perf: reuse requests to reduce allocs (#127)

Author: abemedia

decoder/compile.go

@@ -76,8 +76,7 @@ func compile(typ reflect.Type, tagKey string, isPtr bool) (decoder, error) {
 		case reflect.Bool:
 			decoders = append(decoders, decodeBool(set[bool](ptr, i, t), tag))
 		case reflect.Slice:
-			_, sk, _ := typeKind(t.Elem())
-			switch sk {
+			switch t.Elem().Kind() {
 			case reflect.String:
 				decoders = append(decoders, decodeStrings(set[[]string](ptr, i, t), tag))
 			case reflect.Uint8:

decoder/decode.go

@@ -60,7 +60,12 @@ type CachedDecoder[V any] struct {
 }
 
 func NewCached[V any](v V, tag string) (*CachedDecoder[V], error) {
-	t, k, ptr := typeKind(reflect.TypeOf(v))
+	t := reflect.TypeOf(v)
+	if t == nil {
+		return nil, ErrUnsupportedType
+	}
+
+	t, k, ptr := typeKind(t)
 	if k != reflect.Struct {
 		return nil, ErrUnsupportedType
 	}

decoder/decode_test.go

@@ -144,6 +144,10 @@ func TestDecodeError(t *testing.T) {
 		target any
 		error  error
 	}{
+		{
+			target: nil,
+			error:  decoder.ErrUnsupportedType,
+		},
 		{
 			target: "",
 			error:  decoder.ErrUnsupportedType,

encoding/protobuf/protobuf.go

@@ -13,8 +13,7 @@ var messageType = reflect.TypeOf((*proto.Message)(nil)).Elem()
 func unmarshal(b []byte, v any) error {
 	// TODO: Cache reflect results to improve performance.
 	elem := reflect.ValueOf(v).Elem()
-	if elem.Type().Implements(messageType) && elem.IsNil() {
-		elem.Set(reflect.New(elem.Type().Elem()))
+	if elem.Type().Implements(messageType) {
 		v = elem.Interface()
 	}
 

export_test.go

@@ -1,3 +1,7 @@
 package don
 
 var MakeNilCheck = makeNilCheck
+
+func NewRequestPool[T any](v T) pool[T] {
+	return newRequestPool(v)
+}

handler.go

@@ -26,6 +26,7 @@ type Handle[T, O any] func(ctx context.Context, request T) (O, error)
 
 // H wraps your handler function with the Go generics magic.
 func H[T, O any](handle Handle[T, O]) httprouter.Handle {
+	pool := newRequestPool(*new(T))
 	decodeRequest := newRequestDecoder(*new(T))
 	isNil := makeNilCheck(*new(O))
 
@@ -38,13 +39,10 @@ func H[T, O any](handle Handle[T, O]) httprouter.Handle {
 			return
 		}
 
-		var (
-			req = new(T)
-			res any
-			err error
-		)
+		var res any
 
-		err = decodeRequest(req, ctx, p)
+		req := pool.Get()
+		err := decodeRequest(req, ctx, p)
 		if err != nil {
 			res = Error(err, getStatusCode(err, http.StatusBadRequest))
 		} else {
@@ -53,6 +51,7 @@ func H[T, O any](handle Handle[T, O]) httprouter.Handle {
 				res = Error(err, 0)
 			}
 		}
+		pool.Put(req)
 
 		ctx.SetContentType(contentType + "; charset=utf-8")
 

internal/test/encoding.go

@@ -39,18 +39,18 @@ func Encoding[T any](t *testing.T, opt EncodingOptions[T]) {
 func Decode[T any](t *testing.T, opt EncodingOptions[T]) {
 	t.Helper()
 
-	var got T
+	var diff string
 
 	api := don.New(nil)
-	api.Post("/", don.H(func(ctx context.Context, req T) (don.Empty, error) {
-		got = req
-		return don.Empty{}, nil
+	api.Post("/", don.H(func(ctx context.Context, req T) (any, error) {
+		diff = cmp.Diff(opt.Parsed, req, ignoreUnexported[T]())
+		return nil, nil
 	}))
 
 	ctx := httptest.NewRequest(http.MethodPost, "/", opt.Raw, map[string]string{"Content-Type": opt.Mime})
 	api.RequestHandler()(ctx)
 
-	if diff := cmp.Diff(opt.Parsed, got, ignoreUnexported[T]()); diff != "" {
+	if diff != "" {
 		t.Error(diff)
 	}
 
@@ -63,7 +63,7 @@ func Encode[T any](t *testing.T, opt EncodingOptions[T]) {
 	t.Helper()
 
 	api := don.New(nil)
-	api.Post("/", don.H(func(ctx context.Context, req don.Empty) (T, error) {
+	api.Post("/", don.H(func(ctx context.Context, req any) (T, error) {
 		return opt.Parsed, nil
 	}))
 
@@ -113,9 +113,14 @@ func BenchmarkDecode[T any](b *testing.B, opt EncodingOptions[T]) {
 	ctx := httptest.NewRequest("POST", "/", "", nil)
 	ctx.Request.SetBodyStream(rd, len(opt.Raw))
 
+	v := new(T)
+	if val := reflect.ValueOf(v).Elem(); val.Kind() == reflect.Pointer {
+		val.Set(reflect.New(val.Type().Elem()))
+	}
+
 	for i := 0; i < b.N; i++ {
 		rd.Seek(0, io.SeekStart) //nolint:errcheck
-		dec(ctx, new(T))         //nolint:errcheck
+		dec(ctx, v)              //nolint:errcheck
 	}
 }
 

pool.go

@@ -0,0 +1,74 @@
+package don
+
+import (
+	"reflect"
+	"sync"
+)
+
+type pool[T any] interface {
+	Get() *T
+	Put(*T)
+}
+
+type resetter interface {
+	Reset()
+}
+
+var resetterType = reflect.TypeOf((*resetter)(nil)).Elem()
+
+type requestPool[T any] struct {
+	pool  sync.Pool
+	reset func(*T)
+}
+
+func newRequestPool[T any](zero T) pool[T] {
+	typ := reflect.TypeOf(zero)
+	if typ == nil {
+		return &fakePool[T]{&zero}
+	}
+
+	p := &requestPool[T]{}
+
+	if typ.Kind() != reflect.Pointer {
+		p.pool.New = func() any {
+			return new(T)
+		}
+		p.reset = func(v *T) {
+			*v = zero
+		}
+	} else {
+		elem := typ.Elem()
+		p.pool.New = func() any {
+			v := reflect.New(elem).Interface().(T) //nolint:forcetypeassert
+			return &v
+		}
+
+		if typ.Implements(resetterType) {
+			p.reset = func(v *T) {
+				any(*v).(resetter).Reset() //nolint:forcetypeassert
+			}
+		} else {
+			zeroValue := reflect.New(elem).Elem()
+			p.reset = func(v *T) {
+				reflect.ValueOf(v).Elem().Elem().Set(zeroValue)
+			}
+		}
+	}
+
+	return p
+}
+
+func (p *requestPool[T]) Get() *T {
+	return p.pool.Get().(*T) //nolint:forcetypeassert
+}
+
+func (p *requestPool[T]) Put(v *T) {
+	p.reset(v)
+	p.pool.Put(v)
+}
+
+type fakePool[T any] struct{ v *T }
+
+func (p *fakePool[T]) Get() *T { return p.v }
+
+func (p *fakePool[T]) Put(*T) {}

pool_test.go

@@ -0,0 +1,91 @@
+package don_test
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/abemedia/go-don"
+)
+
+func TestRequestPool(t *testing.T) {
+	type item struct {
+		String  string
+		Pointer *string
+	}
+
+	t.Run("Nil", func(t *testing.T) {
+		var zero any
+		pool := don.NewRequestPool(zero)
+
+		pool.Put(pool.Get())
+
+		if !reflect.DeepEqual(&zero, pool.Get()) {
+			t.Fatal("should be zero value")
+		}
+	})
+
+	t.Run("Struct", func(t *testing.T) {
+		zero := item{}
+		pool := don.NewRequestPool(zero)
+
+		for i := 0; i < 100; i++ {
+			v := pool.Get()
+			v.String = "test"
+			v.Pointer = &v.String
+			pool.Put(v)
+		}
+
+		for i := 0; i < 100; i++ {
+			if !reflect.DeepEqual(&zero, pool.Get()) {
+				t.Fatal("should be zero value")
+			}
+		}
+	})
+
+	t.Run("Pointer", func(t *testing.T) {
+		zero := &item{}
+		pool := don.NewRequestPool(zero)
+
+		for i := 0; i < 100; i++ {
+			p := pool.Get()
+			v := *p
+			v.String = "test"
+			v.Pointer = &v.String
+			pool.Put(p)
+		}
+
+		for i := 0; i < 100; i++ {
+			if !reflect.DeepEqual(&zero, pool.Get()) {
+				t.Fatal("should be zero value")
+			}
+		}
+	})
+
+	t.Run("Resetter", func(t *testing.T) {
+		zero := &itemResetter{}
+		pool := don.NewRequestPool(zero)
+
+		for i := 0; i < 100; i++ {
+			p := pool.Get()
+			v := *p
+			v.String = "test"
+			v.Pointer = &v.String
+			pool.Put(p)
+		}
+
+		for i := 0; i < 100; i++ {
+			if !reflect.DeepEqual(&zero, pool.Get()) {
+				t.Fatal("should be zero value")
+			}
+		}
+	})
+}
+
+type itemResetter struct {
+	String  string
+	Pointer *string
+}
+
+func (ir *itemResetter) Reset() {
+	*ir = itemResetter{}
+}