Cache lazily the main connected component (#537)

Signed-off-by: Florian Dupuy <florian.dupuy@rte-france.com>
powsybl · May 30, 2022 · 0ad740c · 0ad740c
1 parent 478d19c
commit 0ad740c
Showing 1 changed file with 10 additions and 5 deletions.
diff --git a/src/main/java/com/powsybl/openloadflow/graph/EvenShiloachGraphDecrementalConnectivity.java b/src/main/java/com/powsybl/openloadflow/graph/EvenShiloachGraphDecrementalConnectivity.java
@@ -36,6 +36,7 @@ public class EvenShiloachGraphDecrementalConnectivity<V, E> implements GraphDecr
 
     private final List<Set<V>> newConnectedComponents;
     private final Map<V, LevelNeighbours> levelNeighboursMap;
+    private Set<V> mainConnectedComponent;
 
     private final List<Triple<V, E, V>> cutEdges;
     private final List<E> edgesToCut;
@@ -83,7 +84,7 @@ private void invalidateInit() {
         cutEdges.clear();
         edgesToCut.clear();
         newConnectedComponents.clear();
-        invalidateVertexMapCache();
+        invalidateConnectedComponentCache();
     }
 
     @Override
@@ -94,12 +95,13 @@ public void cut(E edge) {
         if (edgesToCut.contains(edge)) {
             throw new PowsyblException("Edge already cut: " + edge);
         }
-        invalidateVertexMapCache();
+        invalidateConnectedComponentCache();
 
         edgesToCut.add(edge);
     }
 
-    private void invalidateVertexMapCache() {
+    private void invalidateConnectedComponentCache() {
+        mainConnectedComponent = null;
         vertexMapCacheInvalidated = true;
         vertexToConnectedComponent.clear();
     }
@@ -120,7 +122,7 @@ public void initLevels() {
     }
 
     public void reset() {
-        invalidateVertexMapCache();
+        invalidateConnectedComponentCache();
         newConnectedComponents.clear();
         allSavedChangedLevels.descendingIterator().forEachRemaining(levelNeighboursMap::putAll);
         allSavedChangedLevels.clear();
@@ -155,7 +157,10 @@ public Set<V> getConnectedComponent(V vertex) {
     }
 
     private Set<V> getMainConnectedComponent() {
-        return vertices.stream().filter(v -> newConnectedComponents.stream().noneMatch(cc -> cc.contains(v))).collect(Collectors.toSet());
+        if (mainConnectedComponent == null) {
+            mainConnectedComponent = vertices.stream().filter(v -> newConnectedComponents.stream().noneMatch(cc -> cc.contains(v))).collect(Collectors.toSet());
+        }
+        return mainConnectedComponent;
     }
 
     @Override