Remove background correction in AsyncTimerSequence (#289)

# Motivation Currently, the `AsyncTimerSequence` is trying to correct for when an application becomes suspended and the timer might fire multiple times once the application gets foregrounded again. However, this is already handled by the `Clock` types themselves. The `SuspendingClock` is correcting for suspension of the app whereas the `ContinuousClock` is not. Additionally, this was not only hit by background an application but by just calling `Task.sleep` in the for-await loop that is consuming the sequence. # Modification This removes the part of the code in `AsyncTimerSequence` which corrected for suspension of the application.

Author: FranzBusch

Sources/AsyncAlgorithms/AsyncTimerSequence.swift

@@ -13,59 +13,49 @@
 @available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0,*)
 publicstructAsyncTimerSequence<C:Clock>:AsyncSequence{
 publictypealiasElement=C.Instant
-
+
  /// The iterator for an `AsyncTimerSequence` instance.
 publicstructIterator:AsyncIteratorProtocol{
 varclock:C?
 letinterval:C.Instant.Duration
 lettolerance:C.Instant.Duration?
 varlast:C.Instant?
-
+
 init(interval:C.Instant.Duration, tolerance:C.Instant.Duration?, clock:C){
 self.clock = clock
 self.interval = interval
 self.tolerance = tolerance
 }
-
-func nextDeadline(_ clock:C)->C.Instant{
-letnow= clock.now
-letlast=self.last ?? now
-letnext= last.advanced(by: interval)
-if next < now {
-return last.advanced(by: interval * Int(((next.duration(to: now))/ interval).rounded(.up)))
-}else{
-return next
-}
-}
-
+
 publicmutatingfunc next()async->C.Instant?{
-guardlet clock = clock else{
+guardlet clock =self.clock else{
 returnnil
 }
-letnext=nextDeadline(clock)
+
+letnext=(self.last ?? clock.now).advanced(by:self.interval)
 do{
-tryawait clock.sleep(until: next, tolerance: tolerance)
+tryawait clock.sleep(until: next, tolerance:self.tolerance)
 }catch{
 self.clock =nil
 returnnil
 }
 letnow= clock.now
- last = next
+self.last = next
 return now
 }
 }
-
+
 letclock:C
 letinterval:C.Instant.Duration
 lettolerance:C.Instant.Duration?
-
+
  /// Create an `AsyncTimerSequence` with a given repeating interval.
 publicinit(interval:C.Instant.Duration, tolerance:C.Instant.Duration?=nil, clock:C){
 self.clock = clock
 self.interval = interval
 self.tolerance = tolerance
 }
-
+
 publicfunc makeAsyncIterator()->Iterator{
 Iterator(interval: interval, tolerance: tolerance, clock: clock)
 }