[ONOS-3535] Implement control metrics aggregation logic

Change-Id: I9953146851d5f3fdf7bcee9561fa86ddb7c7b3fe
diff --git a/apps/cpman/src/main/java/org/onosproject/cpman/ControlPlaneMonitorService.java b/apps/cpman/src/main/java/org/onosproject/cpman/ControlPlaneMonitorService.java
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+++ b/apps/cpman/src/main/java/org/onosproject/cpman/ControlPlaneMonitorService.java
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+/*
+ * Copyright 2015 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.cpman;
+
+import org.onosproject.cluster.NodeId;
+import org.onosproject.net.DeviceId;
+
+import java.util.Optional;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Control Plane Statistics Service Interface.
+ */
+public interface ControlPlaneMonitorService {
+
+    /**
+     * Adds a new control metric value with a certain update interval.
+     *
+     * @param controlMetric  control plane metric (e.g., control message rate, cpu, memory, etc.)
+     * @param updateInterval value update interval (time unit will be in minute)
+     */
+    void updateMetric(ControlMetric controlMetric, int updateInterval, Optional<DeviceId> deviceId);
+
+    /**
+     * Obtains the control plane load of a specific device.
+     *
+     * @param nodeId   node id {@link org.onosproject.cluster.NodeId}
+     * @param type     control metric type
+     * @param deviceId device id {@link org.onosproject.net.DeviceId}
+     * @return control plane load
+     */
+    ControlLoad getLoad(NodeId nodeId, ControlMetricType type, Optional<DeviceId> deviceId);
+
+    /**
+     * Obtains the control plane load of a specific device with a specific time duration.
+     *
+     * @param nodeId   node id {@link org.onosproject.cluster.NodeId}
+     * @param type     control metric type
+     * @param duration time duration
+     * @param unit     time unit
+     * @param deviceId device id {@link org.onosproject.net.Device}
+     * @return control plane load
+     */
+    ControlLoad getLoad(NodeId nodeId, ControlMetricType type, Optional<DeviceId> deviceId,
+                        int duration, TimeUnit unit);
+}
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