sig
  type runtime_counter =
      EV_C_FORCE_MINOR_ALLOC_SMALL
    | EV_C_FORCE_MINOR_MAKE_VECT
    | EV_C_FORCE_MINOR_SET_MINOR_HEAP_SIZE
    | EV_C_FORCE_MINOR_MEMPROF
    | EV_C_MINOR_PROMOTED
    | EV_C_MINOR_ALLOCATED
    | EV_C_REQUEST_MAJOR_ALLOC_SHR
    | EV_C_REQUEST_MAJOR_ADJUST_GC_SPEED
    | EV_C_REQUEST_MINOR_REALLOC_REF_TABLE
    | EV_C_REQUEST_MINOR_REALLOC_EPHE_REF_TABLE
    | EV_C_REQUEST_MINOR_REALLOC_CUSTOM_TABLE
    | EV_C_MAJOR_HEAP_POOL_WORDS
    | EV_C_MAJOR_HEAP_POOL_LIVE_WORDS
    | EV_C_MAJOR_HEAP_LARGE_WORDS
    | EV_C_MAJOR_HEAP_POOL_FRAG_WORDS
    | EV_C_MAJOR_HEAP_POOL_LIVE_BLOCKS
    | EV_C_MAJOR_HEAP_LARGE_BLOCKS
    | EV_C_MAJOR_HEAP_WORDS
    | EV_C_MAJOR_ALLOCATED_WORDS
    | EV_C_MAJOR_ALLOCATED_WORK
    | EV_C_MAJOR_DEPENDENT_WORK
    | EV_C_MAJOR_EXTRA_WORK
    | EV_C_MAJOR_WORK_COUNTER
    | EV_C_MAJOR_ALLOC_COUNTER
    | EV_C_MAJOR_SLICE_TARGET
    | EV_C_MAJOR_SLICE_BUDGET
    | EV_C_MINOR_ALLOCATED_WORDS
    | EV_C_MINOR_PROMOTED_WORDS
  type runtime_phase =
      EV_EXPLICIT_GC_SET
    | EV_EXPLICIT_GC_STAT
    | EV_EXPLICIT_GC_MINOR
    | EV_EXPLICIT_GC_MAJOR
    | EV_EXPLICIT_GC_FULL_MAJOR
    | EV_EXPLICIT_GC_COMPACT
    | EV_MAJOR
    | EV_MAJOR_SWEEP
    | EV_MAJOR_MARK_ROOTS
    | EV_MAJOR_MEMPROF_ROOTS
    | EV_MAJOR_MARK
    | EV_MINOR
    | EV_MINOR_LOCAL_ROOTS
    | EV_MINOR_MEMPROF_ROOTS
    | EV_MINOR_MEMPROF_CLEAN
    | EV_MINOR_FINALIZED
    | EV_EXPLICIT_GC_MAJOR_SLICE
    | EV_FINALISE_UPDATE_FIRST
    | EV_FINALISE_UPDATE_LAST
    | EV_INTERRUPT_REMOTE
    | EV_MAJOR_EPHE_MARK
    | EV_MAJOR_EPHE_SWEEP
    | EV_MAJOR_FINISH_MARKING
    | EV_MAJOR_GC_CYCLE_DOMAINS
    | EV_MAJOR_GC_PHASE_CHANGE
    | EV_MAJOR_GC_STW
    | EV_MAJOR_MARK_OPPORTUNISTIC
    | EV_MAJOR_SLICE
    | EV_MAJOR_FINISH_CYCLE
    | EV_MINOR_CLEAR
    | EV_MINOR_FINALIZERS_OLDIFY
    | EV_MINOR_GLOBAL_ROOTS
    | EV_MINOR_LEAVE_BARRIER
    | EV_STW_API_BARRIER
    | EV_STW_HANDLER
    | EV_STW_LEADER
    | EV_MAJOR_FINISH_SWEEPING
    | EV_MAJOR_MEMPROF_CLEAN
    | EV_MINOR_FINALIZERS_ADMIN
    | EV_MINOR_REMEMBERED_SET
    | EV_MINOR_REMEMBERED_SET_PROMOTE
    | EV_MINOR_LOCAL_ROOTS_PROMOTE
    | EV_DOMAIN_CONDITION_WAIT
    | EV_DOMAIN_RESIZE_HEAP_RESERVATION
    | EV_COMPACT
    | EV_COMPACT_EVACUATE
    | EV_COMPACT_FORWARD
    | EV_COMPACT_RELEASE
    | EV_EMPTY_MINOR
  type lifecycle =
      EV_RING_START
    | EV_RING_STOP
    | EV_RING_PAUSE
    | EV_RING_RESUME
    | EV_FORK_PARENT
    | EV_FORK_CHILD
    | EV_DOMAIN_SPAWN
    | EV_DOMAIN_TERMINATE
  val lifecycle_name : Runtime_events.lifecycle -> string
  val runtime_phase_name : Runtime_events.runtime_phase -> string
  val runtime_counter_name : Runtime_events.runtime_counter -> string
  type cursor
  module Timestamp :
    sig
      type t
      val to_int64 : Runtime_events.Timestamp.t -> int64
      val get_current : unit -> Runtime_events.Timestamp.t
    end
  module Type :
    sig
      type 'a t
      val unit : unit Runtime_events.Type.t
      type span = Begin | End
      val span : Runtime_events.Type.span Runtime_events.Type.t
      val int : int Runtime_events.Type.t
      val register :
        encode:(bytes -> 'a -> int) ->
        decode:(bytes -> int -> 'a) -> 'a Runtime_events.Type.t
    end
  module User :
    sig
      type tag = ..
      type 'value t
      val register :
        string ->
        Runtime_events.User.tag ->
        'value Runtime_events.Type.t -> 'value Runtime_events.User.t
      val write : 'value Runtime_events.User.t -> 'value -> unit
      val name : 'a Runtime_events.User.t -> string
      val tag : 'a Runtime_events.User.t -> Runtime_events.User.tag
    end
  module Callbacks :
    sig
      type t
      val create :
        ?runtime_begin:(int ->
                        Runtime_events.Timestamp.t ->
                        Runtime_events.runtime_phase -> unit) ->
        ?runtime_end:(int ->
                      Runtime_events.Timestamp.t ->
                      Runtime_events.runtime_phase -> unit) ->
        ?runtime_counter:(int ->
                          Runtime_events.Timestamp.t ->
                          Runtime_events.runtime_counter -> int -> unit) ->
        ?alloc:(int -> Runtime_events.Timestamp.t -> int array -> unit) ->
        ?lifecycle:(int ->
                    Runtime_events.Timestamp.t ->
                    Runtime_events.lifecycle -> int option -> unit) ->
        ?lost_events:(int -> int -> unit) ->
        unit -> Runtime_events.Callbacks.t
      val add_user_event :
        'a Runtime_events.Type.t ->
        (int ->
         Runtime_events.Timestamp.t -> 'a Runtime_events.User.t -> 'a -> unit) ->
        Runtime_events.Callbacks.t -> Runtime_events.Callbacks.t
    end
  val start : unit -> unit
  val path : unit -> string option
  val pause : unit -> unit
  val resume : unit -> unit
  val create_cursor : (string * int) option -> Runtime_events.cursor
  val free_cursor : Runtime_events.cursor -> unit
  val read_poll :
    Runtime_events.cursor -> Runtime_events.Callbacks.t -> int option -> int
end