Close #749, memory leak of custom objects. ObjectOwnershipHelp didn't…

… remove the custom object from the map properly. We need to remove it when retain count is 2, not 1, as the last retain is due to us allocating the object. Also added logging of retain/release of custom objects, see ObjCObject#logRetainRelease

objc/src/main/java/org/robovm/objc/ObjCObject.java

@@ -325,6 +325,7 @@ public ObjCObjectRef(ObjCObject referent) {
     static class ObjectOwnershipHelper {
         private static final LongMap<Object> CUSTOM_OBJECTS = new LongMap<>();
 
+        private static volatile boolean logRetainRelease = false;
         private static final long retainCount = Selector.register("retainCount").getHandle();
         private static final long retain = Selector.register("retain").getHandle();
         private static final long originalRetain = Selector.register("original_retain").getHandle();
@@ -333,7 +334,7 @@ static class ObjectOwnershipHelper {
 
         private static final Method retainMethod;
         private static final Method releaseMethod;
-        
+
         private static final LongMap<Long> customClassToNativeSuper = new LongMap<>();
 
         static {
@@ -358,38 +359,42 @@ private static void registerCallbackMethod(long cls, long selector, long newSele
                 throw new Error(
                         "Failed to register callback method on the ObjectOwnershipHelper: class_addMethod(...) failed");
             }
-            
+
             // find the super class that is a native class and cache it
             long superClass = ObjCRuntime.class_getSuperclass(cls);
             long nativeSuper = 0;
-            while(superClass != 0) {
+            while (superClass != 0) {
                 ObjCClass objCClass = ObjCClass.toObjCClass(superClass);
-                if(!objCClass.isCustom()) {
+                if (!objCClass.isCustom()) {
                     nativeSuper = superClass;
                     break;
                 }
                 superClass = ObjCRuntime.class_getSuperclass(superClass);
             }
-            if(nativeSuper == 0) {
-                throw new Error("Couldn't find native super class for " + VM.newStringUTF(ObjCRuntime.class_getName(cls)));
+            if (nativeSuper == 0) {
+                throw new Error("Couldn't find native super class for "
+                        + VM.newStringUTF(ObjCRuntime.class_getName(cls)));
             }
-            synchronized(customClassToNativeSuper) {
+            synchronized (customClassToNativeSuper) {
                 customClassToNativeSuper.put(cls, nativeSuper);
             }
         }
 
         @Callback
         private static @Pointer long retain(@Pointer long self, @Pointer long sel) {
-            if (ObjCRuntime.int_objc_msgSend(self, retainCount) <= 1) {
+            int count = ObjCRuntime.int_objc_msgSend(self, retainCount);
+            if (count <= 1) {
                 synchronized (CUSTOM_OBJECTS) {
                     ObjCClass cls = ObjCClass.toObjCClass(ObjCRuntime.object_getClass(self));
                     ObjCObject obj = ObjCObject.toObjCObject(cls.getType(), self, 0);
                     CUSTOM_OBJECTS.put(self, obj);
                 }
-            }     
+            }
             long cls = ObjCRuntime.object_getClass(self);
+            if (logRetainRelease)
+                logRetainRelease(cls, self, count, true);
             long nativeSuper = 0;
-            synchronized(customClassToNativeSuper) {
+            synchronized (customClassToNativeSuper) {
                 nativeSuper = customClassToNativeSuper.get(cls);
             }
             Super sup = new Super(self, nativeSuper);
@@ -398,30 +403,40 @@ private static void registerCallbackMethod(long cls, long selector, long newSele
 
         @Callback
         private static void release(@Pointer long self, @Pointer long sel) {
-            if (ObjCRuntime.int_objc_msgSend(self, retainCount) == 1) {
+            int count = ObjCRuntime.int_objc_msgSend(self, retainCount);
+            if (count == 2) {
                 synchronized (CUSTOM_OBJECTS) {
                     CUSTOM_OBJECTS.remove(self);
                 }
-            }            
+            }
             long cls = ObjCRuntime.object_getClass(self);
+            if (logRetainRelease)
+                logRetainRelease(cls, self, count, false);
             long nativeSuper = 0;
-            synchronized(customClassToNativeSuper) {
+            synchronized (customClassToNativeSuper) {
                 nativeSuper = customClassToNativeSuper.get(cls);
             }
             Super sup = new Super(self, nativeSuper);
             ObjCRuntime.void_objc_msgSendSuper(sup.getHandle(), sel);
         }
-        
+
         public static boolean isObjectRetained(ObjCObject object) {
             synchronized (CUSTOM_OBJECTS) {
                 return CUSTOM_OBJECTS.containsKey(object.getHandle());
             }
         }
+
+        private static void logRetainRelease(long cls, long self, int count, boolean isRetain) {
+            String className = ObjCClass.getFromObject(cls).getType().getName();
+            System.err.println(String.format("[Debug] %s %s@0x%s, retain count: %d",
+                    isRetain ? "Retained" : "Released", className, Long.toHexString(self), isRetain ? count + 1
+                            : count - 1));
+        }
     }
 
     static class AssociatedObjectHelper {
         private static final String STRONG_REFS_KEY = AssociatedObjectHelper.class.getName() + ".StrongRefs";
-
+        
         private static final int OBJC_ASSOCIATION_RETAIN_NONATOMIC = 1;
         private static final long RELEASE_LISTENER_CLASS;
         private static final String OWNER_IVAR_NAME = "value";
@@ -583,4 +598,18 @@ public Super(long receiver, long objcClass) {
         @StructMember(1)
         public native Super objCClass(@Pointer long objCClass);
     }
+
+    /**
+     * Sets whether retain/release of custom {@link ObjCObject} should be logged
+     * to the console to identify retain/release leaks. Note that the GC has to
+     * be able to collect the custom object for the final release to be
+     * triggered.</p>
+     * 
+     * The output logs the class, memory address and retain count after the
+     * release/retain invocation. You can use the memory address to inspect
+     * custom objects in Instruments.
+     */
+    public static void logRetainRelease(boolean enabled) {
+        ObjectOwnershipHelper.logRetainRelease = enabled;
+    }
 }