nimbus-eth2/beacon_chain/beacon_clock.nim

126 lines
4.5 KiB
Nim

# beacon_chain
# Copyright (c) 2018-2023 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
std/math,
chronos/timer, chronicles,
./spec/beacon_time
from times import Time, getTime, fromUnix, `<`, `-`, inNanoseconds
export timer.Duration, Moment, now, beacon_time
type
BeaconClock* = object
## The beacon clock represents time as it passes on a beacon chain. Beacon
## time is locked to unix time, starting at a particular offset set during
## beacon chain instantiation.
##
## Time on the beacon chain determines what actions should be taken and
## which blocks are valid - in particular, blocks are not valid if they
## come from the future as seen from the local clock.
##
## https://github.com/ethereum/consensus-specs/blob/v1.4.0-beta.3/specs/phase0/fork-choice.md#fork-choice
##
# TODO consider NTP and network-adjusted timestamps as outlined here:
# https://ethresear.ch/t/network-adjusted-timestamps/4187
genesis: Time
GetBeaconTimeFn* = proc(): BeaconTime {.gcsafe, raises: [].}
proc init*(T: type BeaconClock, genesis_time: uint64): T =
# ~290 billion years into the future
doAssert genesis_time <= high(int64).uint64
let
unixGenesis = fromUnix(genesis_time.int64)
# GENESIS_SLOT offsets slot time, but to simplify calculations, we apply that
# offset to genesis instead of applying it at every time conversion
unixGenesisOffset = times.seconds(int(GENESIS_SLOT * SECONDS_PER_SLOT))
T(genesis: unixGenesis - unixGenesisOffset)
func toBeaconTime*(c: BeaconClock, t: Time): BeaconTime =
BeaconTime(ns_since_genesis: inNanoseconds(t - c.genesis))
func toSlot*(c: BeaconClock, t: Time): tuple[afterGenesis: bool, slot: Slot] =
c.toBeaconTime(t).toSlot()
proc now*(c: BeaconClock): BeaconTime =
## Current time, in slots - this may end up being less than GENESIS_SLOT(!)
toBeaconTime(c, getTime())
func getBeaconTimeFn*(c: BeaconClock): GetBeaconTimeFn =
return proc(): BeaconTime = c.now()
proc fromNow*(c: BeaconClock, t: BeaconTime): tuple[inFuture: bool, offset: Duration] =
let now = c.now()
if t > now:
(true, nanoseconds((t - now).nanoseconds))
else:
(false, nanoseconds((now - t).nanoseconds))
proc fromNow*(c: BeaconClock, slot: Slot): tuple[inFuture: bool, offset: Duration] =
c.fromNow(slot.start_beacon_time())
proc durationToNextSlot*(c: BeaconClock): Duration =
let
currentTime = c.now()
currentSlot = currentTime.toSlot()
if currentSlot.afterGenesis:
let nextSlot = currentSlot.slot + 1
nanoseconds(
(nextSlot.start_beacon_time() - currentTime).nanoseconds)
else:
# absoluteTime = BeaconTime(-currentTime.ns_since_genesis).
let
absoluteTime = Slot(0).start_beacon_time() +
(Slot(0).start_beacon_time() - currentTime)
timeToNextSlot = absoluteTime - currentSlot.slot.start_beacon_time()
nanoseconds(timeToNextSlot.nanoseconds)
proc durationToNextEpoch*(c: BeaconClock): Duration =
let
currentTime = c.now()
currentSlot = currentTime.toSlot()
if currentSlot.afterGenesis:
let nextEpochSlot = (currentSlot.slot.epoch() + 1).start_slot()
nanoseconds(
(nextEpochSlot.start_beacon_time() - currentTime).nanoseconds)
else:
# absoluteTime = BeaconTime(-currentTime.ns_since_genesis).
let
absoluteTime = Slot(0).start_beacon_time() +
(Slot(0).start_beacon_time() - currentTime)
timeToNextEpoch = absoluteTime -
currentSlot.slot.epoch().start_slot().start_beacon_time()
nanoseconds(timeToNextEpoch.nanoseconds)
func saturate*(d: tuple[inFuture: bool, offset: Duration]): Duration =
if d.inFuture: d.offset else: seconds(0)
func shortLog*(d: Duration): string =
$d
func toFloatSeconds*(d: Duration): float =
float(milliseconds(d)) / 1000.0
func fromFloatSeconds*(T: type Duration, f: float): Duration =
case classify(f)
of fcNormal:
if f >= float(int64.high() div 1_000_000_000): InfiniteDuration
elif f <= 0: ZeroDuration
else: nanoseconds(int64(f * 1_000_000_000))
of fcSubnormal, fcZero, fcNegZero, fcNan, fcNegInf: ZeroDuration
of fcInf: InfiniteDuration
chronicles.formatIt Duration: $it