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