+     * @param deviceId  the device identifier
+     * @return the instance identifier of the master
+     */
+    NodeId getMaster(NetworkId networkId, DeviceId deviceId);
+
+    /**
+     * Returns the master and backup nodes for a device.
+     *
+     * @param networkId virtual network identifier
+     * @param deviceId  the device identifier
+     * @return a RoleInfo containing controller IDs
+     */
+    RoleInfo getNodes(NetworkId networkId, DeviceId deviceId);
+
+    /**
+     * Returns the devices that a controller instance is master of.
+     *
+     * @param networkId virtual network identifier
+     * @param nodeId    the instance identifier
+     * @return a set of device identifiers
+     */
+    Set<DeviceId> getDevices(NetworkId networkId, NodeId nodeId);
+
+
+    /**
+     * Sets a device's role for a specified controller instance.
+     *
+     * @param networkId virtual network identifier
+     * @param nodeId    controller instance identifier
+     * @param deviceId  device identifier
+     * @return a mastership event
+     */
+    CompletableFuture<MastershipEvent> setMaster(NetworkId networkId,
+                                                 NodeId nodeId, DeviceId deviceId);
+
+    /**
+     * Returns the current master and number of past mastership hand-offs
+     * (terms) for a device.
+     *
+     * @param networkId virtual network identifier
+     * @param deviceId  the device identifier
+     * @return the current master's ID and the term value for device, or null
+     */
+    MastershipTerm getTermFor(NetworkId networkId, DeviceId deviceId);
+
+    /**
+     * Sets a controller instance's mastership role to STANDBY for a device.
+     * If the role is MASTER, another controller instance will be selected
+     * as a candidate master.
+     *
+     * @param networkId virtual network identifier
+     * @param nodeId    the controller instance identifier
+     * @param deviceId  device to revoke mastership role for
+     * @return a mastership event
+     */
+    CompletableFuture<MastershipEvent> setStandby(NetworkId networkId,
+                                                  NodeId nodeId, DeviceId deviceId);
+
+    /**
+     * Allows a controller instance to give up its current role for a device.
+     * If the role is MASTER, another controller instance will be selected
+     * as a candidate master.
+     *
+     * @param networkId virtual network identifier
+     * @param nodeId    the controller instance identifier
+     * @param deviceId  device to revoke mastership role for
+     * @return a mastership event
+     */
+    CompletableFuture<MastershipEvent> relinquishRole(NetworkId networkId,
+                                                      NodeId nodeId, DeviceId deviceId);
+
+    /**
+     * Removes all the roles for the specified controller instance.
+     * If the role was MASTER, another controller instance will be selected
+     * as a candidate master.
+     *
+     * @param networkId virtual network identifier
+     * @param nodeId    the controller instance identifier
+     */
+    void relinquishAllRole(NetworkId networkId, NodeId nodeId);
+}