Added an impl for log-rotator

client/driver/logs.go

@@ -0,0 +1,71 @@
+package driver
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+)
+
+type LogRotator struct {
+	maxFiles   int
+	fileSize   int64
+	path       string
+	fileName   string
+	logFileIdx int
+}
+
+func NewLogRotor(path string, fileName string, maxFiles int, fileSize int64) (*LogRotator, error) {
+	files, err := ioutil.ReadDir(path)
+	if err != nil {
+		return nil, err
+	}
+
+	logFileIdx := 0
+	for _, f := range files {
+		if strings.HasPrefix(f.Name(), fileName) {
+			fileIdx := strings.TrimPrefix(f.Name(), fmt.Sprintf("%s.", fileName))
+			n, err := strconv.Atoi(fileIdx)
+			if err != nil {
+				continue
+			}
+			if n > logFileIdx {
+				logFileIdx = n
+			}
+		}
+	}
+
+	return &LogRotator{
+		maxFiles:   maxFiles,
+		fileSize:   fileSize,
+		path:       path,
+		fileName:   fileName,
+		logFileIdx: logFileIdx,
+	}, nil
+}
+
+func (l *LogRotator) Start(r io.Reader) error {
+	for {
+		logFileName := filepath.Join(l.path, fmt.Sprintf("%s.%d", l.fileName, l.logFileIdx))
+		f, err := os.OpenFile(logFileName, os.O_RDWR|os.O_CREATE|os.O_APPEND, 066)
+		if err != nil {
+			return err
+		}
+		remainingSize := l.fileSize
+		if finfo, err := os.Stat(logFileName); err == nil {
+			remainingSize = l.fileSize - finfo.Size()
+		}
+		if remainingSize < 1 {
+			l.logFileIdx = l.logFileIdx + 1
+			continue
+		}
+		if _, err := io.Copy(f, io.LimitReader(r, remainingSize)); err != nil {
+			return err
+		}
+		l.logFileIdx = l.logFileIdx + 1
+	}
+	return nil
+}

client/driver/logs_test.go

@@ -0,0 +1,40 @@
+package driver
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestLogRotator_IncorrectPath(t *testing.T) {
+	incorrectPath := "/foo"
+
+	if _, err := NewLogRotor(incorrectPath, "redis.stdout", 10, 10); err == nil {
+		t.Fatal("expected err")
+	}
+}
+
+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)
+	}
+
+	fname := filepath.Join(path, "redis.stdout.1")
+	if f, err := os.Create(fname); err == nil {
+		f.Close()
+	}
+
+	fname = filepath.Join(path, "redis.stdout.2")
+	if f, err := os.Create(fname); err == nil {
+		f.Close()
+	}
+
+	r, err := NewLogRotor(path, "redis.stdout", 10, 10)
+	if err != nil {
+		t.Fatalf("test setup err: %v", err)
+	}
+	if r.logFileIdx != 2 {
+		t.Fatalf("Expected log file idx: %v, actual: %v", 2, r.logFileIdx)
+	}
+}