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xnotify.go
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xnotify.go
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package main
import (
"bufio"
"bytes"
"encoding/json"
"errors"
"fmt"
"io"
"log"
"net/http"
"os"
"os/exec"
"path"
"path/filepath"
"regexp"
"strings"
"sync/atomic"
"time"
"github.com/fsnotify/fsnotify"
"gopkg.in/urfave/cli.v1"
)
// Event for each file change
type Event struct {
Operation string `json:"operation"`
Path string `json:"path"`
Time int64 `json:"time"`
}
type program struct {
eventChannel chan Event // track file change events
tasks [][]string
process *os.Process
processChannel chan bool // track the process we are spawning
clientAddress string
batchMS int
batchSize int32
base string
defaultBase string
trigger bool
hasTasks bool
excludePatterns []string
}
func main() {
log.SetPrefix("[xnotify] ")
log.SetFlags(0)
prog := program{
eventChannel: make(chan Event),
processChannel: make(chan bool, 3),
defaultBase: "./",
}
app := cli.NewApp()
app.Name = "xnotify"
app.Version = "0.2.4"
app.Usage = "Watch files for changes." +
"\n File changes will be printed to stdout in the format <operation_name> <file_path>." +
"\n stdin accepts a list of files to watch." +
"\n Use -- to execute 1 or more commands in sequence, stopping if any command exits unsuccessfully."
app.UsageText = "xnotify [options] [-- <command> [args...]...]"
app.HideHelp = true
app.Flags = []cli.Flag{
cli.StringSliceFlag{
Name: "include, i",
Usage: "Include path to watch recursively.",
},
cli.StringSliceFlag{
Name: "exclude, e",
Usage: "Exclude changes from files that match the Regular Expression. This will also apply to events recieved in server mode.",
},
cli.BoolFlag{
Name: "shallow",
Usage: "Disable recursive file globbing. If the path is a directory, the contents will not be included.",
},
cli.StringFlag{
Name: "listen",
Usage: "Listen on address for file changes e.g. localhost:8080 or just :8080. See --client on how to send file changes.",
},
cli.StringFlag{
Name: "base",
Value: prog.defaultBase,
Usage: "Use this base path instead of the working directory. This will affect where --include finds the files. If using --listen, it will replace the original base path that was used at the sender.",
Destination: &prog.base,
},
cli.StringFlag{
Name: "client",
Usage: "Send file changes to the address e.g. localhost:8080 or just :8080. See --listen on how to receive events.",
Destination: &prog.clientAddress,
},
cli.IntFlag{
Name: "batch",
Usage: "Send the events together if they occur within given `milliseconds`. The program will only execute given milliseconds after the last event was fired. Only valid with -- argument.",
Destination: &prog.batchMS,
},
cli.BoolFlag{
Name: "trigger",
Usage: "Run the given command immediately even if there is no file change. Only valid with -- argument.",
Destination: &prog.trigger,
},
cli.BoolFlag{
Name: "verbose",
Usage: "Print verbose logs.",
Destination: &verbose,
},
cli.BoolFlag{
Name: "help, h",
Usage: "Print this help.",
},
}
app.Action = prog.action
if err := app.Run(os.Args); err != nil {
panic(err)
}
}
func (prog *program) action(c *cli.Context) (err error) {
if c.Bool("help") {
err = cli.ShowAppHelp(c)
if err != nil {
return
}
return
}
// create tasks
prog.tasks = make([][]string, 0)
for i, arg := range os.Args {
if isExecFlag(arg) {
foundNext := false
start := i + 1
for j, a := range os.Args[start:] {
if isExecFlag(a) {
prog.tasks = append(prog.tasks, os.Args[start:start+j])
foundNext = true
break
}
}
if !foundNext {
prog.tasks = append(prog.tasks, os.Args[i+1:])
}
}
}
prog.hasTasks = len(prog.tasks) > 0
// check for unused flags
if prog.base != prog.defaultBase && c.String("listen") == "" {
noEffect("base")
}
if prog.batchMS != 0 && !prog.hasTasks {
noEffect("batch")
}
if prog.trigger && !prog.hasTasks {
noEffect("trigger")
}
// convert base to absolute path
prog.base, err = filepath.Abs(prog.base)
if err != nil {
return
}
// convert clientAddress to full url
if prog.clientAddress != "" {
prog.clientAddress = fullURL(prog.clientAddress)
logVerbose("Sending events to client at " + prog.clientAddress)
}
// find files from stdin and --include
prog.excludePatterns = c.StringSlice("exclude")
watchList := pathsFromStdin()
for _, arg := range c.StringSlice("include") {
watchList = append(watchList, prog.findPaths(prog.base, arg, !c.Bool("shallow"))...)
}
if verbose {
for _, p := range watchList {
logVerbose("Watching: " + p)
}
}
// fail if nothing to watch
serverAddr := c.String("listen")
if serverAddr == "" && len(watchList) == 0 {
logError("No files to watch. See --help on how to use this command.")
return
}
// start exec loop
go prog.execLoop()
if prog.hasTasks && prog.trigger {
prog.eventChannel <- Event{}
}
// watch files at paths
if len(watchList) > 0 {
prog.startWatching(prog.base, watchList)
}
// watch files form http
if serverAddr != "" {
prog.startServer(fullAddress(serverAddr))
}
// so we don't exit
wait := make(chan bool)
_ = <-wait
return
}
func isExecFlag(flag string) bool {
return flag == "--"
}
func pathsFromStdin() []string {
paths := make([]string, 0)
fi, err := os.Stdin.Stat()
if err != nil {
panic(err)
}
if fi.Size() > 0 {
scanner := bufio.NewScanner(os.Stdin)
for scanner.Scan() {
paths = append(paths, scanner.Text())
}
if err := scanner.Err(); err != nil {
panic(err)
}
}
return paths
}
func (prog *program) findPaths(base string, pattern string, recursive bool) []string {
paths, err := filepath.Glob(path.Join(base, pattern))
if err != nil {
panic(err)
}
allPaths := make([]string, 0)
for _, p := range paths {
// check excludes
if prog.isExcluded(p) {
continue
}
allPaths = append(allPaths, p)
// if recursive and is dir, go deeper
if recursive {
fileInfo, err := os.Stat(p)
if err != nil {
panic(err)
}
if fileInfo.IsDir() {
allPaths = append(allPaths, prog.findPaths(p, "*", true)...)
}
}
}
return allPaths
}
func (prog *program) isExcluded(path string) bool {
var rel string
if filepath.IsAbs(path) {
var err error
rel, err = filepath.Rel(prog.base, path)
if err != nil {
panic(err)
}
} else {
rel = path
}
for _, ex := range prog.excludePatterns {
excluded, err := regexp.MatchString(ex, rel)
if err != nil {
panic(err)
}
if excluded {
return true
}
}
return false
}
//
// ----- Watchers -----
//
// start server that watch for files changes from other watchers
func (prog *program) startServer(address string) {
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
decoder := json.NewDecoder(r.Body)
var e Event
err := decoder.Decode(&e)
if err != nil {
logError(err)
}
// need to udpate time because of the time difference
e.Time = time.Now().UnixNano() / 1000000
prog.fileChanged(e)
})
logVerbose("Listening on " + address)
go (func() {
if err := http.ListenAndServe(address, nil); err != nil {
panic(err)
}
})()
}
// start watching files at the given paths
func (prog *program) startWatching(base string, paths []string) {
watcher, err := fsnotify.NewWatcher()
if err != nil {
panic(err)
}
// defer watcher.Close()
go func() {
for {
select {
case event, ok := <-watcher.Events:
if !ok {
return
}
if event.Op&fsnotify.Write == fsnotify.Write {
rp, err := filepath.Rel(base, event.Name)
if err != nil {
logError(err)
} else {
prog.fileChanged(Event{
Operation: opToString(event.Op),
Path: filepath.ToSlash(rp),
Time: time.Now().UnixNano() / 1000000,
})
}
}
case err, ok := <-watcher.Errors:
if !ok {
return
}
logError(err)
}
}
}()
for _, p := range paths {
err = watcher.Add(p)
if err != nil {
panic(err)
}
}
}
//
// ----- Runners -----
//
// triggered when a file changes
func (prog *program) fileChanged(e Event) {
if prog.isExcluded(e.Path) {
// a file change event might cause a dir change event even though it was excluded
return
}
// fmt.Printf("%+v\n", e)
go prog.printRunner(e)
if prog.clientAddress != "" {
go prog.httpRunner(e)
}
if prog.hasTasks {
go prog.programRunner(prog.eventChannel, e)
}
}
// runner that prints to stdout
func (prog *program) printRunner(e Event) {
fmt.Printf("%s %s\n", e.Operation, e.Path)
}
// runner that sends to a another client via http
func (prog *program) httpRunner(e Event) {
b, err := json.Marshal(&e)
if err != nil {
logError(err)
return
}
req, err := http.NewRequest("POST", prog.clientAddress, bytes.NewBuffer(b))
req.Header.Set("Content-Type", "application/json")
client := &http.Client{}
resp, err := client.Do(req)
if err != nil {
logError(err)
return
}
if resp.Body != nil {
resp.Body.Close()
}
}
//
// ----- Batch program runner -----
//
// runner that executes an external program
func (prog *program) programRunner(eventChannel chan Event, e Event) {
// run later
dur, err := time.ParseDuration(fmt.Sprint(prog.batchMS, "ms"))
if err != nil {
panic(err)
}
atomic.AddInt32(&prog.batchSize, 1)
time.AfterFunc(dur, func() {
if atomic.LoadInt32(&prog.batchSize) == 1 {
// if program is already done, there will be no effect
if prog.process != nil {
logVerbose("Killing program")
prog.process.Kill()
}
for len(prog.processChannel) > 0 {
// need to clear anything from previous run
<-prog.processChannel
}
eventChannel <- e
// wait until the process is captured before proceeding so we can kill it later
<-prog.processChannel
}
atomic.AddInt32(&prog.batchSize, -1)
})
}
// runs forever to try execTasks only if the batch threshold has passed, otherwise wait for the next event
func (prog *program) execLoop() {
for {
<-prog.eventChannel // wait for event
prog.execTasks()
}
}
func (prog *program) execTasks() bool {
logVerbose("Executing program")
start := time.Now()
var ok bool
for _, task := range prog.tasks {
if len(task) > 1 {
ok = prog.exec(task[0], task[1:]...)
} else {
ok = prog.exec(task[0])
}
if !ok {
break
}
}
logVerbose(fmt.Sprintf("Completed in %s", time.Since(start)))
return ok
}
func (prog *program) exec(name string, args ...string) bool {
cmd := exec.Command(name, args...)
cmd.Dir = prog.base
stdout, err := cmd.StdoutPipe()
if err != nil {
logError(err)
return false
}
stderr, err := cmd.StderrPipe()
if err != nil {
logError(err)
return false
}
if err := cmd.Start(); err != nil {
logError(err)
return false
}
prog.process = cmd.Process
if len(prog.processChannel) == 0 { // don't overflow the buffer
prog.processChannel <- true
}
// print program output to stderr
go io.Copy(os.Stderr, stdout)
go io.Copy(os.Stderr, stderr)
if err := cmd.Wait(); err != nil {
logError(err)
return false
}
return true
}
//
// ----- Helpers -----
//
var verbose = false
func logVerbose(msg interface{}) {
if verbose {
log.Printf("\033[1;34m%s\033[0m", msg)
}
}
func logError(msg interface{}) {
log.Printf("\033[1;31m%s\033[0m", msg)
}
func noEffect(name string) {
log.Printf("\033[1;33m%s\033[0m", fmt.Sprint("WARNING: --", name, " has not effect. See --help for more info."))
}
func opToString(op fsnotify.Op) string {
switch op {
case fsnotify.Create:
return "create"
case fsnotify.Write:
return "write"
case fsnotify.Remove:
return "remove"
case fsnotify.Rename:
return "rename"
case fsnotify.Chmod:
return "chmod"
default:
return "write"
}
panic(errors.New("No such op"))
}
func fullAddress(addr string) string {
if addr[0] == ':' {
addr = "localhost" + addr
}
return addr
}
func fullURL(addr string) string {
addr = fullAddress(addr)
if !strings.Contains(addr, "://") {
addr = "http://" + addr
}
return addr
}