ONOS-2689: Register a link as resource when it is added

Change-Id: I64c6065411731ba3ad5032730ce7b9ae122d01cc

+/*
+ * 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.net.newresource.impl;
+
+import org.onosproject.net.Link;
+import org.onosproject.net.LinkKey;
+import org.onosproject.net.link.LinkEvent;
+import org.onosproject.net.link.LinkListener;
+import org.onosproject.net.newresource.ResourceAdminService;
+import org.onosproject.net.newresource.ResourcePath;
+
+import java.util.concurrent.ExecutorService;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * An implementation of LinkListener registering links as resources.
+ */
+final class ResourceLinkListener implements LinkListener {
+
+    private final ResourceAdminService adminService;
+    private final ExecutorService executor;
+
+    /**
+     * Creates an instance with the specified ResourceAdminService and ExecutorService.
+     *
+     * @param adminService instance invoked to register resources
+     * @param executor executor used for processing resource registration
+     */
+    ResourceLinkListener(ResourceAdminService adminService, ExecutorService executor) {
+        this.adminService = checkNotNull(adminService);
+        this.executor = checkNotNull(executor);
+    }
+
+    @Override
+    public void event(LinkEvent event) {
+        Link link = event.subject();
+        switch (event.type()) {
+            case LINK_ADDED:
+                registerLinkResource(link);
+                break;
+            default:
+                break;
+        }
+    }
+
+    private void registerLinkResource(Link link) {
+        LinkKey linkKey = LinkKey.linkKey(link);
+        executor.submit(() -> adminService.registerResources(ResourcePath.ROOT, linkKey));
+    }
+}

+/*
+ * 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.net.newresource.impl;
+
+import com.google.common.annotations.Beta;
+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.onosproject.net.link.LinkListener;
+import org.onosproject.net.link.LinkService;
+import org.onosproject.net.newresource.ResourceAdminService;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+import static org.onlab.util.Tools.groupedThreads;
+
+/**
+ * A class registering resources when they are detected.
+ */
+@Component(immediate = true, enabled = false)
+@Beta
+public final class ResourceRegistrar {
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected ResourceAdminService adminService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected LinkService linkService;
+
+    private LinkListener linkListener;
+    private final ExecutorService executor =
+            Executors.newSingleThreadExecutor(groupedThreads("onos/resource", "registrar"));
+
+    @Activate
+    public void activate() {
+        linkListener = new ResourceLinkListener(adminService, executor);
+        linkService.addListener(linkListener);
+    }
+
+    @Deactivate
+    public void deactivate() {
+        linkService.removeListener(linkListener);
+    }
+}