add state change listner to Snapshot resource

server/src/com/cloud/storage/listener/SnapshotStateListener.java

@@ -0,0 +1,85 @@
+package com.cloud.storage.listener;
+
+import com.cloud.event.EventCategory;
+import com.cloud.storage.Snapshot;
+import com.cloud.storage.Snapshot.Event;
+import com.cloud.storage.Snapshot.State;
+import com.cloud.server.ManagementServer;
+import com.cloud.utils.component.Adapters;
+import com.cloud.utils.component.ComponentLocator;
+import com.cloud.utils.fsm.StateListener;
+import org.apache.cloudstack.framework.events.EventBus;
+import org.apache.cloudstack.framework.events.EventBusException;
+import org.apache.log4j.Logger;
+
+import java.util.Enumeration;
+import java.util.HashMap;
+import java.util.Map;
+
+public class SnapshotStateListener implements StateListener<State, Event, Snapshot> {
+
+    // get the event bus provider if configured
+    protected static EventBus _eventBus = null;
+    static {
+        Adapters<EventBus> eventBusImpls = ComponentLocator.getLocator(ManagementServer.Name).getAdapters(EventBus.class);
+        if (eventBusImpls != null) {
+            Enumeration<EventBus> eventBusenum = eventBusImpls.enumeration();
+            if (eventBusenum != null && eventBusenum.hasMoreElements()) {
+                _eventBus = eventBusenum.nextElement(); // configure event bus if configured
+            }
+        }
+    }
+
+    private static final Logger s_logger = Logger.getLogger(VolumeStateListener.class);
+
+    public SnapshotStateListener() {
+
+    }
+
+    @Override
+    public boolean preStateTransitionEvent(State oldState, Event event, State newState, Snapshot vo, boolean status, Object opaque) {
+        pubishOnEventBus(event.name(), "preStateTransitionEvent", vo, oldState, newState);
+        return true;
+    }
+
+    @Override
+    public boolean postStateTransitionEvent(State oldState, Event event, State newState, Snapshot vo, boolean status, Object opaque) {
+        pubishOnEventBus(event.name(), "postStateTransitionEvent", vo, oldState, newState);
+        return true;
+    }
+
+    private void pubishOnEventBus(String event, String status, Snapshot vo, State oldState, State newState) {
+
+        if (_eventBus == null) {
+            return;  // no provider is configured to provide events bus, so just return
+        }
+
+        String resourceName = getEntityFromClassName(Snapshot.class.getName());
+        org.apache.cloudstack.framework.events.Event eventMsg =  new org.apache.cloudstack.framework.events.Event(
+                ManagementServer.Name,
+                EventCategory.RESOURCE_STATE_CHANGE_EVENT.getName(),
+                event,
+                resourceName,
+                vo.getUuid());
+        Map<String, String> eventDescription = new HashMap<String, String>();
+        eventDescription.put("resource", resourceName);
+        eventDescription.put("id", vo.getUuid());
+        eventDescription.put("old-state", oldState.name());
+        eventDescription.put("new-state", newState.name());
+        eventMsg.setDescription(eventDescription);
+        try {
+            _eventBus.publish(eventMsg);
+        } catch (EventBusException e) {
+            s_logger.warn("Failed to publish action event on the the event bus.");
+        }
+    }
+
+    private String getEntityFromClassName(String entityClassName) {
+        int index = entityClassName.lastIndexOf(".");
+        String entityName = entityClassName;
+        if (index != -1) {
+            entityName = entityClassName.substring(index+1);
+        }
+        return entityName;
+    }
+}

server/src/com/cloud/storage/snapshot/SnapshotManagerImpl.java

@@ -48,6 +48,7 @@ import com.cloud.storage.*;
 import com.cloud.storage.Snapshot.Type;
 import com.cloud.storage.Storage.StoragePoolType;
 import com.cloud.storage.dao.*;
+import com.cloud.storage.listener.SnapshotStateListener;
 import com.cloud.storage.s3.S3Manager;
 import com.cloud.storage.secondary.SecondaryStorageVmManager;
 import com.cloud.storage.swift.SwiftManager;
@@ -1424,6 +1425,7 @@ public class SnapshotManagerImpl implements SnapshotManager, SnapshotService, Ma
         s_logger.info("Snapshot Manager is configured.");
 
         _snapshotFsm = Snapshot.State.getStateMachine();
+        _snapshotFsm.registerListener(new SnapshotStateListener());
 
         return true;
     }