Add garbage collection memory mangement mode (gogc). Lots of fixes

related to pointer handling and memory management.

examples/app/main.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"git.wow.st/gmp/nswrap/examples/app/ns"
 	"runtime"
+	"time"
 )
 
 //Shortcut for literal NSStrings
@@ -31,8 +32,9 @@ func didFinishLaunching(n *ns.NSNotification) {
 		ns.NSBackingStoreBuffered,
 		0,
 	)
-	// retain win since we called Alloc and did not add it to a collection
-	win.Retain()
+	// We do not need to retain this because we are in garbage collection mode
+	// and have assigned it to a global variable.
+	//win.Retain()
 
 	win.SetTitle(nst("Hi World"))
 	win.MakeKeyAndOrderFront(win)
@@ -119,12 +121,12 @@ var (
 )
 
 func app() {
-	//Lock OS thread because Cocoa uses thread-local storage
+	// Lock OS thread because Cocoa uses thread-local storage
 	runtime.LockOSThread()
 	a = ns.NSApplicationSharedApplication()
 	a.SetActivationPolicy(ns.NSApplicationActivationPolicyRegular)
 
-	//Set up an AppDelegate
+	// Set up an AppDelegate
 	del := ns.AppDelegateAlloc()
 	del.ApplicationDidFinishLaunchingCallback(didFinishLaunching)
 	del.ApplicationShouldTerminateAfterLastWindowClosedCallback(shouldTerminateAfterLastWindowClosed)
@@ -133,12 +135,20 @@ func app() {
 
 	a.SetDelegate(del)
 
-	//Run the app
+	// Run the app
 	a.Run()
 }
 
 func main() {
-	//Run our app in an autorelease pool just for fun
+	// Run GC every second to ensure pointers are not being prematurely released.
+	go func() {
+		for {
+			runtime.GC()
+			time.Sleep(time.Second)
+		}
+	}()
+
+	// Run our app in an autorelease pool just for fun
 	go ns.Autoreleasepool(app)
 	select {}
 }

examples/app/nswrap.yaml

@@ -44,4 +44,5 @@ subclasses:
 
 frameworks: [ Foundation, AppKit ]
 pragma: [ clang diagnostic ignored "-Wformat-security" ]
-autorelease: true
+#autorelease: true
+gogc: true

examples/bluetooth/main.go

@@ -5,6 +5,8 @@ import "C"
 import (
 	"encoding/binary"
 	"fmt"
+	"runtime"
+	"time"
 	"git.wow.st/gmp/nswrap/examples/bluetooth/ns"
 )
 
@@ -25,34 +27,53 @@ func updateState(c *ns.CBCentralManager) {
 		fmt.Printf("  powered on\n")
 		cm.ScanForPeripheralsWithServices(ns.NSArrayWithObjects(hrm_uuid), nil)
 	}
+	fmt.Printf("Go: updateState returning\n")
 }
 
 func discoverPeripheral(c *ns.CBCentralManager, p *ns.CBPeripheral, d *ns.NSDictionary, rssi *ns.NSNumber) {
 	fmt.Printf("Did discover peripheral\n")
 	c.StopScan()
-	if peripheral.Ptr() != nil {
+
+	// if we already have a pointer to a peripheral, check that this one is different,
+	// and if so release the old one. Be careful to check the Objective-C pointers
+	// here as the Go pointers will differ.
+
+	if peripheral != nil && p.Ptr() != peripheral.Ptr() {
 		peripheral.Release()
 	}
+
 	peripheral = p
+
+	// we need to take ownership of this peripheral so CoreBluetooth doesn't
+	// dealloc it.
+
 	peripheral.Retain()
 	c.ConnectPeripheral(peripheral, nil)
 }
 
 func connectPeripheral(c *ns.CBCentralManager, p *ns.CBPeripheral) {
 	fmt.Printf("Did connect peripheral\n")
+
+	// set ourselves up as a peripheral delegate
+
 	p.SetDelegate(cd)
+
+	// discover all services on this device
+
 	p.DiscoverServices(nil)
+	fmt.Printf("Go: discoverPeripheral returning\n")
 }
 
 func discoverServices(p *ns.CBPeripheral, e *ns.NSError) {
 	fmt.Printf("Did discover services\n")
 	p.Services().ObjectEnumerator().ForIn(func(o *ns.Id) bool {
 		serv := o.CBService()
+		uuid := serv.UUID()
 		switch {
-		case serv.UUID().IsEqualTo(hrm_uuid):
+		case uuid.IsEqualTo(hrm_uuid):
 			fmt.Printf("--heart rate monitor service\n")
 			p.DiscoverCharacteristics(nil, serv)
-		case serv.UUID().IsEqualTo(ns.CBUUIDWithGoString("180A")):
+		case uuid.IsEqualTo(info_uuid):
 			fmt.Printf("--device information service\n")
 			p.DiscoverCharacteristics(nil, serv)
 		default:
@@ -60,6 +81,7 @@ func discoverServices(p *ns.CBPeripheral, e *ns.NSError) {
 		}
 		return true
 	})
+	fmt.Printf("Go: discoverServices returning\n")
 }
 
 func hr(d *ns.NSData) int {
@@ -77,12 +99,14 @@ func hr(d *ns.NSData) int {
 
 func discoverCharacteristics(p *ns.CBPeripheral, s *ns.CBService, e *ns.NSError) {
 	fmt.Printf("Did discover characteristics\n")
-	fmt.Printf("----%s\n", s.UUID().UUIDString().UTF8String())
-	if s.UUID().IsEqualTo(hrm_uuid) {
+	uuid := s.UUID()
+	fmt.Printf("----%s\n", uuid.UUIDString().UTF8String())
+	if uuid.IsEqualTo(hrm_uuid) {
 		s.Characteristics().ObjectEnumerator().ForIn(func(o *ns.Id) bool {
 			chr := o.CBCharacteristic()
-			fmt.Printf("------%s\n", chr.UUID().UUIDString().UTF8String())
-			if chr.UUID().IsEqualTo(hrv_uuid) {
+			chuuid := chr.UUID()
+			fmt.Printf("------%s\n", chuuid.UUIDString().UTF8String())
+			if chuuid.IsEqualTo(hrv_uuid) {
 				p.SetNotifyValue(1, chr)
 				v := chr.Value()
 				fmt.Println(hr(v))
@@ -90,6 +114,7 @@ func discoverCharacteristics(p *ns.CBPeripheral, s *ns.CBService, e *ns.NSError)
 			return true
 		})
 	}
+	fmt.Printf("Go: discoverCharacteristics returning\n")
 }
 
 func updateValue(p *ns.CBPeripheral, chr *ns.CBCharacteristic, e *ns.NSError) {
@@ -97,11 +122,13 @@ func updateValue(p *ns.CBPeripheral, chr *ns.CBCharacteristic, e *ns.NSError) {
 		v := chr.Value()
 		fmt.Printf("Heart rate: %d\n", hr(v))
 	}
+	fmt.Printf("Go: updateValue returning\n")
 }
 
 var (
 	hrm_uuid   *ns.CBUUID
 	hrv_uuid   *ns.CBUUID
+	info_uuid  *ns.CBUUID
 	cd         *ns.CBDelegate
 	cm         *ns.CBCentralManager
 	peripheral *ns.CBPeripheral
@@ -121,9 +148,18 @@ func main() {
 
 	hrm_uuid = ns.CBUUIDWithGoString("180D")
 	hrv_uuid = ns.CBUUIDWithGoString("2A37")
+	info_uuid = ns.CBUUIDWithGoString("180A")
 
-	//We defined our own queue because this won't work on the main queue.
+	// We defined our own queue because this won't work on the main queue.
 	cm = ns.CBCentralManagerAlloc().InitWithDelegateQueue(cd, queue)
 
+	// For debugging purposes, run GC every second to make sure things are not
+	// over-released.
+	go func() {
+		for {
+			runtime.GC()
+			time.Sleep(time.Second)
+		}
+	}()
 	select {}
 }

examples/bluetooth/nswrap.yaml

@@ -22,6 +22,7 @@ classes:
     - NSDictionary
     - NSEnumerator
     - NSString
+    - NSAutoreleasePool
 
 functions: [ NSMakeRange, dispatch_queue_create ]
 enums: [ CB.* ]
@@ -38,4 +39,4 @@ delegates:
             - peripheralDidUpdateValueForCharacteristic
 
 pragma: [ clang diagnostic ignored "-Wformat-security" ]
-#gogc: true
+gogc: true

examples/gc/main.go

@@ -15,6 +15,7 @@ func releaseX(x int) func (ns.MyClassSupermethods) {
 		super.Release() // comment out for leak
 	}
 }
+
 func memtest1() {
 	fmt.Println("memtest1 started")
 	for {
@@ -33,7 +34,7 @@ func memtest1() {
 		// in a real program.
 		runtime.GC()
 		time.Sleep(time.Second/50)
-		fmt.Printf("Loop complete\n")
+		//fmt.Printf("Loop complete\n")
 	}
 }
 
@@ -52,18 +53,35 @@ func memtest2() {
 		o4 := ns.NSStringAlloc()
 		_ = o4
 
-		//arr := ns.NSArrayAlloc().InitWithObjects(o1,o1)
-		arr := ns.NSArrayWithObjects(o1,o2,o3,o4)
-		_ = arr
+		a1 := ns.NSArrayAlloc()
+
+		// init methods in Objective-C always return a retained object.
+		// init may or may not return the same object that was sent in.
+
+		a1 = a1.InitWithObjects(o1,o2,o3,o4)
+
+		a2 := ns.NSArrayWithObjects(o1,o2,o3,o4)
+
+		// you can always nest alloc and init.
+
+		a3 := ns.NSMutableArrayAlloc().Init()
+		a3.AddObject(o1)
+		a3.AddObject(o2)
+		a3.AddObject(o3)
+		a3.AddObject(o4)
+		_ = a1
+		_ = a2
+		_ = a3
 
-		//o1.Release()
-		//o1.Release()
 		runtime.GC()
 		time.Sleep(time.Second/50)
 	}
 }
 
 func addStr(arr *ns.NSMutableArray) {
+	// temporary strings made by the 'WithGoString' methods should be released
+	// automatically by the GC.
+
 	s1 := ns.NSStringAlloc().InitWithGoString("a string")
 	arr.AddObject(s1)
 
@@ -75,24 +93,35 @@ func addStr(arr *ns.NSMutableArray) {
 func memtest3() {
 	fmt.Println("memtest3 started")
 
-	arr := ns.NSMutableArrayAlloc().Init() // arr will be garbage collected by Go
-	addStr(arr)
-	runtime.GC()
-	time.Sleep(time.Second)
-	s1 := arr.ObjectAtIndex(0)
-	fmt.Println(s1.NSString().UTF8String())
-	fmt.Println("memtest3 done")
+	for {
+		// arr will be garbage collected by Go
+		arr := ns.NSMutableArrayAlloc().Init()
+		addStr(arr)
+		runtime.GC()
+		time.Sleep(time.Second)
+
+		// check that our string was retained.
+
+		s1 := arr.ObjectAtIndex(0)
+		gstr := s1.NSString().UTF8String().String()
+		_ = gstr
+	}
 }
 
 func memtest4() {
 	fmt.Println("memtest4 started")
 	for {
-		o1 := ns.NSStringAlloc().InitWithGoString("four string")
+		o1 := ns.NSStringAlloc().InitWithGoString("red string")
+
+		// conversions to UTF8String internally create autoreleased strings
+		// in the Objective-C runtime. NSWrap runs these in a mini-
+		// @autoreleasepool block.
+
 		c1 := o1.UTF8String()
 		_ = o1
 		_ = c1
 		runtime.GC()
-		time.Sleep(time.Second/10)
+		time.Sleep(time.Second/50)
 	}
 }
 
@@ -100,12 +129,21 @@ func memtest5() {
 	fmt.Println("memtest5 started")
 	i := 0
 	for {
-		str := ns.NSStringWithGoString(fmt.Sprintf("five string %d",i))
-		_ = str
+		// by incrementing i we can ensure that Objective-C needs to create
+		// a new NSString object at each loop iteration and cannot be reusing
+		// the same string object.
+
+		str := ns.NSStringWithGoString(fmt.Sprintf("blue string %d",i))
+
+		// SubstringFromIndex should be returning a newly allocated NSString,
+		// which is getting retained by NSWrap and released by a Go GC
+		// finalizer.
+
 		sub := str.SubstringFromIndex(5)
 		_ = sub
-		fmt.Printf("sub = %s\n",sub)
-		time.Sleep(time.Second/10)
+		u := sub.UTF8String()
+		_ = u
+		time.Sleep(time.Second/50)
 		runtime.GC()
 		i++
 	}
@@ -117,5 +155,12 @@ func main() {
 	go memtest3()
 	go memtest4()
 	go memtest5()
+	go func() {
+		for {
+			// print a progress indicator
+			fmt.Printf("t = %s\n",time.Now())
+			time.Sleep(time.Second * 10)
+		}
+	}()
 	select {}
 }

types/convert.go

@@ -246,10 +246,10 @@ func (t *Type) _CType(attrib bool) string {
 	return ct
 }
 
-func (t *Type) GoTypeDecl() string {
+func (t *Type) GoTypeDecl(fin bool) string {
 	gt := t.GoType()
 	if wrapped[gt] {
-		return t.GoInterfaceDecl()
+		return t.GoInterfaceDecl(fin)
 	}
 	if t.Node.IsId() {
 		return ""
@@ -286,7 +286,7 @@ type %s %s
 	}
 }
 
-func (t *Type) GoInterfaceDecl() string {
+func (t *Type) GoInterfaceDecl(fin bool) string {
 	ct := t.CType()
 	gt := t.GoType()
 	if Debug {
@@ -384,7 +384,7 @@ func (t *Type) CToGo(cval string) string {
 }
 
 // Call a C function from Go with a given return type and parameter types
-func GoToC(name string, pnames, snames []string, rtype *Type, ptypes []*Type, fun, fin bool) string {
+func GoToC(name string, pnames, snames []string, rtype *Type, ptypes []*Type, fun, fin bool, cm bool) string {
 	if rtype == nil {
 		//fmt.Println("nil sent to GoToC")
 		return ""
@@ -495,10 +495,24 @@ func GoToC(name string, pnames, snames []string, rtype *Type, ptypes []*Type, fu
 	}
 	if rt != "void" {
 		if fin {
+			cmp := ""
+			if !cm {
+				cmp = fmt.Sprintf(`if ret.ptr == o.ptr { return (%s)(unsafe.Pointer(o)) }
+	`,rtgt)
+			}
+			dbg := ""
+			dbg2 := ""
+			if Debug {
+				dbg = fmt.Sprintf(`fmt.Printf("Setting finalizer (%s): %%p -> %%p\n", ret, ret.ptr)
+	`, rtgt)
+				dbg2 = fmt.Sprintf(`fmt.Printf("Finalizer (%s): release %%p -> %%p\n", o, o.ptr)
+	`, rtgt)
+			}
 			ret.WriteString(fmt.Sprintf(`
-	runtime.SetFinalizer(ret, func(o %s) {
-		o.Release()
-	})`,rtgt))
+	if ret.ptr == nil { return ret }
+	%s%sruntime.SetFinalizer(ret, func(o %s) {
+		%so.Release()
+	})`, cmp, dbg, rtgt, dbg2))
 		}
 		ret.WriteString(`
 	return ret`)

types/convert_test.go

@@ -177,14 +177,14 @@ func TestType(t *testing.T) {
 	chk(tp.PointsTo(), tp2)
 	chk(tp2.PointsTo(), nil)
 
-	chk(tp.GoTypeDecl(), `
+	chk(tp.GoTypeDecl(false), `
 type MyTypedef **C.NSObject
 `)
 	str = "void"
 	n = &Node{"TypeName", "", []*Node{
 		&Node{"TypeSpecifier", "void", []*Node{}}}}
 	chk_newtype()
-	chk(tp.GoTypeDecl(), "")
+	chk(tp.GoTypeDecl(false), "")
 	void := tp
 
 	str = "BOOL"
@@ -206,14 +206,14 @@ type MyTypedef **C.NSObject
 	chk(tp.GoType(), "*NSObject")
 
 	Wrap("NSString")
-	chk(nso.GoTypeDecl(), `
+	chk(nso.GoTypeDecl(false), `
 type NSObject interface {
 	Ptr() unsafe.Pointer
 }
 `)
 	chk(nso.GoType(), "NSObject")
 
-	chk(nst.GoTypeDecl(), `
+	chk(nst.GoTypeDecl(false), `
 type NSString struct { Id }
 func (o *NSString) Ptr() unsafe.Pointer { if o == nil { return nil }; return o.ptr }
 func (o *Id) NSString() *NSString {
@@ -276,8 +276,7 @@ func (o *Id) NSString() *NSString {
 	snames := []string{"", "", "", ""}
 
 	chk_gotoc := func(expected string) {
-		fmt.Printf("chk_gotoc\n")
-		chk(GoToC("myFun", pnames, snames, rtype, ptypes, false, false), expected)
+		chk(GoToC("myFun", pnames, snames, rtype, ptypes, false, false, false), expected)
 	}
 
 	chk_gotoc("")
@@ -352,7 +351,7 @@ func (o *Id) NSString() *NSString {
 	}
 	return ret`)
 
-	chk(GoToC("myFun", pnames, snames, rtype, ptypes, true, false),
+	chk(GoToC("myFun", pnames, snames, rtype, ptypes, true, false, false),
 		`ret := &Id{}
 	ret.ptr = unsafe.Pointer(C.myFun(p1.Ptr(), p2.Ptr(), unsafe.Pointer(&p3p[0]), p4))
 	(*p3) = (*p3)[:cap(*p3)]

wrap/main.go

@@ -52,6 +52,7 @@ type Wrapper struct {
 
 func NewWrapper(debug bool) *Wrapper {
 	Debug = debug
+	types.Debug = Debug
 	if Debug {
 		fmt.Println("// Debug mode")
 	}
@@ -133,8 +134,9 @@ type Subclass struct {
 }
 
 type Property struct {
-	Name, Attr string
-	Type       *types.Type
+	Name, Attr            string
+	Type                  *types.Type
+	retained, notretained bool
 }
 
 type Parameter struct {
@@ -155,9 +157,34 @@ func (m *Method) ShouldFinalize() bool {
 }
 
 func shouldFinalize (grtype, name string) bool {
-	return Gogc && grtype != "NSAutoreleasePool" && (types.ShouldWrap(grtype) || grtype == "Id") && (len(name) < 4 || name[:4] != "init")
+	return Gogc && grtype != "*NSAutoreleasePool" &&
+	(types.PtrShouldWrap(grtype) || grtype == "*Id") &&
+	(len(name) < 6 || name != "retain")
 }
 
+// IsRetained returns true if the name matches a retained property for the
+// given interface.
+func (i *Interface) IsRetained(name string) bool {
+	if p, ok := i.Properties[name]; ok {
+		if p.retained {
+			return true
+		}
+		if p.notretained {
+			return false
+		}
+		attrs := strings.Split(p.Attr," ")
+		for _, a := range attrs {
+			if a == "retain" {
+				p.retained = true // cache this result
+				return true
+			}
+		}
+		p.notretained = true // cache this result
+	}
+	return false
+}
+
+
 //Fully disambiguated method name (m.GoName + all parameter names)
 func (m *Method) LongName() string {
 	ret := m.GoName
@@ -184,13 +211,14 @@ type Protocol struct {
 }
 
 type MethodCollection struct {
-	Class   string
+	Class, GoClass   string
 	Methods []*Method
 }
 
 func NewMethodCollection(class string) *MethodCollection {
 	ret := &MethodCollection{
 		Class:   class,
+		GoClass: strings.Title(class),
 		Methods: []*Method{},
 	}
 	return ret
@@ -564,7 +592,7 @@ func (w *Wrapper) AddEnum(n *ast.EnumDecl, rs []string) {
 func (w *Wrapper) addIntCat(name string, ns []ast.Node) {
 	var i *Interface
 	var ok bool
-	goname := strings.Title(types.NewTypeFromString(name, name).GoType())
+	goname := strings.Title(name)
 	types.Wrap(goname)
 	if i, ok = w.Interfaces[name]; !ok {
 		i = &Interface{}
@@ -572,6 +600,7 @@ func (w *Wrapper) addIntCat(name string, ns []ast.Node) {
 		i.GoName = goname
 		i.InstanceMethods = NewMethodCollection(name)
 		i.ClassMethods = NewMethodCollection(name)
+		i.Properties = map[string]*Property{}
 		i.Protocols = []string{}
 		i.ProcessedInstanceMethods = map[string]bool{}
 	}
@@ -582,19 +611,15 @@ func (w *Wrapper) addIntCat(name string, ns []ast.Node) {
 	for _, c := range ns {
 		switch x := c.(type) {
 		case *ast.ObjCPropertyDecl:
-			//FIXME: Properties are not supported, typically there
-			//will be setter/getter methods you can use instead
 			if Debug {
 				fmt.Printf("ObjCPropertyDecl: %s\n", x.Name)
 			}
-			//p := &Property{
-			//	Name: x.Name,
-			//	Type: types.NewTypeFromString(x.Type,name),
-			//}
-			//_,avail = w.GetParms(x,name) // TODO
-			//if avail {
-			//	i.Properties[p.Name] = p
-			//}
+			p := &Property{
+				Name: x.Name,
+				Type: types.NewTypeFromString(x.Type,name),
+				Attr: x.Attr,
+			}
+			i.Properties[x.Name] = p
 		case *ast.ObjCMethodDecl:
 			if Debug {
 				fmt.Printf("ObjCMethodDecl: %s (%s) %s\n", x.Type, name, x.Name)
@@ -765,7 +790,6 @@ func (w *Wrapper) AddTypedef(n, t string) {
 		}
 		types.Wrap(n)
 		types.SetSuper(n, gt)
-		//w._processType(tp, n)
 		w._processType(tp)
 	} else {
 		cgt := tp.CGoType()
@@ -785,8 +809,6 @@ func (w *Wrapper) processTypes(tps []*types.Type) {
 
 func (w *Wrapper) processType(tp *types.Type) {
 	bt := tp.BaseType()
-	//gt := bt.GoType()
-	//w._processType(bt, gt)
 	w._processType(bt)
 }
 
@@ -804,8 +826,10 @@ func (w *Wrapper) _processType(bt *types.Type) {
 		return
 	}
 	if w.ProcessedTypes[gt] {
+		if Debug { fmt.Printf("  -- already seen\n") }
 		return
 	}
+	if Debug { fmt.Printf("  -- not yet seen\n") }
 	w.ProcessedTypes[gt] = true
 	if gt == "Char" {
 		w.CharHelpers()
@@ -828,7 +852,7 @@ func (w *Wrapper) _processType(bt *types.Type) {
 	if Debug {
 		fmt.Printf("Writing go type for %s -> %s\n",bt.CType(),gt)
 	}
-	w.goTypes.WriteString(bt.GoTypeDecl())
+	w.goTypes.WriteString(bt.GoTypeDecl(Gogc))
 }
 
 func (w *Wrapper) CharHelpers() {
@@ -860,13 +884,19 @@ func (o *NSString) String() string {
 }
 
 func (w *Wrapper) EnumeratorHelpers() {
-	w.goHelpers.WriteString(`
+	var re1, re2 string
+	if Gogc && false { // FIXME: don't need this
+		re1 = "o.Release(); "
+		re2 = `
+		o.Release()`
+	}
+	w.goHelpers.WriteString(fmt.Sprintf(`
 func (e *NSEnumerator) ForIn(f func(*Id) bool) {
 	for o := e.NextObject(); o.Ptr() != nil; o = e.NextObject() {
-		if !f(o) { break }
+		if !f(o) { %sbreak }%s
 	}
 }
-`)
+`, re1, re2))
 }
 
 func (w *Wrapper) AutoreleaseHelpers() {
@@ -898,12 +928,13 @@ func (w *Wrapper) ProcessMethod(m *Method) {
 }
 
 func (w *Wrapper) ProcessMethodForClass(m *Method, class string) {
-	goclass := strings.Title(types.NewTypeFromString(class, class).GoType())
+	goclass := strings.Title(class)
 	m2 := &Method{
 		Name: m.Name, GoName: m.GoName, Class: class, GoClass: goclass,
 		Type:        m.Type.CloneToClass(class),
 		ClassMethod: m.ClassMethod,
 		Parameters:  make([]*Parameter, len(m.Parameters)),
+		Unavailable: m.Unavailable,
 	}
 	for i, p := range m.Parameters {
 		m2.Parameters[i] = &Parameter{
@@ -1004,21 +1035,23 @@ func (w *Wrapper) _processMethod(m *Method, fun bool) {
 	if gname == grtype { // avoid name conflicts between methods and types
 		gname = "Get" + gname
 	}
+	var inter *Interface
 	if m.ClassMethod {
 		if w.ProcessedClassMethods[gname] {
 			return
 		}
 		w.ProcessedClassMethods[gname] = true
 	} else {
-		i, ok := w.Interfaces[m.Class]
+		var ok bool
+		inter,ok = w.Interfaces[m.Class]
 		if !ok {
 			fmt.Printf("Can't find interface %s for method %s\n", m.Class, m.Name)
 			os.Exit(-1)
 		}
-		if i.ProcessedInstanceMethods[gname] {
+		if inter.ProcessedInstanceMethods[gname] {
 			return
 		}
-		i.ProcessedInstanceMethods[gname] = true
+		inter.ProcessedInstanceMethods[gname] = true
 	}
 
 	w.goCode.WriteString(fmt.Sprintf(`
@@ -1048,7 +1081,7 @@ func %s%s(%s) %s {
 `, snames[i], n, n, snames[i], n))
 	}
 	w.goCode.WriteString(`	` +
-		types.GoToC(cname, ns, snames, m.Type, tps, fun, m.ShouldFinalize()) + "\n}\n")
+		types.GoToC(cname, ns, snames, m.Type, tps, fun, m.ShouldFinalize() && (m.ClassMethod || !inter.IsRetained(m.Name)), m.ClassMethod) + "\n}\n")
 
 	cret := ""
 	if !m.isVoid() {
@@ -1088,13 +1121,25 @@ func %s%s(%s) %s {
 	default:
 		if Gogc && !m.isVoid() {
 			rtn := ""
-			//if m.ClassMethod && types.ShouldWrap(m.Type.GoType()) {
-			if types.ShouldWrap(m.Type.GoType()) {
-				if m.ClassMethod {
-				rtn = `
+			if types.PtrShouldWrap(m.Type.GoType()) {
+				switch {
+				case m.ClassMethod:
+					if grtype != "*NSAutoreleasePool" {
+				// retain objects returned by class methods
+						rtn = `
 		[ret retain];`
-				} else {
-				rtn = `
+					}
+
+				case len(m.Name) >= 4 && m.Name[:4] == "init":
+				// init always returns a retained object
+
+				case inter.IsRetained(m.Name):
+				// some methods relate to retained properties
+				// do not retain these again
+
+				default:
+				// by default, retain if returning a new object
+					rtn = `
 		if (o != ret) { [ret retain]; }`
 				}
 			}
@@ -1111,6 +1156,28 @@ func %s%s(%s) %s {
 		}
 	}
 
+	// create SetFinalizer methods when we see an alloc function:
+	if Gogc && m.Name == "alloc" {
+		cls := m.GoClass
+		if types.IsGoInterface(cls) {
+			cls = "Id"
+		}
+		dbg := ""
+		dbg2 := ""
+		if Debug {
+			dbg = fmt.Sprintf(`fmt.Printf("Setting GC finalizer (%s): %%p -> %%p\n", o, o.ptr)
+	`,cls)
+			dbg2 = fmt.Sprintf(`fmt.Printf("GC finalizer (%s): release %%p -> %%p\n", o, o.ptr)`, cls)
+		}
+		w.goCode.WriteString(fmt.Sprintf(`
+func (o *%s) GC() {
+	if o.ptr == nil { return }
+	%sruntime.SetFinalizer(o, func(o *%s) {
+		%so.Release()
+	})
+}
+`, cls, dbg, cls, dbg2))
+	}
 	// create GoString helper method
 	if ok, _ := regexp.MatchString("WithString$", m.Name); ok {
 		if Debug {
@@ -1143,21 +1210,12 @@ func %s%s(%s) %s {
 			obj = "o."
 			ns = ns[1:]
 		}
-		finalizer := ""
-		if m.ShouldFinalize() && false {
-			w.goImports["runtime"] = true
-			finalizer = fmt.Sprintf(
-	`runtime.SetFinalizer(ret, func(o *%s) {
-		o.Release()
-	})
-	`, grtype)
-		}
 		w.goCode.WriteString(fmt.Sprintf(`
 func %s%s(%s) %s {
 	%sret := %s%s(%s)
-	%sreturn ret
+	return ret
 }
-`, receiver, gname2, gplist, grtype, cvts, obj, gname, strings.Join(ns, ", "), finalizer))
+`, receiver, gname2, gplist, grtype, cvts, obj, gname, strings.Join(ns, ", ")))
 	}
 }
 
@@ -1246,7 +1304,40 @@ func (w *Wrapper) MethodFromSig(sig, class string) *Method {
 	return ret
 }
 
+func (mc *MethodCollection) AddMethod(m *Method) {
+	m2 := &Method{
+		Name:        m.Name,
+		GoName:      m.GoName,
+		Class:       mc.Class,
+		GoClass:     mc.GoClass,
+		Type:        m.Type.CloneToClass(mc.Class),
+		ClassMethod: m.ClassMethod,
+		Parameters:  []*Parameter{},
+		Unavailable: m.Unavailable,
+	}
+	for _, p := range m.Parameters {
+		p2 := &Parameter{
+			Pname: p.Pname,
+			Vname: p.Vname,
+			Type:  p.Type.CloneToClass(mc.Class),
+		}
+		m2.Parameters = append(m2.Parameters, p2)
+	}
+	mc.Methods = append(mc.Methods, m2)
+}
+
+func (mc *MethodCollection) AddMethods(smc *MethodCollection) {
+	for _, m := range smc.Methods {
+		mc.AddMethod(m)
+	}
+}
+
 func (w *Wrapper) ProcessSubclass(sname string, sc *Subclass) {
+	i := &Interface{
+		ProcessedInstanceMethods: map[string]bool{},
+		Properties: map[string]*Property{},
+	}
+	w.Interfaces[sname] = i
 	gname := strings.Title(sname)
 	types.Wrap(gname)
 	types.SetSuper(gname, sc.Super)
@@ -1257,12 +1348,17 @@ func (w *Wrapper) ProcessSubclass(sname string, sc *Subclass) {
 		nms[i] = w.MethodFromSig(sig, sname)
 	}
 	if Debug {
-		fmt.Println("ProcessSubclass(%s)\n",sname)
+		fmt.Printf("ProcessSubclass(%s)\n",sname)
 	}
 	w._ProcessDelSub(sname, ps, nms, true)
 }
 
 func (w *Wrapper) ProcessDelegate(dname string, ps map[string][]string) {
+	i := &Interface{
+		ProcessedInstanceMethods: map[string]bool{},
+		Properties: map[string]*Property{},
+	}
+	w.Interfaces[dname] = i
 	w._ProcessDelSub(dname, ps, nil, false)
 }
 
@@ -1276,6 +1372,7 @@ func (w *Wrapper) _ProcessDelSub(dname string, ps map[string][]string, nms []*Me
 	//5. Go constructor
 	//6. Go dispatch database for callbacks
 	//7. Go superclass dispatch function
+	//8. Methods inherited from parent class
 	//To create (per method):
 	//1. ObjC function prototypes for go exports
 	//2. Go callback registration functions
@@ -1290,6 +1387,7 @@ func (w *Wrapper) _ProcessDelSub(dname string, ps map[string][]string, nms []*Me
 	sms := 0             // the number of methods that have super-methods
 	gnames := []string{} // go names for methods
 	pnames := make([]string, len(ps))
+	supmeths := []*Method{}
 	var supr string
 	i := 0
 	for pname, pats := range ps {
@@ -1364,6 +1462,8 @@ func (w *Wrapper) _ProcessDelSub(dname string, ps map[string][]string, nms []*Me
 				fmt.Printf("--Method: %s\n", m.Name)
 			}
 			if !matches(string(m.Name[0])+m.GoName[1:], pats) {
+			//methods from superclass that we are not overriding
+				supmeths = append(supmeths,m)
 				continue
 			}
 			if m.HasUnsupportedType() {
@@ -1606,27 +1706,49 @@ void*
 	}
 
 	//4. Go type
-
-	gotypes.WriteString(
-		types.NewTypeFromString(gname, supr).GoInterfaceDecl())
+	if !w.ProcessedTypes[gname] {
+		gotypes.WriteString(
+		types.NewTypeFromString(gname, supr).GoInterfaceDecl(Gogc))
 
 	//5. Go constructor
-	var finalizer string
-	if shouldFinalize(gname,"") {
-		w.goImports["runtime"] = true
-		finalizer = fmt.Sprintf(
-`runtime.SetFinalizer(ret,func(o *%s) {
-		o.Release()
+		var finalizer string
+		dbg := ""
+		dbg2 := ""
+		if Debug {
+			dbg = fmt.Sprintf(`fmt.Printf("Setting finalizer (%s): %%p -> %%p\n", ret, ret.ptr)
+	`, gname)
+			dbg2 = fmt.Sprintf(`fmt.Printf("Finalizer (%s): release %%p -> %%p\n", o, o.ptr)
+	`, gname)
+		}
+		if Gogc {
+			w.goImports["runtime"] = true
+			if Debug { w.goImports["fmt"] = true }
+			finalizer = fmt.Sprintf(
+`if ret.ptr == nil { return ret }
+	%sruntime.SetFinalizer(ret,func(o *%s) {
+		%so.Release()
 	})
-	`,gname)
-	}
-	gocode.WriteString(fmt.Sprintf(`
+	`, dbg, gname, dbg2)
+		}
+		gocode.WriteString(fmt.Sprintf(`
 func %sAlloc() *%s {
 	ret := &%s{}
 	ret.ptr = unsafe.Pointer(C.%sAlloc())
 	%sreturn ret
 }
 `, gname, gname, gname, dname, finalizer))
+		if Gogc {
+			gocode.WriteString(fmt.Sprintf(`
+func (o *%s) GC() {
+	if o.ptr == nil { return }
+	%sruntime.SetFinalizer(o,func(o *%s) {
+		%so.Release()
+	})
+}
+`, gname, dbg, gname, dbg2))
+		}
+	}
+	w.ProcessedTypes[gname] = true
 
 	//6. Go dispatch database for callbacks
 	dispitems := make([]string, len(gnames))
@@ -1790,7 +1912,7 @@ func (o *%s) Super%s(%s) %s {
 	}
 `, vn, w.Vaargs, vn, vn))
 			}
-			gocode.WriteString("\t" + types.GoToC(dname+"_super_"+m.Name, ns, snames, m.Type, tps, false, m.ShouldFinalize()) + "\n}\n")
+			gocode.WriteString("\t" + types.GoToC(dname+"_super_"+m.Name, ns, snames, m.Type, tps, false, m.ShouldFinalize(), m.ClassMethod) + "\n}\n")
 		}
 	}
 	w.cCode.WriteString(cprotos.String())
@@ -1798,6 +1920,11 @@ func (o *%s) Super%s(%s) %s {
 	w.goTypes.WriteString(gotypes.String())
 	w.goCode.WriteString(gocode.String())
 	w.goExports.WriteString(goexports.String())
+
+	// add methods from parent class that we are not overriding
+	for _,m := range supmeths {
+		w.ProcessMethodForClass(m,dname)
+	}
 }
 
 //Add class and instance methods from super class
@@ -1808,8 +1935,8 @@ func (w *Wrapper) AddSupermethods(i *Interface) {
 			m2 := &Method{
 				Name:        m.Name,
 				GoName:      m.GoName,
-				Class:       i.Name,
-				GoClass:     i.GoName,
+				Class:       mc.Class,
+				GoClass:     mc.GoClass,
 				Type:        m.Type.CloneToClass(i.Name),
 				ClassMethod: m.ClassMethod,
 				Parameters:  []*Parameter{},