Performant event serialization. Update README.

README.md

@@ -96,10 +96,7 @@ event := events.Event{
 }
 
 // 2. Compute the event ID
-id, err := events.GetID(event)
-if err != nil {
-    log.Fatal(err)
-}
+id := events.GetID(event)
 event.ID = id
 
 // 3. Sign the event
@@ -114,19 +111,13 @@ event.Sig = sig
 
 ```go
 // Returns canonical JSON: [0, pubkey, created_at, kind, tags, content]
-serialized, err := events.Serialize(event)
-if err != nil {
-    log.Fatal(err)
-}
+serialized := events.Serialize(event)
 ```
 
 #### Compute event ID manually
 
 ```go
-id, err := events.GetID(event)
-if err != nil {
-    log.Fatal(err)
-}
+id := events.GetID(event)
 // Returns lowercase hex SHA-256 hash of serialized form
 ```
 

errors/errors.go

@@ -20,9 +20,6 @@ var (
 	// MalformedTag indicates an event tag contains fewer than two elements.
 	MalformedTag = errors.New("tags must contain at least two elements")
 
-	// FailedIDComp indicates the event ID could not be computed during validation.
-	FailedIDComp = errors.New("failed to compute event id")
-
 	// NoEventID indicates the event ID field is empty.
 	NoEventID = errors.New("event id is empty")
 

events/id.go

@@ -3,35 +3,80 @@ package events
 import (
 	"crypto/sha256"
 	"encoding/hex"
-	"encoding/json"
+	"strconv"
 )
 
 // Serialize returns the canonical JSON array representation of the event.
 // used for ID computation: [0, pubkey, created_at, kind, tags, content].
-func Serialize(e Event) ([]byte, error) {
-	serialized := []interface{}{
-		0,
-		e.PubKey,
-		e.CreatedAt,
-		e.Kind,
-		e.Tags,
-		e.Content,
-	}
-
-	bytes, err := json.Marshal(serialized)
-	if err != nil {
-		return []byte{}, err
-	}
-	return bytes, nil
+func Serialize(e Event) []byte {
+	buf := make([]byte, 0, 100+len(e.Content)+len(e.Tags)*80)
+	return appendSerialized(buf, e)
 }
 
 // GetID computes and returns the event ID as a lowercase, hex-encoded SHA-256 hash
 // of the serialized event.
-func GetID(e Event) (string, error) {
-	bytes, err := Serialize(e)
-	if err != nil {
-		return "", err
-	}
+func GetID(e Event) string {
+	bytes := Serialize(e)
 	hash := sha256.Sum256(bytes)
-	return hex.EncodeToString(hash[:]), nil
+	return hex.EncodeToString(hash[:])
+}
+
+func appendSerialized(dst []byte, e Event) []byte {
+	dst = append(dst, "[0,\""...)
+	dst = append(dst, e.PubKey...)
+	dst = append(dst, "\","...)
+	dst = strconv.AppendInt(dst, int64(e.CreatedAt), 10)
+	dst = append(dst, ',')
+	dst = strconv.AppendInt(dst, int64(e.Kind), 10)
+	dst = append(dst, ",["...)
+	for i, tag := range e.Tags {
+		if i > 0 {
+			dst = append(dst, ',')
+		}
+		dst = append(dst, '[')
+		for j, s := range tag {
+			if j > 0 {
+				dst = append(dst, ',')
+			}
+			dst = appendEscapedString(dst, s)
+		}
+		dst = append(dst, ']')
+	}
+	dst = append(dst, "],"...)
+	dst = appendEscapedString(dst, e.Content)
+	return append(dst, ']')
+}
+
+func appendEscapedString(dst []byte, s string) []byte {
+	dst = append(dst, '"')
+	for i := 0; i < len(s); i++ {
+		c := s[i]
+		switch {
+		case c == '"':
+			dst = append(dst, '\\', '"')
+		case c == '\\':
+			dst = append(dst, '\\', '\\')
+		case c >= 0x20:
+			dst = append(dst, c)
+		case c == 0x08:
+			dst = append(dst, '\\', 'b')
+		case c == 0x09:
+			dst = append(dst, '\\', 't')
+		case c == 0x0a:
+			dst = append(dst, '\\', 'n')
+		case c == 0x0c:
+			dst = append(dst, '\\', 'f')
+		case c == 0x0d:
+			dst = append(dst, '\\', 'r')
+		case c < 0x09:
+			dst = append(dst, '\\', 'u', '0', '0', '0', '0'+c)
+		case c < 0x10:
+			dst = append(dst, '\\', 'u', '0', '0', '0', 0x57+c)
+		case c < 0x1a:
+			dst = append(dst, '\\', 'u', '0', '0', '1', 0x20+c)
+		case c < 0x20:
+			dst = append(dst, '\\', 'u', '0', '0', '1', 0x47+c)
+		}
+	}
+	return append(dst, '"')
 }

events/id_test.go

@@ -196,8 +196,7 @@ var idTestCases = []IDTestCase{
 func TestEventGetId(t *testing.T) {
 	for _, tc := range idTestCases {
 		t.Run(tc.name, func(t *testing.T) {
-			actual, err := GetID(tc.event)
-			assert.NoError(t, err)
+			actual := GetID(tc.event)
 			assert.Equal(t, tc.expected, actual)
 		})
 	}

events/validate.go

@@ -47,10 +47,7 @@ func ValidateStructure(e Event) error {
 
 // ValidateID recomputes the event ID and verifies it matches the stored ID field.
 func ValidateID(e Event) error {
-	computedID, err := GetID(e)
-	if err != nil {
-		return errors.FailedIDComp
-	}
+	computedID := GetID(e)
 	if e.ID == "" {
 		return errors.NoEventID
 	}