[chore][pkg/stanza] Minor cleanup of fileconsumer setup code

pkg/stanza/fileconsumer/config.go

@@ -149,26 +149,27 @@ func (c Config) buildManager(logger *zap.SugaredLogger, emit emit.Callback, spli
 		return nil, err
 	}
 
+	readerFactory := reader.Factory{
+		SugaredLogger:           logger.With("component", "fileconsumer"),
+		FromBeginning:           startAtBeginning,
+		FingerprintSize:         int(c.FingerprintSize),
+		MaxLogSize:              int(c.MaxLogSize),
+		Encoding:                enc,
+		SplitFunc:               splitFunc,
+		TrimFunc:                trimFunc,
+		FlushTimeout:            c.FlushPeriod,
+		EmitFunc:                emit,
+		IncludeFileName:         c.IncludeFileName,
+		IncludeFilePath:         c.IncludeFilePath,
+		IncludeFileNameResolved: c.IncludeFileNameResolved,
+		IncludeFilePathResolved: c.IncludeFilePathResolved,
+		HeaderConfig:            hCfg,
+		DeleteAtEOF:             c.DeleteAfterRead,
+	}
+
 	return &Manager{
-		SugaredLogger: logger.With("component", "fileconsumer"),
-		cancel:        func() {},
-		readerFactory: reader.Factory{
-			SugaredLogger:           logger.With("component", "fileconsumer"),
-			FromBeginning:           startAtBeginning,
-			FingerprintSize:         int(c.FingerprintSize),
-			MaxLogSize:              int(c.MaxLogSize),
-			Encoding:                enc,
-			SplitFunc:               splitFunc,
-			TrimFunc:                trimFunc,
-			FlushTimeout:            c.FlushPeriod,
-			EmitFunc:                emit,
-			IncludeFileName:         c.IncludeFileName,
-			IncludeFilePath:         c.IncludeFilePath,
-			IncludeFileNameResolved: c.IncludeFileNameResolved,
-			IncludeFilePathResolved: c.IncludeFilePathResolved,
-			HeaderConfig:            hCfg,
-			DeleteAtEOF:             c.DeleteAfterRead,
-		},
+		SugaredLogger:     logger.With("component", "fileconsumer"),
+		readerFactory:     readerFactory,
 		fileMatcher:       fileMatcher,
 		pollInterval:      c.PollInterval,
 		maxBatchFiles:     c.MaxConcurrentFiles / 2,
@@ -179,50 +180,49 @@ func (c Config) buildManager(logger *zap.SugaredLogger, emit emit.Callback, spli
 }
 
 func (c Config) validate() error {
-	if c.DeleteAfterRead && !allowFileDeletion.IsEnabled() {
-		return fmt.Errorf("`delete_after_read` requires feature gate `%s`", allowFileDeletion.ID())
-	}
-
-	if c.Header != nil && !AllowHeaderMetadataParsing.IsEnabled() {
-		return fmt.Errorf("`header` requires feature gate `%s`", AllowHeaderMetadataParsing.ID())
-	}
-
 	if _, err := matcher.New(c.Criteria); err != nil {
 		return err
 	}
 
-	if c.MaxLogSize <= 0 {
-		return fmt.Errorf("`max_log_size` must be positive")
-	}
-
-	if c.MaxConcurrentFiles <= 1 {
-		return fmt.Errorf("`max_concurrent_files` must be greater than 1")
-	}
-
 	if c.FingerprintSize < fingerprint.MinSize {
-		return fmt.Errorf("`fingerprint_size` must be at least %d bytes", fingerprint.MinSize)
+		return fmt.Errorf("'fingerprint_size' must be at least %d bytes", fingerprint.MinSize)
 	}
 
-	if c.DeleteAfterRead && c.StartAt == "end" {
-		return fmt.Errorf("`delete_after_read` cannot be used with `start_at: end`")
+	if c.MaxLogSize <= 0 {
+		return fmt.Errorf("'max_log_size' must be positive")
 	}
 
-	if c.Header != nil && c.StartAt == "end" {
-		return fmt.Errorf("`header` cannot be specified with `start_at: end`")
+	if c.MaxConcurrentFiles <= 1 {
+		return fmt.Errorf("'max_concurrent_files' must be positive")
 	}
 
 	if c.MaxBatches < 0 {
-		return errors.New("`max_batches` must not be negative")
+		return errors.New("'max_batches' must not be negative")
 	}
 
 	enc, err := decode.LookupEncoding(c.Encoding)
 	if err != nil {
 		return err
 	}
 
+	if c.DeleteAfterRead {
+		if !allowFileDeletion.IsEnabled() {
+			return fmt.Errorf("'delete_after_read' requires feature gate '%s'", allowFileDeletion.ID())
+		}
+		if c.StartAt == "end" {
+			return fmt.Errorf("'delete_after_read' cannot be used with 'start_at: end'")
+		}
+	}
+
 	if c.Header != nil {
+		if !AllowHeaderMetadataParsing.IsEnabled() {
+			return fmt.Errorf("'header' requires feature gate '%s'", AllowHeaderMetadataParsing.ID())
+		}
+		if c.StartAt == "end" {
+			return fmt.Errorf("'header' cannot be specified with 'start_at: end'")
+		}
 		if _, err := header.NewConfig(c.Header.Pattern, c.Header.MetadataOperators, enc); err != nil {
-			return fmt.Errorf("invalid config for `header`: %w", err)
+			return fmt.Errorf("invalid config for 'header': %w", err)
 		}
 	}
 

pkg/stanza/fileconsumer/file.go

@@ -85,15 +85,17 @@ func (m *Manager) closePreviousFiles() {
 
 // Stop will stop the file monitoring process
 func (m *Manager) Stop() error {
-	m.cancel()
+	if m.cancel != nil {
+		m.cancel()
+		m.cancel = nil
+	}
 	m.wg.Wait()
 	m.closePreviousFiles()
 	if m.persister != nil {
 		if err := checkpoint.Save(context.Background(), m.persister, m.knownFiles); err != nil {
 			m.Errorw("save offsets", zap.Error(err))
 		}
 	}
-	m.cancel = nil
 	return nil
 }