136 lines
4.7 KiB
Nim
136 lines
4.7 KiB
Nim
# beacon_chain
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# Copyright (c) 2018-2021 Status Research & Development GmbH
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# Licensed and distributed under either of
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# * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
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# * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
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# at your option. This file may not be copied, modified, or distributed except according to those terms.
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{.push raises: [Defect].}
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import
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chronos, chronicles,
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./spec/helpers
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from times import Time, getTime, fromUnix, `<`, `-`, inNanoseconds
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export chronos.Duration, Moment, now
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type
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BeaconClock* = object
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## The beacon clock represents time as it passes on a beacon chain. Beacon
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## time is locked to unix time, starting at a particular offset set during
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## beacon chain instantiation.
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##
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## Time on the beacon chain determines what actions should be taken and
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## which blocks are valid - in particular, blocks are not valid if they
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## come from the future as seen from the local clock.
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##
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## https://github.com/ethereum/eth2.0-specs/blob/v1.0.1/specs/phase0/fork-choice.md#fork-choice
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##
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# TODO consider NTP and network-adjusted timestamps as outlined here:
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# https://ethresear.ch/t/network-adjusted-timestamps/4187
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genesis: Time
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BeaconTime* = distinct Duration ## Nanoseconds from beacon genesis time
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GetTimeFn* = proc(): Time {.gcsafe, raises: [Defect].}
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proc init*(T: type BeaconClock, genesis_time: uint64): T =
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# ~290 billion years into the future
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doAssert genesis_time <= high(int64).uint64
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let
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unixGenesis = fromUnix(genesis_time.int64)
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# GENESIS_SLOT offsets slot time, but to simplify calculations, we apply that
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# offset to genesis instead of applying it at every time conversion
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unixGenesisOffset = times.seconds(int(GENESIS_SLOT * SECONDS_PER_SLOT))
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T(genesis: unixGenesis - unixGenesisOffset)
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template `<`*(a, b: BeaconTime): bool =
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Duration(a) < Duration(b)
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template `<=`*(a, b: BeaconTime): bool =
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Duration(a) <= Duration(b)
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template `+`*(t: BeaconTime, offset: Duration): BeaconTime =
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BeaconTime(Duration(t) + offset)
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template `-`*(t: BeaconTime, offset: Duration): BeaconTime =
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BeaconTime(nanoseconds(nanoseconds(Duration(t)) - nanoseconds(offset)))
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template `-`*(a, b: BeaconTime): Duration =
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nanoseconds(nanoseconds(Duration(a)) - nanoseconds(Duration(b)))
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func toSlot*(t: BeaconTime): tuple[afterGenesis: bool, slot: Slot] =
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let ti = seconds(Duration(t))
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if ti >= 0:
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(true, Slot(uint64(ti) div SECONDS_PER_SLOT))
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else:
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(false, Slot(uint64(-ti) div SECONDS_PER_SLOT))
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func slotOrZero*(time: BeaconTime): Slot =
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let exSlot = time.toSlot
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if exSlot.afterGenesis: exSlot.slot
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else: Slot(0)
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func toBeaconTime*(c: BeaconClock, t: Time): BeaconTime =
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BeaconTime(nanoseconds(inNanoseconds(t - c.genesis)))
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func toSlot*(c: BeaconClock, t: Time): tuple[afterGenesis: bool, slot: Slot] =
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c.toBeaconTime(t).toSlot()
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func toBeaconTime*(s: Slot, offset = Duration()): BeaconTime =
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# BeaconTime/Duration stores nanoseconds, internally
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const maxSlot = (not 0'u64 div 2 div SECONDS_PER_SLOT div 1_000_000_000).Slot
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var slot = s
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if slot > maxSlot:
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slot = maxSlot
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BeaconTime(seconds(int64(uint64(slot) * SECONDS_PER_SLOT)) + offset)
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proc now*(c: BeaconClock): BeaconTime =
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## Current time, in slots - this may end up being less than GENESIS_SLOT(!)
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toBeaconTime(c, getTime())
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proc fromNow*(c: BeaconClock, t: BeaconTime): tuple[inFuture: bool, offset: Duration] =
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let now = c.now()
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if t > now:
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(true, t - now)
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else:
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(false, now - t)
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proc fromNow*(c: BeaconClock, slot: Slot): tuple[inFuture: bool, offset: Duration] =
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c.fromNow(slot.toBeaconTime())
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proc durationToNextSlot*(c: BeaconClock): Duration =
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let (afterGenesis, slot) = c.now().toSlot()
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if afterGenesis:
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c.fromNow(Slot(slot) + 1'u64).offset
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else:
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c.fromNow(Slot(0)).offset
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proc durationToNextEpoch*(c: BeaconClock): Duration =
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let (afterGenesis, slot) = c.now().toSlot()
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if afterGenesis:
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c.fromNow(compute_start_slot_at_epoch(slot.epoch() + 1'u64)).offset
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else:
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c.fromNow(compute_start_slot_at_epoch(Epoch(0))).offset
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func saturate*(d: tuple[inFuture: bool, offset: Duration]): Duration =
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if d.inFuture: d.offset else: seconds(0)
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proc addTimer*(fromNow: Duration, cb: CallbackFunc, udata: pointer = nil) =
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discard setTimer(Moment.now() + fromNow, cb, udata)
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func shortLog*(d: Duration): string =
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$d
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func toFloatSeconds*(d: Duration): float =
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float(milliseconds(d)) / 1000.0
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func `$`*(v: BeaconTime): string = $(Duration v)
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func shortLog*(v: BeaconTime): string = $(Duration v)
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chronicles.formatIt Duration: $it
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chronicles.formatIt BeaconTime: $(Duration it)
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