very simple null host provider

Change-Id: I020ccd525e3e96a933ea9f69865d8e03af151500

+/*
+ * 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.provider.nil.host.impl;
+
+import org.apache.felix.scr.annotations.Activate;
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Deactivate;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.onlab.packet.MacAddress;
+import org.onlab.packet.VlanId;
+import org.onosproject.net.Device;
+import org.onosproject.net.Host;
+import org.onosproject.net.HostId;
+import org.onosproject.net.HostLocation;
+import org.onosproject.net.PortNumber;
+import org.onosproject.net.device.DeviceEvent;
+import org.onosproject.net.device.DeviceListener;
+import org.onosproject.net.device.DeviceService;
+import org.onosproject.net.host.DefaultHostDescription;
+import org.onosproject.net.host.HostDescription;
+import org.onosproject.net.host.HostProvider;
+import org.onosproject.net.host.HostProviderRegistry;
+import org.onosproject.net.host.HostProviderService;
+import org.onosproject.net.provider.AbstractProvider;
+import org.onosproject.net.provider.ProviderId;
+import org.slf4j.Logger;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+/**
+ * Null provider to advertise fake hosts.
+ */
+@Component(immediate = true)
+public class NullHostProvider extends AbstractProvider implements HostProvider {
+
+    private final Logger log = getLogger(getClass());
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected DeviceService deviceService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected HostProviderRegistry providerRegistry;
+
+    private HostProviderService providerService;
+
+    //make sure the device has enough ports to accomodate all of them.
+    private static final int HOSTSPERDEVICE = 5;
+
+    private final InternalHostProvider hostProvider = new InternalHostProvider();
+
+    /**
+     * Creates an OpenFlow host provider.
+     */
+    public NullHostProvider() {
+        super(new ProviderId("null", "org.onosproject.provider.nil"));
+    }
+
+    /**
+     * Creates a provider with the supplier identifier.
+     *
+     * @param id provider id
+     */
+    protected NullHostProvider(ProviderId id) {
+        super(id);
+    }
+
+    @Activate
+    public void activate() {
+        providerService = providerRegistry.register(this);
+        for (Device dev : deviceService.getDevices()) {
+            addHosts(dev);
+        }
+        deviceService.addListener(hostProvider);
+
+        log.info("Started");
+    }
+
+
+
+    @Deactivate
+    public void deactivate() {
+        providerRegistry.unregister(this);
+        deviceService.removeListener(hostProvider);
+        providerService = null;
+        log.info("Stopped");
+    }
+
+    @Override
+    public void triggerProbe(Host host) {}
+
+    private void addHosts(Device device) {
+        for (int i = 0; i < HOSTSPERDEVICE; i++) {
+            providerService.hostDetected(
+                    HostId.hostId(MacAddress.valueOf(i + device.hashCode()),
+                                  VlanId.vlanId((short) -1)),
+                    buildHostDescription(device, i));
+        }
+    }
+
+    private void removeHosts(Device device) {
+        for (int i = 0; i < HOSTSPERDEVICE; i++) {
+            providerService.hostVanished(
+                    HostId.hostId(MacAddress.valueOf(i + device.hashCode()),
+                                  VlanId.vlanId((short) -1)));
+        }
+    }
+
+    private HostDescription buildHostDescription(Device device, int port) {
+        MacAddress mac = MacAddress.valueOf(device.hashCode() + port);
+        HostLocation location = new HostLocation(device.id(),
+                                                 PortNumber.portNumber(port), 0L);
+        return new DefaultHostDescription(mac, VlanId.vlanId((short) -1), location);
+    }
+
+    private class InternalHostProvider implements DeviceListener {
+        @Override
+        public void event(DeviceEvent event) {
+            switch (event.type()) {
+
+                case DEVICE_ADDED:
+                    addHosts(event.subject());
+                    break;
+                case DEVICE_UPDATED:
+                    break;
+                case DEVICE_REMOVED:
+                    removeHosts(event.subject());
+                    break;
+                case DEVICE_SUSPENDED:
+                    break;
+                case DEVICE_AVAILABILITY_CHANGED:
+                    break;
+                case PORT_ADDED:
+                    break;
+                case PORT_UPDATED:
+                    break;
+                case PORT_REMOVED:
+                    break;
+                default:
+                    break;
+            }
+        }
+
+
+    }
+}