reverse scan log

pkg/log/scanlog.go

@@ -3,6 +3,7 @@ package log
 import (
 	"fmt"
 	"git.giftfish.de/ston1th/docstore/pkg/core"
+	"strings"
 	"sync"
 )
 
@@ -39,9 +40,31 @@ func (l *ScanLog) Printf(f string, v ...interface{}) {
 
 func (l *ScanLog) Logs() (logs string) {
 	l.RLock()
-	for i := len(l.logs) - 1; i >= 0; i-- {
-		logs += "\n" + l.logs[i]
-	}
+	logs = reverseJoin(l.logs, "\n")
 	l.RUnlock()
 	return
 }
+
+// reverseJoin is a reverse version of strings.Join
+// code taken from strings.Join
+func reverseJoin(a []string, sep string) string {
+	switch len(a) {
+	case 0:
+		return ""
+	case 1:
+		return a[0]
+	}
+	n := len(sep) * (len(a) - 1)
+	for i := 0; i < len(a); i++ {
+		n += len(a[i])
+	}
+
+	var b strings.Builder
+	b.Grow(n)
+	b.WriteString(a[len(a)-1])
+	for i := len(a) - 2; i >= 0; i-- {
+		b.WriteString(sep)
+		b.WriteString(a[i])
+	}
+	return b.String()
+}