1 //! Bookkeeping to make sure only one long-running operation is being executed
4 pub(crate) type Cause = String;
6 pub(crate) struct OpQueue<Output> {
7 op_requested: Option<Cause>,
9 last_op_result: Output,
12 impl<Output: Default> Default for OpQueue<Output> {
13 fn default() -> Self {
14 Self { op_requested: None, op_in_progress: false, last_op_result: Default::default() }
18 impl<Output> OpQueue<Output> {
19 pub(crate) fn request_op(&mut self, reason: Cause) {
20 self.op_requested = Some(reason);
22 pub(crate) fn should_start_op(&mut self) -> Option<Cause> {
23 if self.op_in_progress {
26 self.op_in_progress = self.op_requested.is_some();
27 self.op_requested.take()
29 pub(crate) fn op_completed(&mut self, result: Output) {
30 assert!(self.op_in_progress);
31 self.op_in_progress = false;
32 self.last_op_result = result;
35 pub(crate) fn last_op_result(&self) -> &Output {
38 pub(crate) fn op_in_progress(&self) -> bool {
41 pub(crate) fn op_requested(&self) -> bool {
42 self.op_requested.is_some()