Cleanup file handling code

We no longer rely on runtime.GC() for closing file,
 at least when analyzing

cmd/run.go

@@ -49,32 +49,34 @@ func runWithConfig(cmd *cobra.Command, args []string, config analyze.AnalyzerCon
 		}
 	}()
 
-	iterator, err := analyzer.OpenFileIterator(filenames[0])
-	if err != nil {
-		return fmt.Errorf("failed to open file: %w", err)
-	}
+	var errCh chan error
+	if !config.Analyze {
+		go func() {
+			errCh <- analyzer.TailFile(filenames[0])
+		}()
 
-	if !config.Analyze && !config.Daemon {
-		go tui.New(analyzer).Run()
+		if !config.Daemon {
+			go tui.New(analyzer).Run()
+		}
+	} else {
+		go func() {
+			errCh <- analyzer.AnalyzeFile(filenames[0])
+		}()
 	}
+
 	if config.Daemon {
 		if err := systemd.NotifyReady(); err != nil {
 			return fmt.Errorf("failed to notify systemd: %w", err)
 		}
 	}
 
-	err = analyzer.RunLoop(iterator)
+	err = <-errCh
 
 	for i := 1; i < len(filenames); i++ {
 		if err != nil {
 			break
 		}
-		iterator, err = analyzer.OpenFileIterator(filenames[i])
-		if err != nil {
-			err = fmt.Errorf("failed to open file: %w", err)
-			break
-		}
-		err = analyzer.RunLoop(iterator)
+		err = analyzer.AnalyzeFile(filenames[i])
 	}
 
 	if config.Analyze {

pkg/analyze/analyze.go

@@ -142,6 +142,23 @@ func (a *Analyzer) RunLoop(iter fileiter.Iterator) error {
 	return nil
 }
 
+func (a *Analyzer) AnalyzeFile(filename string) error {
+	f, err := os.Open(filename)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	return a.RunLoop(fileiter.NewWithScanner(f))
+}
+
+func (a *Analyzer) TailFile(filename string) error {
+	iter, err := a.OpenTailIterator(filename)
+	if err != nil {
+		return err
+	}
+	return a.RunLoop(iter)
+}
+
 func (a *Analyzer) handleLine(line []byte) error {
 	logItem, err := a.logParser.Parse(line)
 	if err != nil {

pkg/analyze/analyze_test.go

@@ -28,12 +28,10 @@ func benchmarkAnalyzeLoop(b *testing.B, parserStr string) {
 		b.Fatal(err)
 	}
 
-	t, err := a.OpenFileIterator(logPath)
+	err = a.AnalyzeFile(logPath)
 	if err != nil {
 		b.Fatal(err)
 	}
-
-	a.RunLoop(t)
 	a.PrintTopValues(nil, SortBySize, "")
 }
 

pkg/analyze/file.go

@@ -1,7 +1,6 @@
 package analyze
 
 import (
-	"bufio"
 	"io"
 	"os"
 
@@ -56,15 +55,3 @@ func (a *Analyzer) OpenTailIterator(filename string) (fileiter.Iterator, error)
 	}
 	return fileiter.NewWithTail(t), nil
 }
-
-func (a *Analyzer) OpenFileIterator(filename string) (fileiter.Iterator, error) {
-	if !a.Config.Analyze {
-		return a.OpenTailIterator(filename)
-	} else {
-		file, err := os.Open(filename)
-		if err != nil {
-			return nil, err
-		}
-		return fileiter.NewWithScanner(bufio.NewScanner(file)), nil
-	}
-}

pkg/fileiter/iterator.go

@@ -2,6 +2,7 @@ package fileiter
 
 import (
 	"bufio"
+	"io"
 
 	"github.com/nxadm/tail"
 )
@@ -14,8 +15,9 @@ type scannerIterator struct {
 	scanner *bufio.Scanner
 }
 
-func NewWithScanner(scanner *bufio.Scanner) Iterator {
+func NewWithScanner(r io.Reader) Iterator {
 	// Prepare a large buffer
+	scanner := bufio.NewScanner(r)
 	scanner.Buffer(make([]byte, 1024*1024), 1024*1024)
 	return &scannerIterator{scanner: scanner}
 }