git.iko.soy/typeable/oauth2-proxy
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typeable/oauth2-proxy/watcher.go
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1// +build go1.3,!plan9,!solaris
3package main
5import (
6 "os"
7 "path/filepath"
8 "time"
10 "github.com/fsnotify/fsnotify"
12 "github.com/oauth2-proxy/oauth2-proxy/pkg/logger"
15// WaitForReplacement waits for a file to exist on disk and then starts a watch
16// for the file
17func WaitForReplacement(filename string, op fsnotify.Op,
18 watcher *fsnotify.Watcher) {
19 const sleepInterval = 50 * time.Millisecond
21 // Avoid a race when fsnofity.Remove is preceded by fsnotify.Chmod.
22 if op&fsnotify.Chmod != 0 {
23 time.Sleep(sleepInterval)
24 }
25 for {
26 if _, err := os.Stat(filename); err == nil {
27 if err := watcher.Add(filename); err == nil {
28 logger.Printf("watching resumed for %s", filename)
29 return
30 }
31 }
32 time.Sleep(sleepInterval)
33 }
36// WatchForUpdates performs an action every time a file on disk is updated
37func WatchForUpdates(filename string, done <-chan bool, action func()) {
38 filename = filepath.Clean(filename)
39 watcher, err := fsnotify.NewWatcher()
40 if err != nil {
41 logger.Fatal("failed to create watcher for ", filename, ": ", err)
42 }
43 go func() {
44 defer watcher.Close()
45 for {
46 select {
47 case <-done:
48 logger.Printf("Shutting down watcher for: %s", filename)
49 return
50 case event := <-watcher.Events:
51 // On Arch Linux, it appears Chmod events precede Remove events,
52 // which causes a race between action() and the coming Remove event.
53 // If the Remove wins, the action() (which calls
54 // UserMap.LoadAuthenticatedEmailsFile()) crashes when the file
55 // can't be opened.
56 if event.Op&(fsnotify.Remove|fsnotify.Rename|fsnotify.Chmod) != 0 {
57 logger.Printf("watching interrupted on event: %s", event)
58 watcher.Remove(filename)
59 WaitForReplacement(filename, event.Op, watcher)
60 }
61 logger.Printf("reloading after event: %s", event)
62 action()
63 case err = <-watcher.Errors:
64 logger.Printf("error watching %s: %s", filename, err)
65 }
66 }
67 }()
68 if err = watcher.Add(filename); err != nil {
69 logger.Fatal("failed to add ", filename, " to watcher: ", err)
70 }
71 logger.Printf("watching %s for updates", filename)