feat: refactor type registry (#1403)

- separate go-runtime/typeregistry and internal schema/typeregistry; add
schema type lookups for ingress encoding
- fixes for deriving schema types for sum type variants

backend/protos/xyz/block/ftl/v1/schema/schema.proto

@@ -215,6 +215,10 @@ message StringValue {
   string value = 2;
 }
 
+message SumTypeVariants {
+  repeated string value = 1;
+}
+
 message Time {
   optional Position pos = 1;
 }
@@ -241,6 +245,11 @@ message TypeParameter {
   string name = 2;
 }
 
+message TypeRegistry {
+  map<string, Type> schemaTypes = 1;
+  map<string, SumTypeVariants> sumTypes = 2;
+}
+
 message TypeValue {
   optional Position pos = 1;
   Type value = 2;

backend/schema/protobuf.go

@@ -21,8 +21,9 @@ var typesWithRuntime = map[string]bool{
 // for the FTL schema.
 func ProtobufSchema() string {
 	messages := map[string]string{}
-	generateMessage(reflect.TypeOf(Schema{}), messages)
-	generateMessage(reflect.TypeOf(ErrorList{}), messages)
+	generateMessage(reflect.TypeFor[Schema](), messages)
+	generateMessage(reflect.TypeFor[ErrorList](), messages)
+	generateMessage(reflect.TypeFor[TypeRegistry](), messages)
 	keys := maps.Keys(messages)
 	slices.Sort(keys)
 	w := &strings.Builder{}

backend/schema/type_registry.go

@@ -0,0 +1,71 @@
+package schema
+
+import (
+	"context"
+	schemapb "github.com/TBD54566975/ftl/backend/protos/xyz/block/ftl/v1/schema"
+)
+
+type contextKeyTypeRegistry struct{}
+
+// ContextWithTypeRegistry adds a type registry to the given context.
+func ContextWithTypeRegistry(ctx context.Context, r *schemapb.TypeRegistry) context.Context {
+	return context.WithValue(ctx, contextKeyTypeRegistry{}, r)
+}
+
+// TypeRegistry is a registry of types that can be resolved to a schema type at runtime.
+// It also records sum types and their variants, for use in encoding and decoding.
+type TypeRegistry struct {
+	// SchemaTypes associates a type name with a schema type.
+	SchemaTypes map[string]Type `protobuf:"1"`
+	// SumTypes associates a sum type discriminator type name with its variant type names.
+	SumTypes map[string]SumTypeVariants `protobuf:"2"`
+}
+
+// NewTypeRegistry creates a new type registry.
+// The type registry is used to instantiate types by their qualified name at runtime.
+func NewTypeRegistry() *TypeRegistry {
+	return &TypeRegistry{
+		SchemaTypes: make(map[string]Type),
+		SumTypes:    make(map[string]SumTypeVariants),
+	}
+}
+
+// RegisterSumType registers a Go sum type with the type registry. Sum types are represented as enums in the
+// FTL schema.
+func (t *TypeRegistry) RegisterSumType(discriminator string, variants map[string]Type) {
+	var values []string
+	for name, vt := range variants {
+		values = append(values, name)
+		t.SchemaTypes[name] = vt
+	}
+	t.SumTypes[discriminator] = SumTypeVariants{Value: values}
+}
+
+func (t *TypeRegistry) ToProto() *schemapb.TypeRegistry {
+	typespb := make(map[string]*schemapb.Type, len(t.SchemaTypes))
+	for k, v := range t.SchemaTypes {
+		typespb[k] = typeToProto(v)
+	}
+
+	return &schemapb.TypeRegistry{
+		SumTypes:    sumTypeVariantsToProto(t.SumTypes),
+		SchemaTypes: typespb,
+	}
+}
+
+type SumTypeVariants struct {
+	// Value is a list of variant names for the sum type.
+	Value []string `protobuf:"1"`
+}
+
+func (s *SumTypeVariants) ToProto() *schemapb.SumTypeVariants {
+	return &schemapb.SumTypeVariants{Value: s.Value}
+}
+
+func sumTypeVariantsToProto(v map[string]SumTypeVariants) map[string]*schemapb.SumTypeVariants {
+	out := make(map[string]*schemapb.SumTypeVariants, len(v))
+	for k, v := range v {
+		out[k] = v.ToProto()
+	}
+	return out
+}

backend/schema/visit.go

@@ -17,6 +17,12 @@ func Visit(n Node, visit func(n Node, next func() error) error) error {
 // stubbed verbs.
 func VisitExcludingMetadataChildren(n Node, visit func(n Node, next func() error) error) error {
 	return visit(n, func() error {
+		if d, ok := n.(Decl); ok {
+			if !d.IsExported() {
+				// Skip non-exported nodes
+				return nil
+			}
+		}
 		if _, ok := n.(Metadata); !ok {
 			for _, child := range n.schemaChildren() {
 				_, isParentVerb := n.(*Verb)

buildengine/build_go_test.go

@@ -2,9 +2,12 @@ package buildengine
 
 import (
 	"fmt"
+	"os"
 	"runtime"
 	"testing"
 
+	"github.com/alecthomas/assert/v2"
+
 	"github.com/TBD54566975/ftl/backend/schema"
 )
 
@@ -261,58 +264,14 @@ func TestGeneratedTypeRegistry(t *testing.T) {
 			}},
 		},
 	}
-	expected := `// Code generated by FTL. DO NOT EDIT.
-package main
-
-import (
-	"context"
-	"reflect"
-
-	"github.com/TBD54566975/ftl/common/plugin"
-	"github.com/TBD54566975/ftl/go-runtime/server"
-	"github.com/TBD54566975/ftl/backend/protos/xyz/block/ftl/v1/ftlv1connect"
-	"github.com/TBD54566975/ftl/go-runtime/ftl"
-
-	"ftl/other"
-	"ftl/another"
-)
-
-func main() {
-	verbConstructor := server.NewUserVerbServer("other",
-		server.HandleCall(other.Echo),
-	)
-	ctx := context.Background()
-	typeRegistry := ftl.NewTypeRegistry()
-	typeRegistry.RegisterSumType(reflect.TypeFor[other.D](), map[string]reflect.Type{
-		"Bool": reflect.TypeFor[other.Bool](),
-		"Bytes": reflect.TypeFor[other.Bytes](),
-		"Float": reflect.TypeFor[other.Float](),
-		"Int": reflect.TypeFor[other.Int](),
-		"U": reflect.TypeFor[other.U](),
-		"List": reflect.TypeFor[other.List](),
-		"Map": reflect.TypeFor[other.Map](),
-		"String": reflect.TypeFor[other.String](),
-		"Struct": reflect.TypeFor[other.Struct](),
-	})
-	typeRegistry.RegisterSumType(reflect.TypeFor[other.SecondSumType](), map[string]reflect.Type{
-		"A": reflect.TypeFor[other.A](),
-		"B": reflect.TypeFor[other.B](),
-	})
-	typeRegistry.RegisterSumType(reflect.TypeFor[another.TypeEnum](), map[string]reflect.Type{
-		"A": reflect.TypeFor[another.A](),
-		"B": reflect.TypeFor[another.B](),
-	})
-	ctx = context.WithValue(ctx, "typeRegistry", typeRegistry)
-
-	plugin.Start(ctx, "other", verbConstructor, ftlv1connect.VerbServiceName, ftlv1connect.NewVerbServiceHandler)
-}
-`
+	expected, err := os.ReadFile("testdata/type_registry_main.go")
+	assert.NoError(t, err)
 	bctx := buildContext{
 		moduleDir: "testdata/projects/other",
 		buildDir:  "_ftl",
 		sch:       sch,
 	}
 	testBuild(t, bctx, "", []assertion{
-		assertGeneratedMain(expected),
+		assertGeneratedMain(string(expected)),
 	})
 }

buildengine/testdata/projects/other/other.go

@@ -3,14 +3,15 @@ package other
 import (
 	"context"
 	"fmt"
+	"time"
 
 	"github.com/TBD54566975/ftl/go-runtime/ftl" // Import the FTL SDK.
 
 	"ftl/another"
 )
 
 //ftl:enum
-type D interface {
+type TypeEnum interface {
 	tag()
 }
 
@@ -30,13 +31,9 @@ type Int int
 
 func (Int) tag() {}
 
-//type Time time.Time
-//
-//func (Time) tag() {}
+type Time time.Time
 
-type U ftl.Unit
-
-func (U) tag() {}
+func (Time) tag() {}
 
 type List []string
 
@@ -54,8 +51,16 @@ type Struct struct{}
 
 func (Struct) tag() {}
 
+type Option ftl.Option[string]
+
+func (Option) tag() {}
+
+type Unit ftl.Unit
+
+func (Unit) tag() {}
+
 //ftl:enum
-type SecondSumType interface {
+type SecondTypeEnum interface {
 	tag2()
 }