[571400] Add a cache for getSubEvents()

Bug: 571400
Cherry-picked-from: 567517
Change-Id: Idabc46861c11e37d3e5d943752804af426204dbc
Signed-off-by: Nathalie Lepine <nathalie.lepine@obeo.fr>

2 files changed, 23 insertions, 0 deletions

diff --git a/plugins/org.eclipse.sirius.diagram.sequence/src/org/eclipse/sirius/diagram/sequence/business/internal/util/CacheHelper.java b/plugins/org.eclipse.sirius.diagram.sequence/src/org/eclipse/sirius/diagram/sequence/business/internal/util/CacheHelper.java
index 31f243072d..83190a3cde 100644
--- a/plugins/org.eclipse.sirius.diagram.sequence/src/org/eclipse/sirius/diagram/sequence/business/internal/util/CacheHelper.java
+++ b/plugins/org.eclipse.sirius.diagram.sequence/src/org/eclipse/sirius/diagram/sequence/business/internal/util/CacheHelper.java
@@ -15,6 +15,7 @@ import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
 import org.eclipse.sirius.diagram.sequence.business.internal.elements.AbstractFrame;
+import org.eclipse.sirius.diagram.sequence.business.internal.elements.ISequenceEvent;
 import org.eclipse.sirius.diagram.sequence.business.internal.elements.Lifeline;
 
 /**
@@ -29,6 +30,8 @@ public final class CacheHelper {
 
     private static Map<AbstractFrame, Collection<Lifeline>> coverageCache = new ConcurrentHashMap<>();
 
+    private static ConcurrentHashMap<ISequenceEvent, Collection<ISequenceEvent>> subEventsCache = new ConcurrentHashMap<>();
+
     /**
      * Avoid instantiation.
      */
@@ -60,6 +63,7 @@ public final class CacheHelper {
      */
     public static void clearDragTrackerCaches() {
         coverageCache.clear();
+        subEventsCache.clear();
     }
 
     /**
@@ -86,4 +90,14 @@ public final class CacheHelper {
     public static Map<AbstractFrame, Collection<Lifeline>> getCoverageCache() {
         return coverageCache;
     }
+
+    /**
+     * get subEvents cache.
+     * 
+     * @return the subEventsCache
+     */
+    public static ConcurrentHashMap<ISequenceEvent, Collection<ISequenceEvent>> getSubEventsCache() {
+        return subEventsCache;
+    }
+
 }
diff --git a/plugins/org.eclipse.sirius.diagram.sequence/src/org/eclipse/sirius/diagram/sequence/business/internal/util/SubEventsHelper.java b/plugins/org.eclipse.sirius.diagram.sequence/src/org/eclipse/sirius/diagram/sequence/business/internal/util/SubEventsHelper.java
index f35eb38279..92931ee94a 100644
--- a/plugins/org.eclipse.sirius.diagram.sequence/src/org/eclipse/sirius/diagram/sequence/business/internal/util/SubEventsHelper.java
+++ b/plugins/org.eclipse.sirius.diagram.sequence/src/org/eclipse/sirius/diagram/sequence/business/internal/util/SubEventsHelper.java
@@ -87,8 +87,17 @@ public final class SubEventsHelper {
      *         bottom.
      */
     public List<ISequenceEvent> getSubEvents() {
+        Collection<ISequenceEvent> subEvents = CacheHelper.getSubEventsCache().get(parentEvent);
+        if (subEvents != null) {
+            return new ArrayList<ISequenceEvent>(subEvents);
+        }
+
         List<ISequenceEvent> result = getValidSubEvents();
         Collections.sort(result, RangeHelper.lowerBoundOrdering().onResultOf(ISequenceEvent.VERTICAL_RANGE));
+
+        if (CacheHelper.isDragTrackerCacheEnabled()) {
+            CacheHelper.getSubEventsCache().put(parentEvent, new ArrayList<>(result));
+        }
         return result;
     }