Remove reference from IntrusivePage to its SoftReference

Util/src/main/java/io/deephaven/util/datastructures/intrusive/IntrusiveSoftLRU.java

@@ -22,6 +22,7 @@
  * @param <T> the cached type
  */
 public class IntrusiveSoftLRU<T> {
+
     private static final SoftReference<?> NULL = new SoftReference<>(null);
 
     private final Adapter<T> adapter;
@@ -126,7 +127,7 @@ private void touchLRU(@NotNull T itemToTouch) {
                 softReferences[slot].get() != itemToTouch) {
             // A new entry, place it on top of the tail
             adapter.setSlot(itemToTouch, tail);
-            softReferences[tail] = adapter.getOwner(itemToTouch);
+            softReferences[tail] = new SoftReference<>(itemToTouch);
 
             // Move the tail back one slot
             tail = prevs[tail];
@@ -170,7 +171,7 @@ private void touchSimple(@NotNull final T itemToTouch) {
                 // No, cool. Just add it.
                 final int slotForItem = size++;
                 adapter.setSlot(itemToTouch, slotForItem);
-                softReferences[slotForItem] = adapter.getOwner(itemToTouch);
+                softReferences[slotForItem] = new SoftReference<>(itemToTouch);
             } else {
                 // Yep, resize, copy, and potentially switch to LRU mode.
                 doResize();
@@ -270,20 +271,11 @@ int size() {
     /**
      * An interface defining the required intrusive property getters and setters. Users should not directly call these
      * methods, or they risk corrupting the internal data structure.
-     * 
+     *
      * @param <T>
      */
     public interface Adapter<T> {
 
-        /**
-         * Get a {@link SoftReference} object which refers to the object being cached and will act as its "owner" in the
-         * cache.
-         *
-         * @param cachedObject the object being cached.
-         * @return a {@link SoftReference} that refers to the item and will act as its "owner" in the cache.
-         */
-        SoftReference<T> getOwner(T cachedObject);
-
         /**
          * Get the slot in which the object is stored in the cache.
          *
@@ -303,38 +295,24 @@ public interface Adapter<T> {
 
     /**
      * An intrusive node for storing items in the cache.
-     * 
-     * @param <T> the actual node type
      */
-    public interface Node<T extends Node<T>> {
-
-        SoftReference<T> getOwner();
+    public interface Node {
 
         int getSlot();
 
         void setSlot(int slot);
 
         /**
          * The base node implementation for items in the cache.
-         * 
-         * @param <T>
          */
-        class Impl<T extends Impl<T>> implements Node<T> {
+        class Impl implements Node {
 
-            private final SoftReference<T> owner;
             private int slot;
 
             protected Impl() {
-                // noinspection unchecked
-                owner = new SoftReference<>((T) this);
                 slot = -1;
             }
 
-            @Override
-            public SoftReference<T> getOwner() {
-                return owner;
-            }
-
             @Override
             public int getSlot() {
                 return slot;
@@ -351,20 +329,15 @@ public void setSlot(int slot) {
          * 
          * @param <T>
          */
-        class Adapter<T extends Node<T>> implements IntrusiveSoftLRU.Adapter<T> {
+        class Adapter<T extends Node> implements IntrusiveSoftLRU.Adapter<T> {
 
             private static final IntrusiveSoftLRU.Adapter<?> INSTANCE = new Adapter<>();
 
-            public static <T extends Node<T>> IntrusiveSoftLRU.Adapter<T> getInstance() {
+            public static <T extends Node> IntrusiveSoftLRU.Adapter<T> getInstance() {
                 // noinspection unchecked
                 return (IntrusiveSoftLRU.Adapter<T>) INSTANCE;
             }
 
-            @Override
-            public SoftReference<T> getOwner(@NotNull T cachedObject) {
-                return cachedObject.getOwner();
-            }
-
             @Override
             public int getSlot(@NotNull T cachedObject) {
                 return cachedObject.getSlot();

Util/src/test/java/io/deephaven/util/datastructures/intrusive/TestIntrusiveSoftLRU.java

@@ -16,7 +16,8 @@ public class TestIntrusiveSoftLRU {
 
     private final IntrusiveSoftLRU.Adapter<TestNode> ADAPTER = new IntrusiveSoftLRU.Node.Adapter<>();
 
-    static class TestNode extends IntrusiveSoftLRU.Node.Impl<TestNode> {
+    static class TestNode extends IntrusiveSoftLRU.Node.Impl {
+
         final int index;
 
         TestNode(int index) {
@@ -126,7 +127,6 @@ public void testExpandToMax() {
                 i.remove();
             } else {
                 assertTrue(testNode.index < 16 || testNode.index >= 272);
-                assertEquals(testNode, ADAPTER.getOwner(testNode).get());
                 assertTrue(used.add(ADAPTER.getSlot(testNode)));
             }
         }
@@ -163,7 +163,6 @@ private void iterateAssertAndCount(@NotNull final List<WeakReference<TestNode>>
             } else {
                 nonNullItems++;
                 assertTrue(testNode.index >= lru.currentCapacity());
-                assertEquals(testNode, ADAPTER.getOwner(testNode).get());
                 assertTrue(used.add(ADAPTER.getSlot(testNode)));
             }
         }

extensions/parquet/table/src/main/java/io/deephaven/parquet/table/pagestore/PageCache.java

@@ -33,7 +33,7 @@ public static <ATTR extends Any> WeakReference<IntrusivePage<ATTR>> getNullPage(
     /**
      * Intrusive data structure for page caching.
      */
-    public static class IntrusivePage<ATTR extends Any> extends IntrusiveSoftLRU.Node.Impl<IntrusivePage<ATTR>> {
+    public static class IntrusivePage<ATTR extends Any> extends IntrusiveSoftLRU.Node.Impl {
 
         private final ChunkPage<ATTR> page;