Fix scheduling bugs with persisted update time

- The timer was always using its own duration, ignoring the timestamp
  persisted from previous runs.

src/updates.rs

@@ -183,7 +183,6 @@ impl UpdateCheckerThread {
  receiver: Receiver<UpdateCheckerMessage>,
  duration: Duration,
  ) -> Result<Self, Error> {
- // TODO: Load from save directory...
  let persist = Persist::new()?;
 
  Ok(Self {
@@ -195,70 +194,67 @@ impl UpdateCheckerThread {
  })
  }
 
- // TODO: Replace this async runner with a simple threaded runner.
- // - Needs mpsc with a message type for:
- // - Stop
- // - HTTP response
- // - HTTP request timeout
  /// Periodically check for updates.
  fn run(mut self) {
+ // Send update notification on startup if it has been persisted
+ self.send_update_notification();
+
+ // Perform initial update check
+ let mut duration = self.check();
+
+ // Create a timer to periodically ping our message loop
  let mut _timer = Timer::new(
- self.duration,
+ duration,
  self.sender.clone(),
  UpdateCheckerMessage::Ping,
  UpdateCheckerMessage::Timeout,
  );
 
- // Send update notification on startup if it has been persisted
- self.send_update_notification();
-
- // Perform initial update check
- self.check();
-
  for msg in self.receiver.take().expect("Missing receiver").iter() {
  match msg {
  UpdateCheckerMessage::Stop => break,
  UpdateCheckerMessage::Ping => continue,
  UpdateCheckerMessage::Timeout => {
+ duration = self.check();
+
+ // Update the timer
  _timer = Timer::new(
- self.duration,
+ duration,
  self.sender.clone(),
  UpdateCheckerMessage::Ping,
  UpdateCheckerMessage::Timeout,
  );
-
- self.check();
  }
  }
  }
  }
 
  /// Check for the latest version.
- fn check(&mut self) {
+ fn check(&mut self) -> Duration {
  // Check last update time
  match self.persist.last_check() {
  Ok(last_check) => {
  if last_check < self.duration {
- return;
+ return self.duration - last_check;
  }
  }
  Err(error) => {
  error!("SystemTime error: {:?}", error);
- return;
+ return self.duration;
  }
  }
 
  // Send API request
- let req = ureq::get(RELEASES_URL);
- let req = req.timeout(Duration::from_secs(HTTP_TIMEOUT));
- let req = req.set("Accept", "application/vnd.github.v3+json");
- let req = req.set("User-Agent", USER_AGENT);
+ let req = ureq::get(RELEASES_URL)
+  .timeout(Duration::from_secs(HTTP_TIMEOUT))
+  .set("Accept", "application/vnd.github.v3+json")
+  .set("User-Agent", USER_AGENT);
 
  let res = match req.call() {
  Ok(res) => res,
  Err(error) => {
  error!("HTTP request error: {:?}", error);
- return;
+ return self.duration;
  }
  };
 
@@ -267,7 +263,7 @@ impl UpdateCheckerThread {
  Ok(body) => body,
  Err(error) => {
  error!("HTTP response error: {:?}", error);
- return;
+ return self.duration;
  }
  };
 
@@ -276,14 +272,14 @@ impl UpdateCheckerThread {
  Ok(version) => version,
  Err(error) => {
  error!("SemVer parse error: {:?}", error);
- return;
+ return self.duration;
  }
  };
 
  // Save the last update time
  if let Err(error) = self.persist.update_last_check() {
  error!("SystemTime error: {:?}", error);
- return;
+ return self.duration;
  }
 
  // Update persistence
@@ -295,11 +291,13 @@ impl UpdateCheckerThread {
  // Write persistence to the file system
  if let Err(error) = self.persist.write_toml() {
  error!("Persistence error: {:?}", error);
- return;
+ return self.duration;
  }
 
  // Send the update notification
  self.send_update_notification();
+
+ self.duration
  }
 
  fn send_update_notification(&self) {