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src/stun_shaper.erl

%%%----------------------------------------------------------------------
%%% File : stun_shaper.erl
%%% Author : Alexey Shchepin <alexey@process-one.net>
%%% Purpose : Functions to control connections traffic
%%% Created : 9 Feb 2003 by Alexey Shchepin <alexey@process-one.net>
%%%
%%%
%%% Copyright (C) 2002-2023 ProcessOne, SARL. All Rights Reserved.
%%%
%%% Licensed under the Apache License, Version 2.0 (the "License");
%%% you may not use this file except in compliance with the License.
%%% You may obtain a copy of the License at
%%%
%%% http://www.apache.org/licenses/LICENSE-2.0
%%%
%%% Unless required by applicable law or agreed to in writing, software
%%% distributed under the License is distributed on an "AS IS" BASIS,
%%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%%% See the License for the specific language governing permissions and
%%% limitations under the License.
%%%
%%%----------------------------------------------------------------------
-module(stun_shaper).
-author('alexey@process-one.net').
-export([new/1, update/2]).
-record(maxrate, {maxrate = 0 :: integer(),
lastrate = 0.0 :: float(),
lasttime = 0 :: integer()}).
-type shaper() :: none | #maxrate{}.
-export_type([shaper/0]).
%%%===================================================================
%%% API
%%%===================================================================
-spec new(none | integer()) -> shaper().
new(none) -> none;
new(MaxRate) when is_integer(MaxRate) ->
#maxrate{maxrate = MaxRate, lastrate = 0.0,
lasttime = p1_time_compat:monotonic_time(micro_seconds)}.
-spec update(shaper(), integer()) -> {shaper(), integer()}.
update(none, _Size) -> {none, 0};
update(#maxrate{} = State, Size) ->
MinInterv = 1000 * Size /
(2 * State#maxrate.maxrate - State#maxrate.lastrate),
Interv = (p1_time_compat:monotonic_time(micro_seconds) - State#maxrate.lasttime) /
1000,
Pause = if MinInterv > Interv ->
1 + trunc(MinInterv - Interv);
true -> 0
end,
NextNow = p1_time_compat:monotonic_time(micro_seconds) + Pause * 1000,
{State#maxrate{lastrate =
(State#maxrate.lastrate +
1000000 * Size / (NextNow - State#maxrate.lasttime))
/ 2,
lasttime = NextNow},
Pause}.