[AETHER-1211] Allowing toggling of link labels via Alt-L

Change-Id: I772b6ee0c6c24eeb48466a96a45b44b9ee6eef50
diff --git a/providers/null/src/main/java/org/onosproject/provider/nil/NullProviders.java b/providers/null/src/main/java/org/onosproject/provider/nil/NullProviders.java
index d95943b..ed870f4 100644
--- a/providers/null/src/main/java/org/onosproject/provider/nil/NullProviders.java
+++ b/providers/null/src/main/java/org/onosproject/provider/nil/NullProviders.java
@@ -135,6 +135,7 @@
     private final NullGroupProvider groupProvider = new NullGroupProvider();
     private final NullPacketProvider packetProvider = new NullPacketProvider();
     private final TopologyMutationDriver topologyMutationDriver = new TopologyMutationDriver();
+    private final PortStatsDriver portStatsDriver = new PortStatsDriver();
 
     private DeviceProviderService deviceProviderService;
     private HostProviderService hostProviderService;
@@ -349,6 +350,7 @@
         topologyMutationDriver.start(mutationRate, linkService, deviceService,
                                      linkProviderService, deviceProviderService,
                                      simulator);
+        portStatsDriver.start(deviceService, deviceProviderService);
     }
 
     // Selects the simulator based on the specified name.
diff --git a/providers/null/src/main/java/org/onosproject/provider/nil/PortStatsDriver.java b/providers/null/src/main/java/org/onosproject/provider/nil/PortStatsDriver.java
new file mode 100644
index 0000000..8ad269c
--- /dev/null
+++ b/providers/null/src/main/java/org/onosproject/provider/nil/PortStatsDriver.java
@@ -0,0 +1,101 @@
+/*
+ * Copyright 2015-present Open Networking Foundation
+ *
+ * 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.provider.nil;
+
+import org.onosproject.net.Device;
+import org.onosproject.net.Port;
+import org.onosproject.net.device.DefaultPortStatistics;
+import org.onosproject.net.device.DeviceProviderService;
+import org.onosproject.net.device.DeviceService;
+import org.onosproject.net.device.PortStatistics;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.security.SecureRandom;
+import java.util.HashSet;
+import java.util.Random;
+import java.util.Set;
+import java.util.concurrent.ExecutorService;
+
+import static java.util.concurrent.Executors.newSingleThreadScheduledExecutor;
+import static org.onlab.util.Tools.delay;
+import static org.onlab.util.Tools.groupedThreads;
+
+/**
+ * Drives port statistics simulation using random generator.
+ */
+class PortStatsDriver implements Runnable {
+
+    private final Logger log = LoggerFactory.getLogger(getClass());
+
+    private static final int WAIT_DELAY = 2_000;
+
+    private final Random random = new SecureRandom();
+
+    private volatile boolean stopped = true;
+
+    private DeviceService deviceService;
+    private DeviceProviderService deviceProviderService;
+
+    private final ExecutorService executor =
+            newSingleThreadScheduledExecutor(groupedThreads("onos/null", "port-stats-mutator", log));
+
+    /**
+     * Starts the mutation process.
+     *
+     * @param deviceService         device service
+     * @param deviceProviderService device provider service
+     */
+    void start(DeviceService deviceService,
+               DeviceProviderService deviceProviderService) {
+        stopped = false;
+        this.deviceService = deviceService;
+        this.deviceProviderService = deviceProviderService;
+        executor.execute(this);
+    }
+
+    /**
+     * Stops the mutation process.
+     */
+    void stop() {
+        stopped = true;
+    }
+
+    @Override
+    public void run() {
+        while (!stopped) {
+            delay(WAIT_DELAY);
+            deviceService.getAvailableDevices().forEach(this::updatePorts);
+        }
+    }
+
+    public void updatePorts(Device device) {
+        Set<PortStatistics> portStats = new HashSet<>();
+        for (Port port : deviceService.getPorts(device.id())) {
+            portStats.add(DefaultPortStatistics.builder()
+                                  .setBytesReceived(Math.abs(random.nextInt()))
+                                  .setBytesSent(Math.abs(random.nextInt()))
+                                  .setPacketsReceived(Math.abs(random.nextInt()))
+                                  .setPacketsSent(Math.abs(random.nextInt()))
+                                  .setDurationSec(2)
+                                  .setDeviceId(device.id())
+                                  .setPort(port.number())
+                                  .build());
+        }
+        deviceProviderService.updatePortStatistics(device.id(), portStats);
+    }
+
+}