logs: Factorize some code for readability

Create the line of logs in two passes: the first part of the line is
the same in all cases, it's only the second part that varies depending
on the situation. Now it's clear from reading the code.

Author: elboulangero

logs/logs.go

@@ -169,6 +169,8 @@ func LogDownload(typ string, method string, statuscode int, p *mirrors.Results,
 		errstr = err.Error()
 	}
 
+	line := fmt.Sprintf("%s %d %s \"%s\" ip:%s", typ, statuscode, method, path, ip)
+
 	if (statuscode == 302 || statuscode == 200) && p != nil && len(p.MirrorList) > 0 {
 		var distance, countries string
 		m := p.MirrorList[0]
@@ -182,18 +184,19 @@ func LogDownload(typ string, method string, statuscode int, p *mirrors.Results,
 		if m.Asnum > 0 && m.Asnum == p.ClientInfo.ASNum {
 			sameASNum = "same"
 		}
-
-		dlogger.l.Printf("%s %d %s \"%s\" ip:%s mirror:%s%s %sasn:%d distance:%skm countries:%s",
-			typ, statuscode, method, path, ip, m.Name, fallback, sameASNum, m.Asnum, distance, countries)
+		line += fmt.Sprintf(" mirror:%s%s %sasn:%d distance:%skm countries:%s",
+			m.Name, fallback, sameASNum, m.Asnum, distance, countries)
 	} else if statuscode == 404 && p != nil {
-		dlogger.l.Printf("%s %d %s \"%s\" ip:%s", typ, statuscode, method, path, ip)
+		// nothing to add to the log line
 	} else if statuscode == 500 && p != nil {
 		mirrorName := "unknown"
 		if len(p.MirrorList) > 0 {
 			mirrorName = p.MirrorList[0].Name
 		}
-		dlogger.l.Printf("%s %d %s \"%s\" ip:%s mirror:%s error:%s", typ, statuscode, method, path, ip, mirrorName, errstr)
+		line += fmt.Sprintf(" mirror:%s error:%s", mirrorName, errstr)
 	} else {
-		dlogger.l.Printf("%s %d %s \"%s\" ip:%s error:%s", typ, statuscode, method, path, ip, errstr)
+		line += fmt.Sprintf(" error:%s", errstr)
 	}
+
+	dlogger.l.Print(line)
 }