HWKALERTS-243 Ensure DefinitionsEvents are notified to listeners in o…

…rder (#308)

hawkular-alerts-api/src/main/java/org/hawkular/alerts/api/services/DefinitionsListener.java

@@ -16,7 +16,7 @@
  */
 package org.hawkular.alerts.api.services;
 
-import java.util.Set;
+import java.util.List;
 
 /**
  * A listener for reacting to definitions changes.
@@ -37,5 +37,5 @@ public interface DefinitionsListener {
      *
      * @param events change events triggering the notification.
      */
-    void onChange(Set<DefinitionsEvent> events);
+    void onChange(List<DefinitionsEvent> events);
 }

hawkular-alerts-engine/src/main/java/org/hawkular/alerts/engine/cache/PublishCacheManager.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2016 Red Hat, Inc. and/or its affiliates
+ * Copyright 2015-2017 Red Hat, Inc. and/or its affiliates
  * and other contributors as indicated by the @author tags.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -98,6 +98,7 @@ public void init() {
             initialCacheUpdate();
 
             definitions.registerListener(events -> {
+                log.debugf("Receiving %s", events);
                 events.stream().forEach(e -> {
                     String tenantId = e.getTargetTenantId();
                     String triggerId = e.getTargetId();

hawkular-alerts-engine/src/main/java/org/hawkular/alerts/engine/impl/AlertsContext.java

@@ -131,7 +131,7 @@ public List<ActionListener> getActionsListeners() {
         return actionsListeners;
     }
 
-    public void notifyListeners(Set<DefinitionsEvent> notifications) {
+    public void notifyListeners(List<DefinitionsEvent> notifications) {
         Set<DefinitionsEvent.Type> notificationTypes = notifications.stream()
                 .map(n -> n.getType())
                 .collect(Collectors.toSet());
@@ -142,7 +142,7 @@ public void notifyListeners(Set<DefinitionsEvent> notifications) {
                     log.debugf("Notified Listener %s of %s", e.getKey(), notificationTypes);
                     e.getKey().onChange(notifications.stream()
                             .filter(de -> e.getValue().contains(de.getType()))
-                            .collect(Collectors.toSet()));
+                            .collect(Collectors.toList()));
                 });
         if (!distributed) {
             distributedListener.stream().forEach(listener -> listener.onChange(mapDistributedEvents(notifications)));
@@ -155,7 +155,7 @@ private boolean shouldNotify(Set<DefinitionsEvent.Type> listenerTypes, Set<Defin
         return !intersection.isEmpty();
     }
 
-    private Set<DistributedEvent> mapDistributedEvents(Set<DefinitionsEvent> notification) {
+    private Set<DistributedEvent> mapDistributedEvents(List<DefinitionsEvent> notification) {
         if (notification == null) {
             return null;
         }

hawkular-alerts-engine/src/main/java/org/hawkular/alerts/engine/impl/CassDefinitionsServiceImpl.java

@@ -21,12 +21,12 @@
 import static org.hawkular.alerts.api.services.DefinitionsEvent.Type.ACTION_DEFINITION_UPDATE;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
-import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -124,7 +124,7 @@ public class CassDefinitionsServiceImpl implements DefinitionsService {
     // desirable to only send a listener update one time, at the end, because we want listeners to be
     // efficient (i.e. don't update a cache 100 times in a row for one import of 100 triggers). Methods should not
     // manipulate these variables directly, instead call deferNotifications() and releaseNotifications().
-    private Set<DefinitionsEvent> deferredNotifications = new LinkedHashSet<>();
+    private List<DefinitionsEvent> deferredNotifications = new ArrayList<>();
     private int deferNotificationsCount = 0;
     private int batchSize;
     private final BatchStatement.Type batchType = BatchStatement.Type.LOGGED;
@@ -3110,16 +3110,16 @@ private void notifyListeners(final DefinitionsEvent de) {
             deferredNotifications.add(de);
             return;
         }
-        alertsContext.notifyListeners(Collections.singleton(de));
+        alertsContext.notifyListeners(Arrays.asList(de));
     }
 
     private void notifyListenersDeferred() {
         if (deferredNotifications.isEmpty()) {
             return;
         }
 
-        Set<DefinitionsEvent> notifications = deferredNotifications;
-        deferredNotifications = new LinkedHashSet<>();
+        List<DefinitionsEvent> notifications = deferredNotifications;
+        deferredNotifications = new ArrayList<>();
         alertsContext.notifyListeners(notifications);
     }