tail.go

package main

import (
	"bufio"
	"fmt"
	"github.com/fsnotify/fsnotify"
	"io"
	"log"
	"os"
	"path"
	"time"
)

func addaWatch(fileName string, watcher *fsnotify.Watcher) error {
	for {

		err := watcher.Add(fileName)
		if err != nil {
			log.Println(err)
			time.Sleep(1 * time.Second)
		} else {
			return nil
		}
	}
}

func openFile(fileName string) *os.File {
	for {
		file, err := os.Open(fileName)
		if err != nil {
			log.Println(err)
			time.Sleep(1 * time.Second)
		} else {
			return file
		}
	}
}

func readFile(quit chan bool, fileName string) {
	println("reading file...........", fileName)
	file := openFile(fileName)
	defer file.Close()
	reader := bufio.NewReader(file)
	for {
		select {
		case canQuit := <-quit:
			if canQuit {
				println("quit goroutine")
				return
			}
		default:
			line, err := reader.ReadString('\n')
			if err != nil {
				if err == io.EOF {
					time.Sleep(1 * time.Second)
				} else {
					break
				}
			}
			fmt.Print(string(line))
			//fmt.Println("num of goroutine", runtime.NumGoroutine())
		}
	}

}

func main() {
	absPath := "/Users/garland/code/go/src/yat/tt"
	basePath, targetFile := path.Split(absPath)

	println(basePath, targetFile)

	watcher, err := fsnotify.NewWatcher()
	if err != nil {
		log.Fatal(err)
	}
	defer watcher.Close()

	done := make(chan bool)
	quit := make(chan bool)

	go readFile(quit, absPath)

	go func() {
		for {
			select {
			case event := <-watcher.Events:
				if event.Op&fsnotify.Create == fsnotify.Create {
					log.Println("create file:", event.Name, event.Op)
					if event.Name == absPath {
						//println("------newfile created----------------")
						quit <- true
						time.Sleep(2 * time.Second)
						go readFile(quit, absPath)
					}
				}
			case err := <-watcher.Errors:
				log.Println("error:", err)

			}
		}
	}()

	addaWatch(basePath, watcher)

	<-done
}