Fix behaviour of freeNatives()

Summary:
@public

Prevents repeated deallocation of weak references.

Reviewed By: pasqualeanatriello

Differential Revision: D9131551

fbshipit-source-id: bc79596e056ae0657a55146ad786422fd0f5badc

java/com/facebook/yoga/YogaNodePropertiesByteBuffer.java

@@ -25,6 +25,7 @@ public class YogaNodePropertiesByteBuffer implements YogaNodeProperties, Cloneab
   private final long mNativePointer;
   private boolean mHasBorderSet = false;
   private boolean mHasNewLayout = true;
+  private boolean isFreed = false;
 
   private static native ByteBuffer jni_getStyleBuffer(long nativePointer);
 
@@ -48,12 +49,10 @@ public class YogaNodePropertiesByteBuffer implements YogaNodeProperties, Cloneab
     mLayoutBuffer = jni_getLayoutBuffer(nativePointer).order(ByteOrder.LITTLE_ENDIAN);
   }
 
-  private static native void jni_YGNodeFree(long nativePointer);
-
   @Override
   protected void finalize() throws Throwable {
     try {
-      jni_YGNodeFree(getNativePointer());
+      freeNatives();
     } finally {
       super.finalize();
     }
@@ -482,10 +481,15 @@ public class YogaNodePropertiesByteBuffer implements YogaNodeProperties, Cloneab
     return YogaDirection.fromInt(getLayoutDirectionInt());
   }
 
+  private static native void jni_YGNodeFree(long nativePointer);
+
   @Override
   public void freeNatives() {
+    if (!isFreed) {
+      isFreed = true;
       jni_YGNodeFree(mNativePointer);
     }
+  }
 
   private int getLayoutDirectionInt() {
     return mLayoutBuffer.getInt(YogaNodeMemoryLayout.layoutDirection);

java/com/facebook/yoga/YogaNodePropertiesJNI.java

@@ -66,12 +66,13 @@ public class YogaNodePropertiesJNI implements Cloneable, YogaNodeProperties {
     }
   }
 
-  private native void jni_YGNodeFree(long nativePointer);
+  private static native void jni_YGNodeFree(long nativePointer);
 
   @Override
   public void freeNatives() {
-    jni_YGNodeFree(mNativePointer);
+    long nativePointer = mNativePointer;
     mNativePointer = 0;
+    jni_YGNodeFree(nativePointer);
   }
 
   @Override

java/jni/YGJNI.cpp

@@ -384,7 +384,7 @@ jlong jni_YGNodeCloneNoProps(
   return jni_YGNodeClone(cls, nativePointer, clonedJavaObject, nullptr);
 }
 
-void jni_YGNodeFree(alias_ref<jobject> thiz, jlong nativePointer) {
+void jni_YGNodeFree(alias_ref<jclass> thiz, jlong nativePointer) {
   if (nativePointer == 0) {
     return;
   }