perf: optimize header parsing with zero-copy ReadSlice

- Replace ReadString with ReadSlice to eliminate allocations
- Use bytes operations instead of strings
- Add FromBytes variant for in-memory parsing

server/header.go

@@ -4,7 +4,6 @@ import (
 	"bufio"
 	"bytes"
 	"fmt"
-	"strings"
 )
 
 type HeaderManager interface {
@@ -44,43 +43,132 @@ type requestHeaderFactory struct {
 	headers   map[string]string
 }
 
-func NewRequestHeaderFactory(br *bufio.Reader) (RequestHeaderManager, error) {
+func NewRequestHeaderFactory(r interface{}) (RequestHeaderManager, error) {
+	switch v := r.(type) {
+	case []byte:
+		return parseHeadersFromBytes(v)
+	case *bufio.Reader:
+		return parseHeadersFromReader(v)
+	default:
+		return nil, fmt.Errorf("unsupported type: %T", r)
+	}
+}
+
+func parseHeadersFromBytes(headerData []byte) (RequestHeaderManager, error) {
 	header := &requestHeaderFactory{
-		headers: make(map[string]string),
+		headers: make(map[string]string, 16),
 	}
 
-	startLine, err := br.ReadString('\n')
-	if err != nil {
-		return nil, err
+	lineEnd := bytes.IndexByte(headerData, '\n')
+	if lineEnd == -1 {
+		return nil, fmt.Errorf("invalid request: no newline found")
 	}
-	startLine = strings.TrimRight(startLine, "\r\n")
-	header.startLine = []byte(startLine)
 
-	parts := strings.Split(startLine, " ")
+	startLine := bytes.TrimRight(headerData[:lineEnd], "\r\n")
+	header.startLine = make([]byte, len(startLine))
+	copy(header.startLine, startLine)
+
+	parts := bytes.Split(startLine, []byte{' '})
 	if len(parts) < 3 {
 		return nil, fmt.Errorf("invalid request line")
 	}
 
-	header.method = parts[0]
-	header.path = parts[1]
-	header.version = parts[2]
+	header.method = string(parts[0])
+	header.path = string(parts[1])
+	header.version = string(parts[2])
 
-	for {
-		line, err := br.ReadString('\n')
-		if err != nil {
-			return nil, err
+	remaining := headerData[lineEnd+1:]
+
+	for len(remaining) > 0 {
+		lineEnd = bytes.IndexByte(remaining, '\n')
+		if lineEnd == -1 {
+			lineEnd = len(remaining)
 		}
-		line = strings.TrimRight(line, "\r\n")
 
-		if line == "" {
+		line := bytes.TrimRight(remaining[:lineEnd], "\r\n")
+
+		if len(line) == 0 {
 			break
 		}
 
-		kv := strings.SplitN(line, ":", 2)
-		if len(kv) != 2 {
+		colonIdx := bytes.IndexByte(line, ':')
+		if colonIdx != -1 {
+			key := bytes.TrimSpace(line[:colonIdx])
+			value := bytes.TrimSpace(line[colonIdx+1:])
+			header.headers[string(key)] = string(value)
+		}
+
+		if lineEnd == len(remaining) {
+			break
+		}
+		remaining = remaining[lineEnd+1:]
+	}
+
+	return header, nil
+}
+
+func parseHeadersFromReader(br *bufio.Reader) (RequestHeaderManager, error) {
+	header := &requestHeaderFactory{
+		headers: make(map[string]string, 16),
+	}
+
+	startLineBytes, err := br.ReadSlice('\n')
+	if err != nil {
+		if err == bufio.ErrBufferFull {
+			var startLine string
+			startLine, err = br.ReadString('\n')
+			if err != nil {
+				return nil, err
+			}
+			startLineBytes = []byte(startLine)
+		} else {
+			return nil, err
+		}
+	}
+
+	startLineBytes = bytes.TrimRight(startLineBytes, "\r\n")
+	header.startLine = make([]byte, len(startLineBytes))
+	copy(header.startLine, startLineBytes)
+
+	parts := bytes.Split(startLineBytes, []byte{' '})
+	if len(parts) < 3 {
+		return nil, fmt.Errorf("invalid request line")
+	}
+
+	header.method = string(parts[0])
+	header.path = string(parts[1])
+	header.version = string(parts[2])
+
+	for {
+		lineBytes, err := br.ReadSlice('\n')
+		if err != nil {
+			if err == bufio.ErrBufferFull {
+				var line string
+				line, err = br.ReadString('\n')
+				if err != nil {
+					return nil, err
+				}
+				lineBytes = []byte(line)
+			} else {
+				return nil, err
+			}
+		}
+
+		lineBytes = bytes.TrimRight(lineBytes, "\r\n")
+
+		if len(lineBytes) == 0 {
+			break
+		}
+
+		colonIdx := bytes.IndexByte(lineBytes, ':')
+		if colonIdx == -1 {
 			continue
 		}
-		header.headers[strings.TrimSpace(kv[0])] = strings.TrimSpace(kv[1])
+
+		key := bytes.TrimSpace(lineBytes[:colonIdx])
+		value := bytes.TrimSpace(lineBytes[colonIdx+1:])
+
+		header.headers[string(key)] = string(value)
 	}
 
 	return header, nil