rpc: improve the realtime notify performance by 30%

rpc/subscription.go

@@ -105,7 +105,7 @@ type Notifier struct {
 
 	mu           sync.Mutex
 	sub          *Subscription
-	buffer       []json.RawMessage
+	buffer       []interface{}
 	callReturned bool
 	activated    bool
 }
@@ -130,11 +130,6 @@ func (n *Notifier) CreateSubscription() *Subscription {
 // Notify sends a notification to the client with the given data as payload.
 // If an error occurs the RPC connection is closed and the error is returned.
 func (n *Notifier) Notify(id ID, data interface{}) error {
-	enc, err := json.Marshal(data)
-	if err != nil {
-		return err
-	}
-
 	n.mu.Lock()
 	defer n.mu.Unlock()
 
@@ -144,9 +139,9 @@ func (n *Notifier) Notify(id ID, data interface{}) error {
 		panic("Notify with wrong ID")
 	}
 	if n.activated {
-		return n.send(n.sub, enc)
+		return n.send(n.sub, data)
 	}
-	n.buffer = append(n.buffer, enc)
+	n.buffer = append(n.buffer, data)
 	return nil
 }
 
@@ -181,8 +176,11 @@ func (n *Notifier) activate() error {
 	return nil
 }
 
-func (n *Notifier) send(sub *Subscription, data json.RawMessage) error {
-	params, _ := json.Marshal(&subscriptionResult{ID: string(sub.ID), Result: data})
+func (n *Notifier) send(sub *Subscription, data interface{}) error {
+	params, _ := json.Marshal(struct {
+		ID     string      `json:"subscription"`
+		Result interface{} `json:"result,omitempty"`
+	}{ID: string(sub.ID), Result: data})
 	ctx := context.Background()
 
 	msg := &jsonrpcMessage{

rpc/subscription_test.go

@@ -17,12 +17,17 @@
 package rpc
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
+	"math/big"
 	"net"
 	"strings"
 	"testing"
 	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
 )
 
 func TestNewID(t *testing.T) {
@@ -218,3 +223,33 @@ func readAndValidateMessage(in *json.Decoder) (*subConfirmation, *subscriptionRe
 		return nil, nil, fmt.Errorf("unrecognized message: %v", msg)
 	}
 }
+
+type mockConn struct{}
+
+// writeJSON writes a message to the connection.
+func (c *mockConn) writeJSON(ctx context.Context, msg interface{}, isError bool) error { return nil }
+
+// Closed returns a channel which is closed when the connection is closed.
+func (c *mockConn) closed() <-chan interface{} { return nil }
+
+// RemoteAddr returns the peer address of the connection.
+func (c *mockConn) remoteAddr() string { return "" }
+
+// BenchmarkNotify benchmarks the performance of notifying a subscription.
+func BenchmarkNotify(b *testing.B) {
+	id := ID("test")
+	notifier := &Notifier{
+		h:         &handler{conn: &mockConn{}},
+		sub:       &Subscription{ID: id},
+		activated: true,
+	}
+
+	msg := &types.Header{
+		ParentHash: common.HexToHash("0x01"),
+		Number:     big.NewInt(100),
+	}
+
+	for i := 0; i < b.N; i++ {
+		notifier.Notify(id, msg)
+	}
+}