8272158: SoftReference related bugs under memory pressure

Reviewed-by: jjg

Author: hns

src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/toolkit/builders/MemberSummaryBuilder.java

@@ -270,9 +270,6 @@ private void buildSummary(MemberSummaryWriter writer,
                                     new DocFinder.Input(utils, member));
                     if (inheritedDoc.holder != null
                             && !utils.getFirstSentenceTrees(inheritedDoc.holder).isEmpty()) {
-                        // let the comment helper know of the overridden element
-                        CommentHelper ch = utils.getCommentHelper(member);
-                        ch.setOverrideElement(inheritedDoc.holder);
                         firstSentenceTags = utils.getFirstSentenceTrees(inheritedDoc.holder);
                     }
                 }

src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/toolkit/util/CommentHelper.java

@@ -31,6 +31,7 @@
 import java.util.stream.Collectors;
 
 import javax.lang.model.element.Element;
+import javax.lang.model.element.ExecutableElement;
 import javax.lang.model.element.ModuleElement;
 import javax.lang.model.element.PackageElement;
 import javax.lang.model.element.TypeElement;
@@ -87,7 +88,6 @@ public class CommentHelper {
     public final TreePath path;
     public final DocCommentTree dcTree;
     public final Element element;
-    private Element overriddenElement;
 
     public static final String SPACER = " ";
 
@@ -106,13 +106,6 @@ public CommentHelper(BaseConfiguration configuration, Element element, TreePath
         this.dcTree = dcTree;
     }
 
-    public void setOverrideElement(Element ove) {
-        if (this.element == ove) {
-            throw new AssertionError("cannot set given element as overridden element");
-        }
-        overriddenElement = ove;
-    }
-
     public String getTagName(DocTree dtree) {
         switch (dtree.getKind()) {
             case AUTHOR:
@@ -679,22 +672,28 @@ public ReferenceTree getType(DocTree dtree) {
     }
 
     public DocTreePath getDocTreePath(DocTree dtree) {
-        if (dcTree == null && overriddenElement != null) {
-            // This is an inherited comment, return path from ancestor.
-            return configuration.utils.getCommentHelper(overriddenElement).getDocTreePath(dtree);
-        } else if (path == null || dcTree == null || dtree == null) {
+        if (dcTree == null && element instanceof ExecutableElement ee) {
+            return getInheritedDocTreePath(dtree, ee);
+        }
+        if (path == null || dcTree == null || dtree == null) {
             return null;
         }
         DocTreePath dtPath = DocTreePath.getPath(path, dcTree, dtree);
-        if (dtPath == null && overriddenElement != null) {
+        if (dtPath == null && element instanceof ExecutableElement ee) {
             // The overriding element has a doc tree, but it doesn't contain what we're looking for.
-            return configuration.utils.getCommentHelper(overriddenElement).getDocTreePath(dtree);
+            return getInheritedDocTreePath(dtree, ee);
         }
         return dtPath;
     }
 
-    public Element getOverriddenElement() {
-        return overriddenElement;
+    private DocTreePath getInheritedDocTreePath(DocTree dtree, ExecutableElement ee) {
+        Utils utils = configuration.utils;
+        DocFinder.Output inheritedDoc =
+                DocFinder.search(configuration,
+                        new DocFinder.Input(utils, ee));
+        return inheritedDoc == null || inheritedDoc.holder == ee
+                ? null
+                : utils.getCommentHelper(inheritedDoc.holder).getDocTreePath(dtree);
     }
 
     /**
@@ -708,14 +707,6 @@ public String toString() {
         sb.append(element.getEnclosingElement());
         sb.append("::");
         sb.append(element);
-        sb.append(", overriddenElement=");
-        if (overriddenElement != null) {
-            sb.append(overriddenElement.getEnclosingElement());
-            sb.append("::");
-            sb.append(overriddenElement);
-        } else {
-            sb.append("<none>");
-        }
         sb.append('}');
         return sb.toString();
     }

src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/toolkit/util/VisibleMemberTable.java

@@ -947,13 +947,14 @@ private void computeVisibleProperties(LocalMemberTable lmt) {
     Map<ExecutableElement, SoftReference<ImplementedMethods>> implementMethodsFinders = new HashMap<>();
 
     private ImplementedMethods getImplementedMethodsFinder(ExecutableElement method) {
-        SoftReference<ImplementedMethods> imf = implementMethodsFinders.get(method);
-        // IMF does not exist or referent was gc'ed away ?
-        if (imf == null || imf.get() == null) {
-            imf = new SoftReference<>(new ImplementedMethods(method));
-            implementMethodsFinders.put(method, imf);
+        SoftReference<ImplementedMethods> ref = implementMethodsFinders.get(method);
+        ImplementedMethods imf = ref == null ? null : ref.get();
+        // imf does not exist or was gc'ed away?
+        if (imf == null) {
+            imf = new ImplementedMethods(method);
+            implementMethodsFinders.put(method, new SoftReference<>(imf));
         }
-        return imf.get();
+        return imf;
     }
 
     public List<ExecutableElement> getImplementedMethods(ExecutableElement method) {