Add logfile rotation and size limit

.gitignore

@@ -10,3 +10,7 @@
 
 # Output of the go coverage tool, specifically when used with LiteIDE
 *.out
+
+# tests files
+testdata/*log*
+

config/config.go

@@ -27,7 +27,7 @@ type Config struct {
 // Params type for characteristics of a stream
 type Params struct {
 	File    string
-	Maxsize uint
+	Maxsize int
 	Backups int
 }
 
@@ -113,7 +113,7 @@ func (c *Config) GetParams(stream string) (*Params, error) {
 		return nil, err
 	}
 	p := &Params{
-		Maxsize: maxsize,
+		Maxsize: int(maxsize),
 		Backups: backups,
 		File:    file,
 	}

config/config_test.go

@@ -147,7 +147,7 @@ func TestErrFromFile(t *testing.T) {
 
 func TestParams(t *testing.T) {
 	defaultFile := "/tmp/correct_err.log"
-	var defaultSize uint = 2 * 1024 * 1024
+	defaultSize := 2 * 1024 * 1024
 	defaultBackups := 3
 
 	c, err := New("testdata", "correct", "dummy")

logwriter/logwriter.go

@@ -42,6 +42,19 @@ func (l *LogWriter) Write(p []byte) (int, error) {
 
 	n := 0
 	for n < len(p) {
+
+		// Manage the limitation
+		if l.params.Backups > 0 && l.currentsize > l.params.Maxsize {
+			err := l.rotation()
+			if err != nil {
+				return n, err
+			}
+			l.currentsize = 0
+		} else if l.params.Backups < 1 {
+			l.currentsize = 0
+		}
+
+		// Write line by line
 		i := bytes.IndexByte(p[n:], byte('\n'))
 		if i == -1 {
 			l.file.Write(p[n:])
@@ -52,6 +65,7 @@ func (l *LogWriter) Write(p []byte) (int, error) {
 			n += i + 1
 			l.currentsize += i + 1
 		}
+
 	}
 	return n, nil
 }
@@ -61,3 +75,31 @@ func (l *LogWriter) Write(p []byte) (int, error) {
 func (l *LogWriter) Close() error {
 	return l.file.Close()
 }
+
+func (l *LogWriter) rotation() error {
+	err := l.file.Close()
+	if err != nil {
+		return err
+	}
+
+	for copy := l.params.Backups - 1; copy > 0; copy-- {
+		src := fmt.Sprintf("%s.%d", l.params.File, copy)
+		dst := fmt.Sprintf("%s.%d", l.params.File, copy+1)
+		if _, err := os.Stat(src); err == nil {
+			os.Rename(src, dst)
+			if err != nil {
+				return err
+			}
+		}
+	}
+	err = os.Rename(l.params.File, l.params.File+".1")
+	if err != nil {
+		return err
+	}
+
+	l.file, err = os.Create(l.params.File)
+	if err != nil {
+		return err
+	}
+	return nil
+}

logwriter/logwriter_test.go

@@ -0,0 +1,147 @@
+package logwriter
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"github.com/marema31/jocasta/config"
+)
+
+func TestWriteWithoutRotation(t *testing.T) {
+	f, err := os.Create("testdata/test.log")
+	if err != nil {
+		t.Errorf("Can not open log file. err=%v", err)
+	}
+
+	l := LogWriter{
+		params: &config.Params{
+			Backups: 0,
+			Maxsize: 0,
+			File:    "testdata/test.log",
+		},
+		currentsize: 0,
+		file:        f,
+	}
+	defer l.Close()
+
+	err = writeTestData(&l)
+	if err != nil {
+		t.Errorf("Can't create test log file. err=%v", err)
+	}
+
+	// Verify the file content
+	b, err := ioutil.ReadFile("testdata/test.log")
+	if err != nil {
+		t.Errorf("Can read log file. err=%v", err)
+	}
+	if !bytes.Equal(b, []byte("12\n34\n56\n78\n90\nab\ncd\n")) {
+		t.Errorf("The content of log file not correct. b=%v", b)
+	}
+	clean()
+}
+
+func TestWriteWithRotation(t *testing.T) {
+	f, err := os.Create("testdata/test.log")
+	if err != nil {
+		t.Errorf("Can not open log file. err=%v", err)
+	}
+
+	l := LogWriter{
+		params: &config.Params{
+			Backups: 2,
+			Maxsize: 4,
+			File:    "testdata/test.log",
+		},
+		currentsize: 0,
+		file:        f,
+	}
+	defer l.Close()
+
+	err = writeTestData(&l)
+	if err != nil {
+		t.Errorf("Can't create test log file. err=%v", err)
+	}
+
+	// Verify the file content
+	b, err := ioutil.ReadFile("testdata/test.log")
+	if err != nil {
+		t.Errorf("Can read first log file. err=%v", err)
+	}
+	if !bytes.Equal(b, []byte("cd\n")) {
+		t.Errorf("The content of log file not correct. b=%v", b)
+	}
+	// Verify the file content
+	b, err = ioutil.ReadFile("testdata/test.log.1")
+	if err != nil {
+		t.Errorf("Can read first backup log file. err=%v", err)
+	}
+	if !bytes.Equal(b, []byte("90\nab\n")) {
+		t.Errorf("The content of first backup log file not correct. b=%v", b)
+	}
+
+	// Verify the file content
+	b, err = ioutil.ReadFile("testdata/test.log.2")
+	if err != nil {
+		t.Errorf("Can read second backup log file. err=%v", err)
+	}
+	if !bytes.Equal(b, []byte("56\n78\n")) {
+		t.Errorf("The content of second backup log file not correct. b=%v", b)
+	}
+
+	// Verify the file content
+	if _, err := os.Stat("testdata/test.log.3"); !os.IsNotExist(err) {
+		t.Errorf("A third backup file should not been created.")
+	}
+	clean()
+}
+
+func writeTestData(l *LogWriter) error {
+	n, err := l.Write([]byte("12\n"))
+	if err != nil {
+		return fmt.Errorf("Can not write the first line. err=%v", err)
+	}
+	if n != 3 {
+		return fmt.Errorf("Wrong number of byte written. n=%d", n)
+	}
+
+	n, err = l.Write([]byte("34\n"))
+	if err != nil {
+		return fmt.Errorf("Can not write the second line. err=%v", err)
+	}
+
+	n, err = l.Write([]byte("56\n"))
+	if err != nil {
+		return fmt.Errorf("Can not write the third line. err=%v", err)
+	}
+
+	n, err = l.Write([]byte("78\n"))
+	if err != nil {
+		return fmt.Errorf("Can not write the fourth line. err=%v", err)
+	}
+
+	n, err = l.Write([]byte("90\n"))
+	if err != nil {
+		return fmt.Errorf("Can not write the fifth line. err=%v", err)
+	}
+
+	n, err = l.Write([]byte("ab\n"))
+	if err != nil {
+		return fmt.Errorf("Can not write the sixth line. err=%v", err)
+	}
+	n, err = l.Write([]byte("cd\n"))
+	if err != nil {
+		return fmt.Errorf("Can not write the seventh line. err=%v", err)
+	}
+	return nil
+}
+
+func clean() {
+	for _, ext := range []string{"log", "log.1", "log.2", "log.3"} {
+		if _, err := os.Stat("testdata/test." + ext); !os.IsNotExist(err) {
+			os.Remove("testdata/test." + ext)
+		}
+	}
+}