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main.go
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main.go
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package main
import (
"bufio"
"context"
"flag"
"fmt"
"log"
"os"
"os/exec"
"path"
"path/filepath"
"strings"
"time"
"github.com/fsnotify/fsnotify"
zglob "github.com/mattn/go-zglob"
)
var fileNames = flag.String("filenames", "", "files to watch separated by commas")
var debounceInterval = flag.Int("t", 0, "debounce interval")
var verbose = flag.Bool("verbose", false, "verbose mode")
var command = flag.String("command", "", "command to execute")
var initial = flag.Bool("initial", false, "run command before any change happens")
var watch *fsnotify.Watcher
func addFilesToWatch(files []string) error {
for _, f := range files {
stat, err := os.Stat(f)
if err != nil {
return fmt.Errorf("can't get stat for file: %s, %s", f, err)
}
if err := watch.Add(f); err != nil {
return fmt.Errorf("can't add file to watch: %s, %s", f, err)
}
if !stat.IsDir() {
if err := watch.Add(path.Dir(f)); err != nil {
return fmt.Errorf("can't add file to watch: %s, %s", f, err)
}
}
}
return nil
}
func debounceThen(events <-chan fsnotify.Event, cb func()) {
event := <-events
if *verbose {
log.Printf("event: %s, wait for next\n", event)
}
LOOP:
for {
select {
case event := <-events:
if *verbose {
log.Printf("event: %s, wait for next\n", event)
}
case <-time.After(time.Duration(*debounceInterval) * time.Second):
break LOOP
}
}
cb()
}
func watchForChanges(patterns []string, dirPatterns []string) chan fsnotify.Event {
events := make(chan fsnotify.Event)
go func() {
for {
select {
case event := <-watch.Events:
absName, err := filepath.Abs(event.Name)
if err != nil {
log.Fatalf("can't get abs path for event: %s %s", event.Name, err)
}
if event.Op & fsnotify.Create == fsnotify.Create {
for _, pattern := range dirPatterns {
stat, err := os.Stat(absName)
if err != nil {
log.Printf("can't get stat for file: %s, %s", absName, err)
}
if stat.IsDir() {
ok, err := zglob.Match(pattern, absName)
if err != nil {
log.Fatalf("can't match name: %s", err)
}
if ok {
addFilesToWatch([]string{absName})
}
}
}
}
for _, pattern := range patterns {
ok, err := zglob.Match(pattern, absName)
if err != nil {
log.Fatalf("can't match name: %s", err)
}
if *verbose {
log.Printf("will match: %s %s res: %v", pattern, absName, ok)
}
if ok {
if event.Op == fsnotify.Chmod {
continue
}
if *verbose {
log.Printf("event: %+v", event.Name)
}
events <- event
}
}
case err := <-watch.Errors:
if err != nil {
log.Fatalf("watch error: %s", err)
} else {
log.Fatalf("unexpected watch error")
}
}
}
}()
return events
}
func runCommand(ctx context.Context, command string) {
cmd := exec.CommandContext(ctx, "sh", "-c", command)
stdout, err := cmd.StdoutPipe()
if err != nil {
log.Fatalf("can't get stdout for command: %s %s", command, err)
}
stderr, err := cmd.StderrPipe()
if err != nil {
log.Fatalf("can't get stderr for command: %s %s", command, err)
}
if err := cmd.Start(); err != nil {
log.Fatalf("can't start command: %s %s", command, err)
}
go func() {
errScanner := bufio.NewScanner(stderr)
for errScanner.Scan() {
log.Printf("[STDERR] %s", errScanner.Text())
}
}()
scanner := bufio.NewScanner(stdout)
for scanner.Scan() {
log.Printf("%s", scanner.Text())
}
if err = cmd.Wait(); err != nil {
if e, ok := err.(*exec.ExitError); ok {
log.Printf("%s", e.ProcessState)
} else {
log.Printf("can't wait for process: %s %s", command, err)
}
}
}
func main() {
flag.Parse()
if *verbose {
log.Printf("filewatch version 0.0.4\n")
}
var err error
watch, err = fsnotify.NewWatcher()
if err != nil {
log.Fatal(err)
}
defer watch.Close()
files := make([]string, 0)
patterns := strings.Split(*fileNames, ",")
for i, p := range patterns {
absPattern, err := filepath.Abs(p)
if err != nil {
log.Fatalf("can't get absolute path for pattern: %s %s", p, err)
}
patterns[i] = absPattern
}
dirPatterns := make([]string, 0)
for _, pattern := range patterns {
parent := strings.SplitN(pattern, "*", 2)
if parent[0] != pattern {
dirPatterns = append(dirPatterns, parent[0])
dirPatterns = append(dirPatterns, parent[0] + "**/*")
} else {
dirPatterns = append(dirPatterns, pattern)
}
}
for _, pattern := range dirPatterns {
matches, err := zglob.Glob(pattern)
if err != nil {
log.Fatalf("can't glob pattern: %s %s", pattern, err)
}
for _, match := range matches {
files = append(files, match)
}
}
if *verbose {
log.Printf("watching for files: %+v", files)
}
if err := addFilesToWatch(files); err != nil {
log.Fatal(err)
}
events := watchForChanges(patterns, dirPatterns)
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
if *initial {
go runCommand(ctx, *command)
}
for {
debounceThen(events, func() {
if *command == "" {
os.Exit(0)
return
}
cancel()
ctx, cancel = context.WithCancel(context.Background())
go runCommand(ctx, *command)
})
}
}