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;; This file is part of scheme-GNUnet.
;; Copyright (C) 2012-2016 GNUnet e.V.
;; Copyright (C) 2021 Maxime Devos
;;
;; scheme-GNUnet is free software: you can redistribute it and/or modify it
;; under the terms of the GNU Affero General Public License as published
;; by the Free Software Foundation, either version 3 of the License,
;; or (at your option) any later version.
;;
;; scheme-GNUnet is distributed in the hope that it will be useful, but
;; WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;; Affero General Public License for more details.
;;
;; You should have received a copy of the GNU Affero General Public License
;; along with this program. If not, see <http://www.gnu.org/licenses/>.
;;
;; SPDX-License-Identifier: AGPL3.0-or-later
;; @author Florian Dold (GNUnet)
;; @author Christian Grothoff (GNUnet)
;; @author Maxime Devos (scheme-GNUnet)
;;
;; @brief General-purpose message queue (priorities, numeric)
(library (gnu gnunet mq prio-prefs)
(export priority-preference priority-preference?
PRIORITY_MASK
prio-prefs->integer
prio-pref:?
prio-pref:prefs
prio-pref:prio
prio->integer)
(import (only (guile) compose)
(gnu gnunet mq prio-prefs2)
(gnu extractor enum)
(srfi srfi-26)
(rnrs arithmetic bitwise)
(rnrs base))
(begin
(define (prio-prefs->integer . values)
"Given a list of priority-preference enum values,
return its numeric value."
(apply bitwise-ior
(map (compose (cute expt 2 <>) value->index) values)))
(define (prio-pref:? integer flag)
"Is the flag @var{flag} (an enum value) set in
the integer @var{integer}?"
(bitwise-bit-set? integer (value->index flag)))
(define (prio-pref:prefs integer)
"Given the numeric priority-preference value @var{integer},
return its preferences as multiple of @code{priority-preference}
enum values. The priority bits are ignored."
(let-syntax
((bit (syntax-rules ()
((_ name ...)
`(,@(let ((flag (symbol-value priority-preference name)))
(if (prio-pref:? integer flag)
`(,flag)
`()))
...)))))
(apply values
(bit pref:unreliable
pref:low-latency
pref:cork-allowed
pref:goodput
pref:out-of-order))))
;; Bit mask to apply to extract the priority bits.
(define PRIORITY_MASK 4)
(define (prio-pref:prio integer)
"Given a numeric priority-preference value @var{integer},
return its priority type as a symbol, i.e. one of
@code{prio:background}, @code{prio:best-effort},
@code{prio:urgent} or @code{prio:critical-control}.
The preference bits are ignored."
(case (bitwise-and integer PRIORITY_MASK)
((0) 'prio:background)
((1) 'prio:best-effort)
((2) 'prio:urgent)
((3) 'prio:critical-control)))
(define (prio->integer sym)
"An inverse of @var{prio-pref:prio}, not adding any
preference bits."
(case sym
;; Lowest priority, i.e. background traffic (i.e. NSE, FS).
;; This is the default!
((prio:background) 0)
((prio:best-effort) 1)
((prio:urgent) 2)
;; Highest priority, control traffic (i.e. CORE/CADET KX).
((prio:critical-control) 3)
(else (assert #f))))))
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