Merge pull request #36 from kei2100/fix-example

fix example

Author: kei2100

README.md

@@ -6,56 +6,46 @@ A file Reader that behaves like `tail -F`
 
 ```go
 func ExampleReader() {
-	dir, _ := ioutil.TempDir("", "follow-test")
-	path := filepath.Join(dir, "test.log")
-	f1, _ := os.Create(path)
-
-	// create follow.Reader.
+	dir, _ := os.MkdirTemp("", "ExampleReader")
+	logpath := filepath.Join(dir, "test.log")
+	logfile, _ := os.Create(logpath)
+	// Create follow.Reader.
 	// follow.Reader is a file Reader that behaves like `tail -F`
-	options := []follow.OptionFunc{
-		// position-file supported
+	opts := []follow.OptionFunc{
 		follow.WithPositionFile(posfile.InMemory(nil, 0)),
-		follow.WithRotatedFilePathPatterns([]string{filepath.Join(dir, "*.log.*")}),
+		follow.WithRotatedFilePathPatterns([]string{filepath.Join(dir, "test.log.*")}),
 		follow.WithDetectRotateDelay(0),
 		follow.WithWatchRotateInterval(100 * time.Millisecond),
 	}
-	reader, _ := follow.Open(path, options...)
-
-	f1.WriteString("1")
-	b, _ := ioutil.ReadAll(reader)
-	fmt.Printf("%s\n", b)
-
-	// rotate
-	f1.Close()
-	os.Rename(path, path+".f1")
-	f2, _ := os.Create(path)
-
-	f2.WriteString("2")
-	time.Sleep(500 * time.Millisecond) // wait for detect rotate
-	b, _ = ioutil.ReadAll(reader)
-	fmt.Printf("%s\n", b)
-
-	// write and rotate while closing the follow.Reader
-	reader.Close()
-	f2.WriteString("3")
-	f2.Close()
-
-	os.Rename(path, path+".f2")
-	f3, _ := os.Create(path)
-	defer f3.Close()
-	f3.WriteString("4")
-
-	// re-open follow.Reader
-	reader, _ = follow.Open(path, options...)
+	reader, _ := follow.Open(logpath, opts...)
 	defer reader.Close()
-
-	time.Sleep(500 * time.Millisecond) // wait for detect rotate
-	b, _ = ioutil.ReadAll(reader)
-	fmt.Printf("%s\n", b)
+	// Reads log files while tracking their rotation
+	go func() {
+		for {
+			b, _ := io.ReadAll(reader)
+			if len(b) > 0 {
+				fmt.Print(string(b))
+			}
+			time.Sleep(100 * time.Millisecond)
+		}
+	}()
+	// Write to logfile
+	fmt.Fprintln(logfile, "1")
+	fmt.Fprintln(logfile, "2")
+	// Rotate logfile
+	logfile.Close()
+	os.Rename(logpath, logpath+".1")
+	logfile, _ = os.Create(logpath)
+	// Write to new logfile
+	fmt.Fprintln(logfile, "3")
+	fmt.Fprintln(logfile, "4")
+	logfile.Close()
+	time.Sleep(time.Second)
 
 	// Output:
 	// 1
 	// 2
-	// 34
+	// 3
+	// 4
 }
 ```

example_test.go

@@ -2,7 +2,7 @@ package follow_test
 
 import (
 	"fmt"
-	"io/ioutil"
+	"io"
 	"os"
 	"path/filepath"
 	"time"
@@ -12,55 +12,45 @@ import (
 )
 
 func ExampleReader() {
-	dir, _ := ioutil.TempDir("", "follow-test")
-	path := filepath.Join(dir, "test.log")
-	f1, _ := os.Create(path)
-
-	// create follow.Reader.
+	dir, _ := os.MkdirTemp("", "ExampleReader")
+	logpath := filepath.Join(dir, "test.log")
+	logfile, _ := os.Create(logpath)
+	// Create follow.Reader.
 	// follow.Reader is a file Reader that behaves like `tail -F`
-	options := []follow.OptionFunc{
-		// position-file supported
+	opts := []follow.OptionFunc{
 		follow.WithPositionFile(posfile.InMemory(nil, 0)),
-		follow.WithRotatedFilePathPatterns([]string{filepath.Join(dir, "*.log.*")}),
+		follow.WithRotatedFilePathPatterns([]string{filepath.Join(dir, "test.log.*")}),
 		follow.WithDetectRotateDelay(0),
 		follow.WithWatchRotateInterval(100 * time.Millisecond),
 	}
-	reader, _ := follow.Open(path, options...)
-
-	f1.WriteString("1")
-	b, _ := ioutil.ReadAll(reader)
-	fmt.Printf("%s\n", b)
-
-	// rotate
-	f1.Close()
-	os.Rename(path, path+".f1")
-	f2, _ := os.Create(path)
-
-	f2.WriteString("2")
-	time.Sleep(500 * time.Millisecond) // wait for detect rotate
-	b, _ = ioutil.ReadAll(reader)
-	fmt.Printf("%s\n", b)
-
-	// write and rotate while closing the follow.Reader
-	reader.Close()
-	f2.WriteString("3")
-	f2.Close()
-
-	os.Rename(path, path+".f2")
-	f3, _ := os.Create(path)
-	defer f3.Close()
-	f3.WriteString("4")
-
-	// re-open follow.Reader
-	reader, _ = follow.Open(path, options...)
+	reader, _ := follow.Open(logpath, opts...)
 	defer reader.Close()
-
-	time.Sleep(500 * time.Millisecond) // wait for detect rotate
-	b, _ = ioutil.ReadAll(reader)
-	fmt.Printf("%s\n", b)
+	// Reads log files while tracking their rotation
+	go func() {
+		for {
+			b, _ := io.ReadAll(reader)
+			if len(b) > 0 {
+				fmt.Print(string(b))
+			}
+			time.Sleep(100 * time.Millisecond)
+		}
+	}()
+	// Write to logfile
+	fmt.Fprintln(logfile, "1")
+	fmt.Fprintln(logfile, "2")
+	// Rotate logfile
+	logfile.Close()
+	os.Rename(logpath, logpath+".1")
+	logfile, _ = os.Create(logpath)
+	// Write to new logfile
+	fmt.Fprintln(logfile, "3")
+	fmt.Fprintln(logfile, "4")
+	logfile.Close()
+	time.Sleep(time.Second)
 
 	// Output:
 	// 1
 	// 2
-	// 34
+	// 3
+	// 4
 }