nim-eth/eth/utp/delay_histogram.nim

72 lines
2.3 KiB
Nim

# Copyright (c) 2021-2023 Status Research & Development GmbH
# Licensed and distributed under either of
# * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
# * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
# at your option. This file may not be copied, modified, or distributed except according to those terms.
{.push raises: [].}
import
chronos,
./utp_utils
const
currentDelaySize = 3
delayBaseHistory = 13
delayBaseUpdateInterval = minutes(1)
type
DelayHistogram* = object
delayBase*: uint32
currentDelayHistory: array[currentDelaySize, uint32]
currentDelayIdx: int
delayBaseHistory: array[delayBaseHistory, uint32]
delayBaseIdx: int
delayBaseTime: Moment
proc init*(T: type DelayHistogram, currentTime: Moment): T =
DelayHistogram(
delayBaseTime: currentTime
)
proc shift*(h: var DelayHistogram, offset: uint32) =
for sample in h.delayBaseHistory.mitems():
sample = sample + offset
h.delayBase = h.delayBase + offset
proc addSample*(h: var DelayHistogram, sample: uint32, currentTime: Moment) =
# if delay base is zero it means it is our first sample. Initialize necessary parts
if h.delayBase == 0:
h.delayBase = sample
for i in h.delayBaseHistory.mitems():
i = sample
if wrapCompareLess(sample, h.delayBaseHistory[h.delayBaseIdx]):
h.delayBaseHistory[h.delayBaseIdx] = sample
if wrapCompareLess(sample, h.delayBase):
h.delayBase = sample
let delay = sample - h.delayBase
h.currentDelayHistory[h.currentDelayIdx] = delay
h.currentDelayIdx = (h.currentDelayIdx + 1) mod currentDelaySize
if (currentTime - h.delayBaseTime > delayBaseUpdateInterval):
h.delayBaseTime = currentTime
h.delayBaseIdx = (h.delayBaseIdx + 1) mod delayBaseHistory
h.delayBaseHistory[h.delayBaseIdx] = sample
h.delayBase = h.delayBaseHistory[0]
for delaySample in h.delayBaseHistory.items():
if (wrapCompareLess(delaySample, h.delayBase)):
h.delayBase = delaySample
proc getValue*(h: DelayHistogram): Duration =
var value = uint32.high
# this will return zero if not all samples are collected
for sample in h.currentDelayHistory:
value = min(sample, value)
microseconds(value)