From 5cc64cc27a58e824a6b0e5a331e30544847f50d8 Mon Sep 17 00:00:00 2001
From: Emmy <emmyy@kth.se>
Date: Tue, 29 Aug 2023 09:52:41 +0000
Subject: [PATCH] 8309463: IGV: Dynamic graph layout algorithm

Reviewed-by: tholenstein, rcastanedalo, chagedorn
---
 .../com/sun/hotspot/igv/graph/Figure.java     |   13 +
 .../hotspot/igv/graph/FigureConnection.java   |   12 +
 .../HierarchicalLayout/pom.xml                |    7 +-
 .../HierarchicalLayoutManager.java            |  119 +-
 .../HierarchicalStableLayoutManager.java      | 1471 +++++++++++++++++
 .../igv/hierarchicallayout/LayoutEdge.java    |   44 +
 .../igv/hierarchicallayout/LayoutNode.java    |   53 +
 .../sun/hotspot/igv/settings/Settings.java    |    3 +-
 .../com/sun/hotspot/igv/util/Statistics.java  |   40 +
 .../sun/hotspot/igv/view/DiagramScene.java    |   17 +-
 .../hotspot/igv/view/DiagramViewModel.java    |   13 +
 .../hotspot/igv/view/EditorTopComponent.java  |   16 +
 .../actions/EnableStableSeaLayoutAction.java  |   49 +
 .../hotspot/igv/view/images/stable_sea.png    |  Bin 0 -> 2111 bytes
 14 files changed, 1767 insertions(+), 90 deletions(-)
 create mode 100644 src/utils/IdealGraphVisualizer/HierarchicalLayout/src/main/java/com/sun/hotspot/igv/hierarchicallayout/HierarchicalStableLayoutManager.java
 create mode 100644 src/utils/IdealGraphVisualizer/HierarchicalLayout/src/main/java/com/sun/hotspot/igv/hierarchicallayout/LayoutEdge.java
 create mode 100644 src/utils/IdealGraphVisualizer/HierarchicalLayout/src/main/java/com/sun/hotspot/igv/hierarchicallayout/LayoutNode.java
 create mode 100644 src/utils/IdealGraphVisualizer/Util/src/main/java/com/sun/hotspot/igv/util/Statistics.java
 create mode 100644 src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/actions/EnableStableSeaLayoutAction.java
 create mode 100644 src/utils/IdealGraphVisualizer/View/src/main/resources/com/sun/hotspot/igv/view/images/stable_sea.png

diff --git a/src/utils/IdealGraphVisualizer/Graph/src/main/java/com/sun/hotspot/igv/graph/Figure.java b/src/utils/IdealGraphVisualizer/Graph/src/main/java/com/sun/hotspot/igv/graph/Figure.java
index 9cc917dedcf..f02b4657cea 100644
--- a/src/utils/IdealGraphVisualizer/Graph/src/main/java/com/sun/hotspot/igv/graph/Figure.java
+++ b/src/utils/IdealGraphVisualizer/Graph/src/main/java/com/sun/hotspot/igv/graph/Figure.java
@@ -384,6 +384,19 @@ public class Figure extends Properties.Entity implements Vertex {
         return new Dimension(width, height);
     }
 
+    @Override
+    public boolean equals(Object o) {
+        if (!(o instanceof Figure)) {
+            return false;
+        }
+        return getInputNode().equals(((Figure) o).getInputNode());
+    }
+
+    @Override
+    public int hashCode() {
+        return getInputNode().hashCode();
+    }
+
     @Override
     public String toString() {
         return idString;
diff --git a/src/utils/IdealGraphVisualizer/Graph/src/main/java/com/sun/hotspot/igv/graph/FigureConnection.java b/src/utils/IdealGraphVisualizer/Graph/src/main/java/com/sun/hotspot/igv/graph/FigureConnection.java
index ac2c88f6913..186a6b63f17 100644
--- a/src/utils/IdealGraphVisualizer/Graph/src/main/java/com/sun/hotspot/igv/graph/FigureConnection.java
+++ b/src/utils/IdealGraphVisualizer/Graph/src/main/java/com/sun/hotspot/igv/graph/FigureConnection.java
@@ -156,5 +156,17 @@ public class FigureConnection implements Connection {
         return true;
     }
 
+    @Override
+    public boolean equals(Object o) {
+        if (!(o instanceof FigureConnection)) {
+            return false;
+        }
+
+        return getInputSlot().getFigure().equals(((FigureConnection)o).getInputSlot().getFigure())
+                && getOutputSlot().getFigure().equals(((FigureConnection)o).getOutputSlot().getFigure())
+                && getInputSlot().getPosition() == ((FigureConnection)o).getInputSlot().getPosition()
+                && getOutputSlot().getPosition() == ((FigureConnection) o).getOutputSlot().getPosition();
+    }
+
 }
 
diff --git a/src/utils/IdealGraphVisualizer/HierarchicalLayout/pom.xml b/src/utils/IdealGraphVisualizer/HierarchicalLayout/pom.xml
index be9cb1d882f..4a99ff829d5 100644
--- a/src/utils/IdealGraphVisualizer/HierarchicalLayout/pom.xml
+++ b/src/utils/IdealGraphVisualizer/HierarchicalLayout/pom.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!--
- Copyright (c) 2021, 2022, Oracle and/or its affiliates. All rights reserved.
+ Copyright (c) 2021, 2023, Oracle and/or its affiliates. All rights reserved.
 
  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions
@@ -51,6 +51,11 @@
             <artifactId>Layout</artifactId>
             <version>${project.version}</version>
         </dependency>
+        <dependency>
+            <groupId>com.sun.hotspot.igv</groupId>
+            <artifactId>Util</artifactId>
+            <version>${project.version}</version>
+        </dependency>
     </dependencies>
     <build>
         <plugins>
diff --git a/src/utils/IdealGraphVisualizer/HierarchicalLayout/src/main/java/com/sun/hotspot/igv/hierarchicallayout/HierarchicalLayoutManager.java b/src/utils/IdealGraphVisualizer/HierarchicalLayout/src/main/java/com/sun/hotspot/igv/hierarchicallayout/HierarchicalLayoutManager.java
index 4bb99cf9cae..0c9e5ccd480 100644
--- a/src/utils/IdealGraphVisualizer/HierarchicalLayout/src/main/java/com/sun/hotspot/igv/hierarchicallayout/HierarchicalLayoutManager.java
+++ b/src/utils/IdealGraphVisualizer/HierarchicalLayout/src/main/java/com/sun/hotspot/igv/hierarchicallayout/HierarchicalLayoutManager.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2023, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -27,6 +27,7 @@ import com.sun.hotspot.igv.layout.LayoutGraph;
 import com.sun.hotspot.igv.layout.LayoutManager;
 import com.sun.hotspot.igv.layout.Link;
 import com.sun.hotspot.igv.layout.Vertex;
+import com.sun.hotspot.igv.util.Statistics;
 import java.awt.Dimension;
 import java.awt.Point;
 import java.util.*;
@@ -79,49 +80,6 @@ public class HierarchicalLayoutManager implements LayoutManager {
     private Set<? extends Link> importantLinks;
     private final Set<Link> linksToFollow;
 
-    private class LayoutNode {
-
-        public int x;
-        public int y;
-        public int width;
-        public int height;
-        public int layer = -1;
-        public int xOffset;
-        public int yOffset;
-        public int bottomYOffset;
-        public Vertex vertex; // Only used for non-dummy nodes, otherwise null
-
-        public List<LayoutEdge> preds = new ArrayList<>();
-        public List<LayoutEdge> succs = new ArrayList<>();
-        public HashMap<Integer, Integer> outOffsets = new HashMap<>();
-        public HashMap<Integer, Integer> inOffsets = new HashMap<>();
-        public int pos = -1; // Position within layer
-
-        public int crossingNumber;
-
-        @Override
-        public String toString() {
-            return "Node " + vertex;
-        }
-    }
-
-    private class LayoutEdge {
-
-        public LayoutNode from;
-        public LayoutNode to;
-        // Horizontal distance relative to start of 'from'.
-        public int relativeFrom;
-        // Horizontal distance relative to start of 'to'.
-        public int relativeTo;
-        public Link link;
-        public boolean vip;
-
-        @Override
-        public String toString() {
-            return "Edge " + from + ", " + to;
-        }
-    }
-
     private abstract static class AlgorithmPart {
 
         public void start() {
@@ -190,6 +148,10 @@ public class HierarchicalLayoutManager implements LayoutManager {
         this.layoutSelfEdges = layoutSelfEdges;
     }
 
+    public List<LayoutNode> getNodes() {
+        return nodes;
+    }
+
     // Remove self-edges, possibly saving them into the selfEdges set.
     private void removeSelfEdges(boolean save) {
         for (LayoutNode node : nodes) {
@@ -305,7 +267,7 @@ public class HierarchicalLayoutManager implements LayoutManager {
             for (LayoutNode n : nodes) {
 
                 for (LayoutEdge e : n.preds) {
-                    if (e.link != null) {
+                    if (e.link != null && !linkPositions.containsKey(e.link)) {
                         ArrayList<Point> points = new ArrayList<>();
 
                         Point p = new Point(e.to.x + e.relativeTo, e.to.y + e.to.yOffset + e.link.getTo().getRelativePosition().y);
@@ -386,14 +348,11 @@ public class HierarchicalLayoutManager implements LayoutManager {
                             linkPositions.put(e.link, points);
                         }
                         pointCount += points.size();
-
-                        // No longer needed!
-                        e.link = null;
                     }
                 }
 
                 for (LayoutEdge e : n.succs) {
-                    if (e.link != null) {
+                    if (e.link != null && !linkPositions.containsKey(e.link)) {
                         ArrayList<Point> points = new ArrayList<>();
                         Point p = new Point(e.from.x + e.relativeFrom, e.from.y + e.from.height - e.from.bottomYOffset + e.link.getFrom().getRelativePosition().y);
                         points.add(p);
@@ -470,7 +429,6 @@ public class HierarchicalLayoutManager implements LayoutManager {
                         }
 
                         pointCount += points.size();
-                        e.link = null;
                     }
                 }
             }
@@ -526,8 +484,8 @@ public class HierarchicalLayoutManager implements LayoutManager {
         }
     }
 
-    private static final Comparator<LayoutNode> nodePositionComparator = Comparator.comparingInt(n -> n.pos);
-    private static final Comparator<LayoutNode> nodeProcessingDownComparator = (n1, n2) -> {
+    public static final Comparator<LayoutNode> nodePositionComparator = Comparator.comparingInt(n -> n.pos);
+    public static final Comparator<LayoutNode> nodeProcessingDownComparator = (n1, n2) -> {
         int n1VIP = 0;
         for (LayoutEdge e : n1.preds) {
             if (e.vip) {
@@ -554,7 +512,7 @@ public class HierarchicalLayoutManager implements LayoutManager {
         }
         return n1.preds.size() - n2.preds.size();
     };
-    private static final Comparator<LayoutNode> nodeProcessingUpComparator = (n1, n2) -> {
+    public static final Comparator<LayoutNode> nodeProcessingUpComparator = (n1, n2) -> {
         int n1VIP = 0;
         for (LayoutEdge e : n1.succs) {
             if (e.vip) {
@@ -661,7 +619,7 @@ public class HierarchicalLayoutManager implements LayoutManager {
                     LayoutEdge e = n.preds.get(i);
                     values[i] = e.from.x + e.relativeFrom - e.relativeTo;
                 }
-                return median(values);
+                return Statistics.median(values);
             } else {
                 int z = 0;
                 int[] values = new int[vipCount];
@@ -671,7 +629,7 @@ public class HierarchicalLayoutManager implements LayoutManager {
                         values[z++] = e.from.x + e.relativeFrom - e.relativeTo;
                     }
                 }
-                return median(values);
+                return Statistics.median(values);
             }
         }
 
@@ -693,7 +651,7 @@ public class HierarchicalLayoutManager implements LayoutManager {
                 i++;
             }
 
-            return median(values);
+            return Statistics.median(values);
         }
 
         private int calculateOptimalUp(LayoutNode n) {
@@ -709,16 +667,7 @@ public class HierarchicalLayoutManager implements LayoutManager {
                     return values[i];
                 }
             }
-            return median(values);
-        }
-
-        private int median(int[] values) {
-            Arrays.sort(values);
-            if (values.length % 2 == 0) {
-                return (values[values.length / 2 - 1] + values[values.length / 2]) / 2;
-            } else {
-                return values[values.length / 2];
-            }
+            return Statistics.median(values);
         }
 
         private void sweepUp() {
@@ -742,7 +691,7 @@ public class HierarchicalLayoutManager implements LayoutManager {
         }
     }
 
-    private static class NodeRow {
+    public static class NodeRow {
 
         private final TreeSet<LayoutNode> treeSet;
         private final ArrayList<Integer> space;
@@ -831,6 +780,9 @@ public class HierarchicalLayoutManager implements LayoutManager {
                         if (!visited.contains(e.to)) {
                             visited.add(e.to);
                             layers[i + 1].add(e.to);
+                            if (!nodes.contains(e.to)) {
+                                nodes.add(e.to);
+                            }
                         }
                     }
                 }
@@ -1221,7 +1173,7 @@ public class HierarchicalLayoutManager implements LayoutManager {
             } else {
                 ArrayList<LayoutNode> currentNodes = new ArrayList<>(nodes);
                 for (LayoutNode n : currentNodes) {
-                    for (LayoutEdge e : n.succs) {
+                    for (LayoutEdge e : List.copyOf(n.succs)) {
                         processSingleEdge(e);
                     }
                 }
@@ -1229,10 +1181,10 @@ public class HierarchicalLayoutManager implements LayoutManager {
         }
 
         private void processSingleEdge(LayoutEdge e) {
-            LayoutNode n = e.from;
-            if (e.to.layer > n.layer + 1) {
+            LayoutNode n = e.to;
+            if (e.to.layer - 1 > e.from.layer) {
                 LayoutEdge last = e;
-                for (int i = n.layer + 1; i < last.to.layer; i++) {
+                for (int i = n.layer - 1; i > last.from.layer; i--) {
                     last = addBetween(last, i);
                 }
             }
@@ -1240,22 +1192,23 @@ public class HierarchicalLayoutManager implements LayoutManager {
 
         private LayoutEdge addBetween(LayoutEdge e, int layer) {
             LayoutNode n = new LayoutNode();
-            n.width = dummyWidth;
-            n.height = dummyHeight;
+            n.width = DUMMY_WIDTH;
+            n.height = DUMMY_HEIGHT;
             n.layer = layer;
-            n.preds.add(e);
+            n.succs.add(e);
             nodes.add(n);
             LayoutEdge result = new LayoutEdge();
             result.vip = e.vip;
-            n.succs.add(result);
-            result.from = n;
-            result.relativeFrom = n.width / 2;
-            result.to = e.to;
-            result.relativeTo = e.relativeTo;
-            e.relativeTo = n.width / 2;
-            e.to.preds.remove(e);
-            e.to.preds.add(result);
-            e.to = n;
+            n.preds.add(result);
+            result.to = n;
+            result.relativeTo = n.width / 2;
+            result.from = e.from;
+            result.relativeFrom = e.relativeFrom;
+            result.link = e.link;
+            e.relativeFrom = n.width / 2;
+            e.from.succs.remove(e);
+            e.from.succs.add(result);
+            e.from = n;
             return result;
         }
 
diff --git a/src/utils/IdealGraphVisualizer/HierarchicalLayout/src/main/java/com/sun/hotspot/igv/hierarchicallayout/HierarchicalStableLayoutManager.java b/src/utils/IdealGraphVisualizer/HierarchicalLayout/src/main/java/com/sun/hotspot/igv/hierarchicallayout/HierarchicalStableLayoutManager.java
new file mode 100644
index 00000000000..875ccb19022
--- /dev/null
+++ b/src/utils/IdealGraphVisualizer/HierarchicalLayout/src/main/java/com/sun/hotspot/igv/hierarchicallayout/HierarchicalStableLayoutManager.java
@@ -0,0 +1,1471 @@
+/*
+ * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+package com.sun.hotspot.igv.hierarchicallayout;
+
+import com.sun.hotspot.igv.layout.LayoutGraph;
+import com.sun.hotspot.igv.layout.Link;
+import com.sun.hotspot.igv.layout.Vertex;
+import com.sun.hotspot.igv.util.Statistics;
+import java.awt.Dimension;
+import java.awt.Point;
+import java.util.*;
+
+public class HierarchicalStableLayoutManager {
+
+    public static final int DUMMY_HEIGHT = 1;
+    public static final int DUMMY_WIDTH = 1;
+    public static final int X_OFFSET = 8;
+    public static final int LAYER_OFFSET = 8;
+    // Algorithm global data structures
+    private HashSet<? extends Vertex> currentVertices;
+    private HashSet<? extends Link> currentLinks;
+    private Set<Link> reversedLinks;
+    private List<LayoutNode> nodes;
+    private final HashMap<Vertex, LayoutNode> vertexToLayoutNode;
+    private HashMap<Link, List<Point>> reversedLinkStartPoints;
+    private HashMap<Link, List<Point>> reversedLinkEndPoints;
+    private HashMap<Integer, List<LayoutNode>> layers;
+
+    private final HierarchicalLayoutManager manager;
+    private HashMap<Vertex, VertexAction> vertexToAction;
+    private List<VertexAction> vertexActions;
+    private List<LinkAction> linkActions;
+    private HashSet<? extends Vertex> oldVertices;
+    private HashSet<? extends Link> oldLinks;
+    private boolean shouldRedrawLayout = true;
+    private boolean shouldRemoveEmptyLayers = true;
+
+    enum Action {
+        ADD,
+        REMOVE
+    }
+
+    private static class VertexAction {
+        public Vertex vertex;
+        public List<LinkAction> linkActions = new LinkedList<>();
+        public Action action;
+
+        public VertexAction(Vertex vertex, Action action) {
+            this.vertex = vertex;
+            this.action = action;
+        }
+    }
+
+    private static class LinkAction {
+        public Link link;
+        public Action action;
+
+        public LinkAction(Link link, Action action) {
+            this.link = link;
+            this.action = action;
+        }
+    }
+
+    public HierarchicalStableLayoutManager() {
+        oldVertices = new HashSet<>();
+        oldLinks = new HashSet<>();
+        manager = new HierarchicalLayoutManager(HierarchicalLayoutManager.Combine.SAME_OUTPUTS);
+        vertexToLayoutNode = new HashMap<>();
+        nodes = new ArrayList<>();
+    }
+
+    private int calculateOptimalBoth(LayoutNode n) {
+        if (n.preds.isEmpty() && n.succs.isEmpty()) {
+            return n.x;
+        }
+
+        int[] values = new int[n.preds.size() + n.succs.size()];
+        int i = 0;
+
+        for (LayoutEdge e : n.preds) {
+            values[i] = e.from.x + e.relativeFrom - e.relativeTo;
+            i++;
+        }
+
+        for (LayoutEdge e : n.succs) {
+            values[i] = e.to.x + e.relativeTo - e.relativeFrom;
+            i++;
+        }
+
+        return Statistics.median(values);
+    }
+
+    /**
+     * Adjust the X-coordinates of the nodes in the given layer, as a new node has
+     * been inserted at that layer
+     */
+    private void adjustXCoordinates(int layer) {
+        List<LayoutNode> nodes = layers.get(layer);
+        ArrayList<Integer> space = new ArrayList<>();
+        List<LayoutNode> nodeProcessingOrder = new ArrayList<>();
+
+        nodes.sort(HierarchicalLayoutManager.nodePositionComparator);
+
+        int curX = 0;
+        for (LayoutNode n : nodes) {
+            space.add(curX);
+            curX += n.width + X_OFFSET;
+            nodeProcessingOrder.add(n);
+        }
+
+        nodeProcessingOrder.sort(HierarchicalLayoutManager.nodeProcessingUpComparator);
+        HierarchicalLayoutManager.NodeRow r = new HierarchicalLayoutManager.NodeRow(space);
+        for (LayoutNode n : nodeProcessingOrder) {
+            int optimal = calculateOptimalBoth(n);
+            r.insert(n, optimal);
+        }
+    }
+
+    private void ensureNeighborEdgeConsistency() {
+        for (LayoutNode n : nodes) {
+            n.succs.removeIf(e -> !nodes.contains(e.to));
+            n.preds.removeIf(e -> !nodes.contains(e.from));
+        }
+    }
+
+    private static final Comparator<VertexAction> vertexActionComparator = (a1, a2) -> {
+        if (a1.action == Action.REMOVE) {
+            if (a2.action == Action.REMOVE) {
+                return a2.linkActions.size() - a1.linkActions.size();
+            }
+            return -1;
+        }
+        if (a2.action == Action.REMOVE) {
+            return 1;
+        }
+
+        return a1.linkActions.size() - a2.linkActions.size();
+    };
+
+    private void generateActions() {
+        HashSet<Link> oldLinks = new HashSet<>(this.oldLinks);
+
+        HashSet<Vertex> addedVertices = new HashSet<>(currentVertices);
+        addedVertices.removeAll(oldVertices);
+
+        HashSet<Vertex> removedVertices = new HashSet<>(oldVertices);
+        removedVertices.removeAll(currentVertices);
+
+        HashSet<Link> addedLinks = new HashSet<>(currentLinks);
+        HashSet<Link> removedLinks = new HashSet<>(oldLinks);
+        for (Link link1 : currentLinks) {
+            for (Link link2 : oldLinks) {
+                if (link1.equals(link2)) {
+                    addedLinks.remove(link1);
+                    removedLinks.remove(link2);
+                    break;
+                }
+            }
+        }
+
+        for (Vertex v : addedVertices) {
+            VertexAction a = new VertexAction(v, Action.ADD);
+            vertexActions.add(a);
+            vertexToAction.put(v, a);
+        }
+
+        for (Vertex v : removedVertices) {
+            VertexAction a = new VertexAction(v, Action.REMOVE);
+            vertexActions.add(a);
+            vertexToAction.put(v, a);
+        }
+
+        for (Link l : addedLinks) {
+            Vertex to = l.getTo().getVertex();
+            Vertex from = l.getFrom().getVertex();
+            LinkAction a = new LinkAction(l, Action.ADD);
+
+            if (addedVertices.contains(to)) {
+                vertexToAction.get(to).linkActions.add(a);
+            }
+            if (addedVertices.contains(from)) {
+                vertexToAction.get(from).linkActions.add(a);
+            }
+            if (!addedVertices.contains(to) && !addedVertices.contains(from)) {
+                linkActions.add(a);
+            }
+        }
+
+        for (Link l : removedLinks) {
+            Vertex to = l.getTo().getVertex();
+            Vertex from = l.getFrom().getVertex();
+            LinkAction a = new LinkAction(l, Action.REMOVE);
+
+            if (removedVertices.contains(to)) {
+                vertexToAction.get(to).linkActions.add(a);
+            }
+            if (removedVertices.contains(from)) {
+                vertexToAction.get(from).linkActions.add(a);
+            }
+            if (!removedVertices.contains(to) && !removedVertices.contains(from)) {
+                linkActions.add(a);
+            }
+        }
+
+        vertexActions.sort(vertexActionComparator);
+    }
+
+    private void findInitialReversedLinks() {
+        for (Link link : oldLinks) {
+            for (Link l : currentLinks) {
+                if (l.equals(link)) {
+                    if (vertexToLayoutNode.get(l.getFrom().getVertex()).layer > vertexToLayoutNode
+                            .get(l.getTo().getVertex()).layer) {
+                        // Link is reversed
+                        reversedLinks.add(l);
+                        updateReversedLinkPositions(l);
+                    }
+                }
+            }
+        }
+    }
+
+    private void updateReversedLinkPositions(Link link) {
+        LayoutNode fromNode = vertexToLayoutNode.get(link.getFrom().getVertex());
+        LayoutNode toNode = vertexToLayoutNode.get(link.getTo().getVertex());
+        // Correct direction, is reversed link
+        assert fromNode != null && toNode != null;
+        assert nodes.contains(fromNode) && nodes.contains(toNode);
+        assert fromNode.layer > toNode.layer;
+        assert reversedLinks.contains(link);
+
+        updateNodeWithReversedEdges(fromNode);
+        updateNodeWithReversedEdges(toNode);
+    }
+
+    private void updateNodeWithReversedEdges(LayoutNode node) {
+        // Reset node data in case there were previous reversed edges
+        node.width = (int) node.vertex.getSize().getWidth();
+        node.height = (int) node.vertex.getSize().getHeight();
+        node.yOffset = 0;
+        node.bottomYOffset = 0;
+        node.xOffset = 0;
+        node.inOffsets.clear();
+        node.outOffsets.clear();
+
+        SortedSet<Integer> reversedDown = new TreeSet<>();
+
+        // Reset relativeFrom for all succ edges
+        for (LayoutEdge e : node.succs) {
+            if (e.link == null) {
+                continue;
+            }
+            e.relativeFrom = e.link.getFrom().getRelativePosition().x;
+            if (reversedLinks.contains(e.link)) {
+                e.relativeFrom = e.link.getTo().getRelativePosition().x;
+                reversedDown.add(e.relativeFrom);
+            }
+        }
+
+        // Whether the node has non-self reversed edges going downwards.
+        // If so, reversed edges going upwards are drawn to the left.
+        boolean hasReversedDown = !reversedDown.isEmpty();
+
+        SortedSet<Integer> reversedUp;
+        if (hasReversedDown) {
+            reversedUp = new TreeSet<>();
+        } else {
+            reversedUp = new TreeSet<>(Collections.reverseOrder());
+        }
+
+        // Reset relativeTo for all pred edges
+        for (LayoutEdge e : node.preds) {
+            if (e.link == null) {
+                continue;
+            }
+            e.relativeTo = e.link.getTo().getRelativePosition().x;
+            if (reversedLinks.contains(e.link)) {
+                e.relativeTo = e.link.getFrom().getRelativePosition().x;
+                reversedUp.add(e.relativeTo);
+            }
+        }
+
+        final int offset = X_OFFSET + DUMMY_WIDTH;
+
+        int curY = 0;
+        int curWidth = node.width + reversedDown.size() * offset;
+        for (int pos : reversedDown) {
+            ArrayList<LayoutEdge> reversedSuccs = new ArrayList<>();
+            for (LayoutEdge e : node.succs) {
+                if (e.relativeFrom == pos && reversedLinks.contains(e.link)) {
+                    reversedSuccs.add(e);
+                    e.relativeFrom = curWidth;
+                }
+            }
+
+            ArrayList<Point> startPoints = new ArrayList<>();
+            startPoints.add(new Point(curWidth, curY));
+            startPoints.add(new Point(pos, curY));
+            startPoints.add(new Point(pos, reversedDown.size() * offset));
+            for (LayoutEdge e : reversedSuccs) {
+                reversedLinkStartPoints.put(e.link, startPoints);
+            }
+
+            node.inOffsets.put(pos, -curY);
+            curY += offset;
+            node.height += offset;
+            node.yOffset += offset;
+            curWidth -= offset;
+        }
+
+        int widthFactor = reversedDown.size();
+        node.width += widthFactor * offset;
+
+        int curX = 0;
+        int minX = 0;
+        if (hasReversedDown) {
+            minX = -offset * reversedUp.size();
+        }
+
+        int oldNodeHeight = node.height;
+        for (int pos : reversedUp) {
+            ArrayList<LayoutEdge> reversedPreds = new ArrayList<>();
+            for (LayoutEdge e : node.preds) {
+                if (e.relativeTo == pos && reversedLinks.contains(e.link)) {
+                    if (hasReversedDown) {
+                        e.relativeTo = curX - offset;
+                    } else {
+                        e.relativeTo = node.width + offset;
+                    }
+
+                    reversedPreds.add(e);
+                }
+            }
+            node.height += offset;
+            ArrayList<Point> endPoints = new ArrayList<>();
+
+            node.width += offset;
+            if (hasReversedDown) {
+                curX -= offset;
+                endPoints.add(new Point(curX, node.height));
+            } else {
+                curX += offset;
+                endPoints.add(new Point(node.width, node.height));
+            }
+
+            node.outOffsets.put(pos - minX, curX);
+            curX += offset;
+            node.bottomYOffset += offset;
+
+            endPoints.add(new Point(pos, node.height));
+            endPoints.add(new Point(pos, oldNodeHeight));
+            for (LayoutEdge e : reversedPreds) {
+                reversedLinkEndPoints.put(e.link, endPoints);
+            }
+        }
+
+        if (minX < 0) {
+            for (LayoutEdge e : node.preds) {
+                e.relativeTo -= minX;
+            }
+
+            for (LayoutEdge e : node.succs) {
+                e.relativeFrom -= minX;
+            }
+
+            node.xOffset = -minX;
+            node.width -= minX;
+        }
+    }
+
+    /**
+     * Indicate that the layout should be redrawn with a static algorithm
+     */
+    public void setShouldRedrawLayout(boolean shouldRedrawLayout) {
+        this.shouldRedrawLayout = shouldRedrawLayout;
+    }
+
+    public void updateLayout(HashSet<? extends Vertex> vertices, HashSet<? extends Link> links) {
+        currentVertices = vertices;
+        currentLinks = links;
+        reversedLinks = new HashSet<>();
+        reversedLinkStartPoints = new HashMap<>();
+        reversedLinkEndPoints = new HashMap<>();
+        vertexActions = new LinkedList<>();
+        linkActions = new LinkedList<>();
+        vertexToAction = new HashMap<>();
+
+        new ProcessInput().run();
+
+        if (shouldRedrawLayout) {
+            // If the layout is too messy it should be redrawn using the static algorithm,
+            // currently HierarchicalLayoutManager
+            manager.doLayout(new LayoutGraph(links, vertices));
+            nodes = manager.getNodes();
+            shouldRedrawLayout = false;
+        } else {
+            generateActions();
+
+            new BuildDatastructure().run();
+
+            findInitialReversedLinks();
+
+            // Only apply updates if there are any
+            if (!linkActions.isEmpty() || !vertexActions.isEmpty()) {
+                new ApplyActionUpdates().run();
+            }
+
+            new AssignYCoordinates().run();
+
+            new WriteResult().run();
+        }
+
+        oldVertices = new HashSet<>(currentVertices);
+        oldLinks = new HashSet<>(currentLinks);
+    }
+
+    private class ProcessInput {
+        public void removeDuplicateLinks() {
+            HashSet<Link> links = new HashSet<>();
+            for (Link link : currentLinks) {
+                if (link.getTo().getVertex().equals(link.getFrom().getVertex())) {
+                    // self-edge
+                    continue;
+                }
+                links.add(link);
+            }
+            currentLinks = links;
+        }
+
+        private void run() {
+            removeDuplicateLinks();
+        }
+    }
+
+    private class BuildDatastructure {
+
+        // In case there are changes in the node size, its layer must be updated
+        Set<Integer> layersToUpdate = new HashSet<>();
+
+        /**
+         * Update the vertex and link object references to the current vertices and
+         * links, resetting any temporary changes caused by previous layout
+         */
+        private void updateNodeObjects() {
+            for (LayoutNode node : nodes) {
+                if (node.vertex != null) {
+                    for (Vertex vertex : currentVertices) {
+                        if (vertex.equals(node.vertex)) {
+                            Dimension size = vertex.getSize();
+                            if (node.width < (int) size.getWidth()) {
+                                layersToUpdate.add(node.layer);
+                            }
+                            node.width = (int) size.getWidth();
+                            node.height = (int) size.getHeight();
+                            node.vertex = vertex;
+                        }
+                    }
+                    vertexToLayoutNode.put(node.vertex, node);
+                } else {
+                    node.height = DUMMY_HEIGHT;
+                    node.width = DUMMY_WIDTH;
+                }
+                for (LayoutEdge edge : node.preds) {
+                    if (edge.link != null) {
+                        for (Link link : currentLinks) {
+                            if (link.equals(edge.link)) {
+                                edge.link = link;
+                                if (link.getTo().getVertex().equals(edge.from.vertex)) {
+                                    // reversed link
+                                    edge.relativeFrom = link.getTo().getRelativePosition().x;
+                                    edge.relativeTo = link.getFrom().getRelativePosition().x;
+                                } else {
+                                    edge.relativeFrom = link.getFrom().getRelativePosition().x;
+                                    edge.relativeTo = link.getTo().getRelativePosition().x;
+                                }
+                                break;
+                            }
+                        }
+                    }
+                }
+                for (LayoutEdge edge : node.succs) {
+                    if (edge.link != null) {
+                        for (Link link : currentLinks) {
+                            if (link.equals(edge.link)) {
+                                edge.link = link;
+                                if (link.getTo().getVertex().equals(edge.from.vertex)) {
+                                    // reversed link
+                                    edge.relativeFrom = link.getTo().getRelativePosition().x;
+                                    edge.relativeTo = link.getFrom().getRelativePosition().x;
+                                } else {
+                                    edge.relativeFrom = link.getFrom().getRelativePosition().x;
+                                    edge.relativeTo = link.getTo().getRelativePosition().x;
+                                }
+                                break;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        /**
+         * Store the nodes that each layer contains
+         */
+        private void storeNodeLayers() {
+            layers = new HashMap<>();
+            for (LayoutNode node : nodes) {
+                if (!layers.containsKey(node.layer)) {
+                    layers.put(node.layer, new ArrayList<>());
+                }
+                layers.get(node.layer).add(node);
+            }
+            for (int i = 0; i < layers.keySet().size(); i++) {
+                if (!layers.containsKey(i)) {
+                    layers.put(i, new ArrayList<>());
+                }
+            }
+        }
+
+        private void updateLayersXCoords() {
+            for (Integer i : layersToUpdate) {
+                adjustXCoordinates(i);
+            }
+        }
+
+        private void run() {
+            updateNodeObjects();
+            storeNodeLayers();
+            updateLayersXCoords();
+        }
+    }
+
+    private class ApplyActionUpdates {
+        /**
+         * Find the optimal position within the given layer to insert the given node.
+         * The optimum is given by the least amount of edge crossings.
+         */
+        private int optimalPosition(LayoutNode node, int layer) {
+            assert layers.containsKey(layer);
+
+            List<LayoutNode> layerNodes = layers.get(layer);
+            layerNodes.sort(HierarchicalLayoutManager.nodePositionComparator);
+            int edgeCrossings = Integer.MAX_VALUE;
+            int optimalPos = -1;
+
+            // Try each possible position in the layer
+            for (int i = 0; i < layerNodes.size() + 1; i++) {
+                int xCoord;
+                if (i == 0) {
+                    xCoord = layerNodes.get(i).x - node.width - 1;
+                } else {
+                    xCoord = layerNodes.get(i - 1).x + layerNodes.get(i - 1).width + 1;
+                }
+
+                int currentCrossings = 0;
+
+                if (layers.containsKey(layer - 1)) {
+                    List<LayoutNode> predNodes = layers.get(layer - 1);
+                    // For each link with an end point in vertex, check how many edges cross it
+                    for (LayoutEdge edge : node.preds) {
+                        if (edge.from.layer == layer - 1) {
+                            int fromNodeXCoord = edge.from.x;
+                            if (edge.from.vertex != null) {
+                                fromNodeXCoord += edge.relativeFrom;
+                            }
+                            int toNodeXCoord = xCoord;
+                            if (node.vertex != null) {
+                                toNodeXCoord += edge.relativeTo;
+                            }
+                            for (LayoutNode n : predNodes) {
+                                for (LayoutEdge e : n.succs) {
+                                    if (e.to == null) {
+                                        continue;
+                                    }
+                                    int compFromXCoord = e.from.x;
+                                    if (e.from.vertex != null) {
+                                        compFromXCoord += e.relativeFrom;
+                                    }
+                                    int compToXCoord = e.to.x;
+                                    if (e.to.vertex != null) {
+                                        compToXCoord += e.relativeTo;
+                                    }
+                                    if ((fromNodeXCoord > compFromXCoord && toNodeXCoord < compToXCoord)
+                                            || (fromNodeXCoord < compFromXCoord
+                                            && toNodeXCoord > compToXCoord)) {
+                                        currentCrossings += 1;
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+                // Edge crossings across current layer and layer below
+                if (layers.containsKey(layer + 1)) {
+                    List<LayoutNode> succsNodes = layers.get(layer + 1);
+                    // For each link with an end point in vertex, check how many edges cross it
+                    for (LayoutEdge edge : node.succs) {
+                        if (edge.to.layer == layer + 1) {
+                            int toNodeXCoord = edge.to.x;
+                            if (edge.to.vertex != null) {
+                                toNodeXCoord += edge.relativeTo;
+                            }
+                            int fromNodeXCoord = xCoord;
+                            if (node.vertex != null) {
+                                fromNodeXCoord += edge.relativeFrom;
+                            }
+                            for (LayoutNode n : succsNodes) {
+                                for (LayoutEdge e : n.preds) {
+                                    if (e.from == null) {
+                                        continue;
+                                    }
+                                    int compFromXCoord = e.from.x;
+                                    if (e.from.vertex != null) {
+                                        compFromXCoord += e.relativeFrom;
+                                    }
+                                    int compToXCoord = e.to.x;
+                                    if (e.to.vertex != null) {
+                                        compToXCoord += e.relativeTo;
+                                    }
+                                    if ((fromNodeXCoord > compFromXCoord && toNodeXCoord < compToXCoord)
+                                            || (fromNodeXCoord < compFromXCoord
+                                            && toNodeXCoord > compToXCoord)) {
+                                        currentCrossings += 1;
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+                if (currentCrossings <= edgeCrossings) {
+                    edgeCrossings = currentCrossings;
+                    optimalPos = i;
+                }
+            }
+            assert optimalPos != -1;
+            return optimalPos;
+        }
+
+        /**
+         * Insert node at the assigned layer, updating the positions of the nodes within
+         * the layer
+         */
+        private void insertNode(LayoutNode node, int layer) {
+            assert layers.containsKey(layer) || layer == 0;
+
+            node.layer = layer;
+            List<LayoutNode> layerNodes = layers.getOrDefault(layer, new ArrayList<LayoutNode>());
+
+            if (layerNodes.isEmpty()) {
+                node.pos = 0;
+            } else {
+                node.pos = optimalPosition(node, layer);
+            }
+
+            for (LayoutNode n : layerNodes) {
+                if (n.pos >= node.pos) {
+                    n.pos += 1;
+                }
+            }
+            layerNodes.add(node);
+            layers.put(layer, layerNodes);
+
+            if (!nodes.contains(node)) {
+                nodes.add(node);
+            }
+            if (node.vertex != null) {
+                vertexToLayoutNode.put(node.vertex, node);
+            }
+
+            adjustXCoordinates(layer);
+        }
+
+        private void processSingleEdge(LayoutEdge e) {
+            LayoutNode n = e.to;
+            if (e.to.layer - 1 > e.from.layer) {
+                LayoutEdge last = e;
+                for (int i = n.layer - 1; i > last.from.layer; i--) {
+                    last = addBetween(last, i);
+                }
+            }
+        }
+
+        private LayoutEdge addBetween(LayoutEdge e, int layer) {
+            LayoutNode n = new LayoutNode();
+            n.width = DUMMY_WIDTH;
+            n.height = DUMMY_HEIGHT;
+            n.succs.add(e);
+            LayoutEdge result = new LayoutEdge();
+            result.vip = e.vip;
+            n.preds.add(result);
+            result.to = n;
+            result.relativeTo = n.width / 2;
+            result.from = e.from;
+            result.relativeFrom = e.relativeFrom;
+            result.link = e.link;
+            e.relativeFrom = n.width / 2;
+            e.from.succs.remove(e);
+            e.from.succs.add(result);
+            e.from = n;
+            insertNode(n, layer);
+            return result;
+        }
+
+        private void insertDummyNodes(LayoutEdge edge) {
+            LayoutNode from = edge.from;
+            LayoutNode to = edge.to;
+
+            boolean hasEdgeFromSamePort = false;
+            LayoutEdge edgeFromSamePort = new LayoutEdge();
+
+            for (LayoutEdge e : edge.from.succs) {
+                if (e.relativeFrom == edge.relativeFrom && e.to.vertex == null) {
+                    edgeFromSamePort = e;
+                    hasEdgeFromSamePort = true;
+                    break;
+                }
+            }
+
+            if (!hasEdgeFromSamePort) {
+                processSingleEdge(edge);
+            } else {
+                LayoutEdge curEdge = edgeFromSamePort;
+                boolean newEdge = true;
+                while (curEdge.to.layer < to.layer - 1 && curEdge.to.vertex == null && newEdge) {
+                    // Traverse down the chain of dummy nodes linking together the edges originating
+                    // from the same port
+                    newEdge = false;
+                    if (curEdge.to.succs.size() == 1) {
+                        curEdge = curEdge.to.succs.get(0);
+                        newEdge = true;
+                    } else {
+                        for (LayoutEdge e : curEdge.to.succs) {
+                            if (e.to.vertex == null) {
+                                curEdge = e;
+                                newEdge = true;
+                                break;
+                            }
+                        }
+                    }
+                }
+
+                LayoutNode prevDummy;
+                if (curEdge.to.vertex != null) {
+                    prevDummy = curEdge.from;
+                } else {
+                    prevDummy = curEdge.to;
+                }
+
+                edge.from = prevDummy;
+                edge.relativeFrom = prevDummy.width / 2;
+                from.succs.remove(edge);
+                prevDummy.succs.add(edge);
+                processSingleEdge(edge);
+            }
+        }
+
+        private boolean canMoveNodeUp(LayoutNode node) {
+            if (node.layer == 0) {
+                return false;
+            }
+            int newLayer = node.layer - 1;
+            for (LayoutEdge e : node.preds) {
+                if (e.from.vertex != null && e.from.layer == newLayer) {
+                    return false;
+                }
+            }
+            return true;
+        }
+
+        private boolean canMoveNodeDown(LayoutNode node) {
+            if (node.layer == layers.keySet().size() - 1) {
+                return false;
+            }
+            int newLayer = node.layer + 1;
+            for (LayoutEdge e : node.succs) {
+                if (e.to.vertex != null && e.to.layer == newLayer) {
+                    return false;
+                }
+            }
+            return true;
+        }
+
+        private void moveNodeUp(LayoutNode node) {
+            assert canMoveNodeUp(node);
+
+            List<LayoutEdge> previousPredEdges = List.copyOf(node.preds);
+            for (LayoutEdge edge : previousPredEdges) {
+                LayoutNode predNode = edge.from;
+                assert predNode.vertex == null;
+                for (LayoutEdge e : predNode.preds) {
+                    e.to = edge.to;
+                    e.relativeTo = edge.relativeTo;
+                    node.preds.add(e);
+                    node.preds.remove(edge);
+                }
+                removeNodeWithoutRemovingLayer(predNode);
+            }
+
+            removeNodeWithoutRemovingLayer(node);
+            insertNode(node, node.layer - 1);
+
+            for (LayoutEdge edge : List.copyOf(node.succs)) {
+                processSingleEdge(edge);
+            }
+        }
+
+        private void moveNodeDown(LayoutNode node) {
+            assert canMoveNodeDown(node);
+
+            List<LayoutEdge> previousSuccEdges = List.copyOf(node.succs);
+            for (LayoutEdge edge : previousSuccEdges) {
+                LayoutNode succNode = edge.to;
+                assert succNode.vertex == null;
+                for (LayoutEdge e : succNode.succs) {
+                    e.from = edge.from;
+                    e.relativeFrom = edge.relativeFrom;
+                    node.succs.add(e);
+                    node.succs.remove(edge);
+                }
+                removeNodeWithoutRemovingLayer(succNode);
+            }
+
+            removeNodeWithoutRemovingLayer(node);
+            insertNode(node, node.layer + 1);
+
+            for (LayoutEdge edge : List.copyOf(node.preds)) {
+                processSingleEdge(edge);
+            }
+        }
+
+        private void handleNeighborNodesOnSameLayer(LayoutNode from, LayoutNode to) {
+            if (canMoveNodeDown(to)) {
+                moveNodeDown(to);
+            } else if (canMoveNodeUp(from)) {
+                moveNodeUp(from);
+            } else {
+                expandNewLayerBeneath(to);
+            }
+
+            ensureNeighborEdgeConsistency();
+        }
+
+        /**
+         * Create a new layer at node.layer + 1 and move the given node there. Adjust
+         * remaining layers numbers
+         */
+        private void expandNewLayerBeneath(LayoutNode node) {
+            int layer = node.layer + 1;
+
+            // Move all necessary layers down one step
+            for (int i = layers.size() - 1; i >= layer; i--) {
+                List<LayoutNode> list = layers.get(i);
+                for (LayoutNode n : list) {
+                    n.layer = i + 1;
+                }
+                layers.remove(i);
+                layers.put(i + 1, list);
+            }
+
+            // Create new empty layer
+            List<LayoutNode> l = new ArrayList<>();
+            layers.put(layer, l);
+
+            assert layers.get(layer).isEmpty();
+            for (LayoutNode n : nodes) {
+                assert n.layer != layer;
+            }
+
+            // Add dummy nodes for edges going across new layer. One for each port on the
+            // nodes that has outgoing edges
+            List<LayoutNode> predLayer = List.copyOf(layers.get(layer - 1));
+            for (LayoutNode n : predLayer) {
+                HashMap<Integer, List<LayoutEdge>> portHashes = new HashMap<>();
+
+                for (LayoutEdge e : n.succs) {
+                    if (!portHashes.containsKey(e.relativeFrom)) {
+                        portHashes.put(e.relativeFrom, new ArrayList<>());
+                    }
+                    portHashes.get(e.relativeFrom).add(e);
+                }
+
+                for (Integer i : portHashes.keySet()) {
+                    List<LayoutEdge> edges = portHashes.get(i);
+
+                    LayoutNode dummy = new LayoutNode();
+                    dummy.width = DUMMY_WIDTH;
+                    dummy.height = DUMMY_HEIGHT;
+
+                    LayoutEdge newEdge = new LayoutEdge();
+                    newEdge.from = n;
+                    newEdge.relativeFrom = i;
+                    newEdge.to = dummy;
+                    newEdge.relativeTo = dummy.width / 2;
+                    newEdge.link = edges.get(0).link; // issue?
+                    n.succs.add(newEdge);
+                    dummy.preds.add(newEdge);
+
+                    for (LayoutEdge e : edges) {
+                        e.from = dummy;
+                        e.relativeFrom = dummy.width / 2;
+                        n.succs.remove(e);
+                        dummy.succs.add(e);
+                        assert e.to.layer == layer + 1;
+                    }
+
+                    insertNode(dummy, layer);
+                }
+            }
+
+            // Move node to new layer
+            moveNodeDown(node);
+            assert layers.get(layer).contains(node);
+            assert node.layer == layer;
+        }
+
+        private void applyAddLinkAction(Link l) {
+            Vertex from = l.getFrom().getVertex();
+            Vertex to = l.getTo().getVertex();
+            LayoutNode fromNode = vertexToLayoutNode.get(from);
+            LayoutNode toNode = vertexToLayoutNode.get(to);
+
+            if (!nodes.contains(fromNode) || !nodes.contains(toNode) || to.equals(from)) {
+                return;
+            }
+
+            if (toNode.layer == fromNode.layer) {
+                handleNeighborNodesOnSameLayer(fromNode, toNode);
+            }
+
+            LayoutEdge edge = new LayoutEdge();
+            edge.link = l;
+            edge.from = fromNode;
+            edge.relativeFrom = l.getFrom().getRelativePosition().x;
+            edge.to = toNode;
+            edge.relativeTo = l.getTo().getRelativePosition().x;
+
+            boolean reversedLink = fromNode.layer > toNode.layer;
+            if (reversedLink) {
+                // Reversed link
+                reversedLinks.add(l);
+
+                LayoutNode temp = fromNode;
+                fromNode = toNode;
+                toNode = temp;
+
+                int oldRelativeFrom = edge.relativeFrom;
+                int oldRelativeTo = edge.relativeTo;
+
+                edge.from = fromNode;
+                edge.to = toNode;
+                edge.relativeFrom = oldRelativeTo;
+                edge.relativeTo = oldRelativeFrom;
+            }
+
+            fromNode.succs.add(edge);
+            toNode.preds.add(edge);
+
+            if (reversedLink) {
+                updateReversedLinkPositions(l);
+            }
+
+            if (fromNode.layer != toNode.layer - 1) {
+                // Edge span multiple layers - must insert dummy nodes
+                insertDummyNodes(edge);
+            }
+
+            ensureNeighborEdgeConsistency();
+        }
+
+        /**
+         * Calculate which layer the given vertex should be inserted at to minimize
+         * reversed edges and edge lengths
+         * If there are multiple options, choose the bottom-most layer
+         *
+         * @return the optimal layer to insert the given vertex
+         */
+        private int optimalLayer(Vertex vertex, List<Link> links) {
+            if (vertex.isRoot()) {
+                return 0;
+            } else if (layers.keySet().isEmpty()) {
+                return 0;
+            }
+
+            int reversedEdges = Integer.MAX_VALUE;
+            int totalEdgeLength = Integer.MAX_VALUE;
+            int neighborsOnSameLayer = Integer.MAX_VALUE;
+            int layer = -1;
+            for (int i = 0; i < layers.keySet().size(); i++) {
+                int curReversedEdges = 0;
+                int curTotalEdgeLength = 0;
+                int curNeighborsOnSameLayer = 0;
+                for (Link link : links) {
+                    LayoutNode fromNode = vertexToLayoutNode.get(link.getFrom().getVertex());
+                    LayoutNode toNode = vertexToLayoutNode.get(link.getTo().getVertex());
+                    if (link.getTo().getVertex().equals(vertex) && fromNode != null) {
+                        if (fromNode.layer > i) {
+                            curReversedEdges += 1;
+                        } else if (fromNode.layer == i) {
+                            curNeighborsOnSameLayer += 1;
+                        }
+                        curTotalEdgeLength += Math.abs(fromNode.layer - i);
+                    }
+                    if (link.getFrom().getVertex().equals(vertex) && toNode != null) {
+                        if (toNode.layer < i) {
+                            curReversedEdges += 1;
+                        } else if (toNode.layer == i) {
+                            curNeighborsOnSameLayer += 1;
+                        }
+                        curTotalEdgeLength += Math.abs(i - toNode.layer);
+                    }
+                }
+
+                curReversedEdges *= 10000;
+                curNeighborsOnSameLayer *= 2;
+
+                if (curReversedEdges + curTotalEdgeLength + curNeighborsOnSameLayer <= reversedEdges + totalEdgeLength
+                        + neighborsOnSameLayer) {
+                    totalEdgeLength = curTotalEdgeLength;
+                    reversedEdges = curReversedEdges;
+                    neighborsOnSameLayer = curNeighborsOnSameLayer;
+                    layer = i;
+                }
+            }
+
+            assert layer != -1;
+            return layer;
+        }
+
+        private void applyAddVertexAction(VertexAction action) {
+            LayoutNode node = new LayoutNode();
+            Dimension size = action.vertex.getSize();
+            node.width = (int) size.getWidth();
+            node.height = (int) size.getHeight();
+            node.vertex = action.vertex;
+
+            List<Link> links = new ArrayList<>();
+            for (LinkAction a : action.linkActions) {
+                links.add(a.link);
+            }
+            int layer = optimalLayer(action.vertex, links);
+
+            // Temporarily add the links so that the node insertion accounts for edge
+            // crossings
+            for (Link l : links) {
+                LayoutEdge e = new LayoutEdge();
+                if (l.getTo().getVertex().equals(action.vertex)
+                        && nodes.contains(vertexToLayoutNode.get(l.getFrom().getVertex()))) {
+                    e.to = node;
+                    e.from = vertexToLayoutNode.get(l.getFrom().getVertex());
+                    e.relativeFrom = l.getFrom().getRelativePosition().x;
+                    e.relativeTo = l.getTo().getRelativePosition().x;
+                    node.preds.add(e);
+                } else if (l.getFrom().getVertex().equals(action.vertex)
+                        && nodes.contains(vertexToLayoutNode.get(l.getTo().getVertex()))) {
+                    e.from = node;
+                    e.to = vertexToLayoutNode.get(l.getTo().getVertex());
+                    e.relativeFrom = l.getFrom().getRelativePosition().x;
+                    e.relativeTo = l.getTo().getRelativePosition().x;
+                    node.succs.add(e);
+                }
+            }
+            insertNode(node, layer);
+            node.succs.clear();
+            node.preds.clear();
+
+            // Add associated edges
+            for (LinkAction a : action.linkActions) {
+                if (a.action == Action.ADD) {
+                    applyAddLinkAction(a.link);
+                }
+            }
+        }
+
+        private void applyRemoveLinkAction(Link l) {
+            Vertex from = l.getFrom().getVertex();
+            Vertex to = l.getTo().getVertex();
+            LayoutNode toNode = vertexToLayoutNode.get(to);
+            LayoutNode fromNode = vertexToLayoutNode.get(from);
+
+            if (toNode.layer < fromNode.layer) {
+                // Reversed edge
+                LayoutNode temp = toNode;
+                toNode = fromNode;
+                fromNode = temp;
+
+                reversedLinks.remove(l);
+                reversedLinkEndPoints.remove(l);
+                reversedLinkStartPoints.remove(l);
+            }
+
+            // Remove preds-edges bottom up, starting at "to" node
+            // Cannot start from "from" node since there might be joint edges
+            List<LayoutEdge> toNodePredsEdges = List.copyOf(toNode.preds);
+            for (LayoutEdge edge : toNodePredsEdges) {
+                LayoutNode n = edge.from;
+                LayoutEdge edgeToRemove;
+
+                if (edge.link != null && edge.link.equals(l)) {
+                    toNode.preds.remove(edge);
+                    edgeToRemove = edge;
+                } else {
+                    // Wrong edge, look at next
+                    continue;
+                }
+
+                if (n.vertex != null && n.vertex.equals(from)) {
+                    // No dummy nodes inbetween 'from' and 'to' vertex
+                    n.succs.remove(edgeToRemove);
+                    break;
+                } else {
+                    // Must remove edges between dummy nodes
+                    boolean found = true;
+                    LayoutNode prev = toNode;
+                    while (n.vertex == null && found) {
+                        found = false;
+
+                        if (n.succs.size() <= 1 && n.preds.size() <= 1) {
+                            // Dummy node used only for this link, remove if not already removed
+                            if (nodes.contains(n)) {
+                                removeNode(n);
+                            }
+                        } else {
+                            // anchor node, should not be removed
+                            break;
+                        }
+
+                        if (n.preds.size() == 1) {
+                            n.succs.remove(edgeToRemove);
+                            prev = n;
+                            edgeToRemove = n.preds.get(0);
+                            n = edgeToRemove.from;
+                            found = true;
+                        }
+                    }
+
+                    n.succs.remove(edgeToRemove);
+                    prev.preds.remove(edgeToRemove);
+                }
+                break;
+            }
+
+            ensureNeighborEdgeConsistency();
+        }
+
+        private void removeNodeWithoutRemovingLayer(LayoutNode node) {
+            boolean prevShouldRemoveEmptyLayers = shouldRemoveEmptyLayers;
+            shouldRemoveEmptyLayers = false;
+            removeNode(node);
+            shouldRemoveEmptyLayers = prevShouldRemoveEmptyLayers;
+        }
+
+        private void removeNode(LayoutNode node) {
+            if (!nodes.contains(node)) {
+                return;
+            }
+            int layer = node.layer;
+            int pos = node.pos;
+            List<LayoutNode> remainingLayerNodes = layers.get(layer);
+            assert remainingLayerNodes.contains(node);
+            remainingLayerNodes.remove(node);
+
+            // Update position of remaining nodes on the same layer
+            boolean onlyDummiesLeft = true;
+            for (LayoutNode n : remainingLayerNodes) {
+                if (n.pos > pos) {
+                    n.pos -= 1;
+                }
+                if (n.vertex != null || n.preds.size() > 1) {
+                    onlyDummiesLeft = false;
+                }
+            }
+
+            if (onlyDummiesLeft && shouldRemoveEmptyLayers) {
+                layers.remove(layer);
+                for (int i = layer + 1; i <= layers.size(); i++) {
+                    List<LayoutNode> list = layers.get(i);
+                    layers.remove(i);
+                    layers.put(i - 1, list);
+                    for (LayoutNode n : list) {
+                        n.layer -= 1;
+                    }
+                }
+                for (LayoutNode n : remainingLayerNodes) {
+                    if (n.preds.size() == 1) {
+                        LayoutEdge predEdge = n.preds.get(0);
+                        LayoutNode fromNode = predEdge.from;
+                        fromNode.succs.remove(predEdge);
+                        for (LayoutEdge e : n.succs) {
+                            e.from = fromNode;
+                            e.relativeFrom = predEdge.relativeFrom;
+                            fromNode.succs.add(e);
+                        }
+                    }
+                    nodes.remove(n);
+                }
+            } else {
+                layers.put(layer, remainingLayerNodes);
+                adjustXCoordinates(layer);
+            }
+
+            // Remove node from graph layout
+            nodes.remove(node);
+        }
+
+        private void applyRemoveVertexAction(VertexAction action) {
+            LayoutNode node = vertexToLayoutNode.get(action.vertex);
+
+            assert nodes.contains(node);
+
+            // Remove associated edges
+            for (LinkAction a : action.linkActions) {
+                if (a.action == Action.REMOVE) {
+                    applyRemoveLinkAction(a.link);
+                }
+            }
+
+            removeNode(node);
+        }
+
+        void run() {
+            for (LinkAction action : linkActions) {
+                if (action.action == Action.REMOVE) {
+                    applyRemoveLinkAction(action.link);
+                }
+            }
+
+            for (VertexAction action : vertexActions) {
+                switch (action.action) {
+                    case REMOVE:
+                        applyRemoveVertexAction(action);
+                        break;
+                    case ADD:
+                        applyAddVertexAction(action);
+                        break;
+                    default:
+                        assert false : "Invalid update action";
+                }
+            }
+
+            for (LinkAction action : linkActions) {
+                if (action.action == Action.ADD) {
+                    applyAddLinkAction(action.link);
+                }
+            }
+
+            // Add or remove wrongful links
+            Set<Link> layoutedLinks = new HashSet<>();
+            Set<LayoutNode> layoutedNodes = new HashSet<>();
+            for (LayoutNode n : nodes) {
+                for (LayoutEdge e : n.preds) {
+                    if (e.link != null) {
+                        layoutedLinks.add(e.link);
+                    }
+                }
+                if (n.vertex != null) {
+                    layoutedNodes.add(n);
+                }
+            }
+            Set<Link> superfluousLinks = new HashSet<>(layoutedLinks);
+            superfluousLinks.removeAll(currentLinks);
+            for (Link l : superfluousLinks) {
+                applyRemoveLinkAction(l);
+                layoutedLinks.remove(l);
+            }
+            Set<Link> missingLinks = new HashSet<>(currentLinks);
+            missingLinks.removeAll(layoutedLinks);
+            for (Link l : missingLinks) {
+                applyAddLinkAction(l);
+                layoutedLinks.add(l);
+            }
+            assert currentVertices.size() == layoutedNodes.size();
+            assert currentLinks.size() == layoutedLinks.size();
+        }
+    }
+
+    private class AssignYCoordinates {
+        void run() {
+
+            // Reset all values before assigning y-coordinates
+            for (LayoutNode n : nodes) {
+                if (n.vertex != null) {
+                    updateNodeWithReversedEdges(n);
+                } else {
+                    n.height = DUMMY_HEIGHT;
+                }
+                n.y = 0;
+            }
+
+            int curY = 0;
+
+            for (int i = 0; i < layers.size(); i++) {
+                List<LayoutNode> layer = layers.get(i);
+                int maxHeight = 0;
+                int baseLine = 0;
+                int bottomBaseLine = 0;
+                for (LayoutNode n : layer) {
+                    maxHeight = Math.max(maxHeight, n.height - n.yOffset - n.bottomYOffset);
+                    baseLine = Math.max(baseLine, n.yOffset);
+                    bottomBaseLine = Math.max(bottomBaseLine, n.bottomYOffset);
+                }
+
+                int maxXOffset = 0;
+                for (LayoutNode n : layer) {
+                    if (n.vertex == null) {
+                        // Dummy node
+                        n.y = curY;
+                        n.height = maxHeight + baseLine + bottomBaseLine;
+
+                    } else {
+                        n.y = curY + baseLine + (maxHeight - (n.height - n.yOffset - n.bottomYOffset)) / 2 - n.yOffset;
+                    }
+
+                    for (LayoutEdge e : n.succs) {
+                        int curXOffset = Math.abs(n.x - e.to.x);
+                        maxXOffset = Math.max(curXOffset, maxXOffset);
+                    }
+                }
+
+                curY += maxHeight + baseLine + bottomBaseLine;
+                curY += LAYER_OFFSET + ((int) (Math.sqrt(maxXOffset) * 1.5));
+            }
+        }
+    }
+
+    private class WriteResult {
+
+        private List<Point> edgePoints(LayoutEdge e) {
+            ArrayList<Point> points = new ArrayList<>();
+
+            Point p = new Point(e.to.x + e.relativeTo,
+                    e.to.y + e.to.yOffset + e.link.getTo().getRelativePosition().y);
+            points.add(p);
+            if (e.to.inOffsets.containsKey(e.relativeTo)) {
+                points.add(new Point(p.x,
+                        p.y + e.to.inOffsets.get(e.relativeTo) + e.link.getTo().getRelativePosition().y));
+            }
+
+            LayoutNode cur = e.from;
+            LayoutEdge curEdge = e;
+            while (cur.vertex == null && !cur.preds.isEmpty()) {
+                if (points.size() > 1 && points.get(points.size() - 1).x == cur.x + cur.width / 2
+                        && points.get(points.size() - 2).x == cur.x + cur.width / 2) {
+                    // On the same vertical line, can remove previous point
+                    points.remove(points.size() - 1);
+                }
+                // Top of the dummy node
+                points.add(new Point(cur.x + cur.width / 2, cur.y + cur.height));
+                if (points.size() > 1 && points.get(points.size() - 1).x == cur.x + cur.width / 2
+                        && points.get(points.size() - 2).x == cur.x + cur.width / 2) {
+                    points.remove(points.size() - 1);
+                }
+                // Bottom of the dummy node
+                points.add(new Point(cur.x + cur.width / 2, cur.y));
+                assert cur.preds.size() == 1;
+                curEdge = cur.preds.get(0);
+                cur = curEdge.from;
+            }
+
+            p = new Point(cur.x + curEdge.relativeFrom, cur.y + cur.height - cur.bottomYOffset
+                    + (curEdge.link == null ? 0 : curEdge.link.getFrom().getRelativePosition().y));
+            if (curEdge.from.outOffsets.containsKey(curEdge.relativeFrom)) {
+                points.add(new Point(p.x, p.y + curEdge.from.outOffsets.get(curEdge.relativeFrom)
+                        + (curEdge.link == null ? 0 : curEdge.link.getFrom().getRelativePosition().y)));
+            }
+            points.add(p);
+
+            Collections.reverse(points);
+
+            if (reversedLinks.contains(e.link)) {
+                Collections.reverse(points);
+
+                assert reversedLinkStartPoints.containsKey(e.link);
+                for (Point p1 : reversedLinkStartPoints.get(e.link)) {
+                    points.add(new Point(p1.x + cur.x, p1.y + cur.y));
+                }
+
+                assert reversedLinkEndPoints.containsKey(e.link);
+                for (Point p1 : reversedLinkEndPoints.get(e.link)) {
+                    points.add(0, new Point(p1.x + e.to.x, p1.y + e.to.y));
+                }
+            }
+
+            return points;
+        }
+
+        void run() {
+            HashMap<Vertex, Point> vertexPositions = new HashMap<>();
+            HashMap<Link, List<Point>> linkPositions = new HashMap<>();
+
+            for (LayoutNode n : nodes) {
+
+                if (n.vertex != null) {
+                    assert !vertexPositions.containsKey(n.vertex);
+                    vertexPositions.put(n.vertex, new Point(n.x + n.xOffset, n.y + n.yOffset));
+                } else {
+                    continue;
+                }
+
+                // All edges can be drawn from bottom up, the links are stored in the preds list
+                // of each node
+                for (LayoutEdge e : n.preds) {
+                    if (e.link != null && !linkPositions.containsKey(e.link)) {
+                        List<Point> points = edgePoints(e);
+                        assert !linkPositions.containsKey(e.link);
+                        linkPositions.put(e.link, points);
+                    }
+                }
+            }
+
+            // Ensure all edges are drawn
+            assert currentLinks.size() <= linkPositions.keySet().size();
+
+            int minX = Integer.MAX_VALUE;
+            int minY = Integer.MAX_VALUE;
+            for (Vertex v : vertexPositions.keySet()) {
+                Point p = vertexPositions.get(v);
+                minX = Math.min(minX, p.x);
+                minY = Math.min(minY, p.y);
+            }
+
+            for (Link l : linkPositions.keySet()) {
+                List<Point> points = linkPositions.get(l);
+                for (Point p : points) {
+                    if (p != null) {
+                        minX = Math.min(minX, p.x);
+                        minY = Math.min(minY, p.y);
+                    }
+                }
+            }
+
+            for (Vertex v : vertexPositions.keySet()) {
+                Point p = vertexPositions.get(v);
+                p.x -= minX;
+                p.y -= minY;
+                v.setPosition(p);
+            }
+
+            for (Link l : linkPositions.keySet()) {
+                List<Point> points = linkPositions.get(l);
+                for (Point p : points) {
+                    if (p != null) {
+                        p.x -= minX;
+                        p.y -= minY;
+                    }
+                }
+                l.setControlPoints(points);
+            }
+        }
+    }
+}
diff --git a/src/utils/IdealGraphVisualizer/HierarchicalLayout/src/main/java/com/sun/hotspot/igv/hierarchicallayout/LayoutEdge.java b/src/utils/IdealGraphVisualizer/HierarchicalLayout/src/main/java/com/sun/hotspot/igv/hierarchicallayout/LayoutEdge.java
new file mode 100644
index 00000000000..081135a2abf
--- /dev/null
+++ b/src/utils/IdealGraphVisualizer/HierarchicalLayout/src/main/java/com/sun/hotspot/igv/hierarchicallayout/LayoutEdge.java
@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+package com.sun.hotspot.igv.hierarchicallayout;
+
+import com.sun.hotspot.igv.layout.Link;
+
+public class LayoutEdge {
+
+        public LayoutNode from;
+        public LayoutNode to;
+        // Horizontal distance relative to start of 'from'.
+        public int relativeFrom;
+        // Horizontal distance relative to start of 'to'.
+        public int relativeTo;
+        public Link link;
+        public boolean vip;
+
+        @Override
+        public String toString() {
+            return "Edge " + from + ", " + to;
+        }
+    }
diff --git a/src/utils/IdealGraphVisualizer/HierarchicalLayout/src/main/java/com/sun/hotspot/igv/hierarchicallayout/LayoutNode.java b/src/utils/IdealGraphVisualizer/HierarchicalLayout/src/main/java/com/sun/hotspot/igv/hierarchicallayout/LayoutNode.java
new file mode 100644
index 00000000000..848ada1b77d
--- /dev/null
+++ b/src/utils/IdealGraphVisualizer/HierarchicalLayout/src/main/java/com/sun/hotspot/igv/hierarchicallayout/LayoutNode.java
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+package com.sun.hotspot.igv.hierarchicallayout;
+
+import com.sun.hotspot.igv.layout.Vertex;
+import java.util.*;
+
+public class LayoutNode {
+
+        public int x;
+        public int y;
+        public int width;
+        public int height;
+        public int layer = -1;
+        public int xOffset;
+        public int yOffset;
+        public int bottomYOffset;
+        public Vertex vertex; // Only used for non-dummy nodes, otherwise null
+
+        public List<LayoutEdge> preds = new ArrayList<>();
+        public List<LayoutEdge> succs = new ArrayList<>();
+        public HashMap<Integer, Integer> outOffsets = new HashMap<>();
+        public HashMap<Integer, Integer> inOffsets = new HashMap<>();
+        public int pos = -1; // Position within layer
+
+        public int crossingNumber;
+
+        @Override
+        public String toString() {
+            return "Node " + vertex;
+        }
+    }
diff --git a/src/utils/IdealGraphVisualizer/Settings/src/main/java/com/sun/hotspot/igv/settings/Settings.java b/src/utils/IdealGraphVisualizer/Settings/src/main/java/com/sun/hotspot/igv/settings/Settings.java
index d80f4ab3687..41af4a1d262 100644
--- a/src/utils/IdealGraphVisualizer/Settings/src/main/java/com/sun/hotspot/igv/settings/Settings.java
+++ b/src/utils/IdealGraphVisualizer/Settings/src/main/java/com/sun/hotspot/igv/settings/Settings.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2023, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -36,6 +36,7 @@ public class Settings {
         public static final int SEA_OF_NODES = 0;
         public static final int CLUSTERED_SEA_OF_NODES = 1;
         public static final int CONTROL_FLOW_GRAPH = 2;
+        public static final int STABLE_SEA_OF_NODES = 3;
     }
 
     public static final String NODE_TEXT = "nodeText";
diff --git a/src/utils/IdealGraphVisualizer/Util/src/main/java/com/sun/hotspot/igv/util/Statistics.java b/src/utils/IdealGraphVisualizer/Util/src/main/java/com/sun/hotspot/igv/util/Statistics.java
new file mode 100644
index 00000000000..b40ce7919df
--- /dev/null
+++ b/src/utils/IdealGraphVisualizer/Util/src/main/java/com/sun/hotspot/igv/util/Statistics.java
@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package com.sun.hotspot.igv.util;
+
+import java.util.Arrays;
+
+public class Statistics {
+
+    public static int median(int[] values) {
+        Arrays.sort(values);
+        if (values.length % 2 == 0) {
+            return (values[values.length / 2 - 1] + values[values.length / 2]) / 2;
+        } else {
+            return values[values.length / 2];
+        }
+    }
+}
diff --git a/src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/DiagramScene.java b/src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/DiagramScene.java
index e4ee0be8311..23cd4a4360f 100644
--- a/src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/DiagramScene.java
+++ b/src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/DiagramScene.java
@@ -26,10 +26,7 @@ package com.sun.hotspot.igv.view;
 import com.sun.hotspot.igv.data.Properties;
 import com.sun.hotspot.igv.data.*;
 import com.sun.hotspot.igv.graph.*;
-import com.sun.hotspot.igv.hierarchicallayout.HierarchicalCFGLayoutManager;
-import com.sun.hotspot.igv.hierarchicallayout.HierarchicalClusterLayoutManager;
-import com.sun.hotspot.igv.hierarchicallayout.HierarchicalLayoutManager;
-import com.sun.hotspot.igv.hierarchicallayout.LinearLayoutManager;
+import com.sun.hotspot.igv.hierarchicallayout.*;
 import com.sun.hotspot.igv.layout.LayoutGraph;
 import com.sun.hotspot.igv.selectioncoordinator.SelectionCoordinator;
 import com.sun.hotspot.igv.util.ColorIcon;
@@ -87,6 +84,7 @@ public class DiagramScene extends ObjectScene implements DiagramViewer, DoubleCl
     private final DiagramViewModel model;
     private ModelState modelState;
     private boolean rebuilding;
+    private final HierarchicalStableLayoutManager hierarchicalStableLayoutManager;
 
     /**
      * The alpha level of partially visible figures.
@@ -487,6 +485,8 @@ public class DiagramScene extends ObjectScene implements DiagramViewer, DoubleCl
                 }
             }
         });
+
+        hierarchicalStableLayoutManager = new HierarchicalStableLayoutManager();
     }
 
     @Override
@@ -688,10 +688,15 @@ public class DiagramScene extends ObjectScene implements DiagramViewer, DoubleCl
         return w1.isVisible() && w2.isVisible();
     }
 
+    private void doStableSeaLayout(HashSet<Figure> visibleFigures, HashSet<Connection> visibleConnections) {
+        hierarchicalStableLayoutManager.updateLayout(visibleFigures, visibleConnections);
+    }
+
     private void doSeaLayout(HashSet<Figure> figures, HashSet<Connection> edges) {
         HierarchicalLayoutManager manager = new HierarchicalLayoutManager(HierarchicalLayoutManager.Combine.SAME_OUTPUTS);
         manager.setMaxLayerLength(10);
         manager.doLayout(new LayoutGraph(edges, figures));
+        hierarchicalStableLayoutManager.setShouldRedrawLayout(true);
     }
 
     private void doClusteredLayout(HashSet<Connection> edges) {
@@ -1187,7 +1192,9 @@ public class DiagramScene extends ObjectScene implements DiagramViewer, DoubleCl
 
         HashSet<Figure> visibleFigures = getVisibleFigures();
         HashSet<Connection> visibleConnections = getVisibleConnections();
-        if (getModel().getShowSea()) {
+        if (getModel().getShowStableSea()) {
+            doStableSeaLayout(visibleFigures, visibleConnections);
+        } else if (getModel().getShowSea()) {
             doSeaLayout(visibleFigures, visibleConnections);
         } else if (getModel().getShowBlocks()) {
             doClusteredLayout(visibleConnections);
diff --git a/src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/DiagramViewModel.java b/src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/DiagramViewModel.java
index 90b84fd7ec6..f48e05ec6b9 100644
--- a/src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/DiagramViewModel.java
+++ b/src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/DiagramViewModel.java
@@ -62,6 +62,7 @@ public class DiagramViewModel extends RangeSliderModel implements ChangedListene
     private final ChangedEvent<DiagramViewModel> selectedNodesChangedEvent = new ChangedEvent<>(this);
     private final ChangedEvent<DiagramViewModel> hiddenNodesChangedEvent = new ChangedEvent<>(this);
     private ChangedListener<InputGraph> titleChangedListener = g -> {};
+    private boolean showStableSea;
     private boolean showSea;
     private boolean showBlocks;
     private boolean showCFG;
@@ -90,6 +91,17 @@ public class DiagramViewModel extends RangeSliderModel implements ChangedListene
         }
     }
 
+    public boolean getShowStableSea() {
+        return showStableSea;
+    }
+
+    public void setShowStableSea(boolean enable) {
+        showStableSea = enable;
+        if (enable) {
+            diagramChangedEvent.fire();
+        }
+    }
+
     public boolean getShowSea() {
         return showSea;
     }
@@ -216,6 +228,7 @@ public class DiagramViewModel extends RangeSliderModel implements ChangedListene
         filtersOrder = provider.getAllFiltersOrdered();
 
         globalSelection = GlobalSelectionAction.get(GlobalSelectionAction.class).isSelected();
+        showStableSea = Settings.get().getInt(Settings.DEFAULT_VIEW, Settings.DEFAULT_VIEW_DEFAULT) == Settings.DefaultView.STABLE_SEA_OF_NODES;
         showSea = Settings.get().getInt(Settings.DEFAULT_VIEW, Settings.DEFAULT_VIEW_DEFAULT) == Settings.DefaultView.SEA_OF_NODES;
         showBlocks = Settings.get().getInt(Settings.DEFAULT_VIEW, Settings.DEFAULT_VIEW_DEFAULT) == Settings.DefaultView.CLUSTERED_SEA_OF_NODES;
         showCFG = Settings.get().getInt(Settings.DEFAULT_VIEW, Settings.DEFAULT_VIEW_DEFAULT) == Settings.DefaultView.CONTROL_FLOW_GRAPH;
diff --git a/src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/EditorTopComponent.java b/src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/EditorTopComponent.java
index 1f1d6fe83d1..57d2b006ac0 100644
--- a/src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/EditorTopComponent.java
+++ b/src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/EditorTopComponent.java
@@ -175,6 +175,11 @@ public final class EditorTopComponent extends TopComponent implements TopCompone
         toolBar.addSeparator();
         ButtonGroup layoutButtons = new ButtonGroup();
 
+        JToggleButton stableSeaLayoutButton = new JToggleButton(new EnableStableSeaLayoutAction(this));
+        stableSeaLayoutButton.setSelected(diagramViewModel.getShowStableSea());
+        layoutButtons.add(stableSeaLayoutButton);
+        toolBar.add(stableSeaLayoutButton);
+
         JToggleButton seaLayoutButton = new JToggleButton(new EnableSeaLayoutAction(this));
         seaLayoutButton.setSelected(diagramViewModel.getShowSea());
         layoutButtons.add(seaLayoutButton);
@@ -191,6 +196,17 @@ public final class EditorTopComponent extends TopComponent implements TopCompone
         layoutButtons.add(cfgLayoutButton);
         toolBar.add(cfgLayoutButton);
 
+        diagramViewModel.getGraphChangedEvent().addListener(model -> {
+            // HierarchicalStableLayoutManager is not reliable for difference graphs
+            boolean isDiffGraph = model.getGraph().isDiffGraph();
+            // deactivate HierarchicalStableLayoutManager for difference graphs
+            stableSeaLayoutButton.setEnabled(!isDiffGraph);
+            if (stableSeaLayoutButton.isSelected() && isDiffGraph) {
+                // fallback to HierarchicalLayoutManager for difference graphs
+                seaLayoutButton.setSelected(true);
+            }
+        });
+
         toolBar.addSeparator();
         toolBar.add(new JToggleButton(new PredSuccAction(diagramViewModel.getShowNodeHull())));
         toolBar.add(new JToggleButton(new ShowEmptyBlocksAction(cfgLayoutAction, diagramViewModel.getShowEmptyBlocks())));
diff --git a/src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/actions/EnableStableSeaLayoutAction.java b/src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/actions/EnableStableSeaLayoutAction.java
new file mode 100644
index 00000000000..069d04a8531
--- /dev/null
+++ b/src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/actions/EnableStableSeaLayoutAction.java
@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+package com.sun.hotspot.igv.view.actions;
+
+import com.sun.hotspot.igv.view.EditorTopComponent;
+import java.beans.PropertyChangeEvent;
+
+public class EnableStableSeaLayoutAction extends EnableLayoutAction {
+
+    public EnableStableSeaLayoutAction(EditorTopComponent etc) {
+        super(etc);
+    }
+
+    @Override
+    protected String iconResource() {
+        return "com/sun/hotspot/igv/view/images/stable_sea.png";
+    }
+
+    @Override
+    protected String getDescription() {
+        return "Show stable sea of nodes";
+    }
+
+    @Override
+    public void propertyChange(PropertyChangeEvent evt) {
+        editor.getModel().setShowStableSea(this.isSelected());
+    }
+}
diff --git a/src/utils/IdealGraphVisualizer/View/src/main/resources/com/sun/hotspot/igv/view/images/stable_sea.png b/src/utils/IdealGraphVisualizer/View/src/main/resources/com/sun/hotspot/igv/view/images/stable_sea.png
new file mode 100644
index 0000000000000000000000000000000000000000..fe366b10b399ce9015834a24ace8ad92b32b044f
GIT binary patch
literal 2111
zcmeAS@N?(olHy`uVBq!ia0vp^0wB!61|;P_|4(FKVBC=D>>S|f?5q$_l%JNFlghxL
zF|l@{tw(gA$nko&ZY9BX3yYG9W-sn6S6LZTNtY0gm90^tHI+YwCQU!>?Ib9}9n0z(
zI3dis<ZZwfi_!ui7RL|GV%A+(P6mlje7>{NYtbThzURmP-~GSy`CRUO^2>r=uHrj!
zqf-5nyve=3ea5T&KLobVXSlm;YH;nt4+28lzvjif310X*ZuUFVAKBLbvXVYmJbnN2
z^!xfa9UGf^^;bzB=dg;l6|7%6XU~Tv1wU%zGXJUFd2k}&Q1q<Ha`IVyRW)HY#zLHm
z$=(uSr+PSF&s!UI>LkbOowJi>&bT)9__k-2XD=G%Z|X6A*;H!0{GW6Eox0Ca^QYJN
z*)#J9A5-vZ)V%a0b8=SqBxR-h&HX=icmETJ6uE5i$a9j=cE|Y|URFn2*_TXqwO)H@
zZiz?P%k4Y&f1Wh$FOTj2g+<$zxQZt}RyL8Fx@DPvz<<VT+o!yo;kq*D(sYjlKf^00
z1#-M`dK;m4@#;(8_xy)8Ctv@2o#$$Cf$8gA(^s#n-m3QO{)fxozSUgr)@L^`Vs^IP
zu!Tq0b7%3NiM3ZmzJL63F6&fz9dAHGqubhqy?($b{FWNwnda-upao=eFmN#PF)#sH
zLO`6yD8#@Fq#1#bfl-Qq70hN}Xke6vvpX0yplX0B84baDd4cLCFdBi`B0%=M_DlvA
zsNPLLn!&j!HL)Z$MWH;iBtya7(>DMlsRK~~p+SNQMtX(@dWIGZ3`Pb<hE|3^WS{_K
z7#mob8Zt02PikXe2kMao;yVkN;5G;>U`DWkatw~a&Yqq?8q?M{vOQ%$3C;qK$YKTt
zJ!KGPtXOIf6l9r`84^(v;p=0SoS&<gn3A8As#lR)05Xrkrosxy%uOvxRH(?!$t$+1
zuvG%9umZ9{!um=IU?nBlwn`B|k2vQSr7D=|8R!`(*>Nc-DA*LGq*(>IxIwi8dA3R!
zB_#z``ugSN<$C4Ddih1^`i7R4mih)p`bI{&Koz>hm3bwJ6}oxF$`C_f=D4I5Cl_TF
zlw{`TDS*sPOv*1Uu~kw6Sp)|Vca~(PA#BPkhI$L=L4A;nzM-ChJ~nNs6`44+fn;!M
zOG$?Ns-Uze2kfVmWc}2f)ZEm(l477fL#);T!xpX)#gP?>1rW=?fe7)N4antIkwK}&
z`8lPaFt9T;FgLN#w=}c?dkRGg5hM_82wkChnI(3{P%UV}=(-{h^5~W!OQCD?FUkaZ
zI}zeWs7=UXNa{hsYUP}tlV22EkeHlm2lNZN5W4En;?yGN{9I7TB83hxjKFElF$YZ)
zCXtf~N`qE8iFxU^N)@^(scDI&IVDPV7<t7;AC$IoGSLhNi=vtibt`rU*`y>}r63Y4
znrR>_Pz{4dGQ@5gI2EUJY=EiI$~QkHGp*7ESXSAAiXdG>ATkJn6+t%oXljt+1SA6v
z!~CL<{QMj{<nj!n4_Owf5fa8o`57EM5K&-hVaEm32`hQ*xX#%g{0}UQx;<SSLo5WB
zPJGDMpuo|x_~*a%F|yoc76E2IC$@YjY_gdj%Wk$K%;m@SFFVs2{)k$81=LK>oh5#}
z;SHzbBR>y@8wCbFpLr)7Ex2CC)NpfJ6O+JZznBwt3%DLEa4b0VLi2M~Y1o<szYA4M
zb?n|shVX<1JdLo4&F6L~HkdJ=$HTfJ?V(1()rBiQf8d_@MnlK=>T+-y@9FC2vd$@?
F2>_?8sQ>@~

literal 0
HcmV?d00001