Allow analyzing multiple files sequentially (#13)

* Allow analyzing multiple files sequentially

* Cleanup file handling code

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

* Analyze and Daemon are mutually exclusive

* Further cleanup code

* Restore old timing of systemd.NotifyReady()

* fileiter.NewWithScanner: Move bufSz to const value

cmd/run.go

@@ -1,6 +1,7 @@
 package cmd
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"os/signal"
@@ -15,16 +16,26 @@ import (
 
 const defaultFilename = "/var/log/nginx/mirrors/access_json.log"
 
-func filenameFromArgs(args []string) string {
+func filenamesFromArgs(args []string) []string {
 	if len(args) == 0 {
-		return defaultFilename
+		return []string{defaultFilename}
 	}
-	return args[0]
+	return args
 }
 
 func runWithConfig(cmd *cobra.Command, args []string, config analyze.AnalyzerConfig) error {
-	filename := filenameFromArgs(args)
-	fmt.Fprintln(cmd.ErrOrStderr(), "Using log file:", filename)
+	// Sanily check
+	if config.Analyze && config.Daemon {
+		return errors.New("analyze mode and daemonizing are mutually exclusive")
+	}
+
+	filenames := filenamesFromArgs(args)
+	// Allow multiple files only in analyze mode
+	if !config.Analyze && len(filenames) != 1 {
+		return errors.New("only one log file can be specified when following or daemonizing")
+	}
+	fmt.Fprintln(cmd.ErrOrStderr(), "Using log files:", filenames)
+
 	analyzer, err := analyze.NewAnalyzer(config)
 	if err != nil {
 		return fmt.Errorf("failed to create analyzer: %w", err)
@@ -43,26 +54,32 @@ func runWithConfig(cmd *cobra.Command, args []string, config analyze.AnalyzerCon
 		}
 	}()
 
-	iterator, err := analyzer.OpenFileIterator(filename)
-	if err != nil {
-		return fmt.Errorf("failed to open file: %w", err)
-	}
-
-	if !config.Analyze && !config.Daemon {
-		go tui.New(analyzer).Run()
-	}
-	if config.Daemon {
-		if err := systemd.NotifyReady(); err != nil {
-			return fmt.Errorf("failed to notify systemd: %w", err)
+	if config.Analyze {
+		for _, filename := range filenames {
+			err = analyzer.AnalyzeFile(filename)
+			if err != nil {
+				break
+			}
+		}
+		analyzer.PrintTopValues(nil, config.SortBy, "")
+		return err
+	} else {
+		// Tail mode
+		iter, err := analyzer.OpenTailIterator(filenames[0])
+		if err != nil {
+			return err
 		}
-	}
 
-	analyzer.RunLoop(iterator)
+		if config.Daemon {
+			if err := systemd.NotifyReady(); err != nil {
+				return fmt.Errorf("failed to notify systemd: %w", err)
+			}
+		} else {
+			go tui.New(analyzer).Run()
+		}
 
-	if config.Analyze {
-		analyzer.PrintTopValues(nil, config.SortBy, "")
+		return analyzer.RunLoop(iter)
 	}
-	return nil
 }
 
 func runCmd() *cobra.Command {
@@ -81,10 +98,9 @@ func runCmd() *cobra.Command {
 
 func analyzeCmd() *cobra.Command {
 	cmd := &cobra.Command{
-		Use:     "analyze [filename]",
+		Use:     "analyze [filename...]",
 		Aliases: []string{"analyse"},
 		Short:   "Log analyse mode (no tail following, only show top N at the end, and implies --whole)",
-		Args:    cobra.MaximumNArgs(1),
 	}
 	config := analyze.DefaultConfig()
 	config.InstallFlags(cmd.Flags())

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"
 )
@@ -14,9 +15,11 @@ type scannerIterator struct {
 	scanner *bufio.Scanner
 }
 
-func NewWithScanner(scanner *bufio.Scanner) Iterator {
+func NewWithScanner(r io.Reader) Iterator {
 	// Prepare a large buffer
-	scanner.Buffer(make([]byte, 1024*1024), 1024*1024)
+	const bufSz = 1024 * 1024
+	scanner := bufio.NewScanner(r)
+	scanner.Buffer(make([]byte, bufSz), bufSz)
 	return &scannerIterator{scanner: scanner}
 }