codec: do conditional compilation for json/v2 experiment

Signed-off-by: Hank Donnay <[email protected]>

Author: hdonnay

internal/codec/codec.go

@@ -4,65 +4,37 @@ package codec
 
 import (
 	"io"
-	"sync"
-
-	"github.com/ugorji/go/codec"
 )
 
-var jsonHandle codec.JsonHandle
-
-func init() {
-	// This is documented to cause "smart buffering".
-	jsonHandle.WriterBufferSize = 4096
-	jsonHandle.ReaderBufferSize = 4096
-	// Force calling time.Time's Marshal function. This causes an allocation on
-	// every time.Time value, but is the same behavior as the stdlib json
-	// encoder. If we decide nulls are OK, this should get removed.
-	jsonHandle.TimeNotBuiltin = true
+// Encoder encodes.
+type Encoder interface {
+	Encode(in any) error
 }
 
-// Encoder and decoder pools, to reuse if possible.
-var (
-	encPool = sync.Pool{
-		New: func() interface{} {
-			return codec.NewEncoder(nil, &jsonHandle)
-		},
-	}
-	decPool = sync.Pool{
-		New: func() interface{} {
-			return codec.NewDecoder(nil, &jsonHandle)
-		},
-	}
-)
+// Decoder decodes.
+type Decoder interface {
+	Decode(out any) error
+}
 
-// Encoder encodes.
-type Encoder = codec.Encoder
+// All the exported functions delegate to an unexported version, which is
+// provided by whichever implementation is selected at compile time.
 
 // GetEncoder returns an encoder configured to write to w.
-func GetEncoder(w io.Writer) *Encoder {
-	e := encPool.Get().(*Encoder)
-	e.Reset(w)
-	return e
+func GetEncoder(w io.Writer) Encoder {
+	return getEncoder(w)
 }
 
 // PutEncoder returns an encoder to the pool.
-func PutEncoder(e *Encoder) {
-	e.Reset(nil)
-	encPool.Put(e)
+func PutEncoder(v Encoder) {
+	putEncoder(v)
 }
 
-// Decoder decodes.
-type Decoder = codec.Decoder
-
 // GetDecoder returns a decoder configured to read from r.
-func GetDecoder(r io.Reader) *Decoder {
-	d := decPool.Get().(*Decoder)
-	d.Reset(r)
-	return d
+func GetDecoder(r io.Reader) Decoder {
+	return getDecoder(r)
 }
 
 // PutDecoder returns a decoder to the pool.
-func PutDecoder(d *Decoder) {
-	d.Reset(nil)
-	decPool.Put(d)
+func PutDecoder(v Decoder) {
+	putDecoder(v)
 }

internal/codec/codec_test.go

@@ -15,11 +15,11 @@ import (
 func Example() {
 	enc := GetEncoder(os.Stdout)
 	defer PutEncoder(enc)
-	enc.MustEncode([]string{"a", "slice", "of", "strings"})
+	enc.Encode([]string{"a", "slice", "of", "strings"})
 	fmt.Fprintln(os.Stdout)
-	enc.MustEncode(nil)
+	enc.Encode(nil)
 	fmt.Fprintln(os.Stdout)
-	enc.MustEncode(map[string]string{})
+	enc.Encode(map[string]string{})
 	fmt.Fprintln(os.Stdout)
 	// Output: ["a","slice","of","strings"]
 	// null

internal/codec/jsonv2.go

@@ -0,0 +1,48 @@
+//go:build go1.25 && goexperiment.jsonv2
+
+package codec
+
+import (
+	"encoding/json/jsontext"
+	"encoding/json/v2"
+	"io"
+)
+
+// The interface built on json/v2 does not use its own pool and instead relies
+// on the json package's pooling.
+
+var options = json.JoinOptions(
+	json.DefaultOptionsV2(),
+	jsontext.Multiline(false),
+	jsontext.SpaceAfterColon(false),
+	jsontext.SpaceAfterComma(false),
+	json.OmitZeroStructFields(true),
+	json.FormatNilMapAsNull(true),
+	json.FormatNilSliceAsNull(true),
+)
+
+type fwdWriter struct {
+	io.Writer
+}
+
+func (w fwdWriter) Encode(in any) error {
+	return json.MarshalWrite(w.Writer, in, options)
+}
+
+type fwdReader struct {
+	io.Reader
+}
+
+func (r fwdReader) Decode(out any) error {
+	return json.UnmarshalRead(r.Reader, out, options)
+}
+
+// GetEncoder returns an encoder configured to write to w.
+func getEncoder(w io.Writer) Encoder { return fwdWriter{w} }
+
+func putEncoder(v Encoder) {}
+
+// GetDecoder returns a decoder configured to read from r.
+func getDecoder(r io.Reader) Decoder { return fwdReader{r} }
+
+func putDecoder(v Decoder) {}

internal/codec/ugorji.go

@@ -0,0 +1,64 @@
+//go:build !go1.25 || !goexperiment.jsonv2
+
+package codec
+
+import (
+	"io"
+	"sync"
+
+	"github.com/ugorji/go/codec"
+)
+
+var jsonHandle codec.JsonHandle
+
+func init() {
+	// This is documented to cause "smart buffering".
+	jsonHandle.WriterBufferSize = 4096
+	jsonHandle.ReaderBufferSize = 4096
+	// Force calling time.Time's Marshal function. This causes an allocation on
+	// every time.Time value, but is the same behavior as the stdlib json
+	// encoder. If we decide nulls are OK, this should get removed.
+	jsonHandle.TimeNotBuiltin = true
+}
+
+// Encoder and decoder pools, to reuse if possible.
+var (
+	encPool = sync.Pool{
+		New: func() any {
+			return codec.NewEncoder(nil, &jsonHandle)
+		},
+	}
+	decPool = sync.Pool{
+		New: func() any {
+			return codec.NewDecoder(nil, &jsonHandle)
+		},
+	}
+)
+
+// GetEncoder returns an encoder configured to write to w.
+func getEncoder(w io.Writer) Encoder {
+	e := encPool.Get().(*codec.Encoder)
+	e.Reset(w)
+	return e
+}
+
+// PutEncoder returns an encoder to the pool.
+func putEncoder(v Encoder) {
+	e := v.(*codec.Encoder)
+	e.Reset(nil)
+	encPool.Put(e)
+}
+
+// GetDecoder returns a decoder configured to read from r.
+func getDecoder(r io.Reader) Decoder {
+	d := decPool.Get().(*codec.Decoder)
+	d.Reset(r)
+	return d
+}
+
+// PutDecoder returns a decoder to the pool.
+func putDecoder(v Decoder) {
+	d := v.(*codec.Decoder)
+	d.Reset(nil)
+	decPool.Put(d)
+}