72 lines
2.0 KiB
Go
72 lines
2.0 KiB
Go
// +build go1.3,!plan9,!solaris
|
|
|
|
package main
|
|
|
|
import (
|
|
"log"
|
|
"os"
|
|
"path/filepath"
|
|
"time"
|
|
|
|
fsnotify "gopkg.in/fsnotify/fsnotify.v1"
|
|
)
|
|
|
|
// WaitForReplacement waits for a file to exist on disk and then starts a watch
|
|
// for the file
|
|
func WaitForReplacement(filename string, op fsnotify.Op,
|
|
watcher *fsnotify.Watcher) {
|
|
const sleepInterval = 50 * time.Millisecond
|
|
|
|
// Avoid a race when fsnofity.Remove is preceded by fsnotify.Chmod.
|
|
if op&fsnotify.Chmod != 0 {
|
|
time.Sleep(sleepInterval)
|
|
}
|
|
for {
|
|
if _, err := os.Stat(filename); err == nil {
|
|
if err := watcher.Add(filename); err == nil {
|
|
log.Printf("watching resumed for %s", filename)
|
|
return
|
|
}
|
|
}
|
|
time.Sleep(sleepInterval)
|
|
}
|
|
}
|
|
|
|
// WatchForUpdates performs an action every time a file on disk is updated
|
|
func WatchForUpdates(filename string, done <-chan bool, action func()) {
|
|
filename = filepath.Clean(filename)
|
|
watcher, err := fsnotify.NewWatcher()
|
|
if err != nil {
|
|
log.Fatal("failed to create watcher for ", filename, ": ", err)
|
|
}
|
|
go func() {
|
|
defer watcher.Close()
|
|
for {
|
|
select {
|
|
case _ = <-done:
|
|
log.Printf("Shutting down watcher for: %s", filename)
|
|
return
|
|
case event := <-watcher.Events:
|
|
// On Arch Linux, it appears Chmod events precede Remove events,
|
|
// which causes a race between action() and the coming Remove event.
|
|
// If the Remove wins, the action() (which calls
|
|
// UserMap.LoadAuthenticatedEmailsFile()) crashes when the file
|
|
// can't be opened.
|
|
if event.Op&(fsnotify.Remove|fsnotify.Rename|fsnotify.Chmod) != 0 {
|
|
log.Printf("watching interrupted on event: %s", event)
|
|
watcher.Remove(filename)
|
|
WaitForReplacement(filename, event.Op, watcher)
|
|
}
|
|
log.Printf("reloading after event: %s", event)
|
|
action()
|
|
case err = <-watcher.Errors:
|
|
log.Printf("error watching %s: %s", filename, err)
|
|
}
|
|
}
|
|
}()
|
|
if err = watcher.Add(filename); err != nil {
|
|
log.Fatal("failed to add ", filename, " to watcher: ", err)
|
|
}
|
|
log.Printf("watching %s for updates", filename)
|
|
}
|