PhysicsSystem: protect the contact listener against GC

stephengold · Sep 25, 2024 · 57fe9bb · 57fe9bb
1 parent 337cda7
commit 57fe9bb
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Showing 2 changed files with 8 additions and 29 deletions.
diff --git a/src/main/java/com/github/stephengold/joltjni/PhysicsSystem.java b/src/main/java/com/github/stephengold/joltjni/PhysicsSystem.java
@@ -46,6 +46,10 @@ public class PhysicsSystem extends NonCopyable {
      * cached reference to the system's no-lock {@code BodyInterface}
      */
     final private BodyInterface bodyInterfaceNoLock;
+    /**
+     * protect the contact listener (if any) from garbage collection
+     */
+    private ContactListener contactListener;
     /**
      * protect the BroadPhaseLayerInterface from garbage collection
      */
@@ -292,23 +296,12 @@ public Constraints getConstraints() {
     }
 
     /**
-     * Access the system's {@code ContactListener}.
+     * Access the (application-provided) contact listener.
      *
-     * @return a new JVM object with the pre-existing native object assigned, or
-     * {@code null} if none
+     * @return the pre-existing instance, or {@code null} if none
      */
     public ContactListener getContactListener() {
-        long systemVa = va();
-        long listenerVa = getContactListener(systemVa);
-
-        ContactListener result;
-        if (listenerVa == 0L) {
-            result = null;
-        } else {
-            result = new ContactListener(listenerVa, false);
-        }
-
-        return result;
+        return contactListener;
     }
 
     /**
@@ -558,6 +551,7 @@ public void setCombineRestitution(CombineFunction function) {
      * @param listener the desired listener
      */
     public void setContactListener(ContactListener listener) {
+        this.contactListener = listener;
         long systemVa = va();
         long listenerVa = listener.va();
         setContactListener(systemVa, listenerVa);
@@ -646,8 +640,6 @@ native private static void getActiveBodies(
 
     native private static long getConstraints(long systemVa);
 
-    native private static long getContactListener(long systemVa);
-
     native private static float getGravityX(long systemVa);
 
     native private static float getGravityY(long systemVa);

diff --git a/src/main/native/glue/p/PhysicsSystem.cpp b/src/main/native/glue/p/PhysicsSystem.cpp
@@ -242,19 +242,6 @@ JNIEXPORT jlong JNICALL Java_com_github_stephengold_joltjni_PhysicsSystem_getCon
     return reinterpret_cast<jlong> (pResult);
 }
 
-/*
- * Class:     com_github_stephengold_joltjni_PhysicsSystem
- * Method:    getContactListener
- * Signature: (J)J
- */
-JNIEXPORT jlong JNICALL Java_com_github_stephengold_joltjni_PhysicsSystem_getContactListener
-  (JNIEnv *, jclass, jlong systemVa) {
-    const PhysicsSystem * const pSystem
-            = reinterpret_cast<PhysicsSystem *> (systemVa);
-    ContactListener * const pResult = pSystem->GetContactListener();
-    return reinterpret_cast<jlong> (pResult);
-}
-
 /*
  * Class:     com_github_stephengold_joltjni_PhysicsSystem
  * Method:    getGravityX