Native serialization of JSON-like slices & maps

dispatchhttp/client.go

@@ -1,3 +1,5 @@
+//go:build !durable
+
 package dispatchhttp
 
 import (

dispatchhttp/header.go

@@ -1,3 +1,5 @@
+//go:build !durable
+
 package dispatchhttp
 
 import (

dispatchhttp/request.go

@@ -1,3 +1,5 @@
+//go:build !durable
+
 package dispatchhttp
 
 import (

dispatchhttp/response.go

@@ -1,3 +1,5 @@
+//go:build !durable
+
 package dispatchhttp
 
 import (

dispatchproto/any.go

@@ -85,9 +85,11 @@ func Duration(v time.Duration) Any {
 // Primitive values (booleans, integers, floats, strings, bytes, timestamps,
 // durations) are supported, along with values that implement either
 // proto.Message, json.Marshaler, encoding.TextMarshaler or
-// encoding.BinaryMarshaler.
+// encoding.BinaryMarshaler. Slices and maps are also supported, as long
+// as they are JSON-like in shape.
 func Marshal(v any) (Any, error) {
-	if rv := reflect.ValueOf(v); rv.Kind() == reflect.Pointer && rv.IsNil() {
+	rv := reflect.ValueOf(v)
+	if rv.Kind() == reflect.Pointer && rv.IsNil() {
 		return Nil(), nil
 	}
 	var m proto.Message
@@ -160,7 +162,10 @@ func Marshal(v any) (Any, error) {
 	case []byte:
 		m = wrapperspb.Bytes(vv)
 	default:
-		return Any{}, fmt.Errorf("cannot serialize %v (%T)", v, v)
+		var err error
+		if m, err = newStructpbValue(rv); err != nil {
+			return Any{}, fmt.Errorf("cannot serialize %v: %w", v, err)
+		}
 	}
 
 	proto, err := anypb.New(m)
@@ -386,6 +391,10 @@ func (a Any) Unmarshal(v any) error {
 		}
 	}
 
+	if s, ok := m.(*structpb.Value); ok {
+		return fromStructpbValue(elem, s)
+	}
+
 	return fmt.Errorf("cannot deserialize %T into %v (%v kind)", m, elem.Type(), elem.Kind())
 }
 
@@ -404,3 +413,144 @@ func (a Any) String() string {
 func (a Any) Equal(other Any) bool {
 	return proto.Equal(a.proto, other.proto)
 }
+
+func newStructpbValue(rv reflect.Value) (*structpb.Value, error) {
+	switch rv.Kind() {
+	case reflect.Bool:
+		return structpb.NewBoolValue(rv.Bool()), nil
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		n := rv.Int()
+		f := float64(n)
+		if int64(f) != n {
+			return nil, fmt.Errorf("cannot serialize %d as number structpb.Value (%v) without losing information", n, f)
+		}
+		return structpb.NewNumberValue(f), nil
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		n := rv.Uint()
+		f := float64(n)
+		if uint64(f) != n {
+			return nil, fmt.Errorf("cannot serialize %d as number structpb.Value (%v) without losing information", n, f)
+		}
+		return structpb.NewNumberValue(f), nil
+	case reflect.Float32, reflect.Float64:
+		return structpb.NewNumberValue(rv.Float()), nil
+	case reflect.String:
+		return structpb.NewStringValue(rv.String()), nil
+	case reflect.Interface:
+		if rv.NumMethod() == 0 { // interface{} aka. any
+			v := rv.Interface()
+			if v == nil {
+				return structpb.NewNullValue(), nil
+			}
+			return newStructpbValue(reflect.ValueOf(v))
+		}
+	case reflect.Slice:
+		list := &structpb.ListValue{Values: make([]*structpb.Value, rv.Len())}
+		for i := range list.Values {
+			elem := rv.Index(i)
+			var err error
+			list.Values[i], err = newStructpbValue(elem)
+			if err != nil {
+				return nil, err
+			}
+		}
+		return structpb.NewListValue(list), nil
+	case reflect.Map:
+		strct := &structpb.Struct{Fields: make(map[string]*structpb.Value, rv.Len())}
+		iter := rv.MapRange()
+		for iter.Next() {
+			k := iter.Key()
+
+			var strKey string
+			var hasStrKey bool
+			switch k.Kind() {
+			case reflect.String:
+				strKey = k.String()
+				hasStrKey = true
+			case reflect.Interface:
+				if s, ok := k.Interface().(string); ok {
+					strKey = s
+					hasStrKey = true
+				}
+			}
+			if !hasStrKey {
+				return nil, fmt.Errorf("cannot serialize map with %s (%s) key", k.Type(), k.Kind())
+			}
+
+			v, err := newStructpbValue(iter.Value())
+			if err != nil {
+				return nil, err
+			}
+			strct.Fields[strKey] = v
+		}
+		return structpb.NewStructValue(strct), nil
+	}
+	return nil, fmt.Errorf("not implemented: %s", rv.Type())
+}
+
+func fromStructpbValue(rv reflect.Value, s *structpb.Value) error {
+	switch rv.Kind() {
+	case reflect.Bool:
+		if b, ok := s.Kind.(*structpb.Value_BoolValue); ok {
+			rv.SetBool(b.BoolValue)
+			return nil
+		}
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		if n, ok := s.Kind.(*structpb.Value_NumberValue); ok {
+			rv.SetInt(int64(n.NumberValue))
+			return nil
+		}
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		if n, ok := s.Kind.(*structpb.Value_NumberValue); ok {
+			rv.SetUint(uint64(n.NumberValue))
+			return nil
+		}
+	case reflect.Float32, reflect.Float64:
+		if n, ok := s.Kind.(*structpb.Value_NumberValue); ok {
+			rv.SetFloat(n.NumberValue)
+			return nil
+		}
+	case reflect.String:
+		if str, ok := s.Kind.(*structpb.Value_StringValue); ok {
+			rv.SetString(str.StringValue)
+			return nil
+		}
+	case reflect.Slice:
+		if l, ok := s.Kind.(*structpb.Value_ListValue); ok {
+			values := l.ListValue.GetValues()
+			rv.Grow(len(values))
+			rv.SetLen(len(values))
+			for i, value := range values {
+				if err := fromStructpbValue(rv.Index(i), value); err != nil {
+					return err
+				}
+			}
+			return nil
+		}
+	case reflect.Map:
+		if strct, ok := s.Kind.(*structpb.Value_StructValue); ok {
+			fields := strct.StructValue.Fields
+			rv.Set(reflect.MakeMapWithSize(rv.Type(), len(fields)))
+			valueType := rv.Type().Elem()
+			for key, value := range fields {
+				mv := reflect.New(valueType).Elem()
+				if err := fromStructpbValue(mv, value); err != nil {
+					return err
+				}
+				rv.SetMapIndex(reflect.ValueOf(key), mv)
+			}
+			return nil
+		}
+	case reflect.Interface:
+		if rv.NumMethod() == 0 { // interface{} aka. any
+			v := s.AsInterface()
+			if v == nil {
+				rv.SetZero()
+			} else {
+				rv.Set(reflect.ValueOf(s.AsInterface()))
+			}
+			return nil
+		}
+	}
+	return fmt.Errorf("cannot deserialize %T into %v (%v kind)", s, rv.Type(), rv.Kind())
+}

dispatchproto/any_test.go

@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"math"
+	"net/http"
 	"reflect"
 	"strings"
 	"testing"
@@ -355,6 +356,20 @@ func TestAny(t *testing.T) {
 			List:   []any{nil, false, []any{"foo", "bar"}, map[string]any{"abc": "xyz"}},
 			Object: map[string]any{"n": 3.14, "flag": true, "tags": []any{"x", "y", "z"}},
 		}},
+
+		// slices
+		[]string{"foo", "bar"},
+		[]int{-1, 1, 111},
+		[]bool{true, false, true},
+		[]float64{3.14, 1.25},
+		[][]string{{"foo", "bar"}, {"abc", "xyz"}},
+		[]any{3.14, true, "x", nil},
+
+		// maps
+		map[string]string{"abc": "xyz", "foo": "bar"},
+		map[string]int{"n": 3},
+		map[string]http.Header{"original": {"X-Foo": []string{"bar"}}},
+		map[any]any{"foo": "bar", "pi": 3.14},
 	} {
 		t.Run(fmt.Sprintf("%v", v), func(t *testing.T) {
 			boxed, err := dispatchproto.Marshal(v)

examples/fanout/main.go

@@ -1,3 +1,5 @@
+//go:build !durable
+
 package main
 
 import (
@@ -12,14 +14,14 @@ import (
 
 func main() {
 	getRepo := dispatch.Func("getRepo", func(ctx context.Context, name string) (*dispatchhttp.Response, error) {
-		return dispatchhttp.Get(context.Background(), "https://api.github.com/repos/dispatchrun/"+name)
+		return dispatchhttp.Get(ctx, "https://api.github.com/repos/dispatchrun/"+name)
 	})
 
 	getStargazers := dispatch.Func("getStargazers", func(ctx context.Context, url string) (*dispatchhttp.Response, error) {
-		return dispatchhttp.Get(context.Background(), url)
+		return dispatchhttp.Get(ctx, url)
 	})
 
-	reduceStargazers := dispatch.Func("reduceStargazers", func(ctx context.Context, stargazerURLs strings) (strings, error) {
+	reduceStargazers := dispatch.Func("reduceStargazers", func(ctx context.Context, stargazerURLs []string) ([]string, error) {
 		responses, err := getStargazers.Gather(stargazerURLs)
 		if err != nil {
 			return nil, err
@@ -39,7 +41,7 @@ func main() {
 		return maps.Keys(stargazers), nil
 	})
 
-	fanout := dispatch.Func("fanout", func(ctx context.Context, repoNames strings) (strings, error) {
+	fanout := dispatch.Func("fanout", func(ctx context.Context, repoNames []string) ([]string, error) {
 		responses, err := getRepo.Gather(repoNames)
 		if err != nil {
 			return nil, err
@@ -65,7 +67,7 @@ func main() {
 	}
 
 	go func() {
-		if _, err := fanout.Dispatch(context.Background(), strings{"coroutine", "dispatch-py"}); err != nil {
+		if _, err := fanout.Dispatch(context.Background(), []string{"coroutine", "dispatch-py"}); err != nil {
 			log.Fatalf("failed to dispatch call: %v", err)
 		}
 	}()
@@ -74,20 +76,3 @@ func main() {
 		log.Fatalf("failed to serve endpoint: %v", err)
 	}
 }
-
-// TODO: update dispatchproto.Marshal to support serializing slices/maps
-// natively (if they can be sent on the wire as structpb.Value)
-type strings []string
-
-func (s strings) MarshalJSON() ([]byte, error) {
-	return json.Marshal([]string(s))
-}
-
-func (s *strings) UnmarshalJSON(b []byte) error {
-	var c []string
-	if err := json.Unmarshal(b, &c); err != nil {
-		return err
-	}
-	*s = c
-	return nil
-}