// NewPinger returns an object that can be pinged by calling its Ping method.
// If this method is not called frequently enough, the connection will be
// dropped.
func NewPinger(st *state.State, resources facade.Resources, authorizer facade.Authorizer) (Pinger, error) {
pingTimeout, ok := resources.Get("pingTimeout").(*pingTimeout)
if !ok {
return nullPinger{}, nil
}
return pingTimeout, nil
}
func extractResourceValue(resources facade.Resources, key string) (string, error) {
res := resources.Get(key)
strRes, ok := res.(common.StringResource)
if !ok {
if res == nil {
strRes = ""
} else {
return "", errors.Errorf("invalid %s resource: %v", key, res)
}
}
return strRes.String(), nil
}
func newMachineStorageIdsWatcher(
st *state.State,
resources facade.Resources,
auth facade.Authorizer,
id string,
parser func([]string) ([]params.MachineStorageId, error),
) (facade.Facade, error) {
if !isAgent(auth) {
return nil, common.ErrPerm
}
watcher, ok := resources.Get(id).(state.StringsWatcher)
if !ok {
return nil, common.ErrUnknownWatcher
}
return &srvMachineStorageIdsWatcher{watcher, id, resources, parser}, nil
}