priority.ml

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open Util

type t =
  { exclusive : bool
  ; stream_dependency : Stream_identifier.t
  ; weight : int
  }

(* From RFC7540§5.3.5:
 *   All streams are initially assigned a non-exclusive dependency on stream
 *   0x0. Pushed streams (Section 8.2) initially depend on their associated
 *   stream. In both cases, streams are assigned a default weight of 16. *)
let default_priority =
  { exclusive = false; stream_dependency = 0l; weight = 16 }

(* From RFC7540§5.4.1:
 *   All dependent streams are allocated an integer weight between 1 and 256
 *   (inclusive). *)
let highest_priority =
  { exclusive = false; stream_dependency = 0l; weight = 256 }

(* --- Exclusive flag ---
 *
 * From RFC7540§5.4.1:
 *   +-+-------------------------------------------------------------+
 *   |E|                  Stream Dependency (31)                     |
 *   +-+-------------+-----------------------------------------------+
 *   |   Weight (8)  |
 *   +-+-------------+
 *)

let test_exclusive n = test_bit_int32 n 31
let set_exclusive n = set_bit_int32 n 31
let clear_exclusive n = clear_bit_int32 n 31

let equal p1 p2 =
  p1.weight = p2.weight
  && Int32.equal p1.stream_dependency p2.stream_dependency
  && p1.exclusive = p2.exclusive