-/// Used to signal to the ChannelManager persister that the manager needs to be re-persisted to
-/// disk/backups, through `await_persistable_update_timeout` and `await_persistable_update`.
-struct PersistenceNotifier {
- /// Users won't access the persistence_lock directly, but rather wait on its bool using
- /// `wait_timeout` and `wait`.
- persistence_lock: (Mutex<bool>, Condvar),
-}
-
-impl PersistenceNotifier {
- fn new() -> Self {
- Self {
- persistence_lock: (Mutex::new(false), Condvar::new()),
- }
- }
-
- fn wait(&self) {
- loop {
- let &(ref mtx, ref cvar) = &self.persistence_lock;
- let mut guard = mtx.lock().unwrap();
- if *guard {
- *guard = false;
- return;
- }
- guard = cvar.wait(guard).unwrap();
- let result = *guard;
- if result {
- *guard = false;
- return
- }
- }
- }
-
- #[cfg(any(test, feature = "std"))]
- fn wait_timeout(&self, max_wait: Duration) -> bool {
- let current_time = Instant::now();
- loop {
- let &(ref mtx, ref cvar) = &self.persistence_lock;
- let mut guard = mtx.lock().unwrap();
- if *guard {
- *guard = false;
- return true;
- }
- guard = cvar.wait_timeout(guard, max_wait).unwrap().0;
- // Due to spurious wakeups that can happen on `wait_timeout`, here we need to check if the
- // desired wait time has actually passed, and if not then restart the loop with a reduced wait
- // time. Note that this logic can be highly simplified through the use of
- // `Condvar::wait_while` and `Condvar::wait_timeout_while`, if and when our MSRV is raised to
- // 1.42.0.
- let elapsed = current_time.elapsed();
- let result = *guard;
- if result || elapsed >= max_wait {
- *guard = false;
- return result;
- }
- match max_wait.checked_sub(elapsed) {
- None => return result,
- Some(_) => continue
- }
- }
- }
-
- // Signal to the ChannelManager persister that there are updates necessitating persisting to disk.
- fn notify(&self) {
- let &(ref persist_mtx, ref cnd) = &self.persistence_lock;
- let mut persistence_lock = persist_mtx.lock().unwrap();
- *persistence_lock = true;
- mem::drop(persistence_lock);
- cnd.notify_all();
- }
-}
-