Allow slot clock to handle clock disparity (#929)

* Add PH & MS slot clock changes

* Account for genesis time

* Use checked mul

* Account for genesis slot

* Change API

* Refactor "duration to..." functions
This commit is contained in:
Paul Hauner 2020-04-01 17:40:04 +11:00 committed by GitHub
parent 5c397c49d8
commit 11a238900a
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5 changed files with 377 additions and 77 deletions

11
Cargo.lock generated
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@ -233,7 +233,7 @@ dependencies = [
"serde_yaml 0.8.11 (registry+https://github.com/rust-lang/crates.io-index)",
"slog 2.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
"sloggers 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
"slot_clock 0.1.0",
"slot_clock 0.2.0",
"state_processing 0.1.0",
"store 0.1.0",
"tempfile 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@ -534,7 +534,7 @@ dependencies = [
"slog 2.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
"slog-async 2.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
"sloggers 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
"slot_clock 0.1.0",
"slot_clock 0.2.0",
"store 0.1.0",
"tokio 0.1.22 (registry+https://github.com/rust-lang/crates.io-index)",
"toml 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)",
@ -3442,7 +3442,7 @@ dependencies = [
"slog 2.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
"slog-async 2.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
"slog-term 2.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
"slot_clock 0.1.0",
"slot_clock 0.2.0",
"state_processing 0.1.0",
"store 0.1.0",
"tokio 0.1.22 (registry+https://github.com/rust-lang/crates.io-index)",
@ -3866,10 +3866,11 @@ dependencies = [
[[package]]
name = "slot_clock"
version = "0.1.0"
version = "0.2.0"
dependencies = [
"lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
"lighthouse_metrics 0.1.0",
"parking_lot 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
"types 0.1.0",
]
@ -4710,7 +4711,7 @@ dependencies = [
"slog 2.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
"slog-async 2.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
"slog-term 2.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
"slot_clock 0.1.0",
"slot_clock 0.2.0",
"tempdir 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
"tokio 0.1.22 (registry+https://github.com/rust-lang/crates.io-index)",
"tokio-timer 0.2.12 (registry+https://github.com/rust-lang/crates.io-index)",

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@ -1,6 +1,6 @@
[package]
name = "slot_clock"
version = "0.1.0"
version = "0.2.0"
authors = ["Paul Hauner <paul@paulhauner.com>"]
edition = "2018"
@ -8,3 +8,4 @@ edition = "2018"
types = { path = "../../types" }
lazy_static = "1.4.0"
lighthouse_metrics = { path = "../lighthouse_metrics" }
parking_lot = "0.9.0"

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@ -1,14 +1,15 @@
#[macro_use]
extern crate lazy_static;
mod manual_slot_clock;
mod metrics;
mod system_time_slot_clock;
mod testing_slot_clock;
use std::time::Duration;
pub use crate::manual_slot_clock::ManualSlotClock;
pub use crate::manual_slot_clock::ManualSlotClock as TestingSlotClock;
pub use crate::system_time_slot_clock::SystemTimeSlotClock;
pub use crate::testing_slot_clock::TestingSlotClock;
pub use metrics::scrape_for_metrics;
pub use types::Slot;
@ -16,13 +17,21 @@ pub use types::Slot;
///
/// The clock is not required to be monotonically increasing and may go backwards.
pub trait SlotClock: Send + Sync + Sized {
/// Creates a new slot clock where the first slot is `genesis_slot`, genesis occured
/// Creates a new slot clock where the first slot is `genesis_slot`, genesis occurred
/// `genesis_duration` after the `UNIX_EPOCH` and each slot is `slot_duration` apart.
fn new(genesis_slot: Slot, genesis_duration: Duration, slot_duration: Duration) -> Self;
/// Returns the slot at this present time.
fn now(&self) -> Option<Slot>;
/// Returns the present time as a duration since the UNIX epoch.
///
/// Returns `None` if the present time is before the UNIX epoch (unlikely).
fn now_duration(&self) -> Option<Duration>;
/// Returns the slot of the given duration since the UNIX epoch.
fn slot_of(&self, now: Duration) -> Option<Slot>;
/// Returns the duration between slots
fn slot_duration(&self) -> Duration;
@ -31,4 +40,18 @@ pub trait SlotClock: Send + Sync + Sized {
/// Returns the duration until the first slot of the next epoch.
fn duration_to_next_epoch(&self, slots_per_epoch: u64) -> Option<Duration>;
/// Returns the first slot to be returned at the genesis time.
fn genesis_slot(&self) -> Slot;
/// Returns the slot if the internal clock were advanced by `duration`.
fn now_with_future_tolerance(&self, tolerance: Duration) -> Option<Slot> {
self.slot_of(self.now_duration()?.checked_add(tolerance)?)
}
/// Returns the slot if the internal clock were reversed by `duration`.
fn now_with_past_tolerance(&self, tolerance: Duration) -> Option<Slot> {
self.slot_of(self.now_duration()?.checked_sub(tolerance)?)
.or_else(|| Some(self.genesis_slot()))
}
}

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@ -0,0 +1,325 @@
use super::SlotClock;
use parking_lot::RwLock;
use std::convert::TryInto;
use std::time::Duration;
use types::Slot;
/// Determines the present slot based upon a manually-incremented UNIX timestamp.
pub struct ManualSlotClock {
genesis_slot: Slot,
/// Duration from UNIX epoch to genesis.
genesis_duration: Duration,
/// Duration from UNIX epoch to right now.
current_time: RwLock<Duration>,
/// The length of each slot.
slot_duration: Duration,
}
impl Clone for ManualSlotClock {
fn clone(&self) -> Self {
ManualSlotClock {
genesis_slot: self.genesis_slot.clone(),
genesis_duration: self.genesis_duration.clone(),
current_time: RwLock::new(self.current_time.read().clone()),
slot_duration: self.slot_duration.clone(),
}
}
}
impl ManualSlotClock {
pub fn set_slot(&self, slot: u64) {
let slots_since_genesis = slot
.checked_sub(self.genesis_slot.as_u64())
.expect("slot must be post-genesis")
.try_into()
.expect("slot must fit within a u32");
*self.current_time.write() =
self.genesis_duration + self.slot_duration * slots_since_genesis;
}
pub fn advance_slot(&self) {
self.set_slot(self.now().unwrap().as_u64() + 1)
}
/// Returns the duration between UNIX epoch and the start of `slot`.
pub fn start_of(&self, slot: Slot) -> Option<Duration> {
let slot = slot
.as_u64()
.checked_sub(self.genesis_slot.as_u64())?
.try_into()
.ok()?;
let unadjusted_slot_duration = self.slot_duration.checked_mul(slot)?;
self.genesis_duration.checked_add(unadjusted_slot_duration)
}
/// Returns the duration from `now` until the start of `slot`.
///
/// Will return `None` if `now` is later than the start of `slot`.
pub fn duration_to_slot(&self, slot: Slot, now: Duration) -> Option<Duration> {
self.start_of(slot)?.checked_sub(now)
}
/// Returns the duration between `now` and the start of the next slot.
pub fn duration_to_next_slot_from(&self, now: Duration) -> Option<Duration> {
if now < self.genesis_duration {
self.genesis_duration.checked_sub(now)
} else {
self.duration_to_slot(self.slot_of(now)? + 1, now)
}
}
/// Returns the duration between `now` and the start of the next epoch.
pub fn duration_to_next_epoch_from(
&self,
now: Duration,
slots_per_epoch: u64,
) -> Option<Duration> {
if now < self.genesis_duration {
self.genesis_duration.checked_sub(now)
} else {
let next_epoch_start_slot =
(self.slot_of(now)?.epoch(slots_per_epoch) + 1).start_slot(slots_per_epoch);
self.duration_to_slot(next_epoch_start_slot, now)
}
}
}
impl SlotClock for ManualSlotClock {
fn new(genesis_slot: Slot, genesis_duration: Duration, slot_duration: Duration) -> Self {
if slot_duration.as_millis() == 0 {
panic!("ManualSlotClock cannot have a < 1ms slot duration");
}
Self {
genesis_slot,
current_time: RwLock::new(genesis_duration.clone()),
genesis_duration,
slot_duration,
}
}
fn now(&self) -> Option<Slot> {
self.slot_of(*self.current_time.read())
}
fn now_duration(&self) -> Option<Duration> {
Some(*self.current_time.read())
}
fn slot_of(&self, now: Duration) -> Option<Slot> {
let genesis = self.genesis_duration;
if now >= genesis {
let since_genesis = now
.checked_sub(genesis)
.expect("Control flow ensures now is greater than or equal to genesis");
let slot =
Slot::from((since_genesis.as_millis() / self.slot_duration.as_millis()) as u64);
Some(slot + self.genesis_slot)
} else {
None
}
}
fn duration_to_next_slot(&self) -> Option<Duration> {
self.duration_to_next_slot_from(*self.current_time.read())
}
fn duration_to_next_epoch(&self, slots_per_epoch: u64) -> Option<Duration> {
self.duration_to_next_epoch_from(*self.current_time.read(), slots_per_epoch)
}
fn slot_duration(&self) -> Duration {
self.slot_duration
}
fn genesis_slot(&self) -> Slot {
self.genesis_slot
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_slot_now() {
let clock = ManualSlotClock::new(
Slot::new(10),
Duration::from_secs(0),
Duration::from_secs(1),
);
assert_eq!(clock.now(), Some(Slot::new(10)));
clock.set_slot(123);
assert_eq!(clock.now(), Some(Slot::new(123)));
}
#[test]
fn start_of() {
// Genesis slot and genesis duration 0.
let clock =
ManualSlotClock::new(Slot::new(0), Duration::from_secs(0), Duration::from_secs(1));
assert_eq!(clock.start_of(Slot::new(0)), Some(Duration::from_secs(0)));
assert_eq!(clock.start_of(Slot::new(1)), Some(Duration::from_secs(1)));
assert_eq!(clock.start_of(Slot::new(2)), Some(Duration::from_secs(2)));
// Genesis slot 1 and genesis duration 10.
let clock = ManualSlotClock::new(
Slot::new(0),
Duration::from_secs(10),
Duration::from_secs(1),
);
assert_eq!(clock.start_of(Slot::new(0)), Some(Duration::from_secs(10)));
assert_eq!(clock.start_of(Slot::new(1)), Some(Duration::from_secs(11)));
assert_eq!(clock.start_of(Slot::new(2)), Some(Duration::from_secs(12)));
// Genesis slot 1 and genesis duration 0.
let clock =
ManualSlotClock::new(Slot::new(1), Duration::from_secs(0), Duration::from_secs(1));
assert_eq!(clock.start_of(Slot::new(0)), None);
assert_eq!(clock.start_of(Slot::new(1)), Some(Duration::from_secs(0)));
assert_eq!(clock.start_of(Slot::new(2)), Some(Duration::from_secs(1)));
// Genesis slot 1 and genesis duration 10.
let clock = ManualSlotClock::new(
Slot::new(1),
Duration::from_secs(10),
Duration::from_secs(1),
);
assert_eq!(clock.start_of(Slot::new(0)), None);
assert_eq!(clock.start_of(Slot::new(1)), Some(Duration::from_secs(10)));
assert_eq!(clock.start_of(Slot::new(2)), Some(Duration::from_secs(11)));
}
#[test]
fn test_duration_to_next_slot() {
let slot_duration = Duration::from_secs(1);
// Genesis time is now.
let clock = ManualSlotClock::new(Slot::new(0), Duration::from_secs(0), slot_duration);
*clock.current_time.write() = Duration::from_secs(0);
assert_eq!(clock.duration_to_next_slot(), Some(Duration::from_secs(1)));
// Genesis time is in the future.
let clock = ManualSlotClock::new(Slot::new(0), Duration::from_secs(10), slot_duration);
*clock.current_time.write() = Duration::from_secs(0);
assert_eq!(clock.duration_to_next_slot(), Some(Duration::from_secs(10)));
// Genesis time is in the past.
let clock = ManualSlotClock::new(Slot::new(0), Duration::from_secs(0), slot_duration);
*clock.current_time.write() = Duration::from_secs(10);
assert_eq!(clock.duration_to_next_slot(), Some(Duration::from_secs(1)));
}
#[test]
fn test_duration_to_next_epoch() {
let slot_duration = Duration::from_secs(1);
let slots_per_epoch = 32;
// Genesis time is now.
let clock = ManualSlotClock::new(Slot::new(0), Duration::from_secs(0), slot_duration);
*clock.current_time.write() = Duration::from_secs(0);
assert_eq!(
clock.duration_to_next_epoch(slots_per_epoch),
Some(Duration::from_secs(32))
);
// Genesis time is in the future.
let clock = ManualSlotClock::new(Slot::new(0), Duration::from_secs(10), slot_duration);
*clock.current_time.write() = Duration::from_secs(0);
assert_eq!(
clock.duration_to_next_epoch(slots_per_epoch),
Some(Duration::from_secs(10))
);
// Genesis time is in the past.
let clock = ManualSlotClock::new(Slot::new(0), Duration::from_secs(0), slot_duration);
*clock.current_time.write() = Duration::from_secs(10);
assert_eq!(
clock.duration_to_next_epoch(slots_per_epoch),
Some(Duration::from_secs(22))
);
// Genesis time is in the past.
let clock = ManualSlotClock::new(
Slot::new(0),
Duration::from_secs(0),
Duration::from_secs(12),
);
*clock.current_time.write() = Duration::from_secs(72_333);
assert!(clock.duration_to_next_epoch(slots_per_epoch).is_some(),);
}
#[test]
fn test_tolerance() {
let clock = ManualSlotClock::new(
Slot::new(0),
Duration::from_secs(10),
Duration::from_secs(1),
);
// Set clock to the 0'th slot.
*clock.current_time.write() = Duration::from_secs(10);
assert_eq!(
clock
.now_with_future_tolerance(Duration::from_secs(0))
.unwrap(),
Slot::new(0),
"future tolerance of zero should return current slot"
);
assert_eq!(
clock
.now_with_past_tolerance(Duration::from_secs(0))
.unwrap(),
Slot::new(0),
"past tolerance of zero should return current slot"
);
assert_eq!(
clock
.now_with_future_tolerance(Duration::from_millis(10))
.unwrap(),
Slot::new(0),
"insignificant future tolerance should return current slot"
);
assert_eq!(
clock
.now_with_past_tolerance(Duration::from_millis(10))
.unwrap(),
Slot::new(0),
"past tolerance that precedes genesis should return genesis slot"
);
// Set clock to part-way through the 1st slot.
*clock.current_time.write() = Duration::from_millis(11_200);
assert_eq!(
clock
.now_with_future_tolerance(Duration::from_secs(0))
.unwrap(),
Slot::new(1),
"future tolerance of zero should return current slot"
);
assert_eq!(
clock
.now_with_past_tolerance(Duration::from_secs(0))
.unwrap(),
Slot::new(1),
"past tolerance of zero should return current slot"
);
assert_eq!(
clock
.now_with_future_tolerance(Duration::from_millis(800))
.unwrap(),
Slot::new(2),
"significant future tolerance should return next slot"
);
assert_eq!(
clock
.now_with_past_tolerance(Duration::from_millis(201))
.unwrap(),
Slot::new(0),
"significant past tolerance should return previous slot"
);
}
}

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@ -1,4 +1,4 @@
use super::SlotClock;
use super::{ManualSlotClock, SlotClock};
use std::time::{Duration, SystemTime, UNIX_EPOCH};
use types::Slot;
@ -7,95 +7,45 @@ pub use std::time::SystemTimeError;
/// Determines the present slot based upon the present system time.
#[derive(Clone)]
pub struct SystemTimeSlotClock {
genesis_slot: Slot,
genesis_duration: Duration,
slot_duration: Duration,
clock: ManualSlotClock,
}
impl SlotClock for SystemTimeSlotClock {
fn new(genesis_slot: Slot, genesis_duration: Duration, slot_duration: Duration) -> Self {
if slot_duration.as_millis() == 0 {
panic!("SystemTimeSlotClock cannot have a < 1ms slot duration.");
}
Self {
genesis_slot,
genesis_duration,
slot_duration,
clock: ManualSlotClock::new(genesis_slot, genesis_duration, slot_duration),
}
}
fn now(&self) -> Option<Slot> {
let now = SystemTime::now().duration_since(UNIX_EPOCH).ok()?;
let genesis = self.genesis_duration;
self.clock.slot_of(now)
}
if now >= genesis {
let since_genesis = now
.checked_sub(genesis)
.expect("Control flow ensures now is greater than or equal to genesis");
let slot =
Slot::from((since_genesis.as_millis() / self.slot_duration.as_millis()) as u64);
Some(slot + self.genesis_slot)
} else {
None
}
fn now_duration(&self) -> Option<Duration> {
SystemTime::now().duration_since(UNIX_EPOCH).ok()
}
fn slot_of(&self, now: Duration) -> Option<Slot> {
self.clock.slot_of(now)
}
fn duration_to_next_slot(&self) -> Option<Duration> {
let now = SystemTime::now().duration_since(UNIX_EPOCH).ok()?;
let genesis = self.genesis_duration;
let slot_start = |slot: Slot| -> Duration {
let slot = slot.as_u64() as u32;
genesis + slot * self.slot_duration
};
if now >= genesis {
Some(
slot_start(self.now()? + 1)
.checked_sub(now)
.expect("The next slot cannot start before now"),
)
} else {
Some(
genesis
.checked_sub(now)
.expect("Control flow ensures genesis is greater than or equal to now"),
)
}
self.clock.duration_to_next_slot_from(now)
}
fn duration_to_next_epoch(&self, slots_per_epoch: u64) -> Option<Duration> {
let now = SystemTime::now().duration_since(UNIX_EPOCH).ok()?;
let genesis = self.genesis_duration;
let slot_start = |slot: Slot| -> Duration {
let slot = slot.as_u64() as u32;
genesis + slot * self.slot_duration
};
let epoch_start_slot = self
.now()
.map(|slot| slot.epoch(slots_per_epoch))
.map(|epoch| (epoch + 1).start_slot(slots_per_epoch))?;
if now >= genesis {
Some(
slot_start(epoch_start_slot)
.checked_sub(now)
.expect("The next epoch cannot start before now"),
)
} else {
Some(
genesis
.checked_sub(now)
.expect("Control flow ensures genesis is greater than or equal to now"),
)
}
self.clock.duration_to_next_epoch_from(now, slots_per_epoch)
}
fn slot_duration(&self) -> Duration {
self.slot_duration
self.clock.slot_duration()
}
fn genesis_slot(&self) -> Slot {
self.clock.genesis_slot()
}
}