func (u *Undertaker) processDyingModel() error {
watcher, err := u.config.Facade.WatchModelResources()
if err != nil {
return errors.Trace(err)
}
if err := u.catacomb.Add(watcher); err != nil {
return errors.Trace(err)
}
defer watcher.Kill() // The watcher is not needed once this func returns.
for {
select {
case <-u.catacomb.Dying():
return u.catacomb.ErrDying()
case <-watcher.Changes():
// TODO(fwereade): this is wrong. If there's a time
// it's ok to ignore an error, it's when we know
// exactly what an error is/means. If there's a
// specific code for "not done yet", *that* is what
// we should be ignoring. But unknown errors are
// *unknown*, and we can't just assume that it's
// safe to continue.
err := u.config.Facade.ProcessDyingModel()
if err == nil {
// ProcessDyingModel succeeded. We're free to
// destroy any remaining environ resources.
return nil
}
// Yes, we ignore the error. See comment above.
}
}
}
func (w *Worker) waitForActiveMigration() (migrationmaster.MigrationStatus, error) {
var empty migrationmaster.MigrationStatus
watcher, err := w.config.Facade.Watch()
if err != nil {
return empty, errors.Annotate(err, "watching for migration")
}
if err := w.catacomb.Add(watcher); err != nil {
return empty, errors.Trace(err)
}
defer watcher.Kill()
for {
select {
case <-w.catacomb.Dying():
return empty, w.catacomb.ErrDying()
case <-watcher.Changes():
}
status, err := w.config.Facade.GetMigrationStatus()
switch {
case params.IsCodeNotFound(err):
if err := w.config.Guard.Unlock(); err != nil {
return empty, errors.Trace(err)
}
continue
case err != nil:
return empty, errors.Annotate(err, "retrieving migration status")
}
if modelHasMigrated(status.Phase) {
return empty, dependency.ErrUninstall
}
if !status.Phase.IsTerminal() {
return status, nil
}
}
}