ONOS-239 Retrigger compilation when new resources are available

When an intent is withdrawn and frees up resources, trigger
recompilation of any failed intents to allow the ones waiting
for resources to be installed.

Change-Id: Ic15678378ce41516a7eab890b4b4898aeb901f78
diff --git a/core/api/src/main/java/org/onlab/onos/net/resource/LinkResourceEvent.java b/core/api/src/main/java/org/onlab/onos/net/resource/LinkResourceEvent.java
new file mode 100644
index 0000000..0428864
--- /dev/null
+++ b/core/api/src/main/java/org/onlab/onos/net/resource/LinkResourceEvent.java
@@ -0,0 +1,48 @@
+/*
+ * Copyright 2014 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.onlab.onos.net.resource;
+
+import java.util.Collection;
+
+import org.onlab.onos.event.AbstractEvent;
+
+import com.google.common.collect.ImmutableList;
+
+/**
+ * Describes an event related to a Link Resource.
+ */
+public final class LinkResourceEvent
+       extends AbstractEvent<LinkResourceEvent.Type, Collection<LinkResourceAllocations>> {
+
+    /**
+     * Type of resource this event is for.
+     */
+    public enum Type {
+        /** Additional resources are now available. */
+        ADDITIONAL_RESOURCES_AVAILABLE
+    }
+
+    /**
+     * Constructs a link resource event.
+     *
+     * @param type type of resource event to create
+     * @param linkResourceAllocations allocations that are now available
+     */
+    public LinkResourceEvent(Type type,
+                             Collection<LinkResourceAllocations> linkResourceAllocations) {
+        super(type, ImmutableList.copyOf(linkResourceAllocations));
+    }
+}