120 lines
2.1 KiB
Go
120 lines
2.1 KiB
Go
// Copyright (c) 2013 ActiveState Software Inc. All rights reserved.
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package watch
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import (
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"github.com/howeyc/fsnotify"
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"os"
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"path/filepath"
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"launchpad.net/tomb"
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)
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// InotifyFileWatcher uses inotify to monitor file changes.
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type InotifyFileWatcher struct {
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Filename string
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Size int64
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}
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func NewInotifyFileWatcher(filename string) *InotifyFileWatcher {
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fw := &InotifyFileWatcher{filename, 0}
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return fw
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}
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func (fw *InotifyFileWatcher) BlockUntilExists(t tomb.Tomb) error {
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w, err := fsnotify.NewWatcher()
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if err != nil {
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return err
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}
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defer w.Close()
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dirname := filepath.Dir(fw.Filename)
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// Watch for new files to be created in the parent directory.
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err = w.WatchFlags(dirname, fsnotify.FSN_CREATE)
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if err != nil {
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return err
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}
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defer w.RemoveWatch(filepath.Dir(fw.Filename))
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// Do a real check now as the file might have been created before
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// calling `WatchFlags` above.
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if _, err = os.Stat(fw.Filename); !os.IsNotExist(err) {
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// file exists, or stat returned an error.
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return err
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}
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for {
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select {
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case evt := <-w.Event:
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if evt.Name == fw.Filename {
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return nil
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}
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case <-t.Dying():
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return tomb.ErrDying
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}
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}
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panic("unreachable")
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}
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// ChangeEvents returns a channel that gets updated when the file is ready to be read.
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func (fw *InotifyFileWatcher) ChangeEvents(t tomb.Tomb, fi os.FileInfo) chan bool {
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w, err := fsnotify.NewWatcher()
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if err != nil {
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panic(err)
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}
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err = w.Watch(fw.Filename)
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if err != nil {
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panic(err)
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}
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ch := make(chan bool)
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fw.Size = fi.Size()
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go func() {
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defer w.Close()
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defer w.RemoveWatch(fw.Filename)
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defer close(ch)
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for {
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prevSize := fw.Size
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var evt *fsnotify.FileEvent
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select {
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case evt = <-w.Event:
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case <-t.Dying():
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return
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}
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switch {
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case evt.IsDelete():
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fallthrough
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case evt.IsRename():
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return
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case evt.IsModify():
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fi, err := os.Stat(fw.Filename)
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if err != nil {
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// XXX: no panic here
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panic(err)
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}
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fw.Size = fi.Size()
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if prevSize > 0 && prevSize > fw.Size {
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return
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}
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// send only if channel is empty.
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select {
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case ch <- true:
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default:
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}
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}
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}
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}()
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return ch
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}
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