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|
package hooks
import (
"context"
"os"
"path/filepath"
"github.com/fsnotify/fsnotify"
"github.com/sirupsen/logrus"
)
// Monitor dynamically monitors hook directories for additions,
// updates, and removals.
//
// This function writes two empty structs to the sync channel: the
// first is written after the watchers are established and the second
// when this function exits. The expected usage is:
//
// ctx, cancel := context.WithCancel(context.Background())
// sync := make(chan error, 2)
// go m.Monitor(ctx, sync)
// err := <-sync // block until writers are established
// if err != nil {
// return err // failed to establish watchers
// }
// // do stuff
// cancel()
// err = <-sync // block until monitor finishes
func (m *Manager) Monitor(ctx context.Context, sync chan<- error) {
watcher, err := fsnotify.NewWatcher()
if err != nil {
sync <- err
return
}
defer watcher.Close()
for _, dir := range m.directories {
err = watcher.Add(dir)
if err != nil {
logrus.Errorf("failed to watch %q for hooks", dir)
sync <- err
return
}
logrus.Debugf("monitoring %q for hooks", dir)
}
sync <- nil
for {
select {
case event := <-watcher.Events:
filename := filepath.Base(event.Name)
if len(m.directories) <= 1 {
if event.Op&fsnotify.Remove == fsnotify.Remove {
ok := m.remove(filename)
if ok {
logrus.Debugf("removed hook %s", event.Name)
}
} else if event.Op&fsnotify.Create == fsnotify.Create || event.Op&fsnotify.Write == fsnotify.Write {
err = m.add(event.Name)
if err == nil {
logrus.Debugf("added hook %s", event.Name)
} else if err != ErrNoJSONSuffix {
logrus.Errorf("failed to add hook %s: %v", event.Name, err)
}
}
} else if event.Op&fsnotify.Create == fsnotify.Create || event.Op&fsnotify.Write == fsnotify.Write || event.Op&fsnotify.Remove == fsnotify.Remove {
err = nil
found := false
for i := len(m.directories) - 1; i >= 0; i-- {
path := filepath.Join(m.directories[i], filename)
err = m.add(path)
if err == nil {
found = true
logrus.Debugf("(re)added hook %s (triggered activity on %s)", path, event.Name)
break
} else if err == ErrNoJSONSuffix {
found = true
break // this is not going to change for fallback directories
} else if os.IsNotExist(err) {
continue // move on to the next fallback directory
} else {
found = true
logrus.Errorf("failed to (re)add hook %s (triggered by activity on %s): %v", path, event.Name, err)
break
}
}
if (found || event.Op&fsnotify.Remove == fsnotify.Remove) && err != nil {
ok := m.remove(filename)
if ok {
logrus.Debugf("removed hook %s (triggered by activity on %s)", filename, event.Name)
}
}
}
case <-ctx.Done():
err = ctx.Err()
logrus.Debugf("hook monitoring canceled: %v", err)
sync <- err
close(sync)
return
}
}
}
|
