(** Profiling probes.

   This basic library can produce Catapult traces (a json file)
   that can be read at [http://ui.perfetto.dev].
 *)

type probe

val null_probe : probe
val enabled : unit -> bool
val instant : string -> unit
val begin_ : string -> probe
val exit : probe -> unit
val with_ : string -> (unit -> 'a) -> 'a
val with1 : string -> ('a -> 'b) -> 'a -> 'b
val with2 : string -> ('a -> 'b -> 'c) -> 'a -> 'b -> 'c

module type BACKEND = sig
  val get_ts : unit -> float

  val emit_duration_event :
    name:string -> start:float -> end_:float -> unit -> unit

  val emit_instant_event : name:string -> ts:float -> unit -> unit
  val teardown : unit -> unit
end

type backend = (module BACKEND)

module Control : sig
  val setup : backend option -> unit
  val teardown : unit -> unit
end