fix cuncurrent [read/]write panic

pkg/fsutils/filecache.go

@@ -3,6 +3,7 @@ package fsutils
 import (
 	"fmt"
 	"io/ioutil"
+	"sync"
 
 	"github.com/golangci/golangci-lint/pkg/logutils"
 
@@ -10,19 +11,17 @@ import (
 )
 
 type FileCache struct {
-	files map[string][]byte
+	files sync.Map
 }
 
 func NewFileCache() *FileCache {
-	return &FileCache{
-		files: map[string][]byte{},
-	}
+	return &FileCache{}
 }
 
 func (fc *FileCache) GetFileBytes(filePath string) ([]byte, error) {
-	cachedBytes := fc.files[filePath]
-	if cachedBytes != nil {
-		return cachedBytes, nil
+	cachedBytes, ok := fc.files.Load(filePath)
+	if ok {
+		return cachedBytes.([]byte), nil
 	}
 
 	fileBytes, err := ioutil.ReadFile(filePath)
@@ -30,7 +29,7 @@ func (fc *FileCache) GetFileBytes(filePath string) ([]byte, error) {
 		return nil, errors.Wrapf(err, "can't read file %s", filePath)
 	}
 
-	fc.files[filePath] = fileBytes
+	fc.files.Store(filePath, fileBytes)
 	return fileBytes, nil
 }
 
@@ -56,9 +55,13 @@ func prettifyBytesCount(n int) string {
 
 func (fc *FileCache) PrintStats(log logutils.Log) {
 	var size int
-	for _, fileBytes := range fc.files {
-		size += len(fileBytes)
-	}
+	var mapLen int
+	fc.files.Range(func(_, fileBytes interface{}) bool {
+		mapLen++
+		size += len(fileBytes.([]byte))
 
-	log.Infof("File cache stats: %d entries of total size %s", len(fc.files), prettifyBytesCount(size))
+		return true
+	})
+
+	log.Infof("File cache stats: %d entries of total size %s", mapLen, prettifyBytesCount(size))
 }