Implemented a method to purge files

client/driver/logs.go

@@ -7,6 +7,7 @@ import (
 	"log"
 	"os"
 	"path/filepath"
+	"sort"
 	"strconv"
 	"strings"
 )
@@ -15,6 +16,8 @@ const (
 	bufSize = 32 * 1024
 )
 
+// LogRotator rotates files for a buffer and retains only the last N rotated
+// files
 type LogRotator struct {
 	maxFiles   int
 	fileSize   int64
@@ -25,6 +28,7 @@ type LogRotator struct {
 	logger *log.Logger
 }
 
+// NewLogRotator configures and returns a new LogRotator
 func NewLogRotator(path string, fileName string, maxFiles int, fileSize int64, logger *log.Logger) (*LogRotator, error) {
 	files, err := ioutil.ReadDir(path)
 	if err != nil {
@@ -55,6 +59,8 @@ func NewLogRotator(path string, fileName string, maxFiles int, fileSize int64, l
 	}, nil
 }
 
+// Start reads from a Reader and writes them to files and rotates them when the
+// size of the file becomes equal to the max size configured
 func (l *LogRotator) Start(r io.Reader) error {
 	buf := make([]byte, bufSize)
 	for {
@@ -111,3 +117,32 @@ func (l *LogRotator) Start(r io.Reader) error {
 	}
 	return nil
 }
+
+// PurgeOldFiles removes older files and keeps only the last N files rotated for
+// a file
+func (l *LogRotator) PurgeOldFiles() {
+	fIndexes := make([]int, l.maxFiles)
+	files, err := ioutil.ReadDir(l.path)
+	if err != nil {
+		return
+	}
+	count := 0
+	for _, f := range files {
+		if strings.HasPrefix(f.Name(), l.fileName) {
+			fileIdx := strings.TrimPrefix(f.Name(), fmt.Sprintf("%s.", l.fileName))
+			n, err := strconv.Atoi(fileIdx)
+			if err != nil {
+				continue
+			}
+			if count == l.maxFiles {
+				sort.Sort(sort.Reverse(sort.IntSlice(fIndexes)))
+				fname := filepath.Join(l.path, fmt.Sprintf("%s.%d", l.fileName, fIndexes[count-1]))
+				l.logger.Printf("[INFO] removing file: %v", fname)
+				os.RemoveAll(fname)
+				count -= 1
+			}
+			fIndexes[count] = n
+			count += 1
+		}
+	}
+}

client/driver/logs_test.go

@@ -12,6 +12,7 @@ import (
 
 var (
 	logger = log.New(os.Stdout, "", log.LstdFlags)
+	path   = "/tmp/logrotator"
 )
 
 func TestLogRotator_IncorrectPath(t *testing.T) {
@@ -23,7 +24,6 @@ func TestLogRotator_IncorrectPath(t *testing.T) {
 }
 
 func TestLogRotator_FindCorrectIndex(t *testing.T) {
-	path := "/tmp/tmplogrator"
 	if err := os.Mkdir(path, os.ModeDir|os.ModePerm); err != nil {
 		t.Fatalf("test setup err: %v", err)
 	}
@@ -49,7 +49,6 @@ func TestLogRotator_FindCorrectIndex(t *testing.T) {
 }
 
 func TestLogRotator_AppendToCurrentFile(t *testing.T) {
-	path := "/tmp/tmplogrator"
 	defer os.RemoveAll(path)
 	if err := os.Mkdir(path, os.ModeDir|os.ModePerm); err != nil {
 		t.Fatalf("test setup err: %v", err)
@@ -84,7 +83,6 @@ func TestLogRotator_AppendToCurrentFile(t *testing.T) {
 }
 
 func TestLogRotator_RotateFiles(t *testing.T) {
-	path := "/tmp/tmplogrator"
 	defer os.RemoveAll(path)
 	if err := os.Mkdir(path, os.ModeDir|os.ModePerm); err != nil {
 		t.Fatalf("test setup err: %v", err)
@@ -127,7 +125,6 @@ func TestLogRotator_RotateFiles(t *testing.T) {
 }
 
 func TestLogRotator_StartFromEmptyDir(t *testing.T) {
-	path := "/tmp/tmplogrator"
 	defer os.RemoveAll(path)
 	if err := os.Mkdir(path, os.ModeDir|os.ModePerm); err != nil {
 		t.Fatalf("test setup err: %v", err)
@@ -159,7 +156,6 @@ func TestLogRotator_StartFromEmptyDir(t *testing.T) {
 }
 
 func TestLogRotator_SetPathAsFile(t *testing.T) {
-	path := "/tmp/tmplogrator"
 	defer os.RemoveAll(path)
 	if _, err := os.Create(path); err != nil {
 		t.Fatalf("test setup problem: %v", err)
@@ -172,7 +168,6 @@ func TestLogRotator_SetPathAsFile(t *testing.T) {
 }
 
 func TestLogRotator_ExcludeDirs(t *testing.T) {
-	path := "/tmp/tmplogrator"
 	defer os.RemoveAll(path)
 	if err := os.Mkdir(path, os.ModeDir|os.ModePerm); err != nil {
 		t.Fatalf("test setup err: %v", err)
@@ -196,7 +191,7 @@ func TestLogRotator_ExcludeDirs(t *testing.T) {
 		t.Fatalf("Failure in logrotator start %v", err)
 	}
 
-	finfo, err := os.Stat("/tmp/tmplogrator/redis.stdout.1")
+	finfo, err := os.Stat(filepath.Join(path, "redis.stdout.1"))
 	if err != nil {
 		t.Fatal("expected rotator to create redis.stdout.1")
 	}
@@ -204,3 +199,35 @@ func TestLogRotator_ExcludeDirs(t *testing.T) {
 		t.Fatalf("expected size: %v, actual: %v", 2, finfo.Size())
 	}
 }
+
+func TestLogRotator_PurgeDirs(t *testing.T) {
+	defer os.RemoveAll(path)
+	if err := os.Mkdir(path, os.ModeDir|os.ModePerm); err != nil {
+		t.Fatalf("test setup err: %v", err)
+	}
+
+	l, err := NewLogRotator(path, "redis.stdout", 2, 4, logger)
+	if err != nil {
+		t.Fatalf("test setup err: %v", err)
+	}
+
+	r, w := io.Pipe()
+	go func() {
+		w.Write([]byte("abcdefghijklmno"))
+		w.Close()
+	}()
+
+	err = l.Start(r)
+	if err != nil && err != io.EOF {
+		t.Fatalf("failure in logrotator start: %v", err)
+	}
+	l.PurgeOldFiles()
+
+	files, err := ioutil.ReadDir(path)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	if len(files) != 2 {
+		t.Fatalf("expected number of files: %v, actual: %v", 2, len(files))
+	}
+}