Add WithDebug option

Makefile

@@ -6,3 +6,5 @@ fmt:
 test:
 	@go test -v -race
 
+bench:
+	@go test -bench .

README.md

@@ -3,7 +3,7 @@
 [![GitHub release](https://img.shields.io/github/release/utahta/go-cronowriter.svg)](https://github.com/utahta/go-cronowriter/releases)
 [![Build Status](https://travis-ci.org/utahta/go-cronowriter.svg?branch=master)](https://travis-ci.org/utahta/go-cronowriter)
 
-This is a simple file writer that writes message to a set of output files, the names of which are constructed like cronolog.
+This is a simple file writer that writes message to a set of output files, the names of which are constructed time-based format like cronolog.
 
 ## Install
 
@@ -48,6 +48,14 @@ with Mutex
 w := writer.MustNew("/path/to/example.log.%Y%m%d", writer.WithMutex())
 ```
 
+with Debug (stdout and stderr)
+```go
+w := writer.MustNew("/path/to/example.log.%Y%m%d", writer.WithDebug())
+
+// output file, stdout and stderr
+// /path/to/2017/02/04/example.log
+```
+
 ## Format
 
 See [lestrrat/go-strftime#supported-conversion-specifications](https://github.com/lestrrat/go-strftime#supported-conversion-specifications)

writer.go

@@ -16,14 +16,21 @@ type cronoWriter struct {
 	fp      *os.File
 	loc     *time.Location
 	mux     sync.Locker
+	stdout  io.Writer
+	stderr  io.Writer
 }
 
 type option func(*cronoWriter)
 
+type noopWriter struct{}
+
+func (*noopWriter) Write([]byte) (int, error) {
+	return 0, nil // no-op
+}
+
 var (
-	_                 io.WriteCloser   = &cronoWriter{} // check if object implements interface
-	now               func() time.Time = time.Now       // for test
-	waitCloseDuration                  = 5 * time.Second
+	_   io.WriteCloser   = &cronoWriter{} // check if object implements interface
+	now func() time.Time = time.Now       // for test
 )
 
 // New returns a cronoWriter with the given pattern and options.
@@ -39,6 +46,8 @@ func New(pattern string, options ...option) (*cronoWriter, error) {
 		fp:      nil,
 		loc:     time.Local,
 		mux:     new(NoMutex), // default mutex off
+		stdout:  &noopWriter{},
+		stderr:  &noopWriter{},
 	}
 
 	for _, option := range options {
@@ -69,6 +78,13 @@ func WithMutex() option {
 	}
 }
 
+func WithDebug() option {
+	return func(c *cronoWriter) {
+		c.stdout = os.Stdout
+		c.stderr = os.Stderr
+	}
+}
+
 func (c *cronoWriter) Write(b []byte) (int, error) {
 	c.mux.Lock()
 	defer c.mux.Unlock()
@@ -81,23 +97,23 @@ func (c *cronoWriter) Write(b []byte) (int, error) {
 			if fp == nil {
 				return
 			}
-			time.Sleep(waitCloseDuration) // any ideas?
 			fp.Close()
 		}(c.fp)
 
 		dir := filepath.Dir(path)
 		if err := os.MkdirAll(dir, os.ModePerm); err != nil {
-			return 0, err
+			return c.write(nil, err)
 		}
 
 		fp, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0644)
 		if err != nil {
-			return 0, err
+			return c.write(nil, err)
 		}
 		c.path = path
 		c.fp = fp
 	}
-	return c.fp.Write(b)
+
+	return c.write(b, nil)
 }
 
 func (c *cronoWriter) Close() error {
@@ -106,3 +122,13 @@ func (c *cronoWriter) Close() error {
 
 	return c.fp.Close()
 }
+
+func (c *cronoWriter) write(b []byte, err error) (int, error) {
+	if err != nil {
+		c.stderr.Write([]byte(err.Error()))
+		return 0, err
+	}
+
+	c.stdout.Write(b)
+	return c.fp.Write(b)
+}

writer_benchmark_test.go

@@ -0,0 +1,48 @@
+package writer
+
+import (
+	"io/ioutil"
+	"path/filepath"
+	"testing"
+)
+
+func BenchmarkCronoWriter_Write(b *testing.B) {
+	stubNow("2017-02-06 20:30:00 +0900")
+	tmpDir, err := ioutil.TempDir("", "cronowriter")
+	if err != nil {
+		b.Fatal(err)
+	}
+
+	c := MustNew(filepath.Join(tmpDir, "benchmark.log.%Y%m%d"))
+	for i := 0; i < b.N; i++ {
+		c.Write([]byte("abcdefg"))
+	}
+}
+
+func BenchmarkCronoWriter_WriteWithMutex(b *testing.B) {
+	stubNow("2017-02-06 20:30:00 +0900")
+	tmpDir, err := ioutil.TempDir("", "cronowriter")
+	if err != nil {
+		b.Fatal(err)
+	}
+
+	c := MustNew(filepath.Join(tmpDir, "benchmark.log.%Y%m%d"), WithMutex())
+	for i := 0; i < b.N; i++ {
+		c.Write([]byte("abcdefg"))
+	}
+}
+
+func BenchmarkCronoWriter_WriteWithDebug(b *testing.B) {
+	stubNow("2017-02-06 20:30:00 +0900")
+	tmpDir, err := ioutil.TempDir("", "cronowriter")
+	if err != nil {
+		b.Fatal(err)
+	}
+
+	c := MustNew(filepath.Join(tmpDir, "benchmark.log.%Y%m%d"), WithDebug())
+	c.stdout = ioutil.Discard
+	c.stderr = ioutil.Discard
+	for i := 0; i < b.N; i++ {
+		c.Write([]byte("abcdefg"))
+	}
+}