Make fileRegister a set (#1653)

Author: arturmelanchyk

AUTHORS

@@ -20,6 +20,7 @@ Andrew Reid <andrew.reid at tixtrack.com>
 Animesh Ray <mail.rayanimesh at gmail.com>
 Arne Hormann <arnehormann at gmail.com>
 Ariel Mashraki <ariel at mashraki.co.il>
+Artur Melanchyk <artur.melanchyk@gmail.com>
 Asta Xie <xiemengjun at gmail.com>
 B Lamarche <blam413 at gmail.com>
 Brian Hendriks <brian at dolthub.com>

infile.go

@@ -17,7 +17,7 @@ import (
 )
 
 var (
-	fileRegister       map[string]bool
+	fileRegister       map[string]struct{}
 	fileRegisterLock   sync.RWMutex
 	readerRegister     map[string]func() io.Reader
 	readerRegisterLock sync.RWMutex
@@ -37,10 +37,10 @@ func RegisterLocalFile(filePath string) {
 	fileRegisterLock.Lock()
 	// lazy map init
 	if fileRegister == nil {
-		fileRegister = make(map[string]bool)
+		fileRegister = make(map[string]struct{})
 	}
 
-	fileRegister[strings.Trim(filePath, `"`)] = true
+	fileRegister[strings.Trim(filePath, `"`)] = struct{}{}
 	fileRegisterLock.Unlock()
 }
 
@@ -123,9 +123,9 @@ func (mc *okHandler) handleInFileRequest(name string) (err error) {
 	} else { // File
 		name = strings.Trim(name, `"`)
 		fileRegisterLock.RLock()
-		fr := fileRegister[name]
+		_, exists := fileRegister[name]
 		fileRegisterLock.RUnlock()
-		if mc.cfg.AllowAllFiles || fr {
+		if mc.cfg.AllowAllFiles || exists {
 			var file *os.File
 			var fi os.FileInfo