Fix memory leaks in render context #1311 (#1408)

* Fix memory leaks in render context

* NativeObject.java: Codacy says "fields should be declared at the top"

* NativeObject.java: style correction (if statement without braces)

* NativeObject.java: use diamond notation (redundant type argument)

* NativeObject.java: provide javadoc for the new method

Co-authored-by: Stephen Gold <sgold@sonic.net>

jme3-core/src/main/java/com/jme3/renderer/RenderContext.java

@@ -31,6 +31,8 @@
  */
 package com.jme3.renderer;
 
+import java.lang.ref.WeakReference;
+
 import com.jme3.material.RenderState;
 import com.jme3.math.ColorRGBA;
 import com.jme3.scene.Mesh;
@@ -219,7 +221,7 @@ public class RenderContext {
      *
      * @see Renderer#setTexture(int, com.jme3.texture.Texture)
      */
-    public final Image[] boundTextures = new Image[16];
+    public final WeakReference<Image> boundTextures[] = new WeakReference[16];
 
     /**
      * IDList for texture units
@@ -252,7 +254,7 @@ public class RenderContext {
      * Vertex attribs currently bound and enabled. If a slot is null, then
      * it is disabled.
      */
-    public final VertexBuffer[] boundAttribs = new VertexBuffer[16];
+    public final WeakReference<VertexBuffer> [] boundAttribs = new WeakReference[16];
 
     /**
      * IDList for vertex attributes

jme3-core/src/main/java/com/jme3/renderer/opengl/GLRenderer.java

@@ -62,6 +62,7 @@
 import com.jme3.util.NativeObjectManager;
 import jme3tools.shader.ShaderDebug;
 
+import java.lang.ref.WeakReference;
 import java.nio.ByteBuffer;
 import java.nio.FloatBuffer;
 import java.nio.IntBuffer;
@@ -2387,9 +2388,9 @@ private void bindTextureAndUnit(int target, Image img, int unit) {
             gl.glActiveTexture(GL.GL_TEXTURE0 + unit);
             context.boundTextureUnit = unit;
         }
-        if (context.boundTextures[unit] != img) {
+        if (context.boundTextures[unit]==null||context.boundTextures[unit].get() != img.getWeakRef().get()) {
             gl.glBindTexture(target, img.getId());
-            context.boundTextures[unit] = img;
+            context.boundTextures[unit] = img.getWeakRef();
             statistics.onTextureUse(img, true);
         } else {
             statistics.onTextureUse(img, false);
@@ -2405,13 +2406,13 @@ private void bindTextureAndUnit(int target, Image img, int unit) {
      * @param unit At what unit to bind the texture.
      */
     private void bindTextureOnly(int target, Image img, int unit) {
-        if (context.boundTextures[unit] != img) {
+        if (context.boundTextures[unit] == null || context.boundTextures[unit].get() != img.getWeakRef().get()) {
             if (context.boundTextureUnit != unit) {
                 gl.glActiveTexture(GL.GL_TEXTURE0 + unit);
                 context.boundTextureUnit = unit;
             }
             gl.glBindTexture(target, img.getId());
-            context.boundTextures[unit] = img;
+            context.boundTextures[unit] = img.getWeakRef();
             statistics.onTextureUse(img, true);
         } else {
             statistics.onTextureUse(img, false);
@@ -2826,7 +2827,7 @@ public void clearVertexAttribs() {
         for (int i = 0; i < attribList.oldLen; i++) {
             int idx = attribList.oldList[i];
             gl.glDisableVertexAttribArray(idx);
-            if (context.boundAttribs[idx].isInstanced()) {
+            if (context.boundAttribs[idx].get().isInstanced()) {
                 glext.glVertexAttribDivisorARB(idx, 0);
             }
             context.boundAttribs[idx] = null;
@@ -2881,13 +2882,13 @@ public void setVertexAttrib(VertexBuffer vb, VertexBuffer idb) {
             updateBufferData(vb);
         }
 
-        VertexBuffer[] attribs = context.boundAttribs;
+        WeakReference<VertexBuffer>[] attribs = context.boundAttribs;
         for (int i = 0; i < slotsRequired; i++) {
             if (!context.attribIndexList.moveToNew(loc + i)) {
                 gl.glEnableVertexAttribArray(loc + i);
             }
         }
-        if (attribs[loc] != vb) {
+        if (attribs[loc]==null||attribs[loc].get() != vb) {
             // NOTE: Use id from interleaved buffer if specified
             int bufId = idb != null ? idb.getId() : vb.getId();
             assert bufId != -1;
@@ -2927,14 +2928,14 @@ public void setVertexAttrib(VertexBuffer vb, VertexBuffer idb) {
 
             for (int i = 0; i < slotsRequired; i++) {
                 int slot = loc + i;
-                if (vb.isInstanced() && (attribs[slot] == null || !attribs[slot].isInstanced())) {
+                if (vb.isInstanced() && (attribs[slot] == null || attribs[slot].get() == null || !attribs[slot].get().isInstanced())) {
                     // non-instanced -> instanced
                     glext.glVertexAttribDivisorARB(slot, vb.getInstanceSpan());
-                } else if (!vb.isInstanced() && attribs[slot] != null && attribs[slot].isInstanced()) {
+                } else if (!vb.isInstanced() && attribs[slot] != null && attribs[slot].get() != null && attribs[slot].get().isInstanced()) {
                     // instanced -> non-instanced
                     glext.glVertexAttribDivisorARB(slot, 0);
                 }
-                attribs[slot] = vb;
+                attribs[slot] = vb.getWeakRef();
             }
         }
     }

jme3-core/src/main/java/com/jme3/util/NativeObject.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2009-2019 jMonkeyEngine
+ * Copyright (c) 2009-2020 jMonkeyEngine
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -31,6 +31,7 @@
  */
 package com.jme3.util;
 
+import java.lang.ref.WeakReference;
 import java.nio.Buffer;
 
 /**
@@ -79,6 +80,8 @@ public abstract class NativeObject implements Cloneable {
      */
     protected boolean updateNeeded = true;
 
+    private WeakReference<NativeObject> weakRef;
+
     /**
      * Creates a new GLObject. Should be
      * called by the subclasses.
@@ -227,4 +230,17 @@ public void dispose() {
             objectManager.enqueueUnusedObject(this);
         }
     }
+
+    /**
+     * Acquire a weak reference to this NativeObject.
+     *
+     * @param <T> the type
+     * @return a weak reference (possibly a pre-existing one)
+     */
+    public <T> WeakReference<T> getWeakRef() {
+        if (weakRef == null) {
+            weakRef = new WeakReference<>(this);
+        }
+        return (WeakReference<T>) weakRef;
+    }
 }