oauth2_proxy/watcher.go
Mike Bland 6a0f119fc2 Provide graceful shutdown of file watcher in tests
This test failure from #92 inspired this change:
https://travis-ci.org/bitly/google_auth_proxy/jobs/62425336

2015/05/13 16:27:33 using authenticated emails file /tmp/test_auth_emails_952353477
2015/05/13 16:27:33 watching /tmp/test_auth_emails_952353477 for updates
2015/05/13 16:27:33 validating: is xyzzy@example.com valid? true
2015/05/13 16:27:33 watching interrupted on event: "/tmp/test_auth_emails_952353477": CHMOD
2015/05/13 16:27:33 watching resumed for /tmp/test_auth_emails_952353477
2015/05/13 16:27:33 reloading after event: "/tmp/test_auth_emails_952353477": CHMOD
2015/05/13 16:27:33 watching interrupted on event: "/tmp/test_auth_emails_952353477": REMOVE
2015/05/13 16:27:33 validating: is xyzzy@example.com valid? false
2015/05/13 16:27:33 watching resumed for /tmp/test_auth_emails_952353477
2015/05/13 16:27:33 reloading after event: "/tmp/test_auth_emails_952353477": REMOVE
2015/05/13 16:27:33 failed opening authenticated-emails-file="/tmp/test_auth_emails_952353477", open /tmp/test_auth_emails_952353477: no such file or directory

I believe that what happened was that the call to reload the file after the
second "reloading after event" lost the race when the test shut down and the
file was removed. This change introduces a `done` channel that ensures
outstanding actions complete and the watcher exits before the test removes the
file.
2015-05-13 18:02:22 -04:00

69 lines
1.7 KiB
Go

// +build go1.3
// +build !plan9,!solaris
package main
import (
"log"
"os"
"path/filepath"
"time"
"gopkg.in/fsnotify.v1"
)
func WaitForReplacement(event fsnotify.Event, watcher *fsnotify.Watcher) {
const sleep_interval = 50 * time.Millisecond
// Avoid a race when fsnofity.Remove is preceded by fsnotify.Chmod.
if event.Op&fsnotify.Chmod != 0 {
time.Sleep(sleep_interval)
}
for {
if _, err := os.Stat(event.Name); err == nil {
if err := watcher.Add(event.Name); err == nil {
log.Printf("watching resumed for %s", event.Name)
return
}
}
time.Sleep(sleep_interval)
}
}
func WatchForUpdates(filename string, done <-chan bool, action func()) bool {
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)
WaitForReplacement(event, 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)
}
return true
}