From 39571ccc560c149c520bf030cd199b838d5f6c96 Mon Sep 17 00:00:00 2001
From: Eelco Cramer <eelco@servicelab.org>
Date: Fri, 9 Oct 2020 15:06:47 +0200
Subject: [PATCH] Improves performance

---
 internal/proto/reader.go      | 37 +++++++++++++++++++++++------------
 internal/proto/reader_test.go |  9 ++++++---
 2 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/internal/proto/reader.go b/internal/proto/reader.go
index 6dda42d3..ebe85ff3 100644
--- a/internal/proto/reader.go
+++ b/internal/proto/reader.go
@@ -55,13 +55,10 @@ func (r *Reader) Reset(rd io.Reader) {
 }
 
 func (r *Reader) ReadLine() ([]byte, error) {
-	line, err := r.rd.ReadBytes('\n')
-	if err != nil && err != io.EOF {
+	line, err := r.readLine()
+	if err != nil {
 		return nil, err
 	}
-	if len(line) == 0 {
-		return nil, fmt.Errorf("redis: reply is empty")
-	}
 	if isNilReply(line) {
 		return nil, Nil
 	}
@@ -72,15 +69,29 @@ func (r *Reader) ReadLine() ([]byte, error) {
 //   - there is a pending read error;
 //   - or line does not end with \r\n.
 func (r *Reader) readLine() ([]byte, error) {
-	b, err := r.rd.ReadSlice('\n')
-	if err != nil {
-		return nil, err
+	var s []byte
+	multi := false
+	for {
+		b, err := r.rd.ReadSlice('\n')
+		if err != nil {
+			// in case the end of the buffer is not reached
+			if err == bufio.ErrBufferFull {
+				s = append(s, b...)
+				multi = true
+				continue
+			} else {
+				return nil, err
+			}
+		}
+		if len(b) <= 2 || b[len(b)-1] != '\n' || b[len(b)-2] != '\r' {
+			return nil, fmt.Errorf("redis: invalid reply: %q", b)
+		}
+		if multi {
+			b = append(s, b...)
+		}
+		b = b[:len(b)-2]
+		return b, nil
 	}
-	if len(b) <= 2 || b[len(b)-1] != '\n' || b[len(b)-2] != '\r' {
-		return nil, fmt.Errorf("redis: invalid reply: %q", b)
-	}
-	b = b[:len(b)-2]
-	return b, nil
 }
 
 func (r *Reader) ReadReply(m MultiBulkParse) (interface{}, error) {
diff --git a/internal/proto/reader_test.go b/internal/proto/reader_test.go
index a57b38b6..b8c99dd6 100644
--- a/internal/proto/reader_test.go
+++ b/internal/proto/reader_test.go
@@ -2,6 +2,7 @@ package proto_test
 
 import (
 	"bytes"
+	"io"
 	"testing"
 
 	"github.com/go-redis/redis/v8/internal/proto"
@@ -29,14 +30,16 @@ func BenchmarkReader_ParseReply_Slice(b *testing.B) {
 
 func TestReader_ReadLine(t *testing.T) {
 	original := bytes.Repeat([]byte("a"), 8192)
+	original[len(original)-2] = '\r'
+	original[len(original)-1] = '\n'
 	r := proto.NewReader(bytes.NewReader(original))
 	read, err := r.ReadLine()
-	if err != nil {
+	if err != nil && err != io.EOF {
 		t.Errorf("Should be able to read the full buffer: %v", err)
 	}
 
-	if bytes.Compare(read, original) != 0 {
-		t.Errorf("Values must be equal: %q", read)
+	if bytes.Compare(read, original[:len(original)-2]) != 0 {
+		t.Errorf("Values must be equal: %d expected %d", len(read), len(original[:len(original)-2]))
 	}
 }