GH-445 collapse repetitive nodes

Author: thurka

visualvm/heapviewer/src/org/graalvm/visualvm/heapviewer/java/impl/HeapPatterns.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2022, 2022, 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 org.graalvm.visualvm.heapviewer.java.impl;
+
+import org.graalvm.visualvm.lib.jfluid.heap.Field;
+import org.graalvm.visualvm.lib.jfluid.heap.FieldValue;
+import org.graalvm.visualvm.lib.jfluid.heap.Instance;
+import org.graalvm.visualvm.lib.jfluid.heap.JavaClass;
+import org.graalvm.visualvm.lib.jfluid.heap.ObjectFieldValue;
+import org.openide.util.NbBundle;
+
+/**
+ *
+ * @author Tomas Hurka
+ */
+@NbBundle.Messages({
+    "HeapPatterns_SkippedInstances={0} ({1} instances of {2})"
+})
+final class HeapPatterns {
+
+    static PathToGCRootPlugin.SkipNode processGCRootReference(ObjectFieldValue reference) {
+        ObjectFieldValue ref = reference;
+        int skipped = 0;
+        for (; ;skipped++) {
+            Instance i = ref.getDefiningInstance();
+            Instance path = i.getNearestGCRootPointer();
+            if (!i.getJavaClass().equals(path.getJavaClass())) {
+                break;
+            }
+            ObjectFieldValue oval = getValueOfField(path, ref.getField());
+            if (oval == null || !oval.getInstance().equals(i)) {
+                break;
+            }
+            ref = oval;
+        }
+        if (skipped>1) {
+            JavaClass jcls = ref.getDefiningInstance().getJavaClass();
+            String text = Bundle.HeapPatterns_SkippedInstances(ref.getField().getName(), skipped, jcls.getName());
+            return new PathToGCRootPlugin.SkipNode(text, ref);
+        }
+        return null;
+    }
+
+    static ObjectFieldValue getValueOfField(Instance i, Field f) {
+        for (FieldValue val : i.getFieldValues()) {
+            if (val instanceof ObjectFieldValue) {
+                ObjectFieldValue oval = (ObjectFieldValue) val;
+                if (oval.getField().equals(f)) {
+                    return oval;
+                }
+            }
+        }
+        return null;
+    }
+}

visualvm/heapviewer/src/org/graalvm/visualvm/heapviewer/java/impl/PathToGCRootPlugin.java

@@ -360,7 +360,7 @@ private static Collection<HeapViewerNode> computeInstanceRoots(Instance instance
             return Collections.singleton(new TextNode(Bundle.PathToGCRootPlugin_IsRoot()));
         } else {
             ToRoot node = null;
-            HeapViewerNode firstNode = null;
+            ToRoot firstNode = null;
             ToRoot previousNode = null;
 
             try {
@@ -371,10 +371,23 @@ private static Collection<HeapViewerNode> computeInstanceRoots(Instance instance
                     List<Value> references = instance.getReferences();
                     for (Value reference : references) {
                         if (nextInstance.equals(reference.getDefiningInstance())) {
-                            if (reference instanceof ObjectFieldValue) node = new FieldToRoot((ObjectFieldValue)reference);
-                            else if (reference instanceof ArrayItemValue) node = new ArrayItemToRoot((ArrayItemValue)reference);
+                            if (reference instanceof ObjectFieldValue) {
+                                ObjectFieldValue ref = (ObjectFieldValue)reference;
+                                SkipNode snode = HeapPatterns.processGCRootReference(ref);
+                                if (snode != null) {
+                                    ref = snode.getNextReference();
+                                    nextInstance = ref.getDefiningInstance();
+                                    node = snode;
+                                    if (firstNode == null) firstNode = node;
+                                    else previousNode.setChildren(new HeapViewerNode[] { (HeapViewerNode)node });
+                                    previousNode = node;
+                                }
+                                node = new FieldToRoot(ref);
+                            } else if (reference instanceof ArrayItemValue) {
+                                node = new ArrayItemToRoot((ArrayItemValue)reference);
+                            }
 
-                            if (firstNode == null) firstNode = (HeapViewerNode)node;
+                            if (firstNode == null) firstNode = node;
                             else previousNode.setChildren(new HeapViewerNode[] { (HeapViewerNode)node });
 
                             break;
@@ -394,7 +407,7 @@ private static Collection<HeapViewerNode> computeInstanceRoots(Instance instance
                 progress.finish();
             }
 
-            return Collections.singleton(firstNode);
+            return Collections.singleton((HeapViewerNode) firstNode);
         }
     }
 
@@ -609,6 +622,23 @@ public void setChildren(HeapViewerNode[] ch) {
 
     }
 
+    static class SkipNode extends TextNode implements ToRoot {
+
+        private ObjectFieldValue reference;
+
+        SkipNode(String text, ObjectFieldValue ref) {
+            super(text);
+            reference = ref;
+        }
+
+        public void setChildren(HeapViewerNode[] ch) {
+            super.setChildren(ch);
+        }
+
+        private ObjectFieldValue getNextReference() {
+            return reference;
+        }
+    }
 
     @ServiceProvider(service=HeapViewPlugin.Provider.class, position = 400)
     public static class Provider extends HeapViewPlugin.Provider {