Add continuation to conversion routines

pkg/api/v1beta1/conversion.go

@@ -19,22 +19,20 @@ package v1beta1
 import (
 	// Alias this so it can be easily changed when we cut the next version.
 	newer "github.com/GoogleCloudPlatform/kubernetes/pkg/api"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/conversion"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"
 )
 
 func init() {
-	// Shortcut for sub-conversions. TODO: This should possibly be refactored
-	// such that this convert function is passed to each conversion func.
-	Convert := runtime.Convert
 	runtime.AddConversionFuncs(
 		// EnvVar's Key is deprecated in favor of Name.
-		func(in *newer.EnvVar, out *EnvVar) error {
+		func(in *newer.EnvVar, out *EnvVar, s conversion.Scope) error {
 			out.Value = in.Value
 			out.Key = in.Name
 			out.Name = in.Name
 			return nil
 		},
-		func(in *EnvVar, out *newer.EnvVar) error {
+		func(in *EnvVar, out *newer.EnvVar, s conversion.Scope) error {
 			out.Value = in.Value
 			if in.Name != "" {
 				out.Name = in.Name
@@ -45,7 +43,7 @@ func init() {
 		},
 
 		// Path & MountType are deprecated.
-		func(in *newer.VolumeMount, out *VolumeMount) error {
+		func(in *newer.VolumeMount, out *VolumeMount, s conversion.Scope) error {
 			out.Name = in.Name
 			out.ReadOnly = in.ReadOnly
 			out.MountPath = in.MountPath
@@ -53,7 +51,7 @@ func init() {
 			out.MountType = "" // MountType is ignored.
 			return nil
 		},
-		func(in *VolumeMount, out *newer.VolumeMount) error {
+		func(in *VolumeMount, out *newer.VolumeMount, s conversion.Scope) error {
 			out.Name = in.Name
 			out.ReadOnly = in.ReadOnly
 			if in.MountPath == "" {
@@ -65,18 +63,18 @@ func init() {
 		},
 
 		// MinionList.Items had a wrong name in v1beta1
-		func(in *newer.MinionList, out *MinionList) error {
+		func(in *newer.MinionList, out *MinionList, s conversion.Scope) error {
-			Convert(&in.JSONBase, &out.JSONBase)
+			s.Convert(&in.JSONBase, &out.JSONBase, 0)
-			Convert(&in.Items, &out.Items)
+			s.Convert(&in.Items, &out.Items, 0)
 			out.Minions = out.Items
 			return nil
 		},
-		func(in *MinionList, out *newer.MinionList) error {
+		func(in *MinionList, out *newer.MinionList, s conversion.Scope) error {
-			Convert(&in.JSONBase, &out.JSONBase)
+			s.Convert(&in.JSONBase, &out.JSONBase, 0)
 			if len(in.Items) == 0 {
-				Convert(&in.Minions, &out.Items)
+				s.Convert(&in.Minions, &out.Items, 0)
 			} else {
-				Convert(&in.Items, &out.Items)
+				s.Convert(&in.Items, &out.Items, 0)
 			}
 			return nil
 		},

pkg/conversion/converter.go

@@ -37,7 +37,7 @@ type Converter struct {
 	// do the conversion.
 	funcs map[typePair]reflect.Value
 
-	// If true, print helpful debugging info. Quite verbose.
+	// If non-nil, will be called to print helpful debugging info. Quite verbose.
 	Debug DebugLogger
 }
 
@@ -48,29 +48,43 @@ func NewConverter() *Converter {
 	}
 }
 
+// Scope is passed to conversion funcs to allow them to continue an ongoing conversion.
+// If multiple converters exist in the system, Scope will allow you to use the correct one
+// from a conversion function--that is, the one your conversion function was called by.
+type Scope interface {
+	// Call Convert to convert sub-objects. Note that if you call it with your own exact
+	// parameters, you'll run out of stack space before anything useful happens.
+	Convert(src, dest interface{}, flags FieldMatchingFlags) error
+}
+
 // Register registers a conversion func with the Converter. conversionFunc must take
-// two parameters, the input and output type. It must take a pointer to each. It must
+// three parameters: a pointer to the input type, a pointer to the output type, and
-// return an error.
+// a conversion.Scope (which should be used if recursive conversion calls are desired).
+// It must return an error.
 //
 // Example:
-// c.Register(func(in *Pod, out *v1beta1.Pod) error { ... return nil })
+// c.Register(func(in *Pod, out *v1beta1.Pod, s Scope) error { ... return nil })
 func (c *Converter) Register(conversionFunc interface{}) error {
 	fv := reflect.ValueOf(conversionFunc)
 	ft := fv.Type()
 	if ft.Kind() != reflect.Func {
 		return fmt.Errorf("expected func, got: %v", ft)
 	}
-	if ft.NumIn() != 2 {
+	if ft.NumIn() != 3 {
-		return fmt.Errorf("expected two in params, got: %v", ft)
+		return fmt.Errorf("expected three 'in' params, got: %v", ft)
 	}
 	if ft.NumOut() != 1 {
-		return fmt.Errorf("expected one out param, got: %v", ft)
+		return fmt.Errorf("expected one 'out' param, got: %v", ft)
 	}
 	if ft.In(0).Kind() != reflect.Ptr {
-		return fmt.Errorf("expected pointer arg for in param 0, got: %v", ft)
+		return fmt.Errorf("expected pointer arg for 'in' param 0, got: %v", ft)
 	}
 	if ft.In(1).Kind() != reflect.Ptr {
-		return fmt.Errorf("expected pointer arg for in param 1, got: %v", ft)
+		return fmt.Errorf("expected pointer arg for 'in' param 1, got: %v", ft)
+	}
+	scopeType := Scope(c)
+	if e, a := reflect.TypeOf(&scopeType).Elem(), ft.In(2); e != a {
+		return fmt.Errorf("expected '%v' arg for 'in' param 2, got '%v' (%v)", e, a, ft)
 	}
 	var forErrorType error
 	// This convolution is necessary, otherwise TypeOf picks up on the fact
@@ -138,7 +152,8 @@ func (c *Converter) convert(sv, dv reflect.Value, flags FieldMatchingFlags) erro
 		if c.Debug != nil {
 			c.Debug.Logf("Calling custom conversion of '%v' to '%v'", st, dt)
 		}
-		ret := fv.Call([]reflect.Value{sv.Addr(), dv.Addr()})[0].Interface()
+		args := []reflect.Value{sv.Addr(), dv.Addr(), reflect.ValueOf(Scope(c))}
+		ret := fv.Call(args)[0].Interface()
 		// This convolution is necssary because nil interfaces won't convert
 		// to errors.
 		if ret == nil {

pkg/conversion/converter_test.go

@@ -27,28 +27,30 @@ import (
 func TestConverter_CallsRegisteredFunctions(t *testing.T) {
 	type A struct {
 		Foo string
+		Baz int
 	}
 	type B struct {
 		Bar string
+		Baz int
 	}
 	type C struct{}
 	c := NewConverter()
-	err := c.Register(func(in *A, out *B) error {
+	err := c.Register(func(in *A, out *B, s Scope) error {
 		out.Bar = in.Foo
-		return nil
+		return s.Convert(&in.Baz, &out.Baz, 0)
 	})
 	if err != nil {
 		t.Fatalf("unexpected error %v", err)
 	}
-	err = c.Register(func(in *B, out *A) error {
+	err = c.Register(func(in *B, out *A, s Scope) error {
 		out.Foo = in.Bar
-		return nil
+		return s.Convert(&in.Baz, &out.Baz, 0)
 	})
 	if err != nil {
 		t.Fatalf("unexpected error %v", err)
 	}
 
-	x := A{"hello, intrepid test reader!"}
+	x := A{"hello, intrepid test reader!", 3}
 	y := B{}
 
 	err = c.Convert(&x, &y, 0)
@@ -58,8 +60,11 @@ func TestConverter_CallsRegisteredFunctions(t *testing.T) {
 	if e, a := x.Foo, y.Bar; e != a {
 		t.Errorf("expected %v, got %v", e, a)
 	}
+	if e, a := x.Baz, y.Baz; e != a {
+		t.Errorf("expected %v, got %v", e, a)
+	}
 
-	z := B{"all your test are belong to us"}
+	z := B{"all your test are belong to us", 42}
 	w := A{}
 
 	err = c.Convert(&z, &w, 0)
@@ -69,8 +74,11 @@ func TestConverter_CallsRegisteredFunctions(t *testing.T) {
 	if e, a := z.Bar, w.Foo; e != a {
 		t.Errorf("expected %v, got %v", e, a)
 	}
+	if e, a := z.Baz, w.Baz; e != a {
+		t.Errorf("expected %v, got %v", e, a)
+	}
 
-	err = c.Register(func(in *A, out *C) error {
+	err = c.Register(func(in *A, out *C, s Scope) error {
 		return fmt.Errorf("C can't store an A, silly")
 	})
 	if err != nil {