IH-628: remove deadlines from timers

These could help with the porting of the redo_log code, but Edwin's has working
code that changes the API of the timed calls to use durations instead of
deadlines.

Signed-off-by: Pau Ruiz Safont <[email protected]>

ocaml/libs/clock/timer.ml

@@ -1,13 +1,12 @@
-type t = {start: Ptime.t; elapsed: Mtime_clock.counter; duration: Mtime.Span.t}
+type t = {elapsed: Mtime_clock.counter; duration: Mtime.Span.t}
 
 type countdown = Remaining of Mtime.Span.t | Expired of Mtime.Span.t
 
 let span_is_shorter a ~than:b = Mtime.Span.compare a b < 0
 
 let span_is_longer a ~than:b = Mtime.Span.compare a b > 0
 
-let start ~duration =
-  {start= Ptime_clock.now (); elapsed= Mtime_clock.counter (); duration}
+let start ~duration = {elapsed= Mtime_clock.counter (); duration}
 
 let duration {duration; _} = duration
 
@@ -25,14 +24,6 @@ let has_expired t =
   let elapsed = Mtime_clock.count t.elapsed in
   not (span_is_shorter elapsed ~than:t.duration)
 
-let deadline_of t =
-  Mtime.Span.to_uint64_ns t.duration
-  |> Int64.to_float
-  |> Ptime.Span.of_float_s
-  |> Option.get
-  |> Ptime.(Span.add Ptime.(to_span t.start))
-  |> Ptime.Span.to_float_s
-
 let shorten_by dur t =
   let duration =
     if span_is_longer dur ~than:t.duration then

ocaml/libs/clock/timer.mli

@@ -24,12 +24,6 @@ val remaining : t -> countdown
 (** [remaining timer] returns the amount of time left until [timer] expires or
     the amount of time since it expired. *)
 
-val deadline_of : t -> float
-(** [deadline_of timer] returns the posix timestamp when the timer expires.
-      This is an approximation as the timer doesn't take leap seconds into
-      account when waiting. The use of this function is discouraged and it's
-      only provided for backwards-compatible reasons. *)
-
 val shorten_by : Mtime.Span.t -> t -> t
 (** [shorten_by amount timer] creates a new timer with the duration of [timer]
     shortened by [amount]. The starting time doesn't change. The duration of a