Implemented multi-instance packet out.

We've defined a PacketStore abstraction through which outbound packets are
sent. The packet store has a simple implementation (basically a no-op) and a
distributed implementation on top of the cluster messaging service.

Change-Id: Ib32753314fe518ef1fd67c858db744b004539938
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/packet/impl/DistributedPacketStore.java b/core/store/dist/src/main/java/org/onlab/onos/store/packet/impl/DistributedPacketStore.java
new file mode 100644
index 0000000..be38785
--- /dev/null
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/packet/impl/DistributedPacketStore.java
@@ -0,0 +1,126 @@
+/*
+ * 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.store.packet.impl;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+import java.io.IOException;
+
+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.apache.felix.scr.annotations.Service;
+import org.onlab.onos.cluster.ClusterService;
+import org.onlab.onos.cluster.NodeId;
+import org.onlab.onos.mastership.MastershipService;
+import org.onlab.onos.net.packet.OutboundPacket;
+import org.onlab.onos.net.packet.PacketEvent;
+import org.onlab.onos.net.packet.PacketEvent.Type;
+import org.onlab.onos.net.packet.PacketStore;
+import org.onlab.onos.net.packet.PacketStoreDelegate;
+import org.onlab.onos.store.AbstractStore;
+import org.onlab.onos.store.cluster.messaging.ClusterCommunicationService;
+import org.onlab.onos.store.cluster.messaging.ClusterMessage;
+import org.onlab.onos.store.cluster.messaging.ClusterMessageHandler;
+import org.onlab.onos.store.cluster.messaging.MessageSubject;
+import org.onlab.onos.store.serializers.KryoNamespaces;
+import org.onlab.onos.store.serializers.KryoSerializer;
+import org.onlab.util.KryoNamespace;
+import org.slf4j.Logger;
+
+/**
+ * Distributed packet store implementation allowing packets to be sent to
+ * remote instances.
+ */
+@Component(immediate = true)
+@Service
+public class DistributedPacketStore
+        extends AbstractStore<PacketEvent, PacketStoreDelegate>
+        implements PacketStore {
+
+    private final Logger log = getLogger(getClass());
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    private MastershipService mastershipService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    private ClusterService clusterService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    private ClusterCommunicationService communicationService;
+
+    private static final MessageSubject PACKET_OUT_SUBJECT =
+            new MessageSubject("packet-out");
+
+    private static final KryoSerializer SERIALIZER = new KryoSerializer() {
+        @Override
+        protected void setupKryoPool() {
+            serializerPool = KryoNamespace.newBuilder()
+                    .register(KryoNamespaces.API)
+                    .build()
+                    .populate(1);
+        }
+    };
+
+    @Activate
+    public void activate() {
+        log.info("Started");
+
+        communicationService.addSubscriber(
+                PACKET_OUT_SUBJECT, new InternalClusterMessageHandler());
+    }
+
+    @Deactivate
+    public void deactivate() {
+        log.info("Stopped");
+    }
+
+    @Override
+    public void emit(OutboundPacket packet) {
+        NodeId myId = clusterService.getLocalNode().id();
+        NodeId master = mastershipService.getMasterFor(packet.sendThrough());
+
+        if (myId.equals(master)) {
+            notifyDelegate(new PacketEvent(Type.EMIT, packet));
+            return;
+        }
+
+        try {
+            communicationService.unicast(new ClusterMessage(
+                    myId, PACKET_OUT_SUBJECT, SERIALIZER.encode(packet)), master);
+        } catch (IOException e) {
+            log.warn("Failed to send packet-out to {}", master);
+        }
+    }
+
+    /**
+     * Handles incoming cluster messages.
+     */
+    private class InternalClusterMessageHandler implements ClusterMessageHandler {
+        @Override
+        public void handle(ClusterMessage message) {
+            if (!message.subject().equals(PACKET_OUT_SUBJECT)) {
+                log.warn("Received message with wrong subject: {}", message);
+            }
+
+            OutboundPacket packet = SERIALIZER.decode(message.payload());
+            notifyDelegate(new PacketEvent(Type.EMIT, packet));
+        }
+    }
+
+}