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hotreloading.go
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126 lines (118 loc) · 3.2 KB
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package main
import (
"github.com/fsnotify/fsnotify"
log "github.com/sirupsen/logrus"
"go.amzn.com/cmd/localstack/filenotify"
"os"
"time"
)
type ChangeListener struct {
watcher filenotify.FileWatcher
changeChannel chan string
debouncedChannel chan bool
debouncingInterval time.Duration
watchedFolders []string
}
func NewChangeListener(debouncingInterval time.Duration) (*ChangeListener, error) {
watcher, err := filenotify.New(200 * time.Millisecond)
if err != nil {
log.Errorln("Cannot create change listener due to filewatcher error.", err)
return nil, err
}
changeListener := &ChangeListener{
changeChannel: make(chan string, 10),
debouncedChannel: make(chan bool, 10),
debouncingInterval: debouncingInterval,
watcher: watcher,
}
return changeListener, nil
}
func (c *ChangeListener) Start() {
c.debounceChannel()
c.Watch()
}
func (c *ChangeListener) Watch() {
for {
select {
case event, ok := <-c.watcher.Events():
if !ok {
close(c.changeChannel)
return
}
log.Debugln("FileWatcher got event: ", event)
if event.Has(fsnotify.Create) {
stat, err := os.Stat(event.Name)
if err != nil {
log.Errorln("Error stating event file: ", event.Name, err)
} else if stat.IsDir() {
subfolders := getSubFolders(event.Name)
for _, folder := range subfolders {
err = c.watcher.Add(folder)
c.watchedFolders = append(c.watchedFolders, folder)
if err != nil {
log.Errorln("Error watching folder: ", folder, err)
}
}
}
// remove in case of remove / rename (rename within the folder will trigger a separate create event)
} else if event.Has(fsnotify.Remove) || event.Has(fsnotify.Rename) {
// remove all file watchers if it is in our folders list
toBeRemovedDirs, newWatchedFolders := getSubFoldersInList(event.Name, c.watchedFolders)
c.watchedFolders = newWatchedFolders
for _, dir := range toBeRemovedDirs {
err := c.watcher.Remove(dir)
if err != nil {
log.Warnln("Error removing path: ", event.Name, err)
}
}
}
c.changeChannel <- event.Name
case err, ok := <-c.watcher.Errors():
if !ok {
log.Println("error:", err)
return
}
log.Println("error:", err)
}
}
}
func (c *ChangeListener) AddTargetPaths(targetPaths []string) {
// Add all target paths and subfolders
for _, targetPath := range targetPaths {
subfolders := getSubFolders(targetPath)
log.Infoln("Subfolders: ", subfolders)
for _, target := range subfolders {
err := c.watcher.Add(target)
if err != nil {
log.Fatal(err)
}
}
}
}
func (c *ChangeListener) debounceChannel() {
// debouncer to limit restarts
timer := time.NewTimer(c.debouncingInterval)
// immediately stop the timer, since we do not want to reload right at the startup
if !timer.Stop() {
// we have to drain the channel in case the timer already fired
<-timer.C
}
go func() {
for {
select {
case _, more := <-c.changeChannel:
if !more {
timer.Stop()
close(c.debouncedChannel)
return
}
timer.Reset(c.debouncingInterval)
case <-timer.C:
c.debouncedChannel <- true
}
}
}()
}
func (c *ChangeListener) Close() error {
return c.watcher.Close()
}