Output file fixes

* Fixed flush/Write race
* Fixed names with underscores

output_file.go

@@ -12,6 +12,7 @@ import (
 	"strconv"
 	"strings"
 	"time"
+	"sync"
 )
 
 var dateFileNameFuncs = map[string]func() string{
@@ -33,6 +34,7 @@ type FileOutputConfig struct {
 
 // FileOutput output plugin
 type FileOutput struct {
+	mu           sync.Mutex
 	pathTemplate string
 	currentName  string
 	file         *os.File
@@ -87,7 +89,9 @@ func setFileIndex(name string, idx int) string {
 	withoutExt := strings.TrimSuffix(name, ext)
 
 	if i := strings.LastIndex(withoutExt, "_"); i != -1 {
-		withoutExt = withoutExt[:i]
+		if _, err := strconv.Atoi(withoutExt[i+1:]); err == nil {
+			withoutExt = withoutExt[:i]
+		}
 	}
 
 	return withoutExt + "_" + idxS + ext
@@ -120,6 +124,9 @@ func (s sortByFileIndex) Less(i, j int) bool {
 }
 
 func (o *FileOutput) filename() string {
+	defer o.mu.Unlock()
+	o.mu.Lock()
+
 	path := o.pathTemplate
 
 	for name, fn := range dateFileNameFuncs {
@@ -172,6 +179,7 @@ func (o *FileOutput) Write(data []byte) (n int, err error) {
 	}
 
 	if o.file == nil || o.currentName != o.file.Name() {
+		o.mu.Lock()
 		o.Close()
 
 		o.file, err = os.OpenFile(o.currentName, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0660)
@@ -188,6 +196,7 @@ func (o *FileOutput) Write(data []byte) (n int, err error) {
 		}
 
 		o.queueLength = 0
+		o.mu.Unlock()
 	}
 
 	o.writer.Write(data)
@@ -199,16 +208,19 @@ func (o *FileOutput) Write(data []byte) (n int, err error) {
 }
 
 func (o *FileOutput) flush() {
+	defer o.mu.Unlock()
+	o.mu.Lock()
+
 	if o.file != nil {
 		if strings.HasSuffix(o.currentName, ".gz") {
 			o.writer.(*gzip.Writer).Flush()
 		} else {
 			o.writer.(*bufio.Writer).Flush()
 		}
-	}
 
-	if stat, err := o.file.Stat(); err != nil {
-		o.chunkSize = int(stat.Size())
+		if stat, err := o.file.Stat(); err != nil {
+			o.chunkSize = int(stat.Size())
+		}
 	}
 }
 

output_file_test.go

@@ -166,6 +166,7 @@ func TestSetFileIndex(t *testing.T) {
 		{"/tmp/logs_1", 0, "/tmp/logs_0"},
 		{"/tmp/logs_0", 10, "/tmp/logs_10"},
 		{"/tmp/logs_0.gz", 10, "/tmp/logs_10.gz"},
+		{"/tmp/logs_underscores.gz", 10, "/tmp/logs_underscores_10.gz"},
 	}
 
 	for _, c := range tests {