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Merge pull request #5 from asynchronics/feature/better-event-cancellation

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Feature/better event cancellation
This commit is contained in:
Serge Barral 2023-07-21 14:52:21 +02:00 committed by GitHub
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11 changed files with 626 additions and 807 deletions
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13
README.md
View File

@ -88,7 +88,7 @@ pub struct DelayedMultiplier {
impl DelayedMultiplier { impl DelayedMultiplier {
pub fn input(&mut self, value: f64, scheduler: &Scheduler<Self>) { pub fn input(&mut self, value: f64, scheduler: &Scheduler<Self>) {
scheduler scheduler
.schedule_in(Duration::from_secs(1), Self::send, 2.0 * value) .schedule_event_in(Duration::from_secs(1), Self::send, 2.0 * value)
.unwrap(); .unwrap();
} }
async fn send(&mut self, value: f64) { async fn send(&mut self, value: f64) {
@ -157,11 +157,12 @@ the posted events. For these reasons, Asynchronix relies on a fully custom
runtime. runtime.
Even though the runtime was largely influenced by Tokio, it features additional Even though the runtime was largely influenced by Tokio, it features additional
optimization that make its faster than any other multi-threaded Rust executor on optimizations that make its faster than any other multi-threaded Rust executor
the typically message-passing-heavy workloads seen in discrete-event simulation on the typically message-passing-heavy workloads seen in discrete-event
(see [benchmark]). Asynchronix also improves over the state of the art with a simulation (see [benchmark]). Asynchronix also improves over the state of the
very fast custom MPSC channel, which performance has been demonstrated through art with a very fast custom MPSC channel, which performance has been
[Tachyonix][tachyonix], a general-purpose offshoot of this channel. demonstrated through [Tachyonix][tachyonix], a general-purpose offshoot of this
channel.
[actor_model]: https://en.wikipedia.org/wiki/Actor_model [actor_model]: https://en.wikipedia.org/wiki/Actor_model

1
asynchronix/Cargo.toml
View File

@ -31,6 +31,7 @@ diatomic-waker = "0.1"
futures-task = "0.3" futures-task = "0.3"
multishot = "0.3" multishot = "0.3"
num_cpus = "1.13" num_cpus = "1.13"
pin-project-lite = "0.2"
recycle-box = "0.2" recycle-box = "0.2"
slab = "0.4" slab = "0.4"
st3 = "0.4" st3 = "0.4"

70
asynchronix/examples/espresso_machine.rs
View File

@ -3,7 +3,7 @@
//! This example demonstrates in particular: //! This example demonstrates in particular:
//! //!
//! * non-trivial state machines, //! * non-trivial state machines,
//! * cancellation of calls scheduled at the current time step using epochs, //! * cancellation of events,
//! * model initialization, //! * model initialization,
//! * simulation monitoring with event slots. //! * simulation monitoring with event slots.
//! //!
@ -37,7 +37,7 @@ use std::time::Duration;
use asynchronix::model::{InitializedModel, Model, Output}; use asynchronix::model::{InitializedModel, Model, Output};
use asynchronix::simulation::{Mailbox, SimInit}; use asynchronix::simulation::{Mailbox, SimInit};
use asynchronix::time::{MonotonicTime, Scheduler, SchedulerKey}; use asynchronix::time::{EventKey, MonotonicTime, Scheduler};
/// Water pump. /// Water pump.
pub struct Pump { pub struct Pump {
@ -79,12 +79,9 @@ pub struct Controller {
brew_time: Duration, brew_time: Duration,
/// Current water sense state. /// Current water sense state.
water_sense: WaterSenseState, water_sense: WaterSenseState,
/// Scheduler key, which if present indicates that the machine is current /// Event key, which if present indicates that the machine is currently
/// brewing -- internal state. /// brewing -- internal state.
stop_brew_key: Option<SchedulerKey>, stop_brew_key: Option<EventKey>,
/// An epoch incremented when the scheduled 'stop_brew` callback must be
/// ignored -- internal state.
stop_brew_epoch: u64,
} }
impl Controller { impl Controller {
@ -98,22 +95,16 @@ impl Controller {
pump_cmd: Output::default(), pump_cmd: Output::default(),
stop_brew_key: None, stop_brew_key: None,
water_sense: WaterSenseState::Empty, // will be overridden during init water_sense: WaterSenseState::Empty, // will be overridden during init
stop_brew_epoch: 0,
} }
} }
/// Signals a change in the water sensing state -- input port. /// Signals a change in the water sensing state -- input port.
pub async fn water_sense(&mut self, state: WaterSenseState, scheduler: &Scheduler<Self>) { pub async fn water_sense(&mut self, state: WaterSenseState) {
// Check if the tank just got empty. // Check if the tank just got empty.
if state == WaterSenseState::Empty && self.water_sense == WaterSenseState::NotEmpty { if state == WaterSenseState::Empty && self.water_sense == WaterSenseState::NotEmpty {
// If a brew was ongoing, we must cancel it. // If a brew was ongoing, we must cancel it.
if let Some(key) = self.stop_brew_key.take() { if let Some(key) = self.stop_brew_key.take() {
// Try to abort the scheduled call to `stop_brew()`. If this will key.cancel_event();
// fails, increment the epoch so that the call is ignored.
if scheduler.cancel(key).is_err() {
self.stop_brew_epoch = self.stop_brew_epoch.wrapping_add(1);
};
self.pump_cmd.send(PumpCommand::Off).await; self.pump_cmd.send(PumpCommand::Off).await;
} }
} }
@ -136,11 +127,8 @@ impl Controller {
if let Some(key) = self.stop_brew_key.take() { if let Some(key) = self.stop_brew_key.take() {
self.pump_cmd.send(PumpCommand::Off).await; self.pump_cmd.send(PumpCommand::Off).await;
// Try to abort the scheduled call to `stop_brew()`. If this will // Abort the scheduled call to `stop_brew()`.
// fails, increment the epoch so that the call is ignored. key.cancel_event();
if scheduler.cancel(key).is_err() {
self.stop_brew_epoch = self.stop_brew_epoch.wrapping_add(1);
};
return; return;
} }
@ -153,19 +141,14 @@ impl Controller {
// Schedule the `stop_brew()` method and turn on the pump. // Schedule the `stop_brew()` method and turn on the pump.
self.stop_brew_key = Some( self.stop_brew_key = Some(
scheduler scheduler
.schedule_in(self.brew_time, Self::stop_brew, self.stop_brew_epoch) .schedule_keyed_event_in(self.brew_time, Self::stop_brew, ())
.unwrap(), .unwrap(),
); );
self.pump_cmd.send(PumpCommand::On).await; self.pump_cmd.send(PumpCommand::On).await;
} }
/// Stops brewing. /// Stops brewing.
async fn stop_brew(&mut self, epoch: u64) { async fn stop_brew(&mut self) {
// Ignore this call if the epoch has been incremented.
if self.stop_brew_epoch != epoch {
return;
}
if self.stop_brew_key.take().is_some() { if self.stop_brew_key.take().is_some() {
self.pump_cmd.send(PumpCommand::Off).await; self.pump_cmd.send(PumpCommand::Off).await;
} }
@ -190,9 +173,6 @@ pub struct Tank {
volume: f64, volume: f64,
/// State that exists when the mass flow rate is non-zero -- internal state. /// State that exists when the mass flow rate is non-zero -- internal state.
dynamic_state: Option<TankDynamicState>, dynamic_state: Option<TankDynamicState>,
/// An epoch incremented when the pending call to `set_empty()` must be
/// ignored -- internal state.
set_empty_epoch: u64,
} }
impl Tank { impl Tank {
/// Creates a new tank with the specified amount of water [m³]. /// Creates a new tank with the specified amount of water [m³].
@ -204,7 +184,6 @@ impl Tank {
Self { Self {
volume: water_volume, volume: water_volume,
dynamic_state: None, dynamic_state: None,
set_empty_epoch: 0,
water_sense: Output::default(), water_sense: Output::default(),
} }
} }
@ -224,11 +203,8 @@ impl Tank {
// If the current flow rate is non-zero, compute the current volume and // If the current flow rate is non-zero, compute the current volume and
// schedule a new update. // schedule a new update.
if let Some(state) = self.dynamic_state.take() { if let Some(state) = self.dynamic_state.take() {
// Try to abort the scheduled call to `set_empty()`. If this will // Abort the scheduled call to `set_empty()`.
// fails, increment the epoch so that the call is ignored. state.set_empty_key.cancel_event();
if scheduler.cancel(state.set_empty_key).is_err() {
self.set_empty_epoch = self.set_empty_epoch.wrapping_add(1);
}
// Update the volume, saturating at 0 in case of rounding errors. // Update the volume, saturating at 0 in case of rounding errors.
let time = scheduler.time(); let time = scheduler.time();
@ -260,11 +236,8 @@ impl Tank {
// If the flow rate was non-zero up to now, update the volume. // If the flow rate was non-zero up to now, update the volume.
if let Some(state) = self.dynamic_state.take() { if let Some(state) = self.dynamic_state.take() {
// Try to abort the scheduled call to `set_empty()`. If this will // Abort the scheduled call to `set_empty()`.
// fails, increment the epoch so that the call is ignored. state.set_empty_key.cancel_event();
if scheduler.cancel(state.set_empty_key).is_err() {
self.set_empty_epoch = self.set_empty_epoch.wrapping_add(1);
}
// Update the volume, saturating at 0 in case of rounding errors. // Update the volume, saturating at 0 in case of rounding errors.
let elapsed_time = time.duration_since(state.last_volume_update).as_secs_f64(); let elapsed_time = time.duration_since(state.last_volume_update).as_secs_f64();
@ -301,7 +274,7 @@ impl Tank {
let duration_until_empty = Duration::from_secs_f64(duration_until_empty); let duration_until_empty = Duration::from_secs_f64(duration_until_empty);
// Schedule the next update. // Schedule the next update.
match scheduler.schedule_in(duration_until_empty, Self::set_empty, self.set_empty_epoch) { match scheduler.schedule_keyed_event_in(duration_until_empty, Self::set_empty, ()) {
Ok(set_empty_key) => { Ok(set_empty_key) => {
let state = TankDynamicState { let state = TankDynamicState {
last_volume_update: time, last_volume_update: time,
@ -319,12 +292,7 @@ impl Tank {
} }
/// Updates the state of the tank to indicate that there is no more water. /// Updates the state of the tank to indicate that there is no more water.
async fn set_empty(&mut self, epoch: u64) { async fn set_empty(&mut self) {
// Ignore this call if the epoch has been incremented.
if epoch != self.set_empty_epoch {
return;
}
self.volume = 0.0; self.volume = 0.0;
self.dynamic_state = None; self.dynamic_state = None;
self.water_sense.send(WaterSenseState::Empty).await; self.water_sense.send(WaterSenseState::Empty).await;
@ -355,7 +323,7 @@ impl Model for Tank {
/// is non-zero. /// is non-zero.
struct TankDynamicState { struct TankDynamicState {
last_volume_update: MonotonicTime, last_volume_update: MonotonicTime,
set_empty_key: SchedulerKey, set_empty_key: EventKey,
flow_rate: f64, flow_rate: f64,
} }
@ -429,7 +397,7 @@ fn main() {
// Drink too much coffee. // Drink too much coffee.
let volume_per_shot = pump_flow_rate * Controller::DEFAULT_BREW_TIME.as_secs_f64(); let volume_per_shot = pump_flow_rate * Controller::DEFAULT_BREW_TIME.as_secs_f64();
let shots_per_tank = (init_tank_volume / volume_per_shot) as u64; // YOLO--who care about floating-point rounding errors? let shots_per_tank = (init_tank_volume / volume_per_shot) as u64; // YOLO--who cares about floating-point rounding errors?
for _ in 0..(shots_per_tank - 1) { for _ in 0..(shots_per_tank - 1) {
simu.send_event(Controller::brew_cmd, (), &controller_addr); simu.send_event(Controller::brew_cmd, (), &controller_addr);
assert_eq!(flow_rate.take(), Some(pump_flow_rate)); assert_eq!(flow_rate.take(), Some(pump_flow_rate));
@ -463,7 +431,7 @@ fn main() {
assert_eq!(flow_rate.take(), Some(0.0)); assert_eq!(flow_rate.take(), Some(0.0));
// Interrupt the brew after 15s by pressing again the brew button. // Interrupt the brew after 15s by pressing again the brew button.
simu.schedule_in( simu.schedule_event_in(
Duration::from_secs(15), Duration::from_secs(15),
Controller::brew_cmd, Controller::brew_cmd,
(), (),

4
asynchronix/examples/stepper_motor.rs
View File

@ -174,7 +174,7 @@ impl Driver {
// Schedule the next pulse. // Schedule the next pulse.
scheduler scheduler
.schedule_in(pulse_duration, Self::send_pulse, ()) .schedule_event_in(pulse_duration, Self::send_pulse, ())
.unwrap(); .unwrap();
} }
} }
@ -224,7 +224,7 @@ fn main() {
assert!(position.next().is_none()); assert!(position.next().is_none());
// Start the motor in 2s with a PPS of 10Hz. // Start the motor in 2s with a PPS of 10Hz.
simu.schedule_in( simu.schedule_event_in(
Duration::from_secs(2), Duration::from_secs(2),
Driver::pulse_rate, Driver::pulse_rate,
10.0, 10.0,

2
asynchronix/src/channel/queue.rs
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@ -79,7 +79,7 @@ enum MessageBox<T: ?Sized> {
None, None,
} }
/// A queue slot that a stamp and either a boxed messaged or an empty box. /// A queue slot with a stamp and either a boxed messaged or an empty box.
struct Slot<T: ?Sized> { struct Slot<T: ?Sized> {
stamp: AtomicUsize, stamp: AtomicUsize,
message: UnsafeCell<MessageBox<T>>, message: UnsafeCell<MessageBox<T>>,

19
asynchronix/src/lib.rs
View File

@ -113,7 +113,7 @@
//! } //! }
//! impl Delay { //! impl Delay {
//! pub fn input(&mut self, value: f64, scheduler: &Scheduler<Self>) { //! pub fn input(&mut self, value: f64, scheduler: &Scheduler<Self>) {
//! scheduler.schedule_in(Duration::from_secs(1), Self::send, value).unwrap(); //! scheduler.schedule_event_in(Duration::from_secs(1), Self::send, value).unwrap();
//! } //! }
//! //!
//! async fn send(&mut self, value: f64) { //! async fn send(&mut self, value: f64) {
@ -184,7 +184,7 @@
//! # } //! # }
//! # impl Delay { //! # impl Delay {
//! # pub fn input(&mut self, value: f64, scheduler: &Scheduler<Self>) { //! # pub fn input(&mut self, value: f64, scheduler: &Scheduler<Self>) {
//! # scheduler.schedule_in(Duration::from_secs(1), Self::send, value).unwrap(); //! # scheduler.schedule_event_in(Duration::from_secs(1), Self::send, value).unwrap();
//! # } //! # }
//! # async fn send(&mut self, value: f64) { // this method can be private //! # async fn send(&mut self, value: f64) { // this method can be private
//! # self.output.send(value).await; //! # self.output.send(value).await;
@ -242,7 +242,7 @@
//! [`Simulation::send_event()`](simulation::Simulation::send_event) or //! [`Simulation::send_event()`](simulation::Simulation::send_event) or
//! [`Simulation::send_query()`](simulation::Simulation::send_query), //! [`Simulation::send_query()`](simulation::Simulation::send_query),
//! 3. by scheduling events, using for instance //! 3. by scheduling events, using for instance
//! [`Simulation::schedule_in()`](simulation::Simulation::schedule_in). //! [`Simulation::schedule_event_in()`](simulation::Simulation::schedule_event_in).
//! //!
//! Simulation outputs can be monitored using //! Simulation outputs can be monitored using
//! [`EventSlot`](simulation::EventSlot)s and //! [`EventSlot`](simulation::EventSlot)s and
@ -275,7 +275,7 @@
//! # } //! # }
//! # impl Delay { //! # impl Delay {
//! # pub fn input(&mut self, value: f64, scheduler: &Scheduler<Self>) { //! # pub fn input(&mut self, value: f64, scheduler: &Scheduler<Self>) {
//! # scheduler.schedule_in(Duration::from_secs(1), Self::send, value).unwrap(); //! # scheduler.schedule_event_in(Duration::from_secs(1), Self::send, value).unwrap();
//! # } //! # }
//! # async fn send(&mut self, value: f64) { // this method can be private //! # async fn send(&mut self, value: f64) { // this method can be private
//! # self.output.send(value).await; //! # self.output.send(value).await;
@ -354,11 +354,12 @@
//! //!
//! The first guarantee (and only the first) also extends to events scheduled //! The first guarantee (and only the first) also extends to events scheduled
//! from a simulation with //! from a simulation with
//! [`Simulation::schedule_in()`](simulation::Simulation::schedule_in) or //! [`Simulation::schedule_event_in()`](simulation::Simulation::schedule_event_in)
//! [`Simulation::schedule_at()`](simulation::Simulation::schedule_at): if the //! or
//! scheduler contains several events to be delivered at the same time to the //! [`Simulation::schedule_event_at()`](simulation::Simulation::schedule_event_at):
//! same model, these events will always be processed in the order in which they //! if the scheduler contains several events to be delivered at the same time to
//! were scheduled. //! the same model, these events will always be processed in the order in which
//! they were scheduled.
//! //!
//! [actor_model]: https://en.wikipedia.org/wiki/Actor_model //! [actor_model]: https://en.wikipedia.org/wiki/Actor_model
//! [pony]: https://www.ponylang.io/ //! [pony]: https://www.ponylang.io/

199
asynchronix/src/simulation.rs
View File

@ -73,7 +73,7 @@
//! //!
//! At the moment, Asynchronix is unfortunately not able to discriminate between //! At the moment, Asynchronix is unfortunately not able to discriminate between
//! such pathological deadlocks and the "expected" deadlock that occurs when all //! such pathological deadlocks and the "expected" deadlock that occurs when all
//! tasks in a given time slice have completed and all models are starved on an //! events in a given time slice have completed and all models are starved on an
//! empty mailbox. Consequently, blocking method such as [`SimInit::init()`], //! empty mailbox. Consequently, blocking method such as [`SimInit::init()`],
//! [`Simulation::step()`], [`Simulation::send_event()`], etc., will return //! [`Simulation::step()`], [`Simulation::send_event()`], etc., will return
//! without error after a pathological deadlock, leaving the user responsible //! without error after a pathological deadlock, leaving the user responsible
@ -91,8 +91,8 @@
//! There is actually a very simple solution to this problem: since the //! There is actually a very simple solution to this problem: since the
//! [`InputFn`](crate::model::InputFn) trait also matches closures of type //! [`InputFn`](crate::model::InputFn) trait also matches closures of type
//! `FnOnce(&mut impl Model)`, it is enough to invoke //! `FnOnce(&mut impl Model)`, it is enough to invoke
//! [`Simulation::send_event()`] with a closure that connects or disconnects //! [`Simulation::send_event()`] with a closure that connects or disconnects a
//! a port, such as: //! port, such as:
//! //!
//! ``` //! ```
//! # use asynchronix::model::{Model, Output}; //! # use asynchronix::model::{Model, Output};
@ -129,15 +129,15 @@ pub use sim_init::SimInit;
use std::error::Error; use std::error::Error;
use std::fmt; use std::fmt;
use std::future::Future; use std::future::Future;
use std::sync::{Arc, Mutex}; use std::sync::{Arc, Mutex, MutexGuard};
use std::time::Duration; use std::time::Duration;
use recycle_box::{coerce_box, RecycleBox}; use recycle_box::{coerce_box, RecycleBox};
use crate::executor::Executor; use crate::executor::Executor;
use crate::model::{InputFn, Model, ReplierFn}; use crate::model::{InputFn, Model, ReplierFn};
use crate::time::{self, CancellationError, MonotonicTime, TearableAtomicTime}; use crate::time::{self, MonotonicTime, TearableAtomicTime};
use crate::time::{ScheduledTimeError, SchedulerKey, SchedulerQueue}; use crate::time::{EventKey, ScheduledTimeError, SchedulerQueue};
use crate::util::futures::SeqFuture; use crate::util::futures::SeqFuture;
use crate::util::slot; use crate::util::slot;
use crate::util::sync_cell::SyncCell; use crate::util::sync_cell::SyncCell;
@ -164,9 +164,9 @@ use crate::util::sync_cell::SyncCell;
/// the case of queries, the response is returned. /// the case of queries, the response is returned.
/// ///
/// Events can also be scheduled at a future simulation time using /// Events can also be scheduled at a future simulation time using
/// [`schedule_in()`](Simulation::schedule_in) or /// [`schedule_event_in()`](Simulation::schedule_event_in) or
/// [`schedule_at()`](Simulation::schedule_at). These methods queue an event /// [`schedule_event_at()`](Simulation::schedule_event_at). These methods queue
/// without blocking. /// an event without blocking.
/// ///
/// Finally, the [`Simulation`] instance manages simulation time. Calling /// Finally, the [`Simulation`] instance manages simulation time. Calling
/// [`step()`](Simulation::step) will increment simulation time until that of /// [`step()`](Simulation::step) will increment simulation time until that of
@ -201,20 +201,20 @@ impl Simulation {
self.time.read() self.time.read()
} }
/// Advances simulation time to that of the next scheduled task, processing /// Advances simulation time to that of the next scheduled event, processing
/// that task as well as all other tasks scheduled for the same time. /// that event as well as all other event scheduled for the same time.
/// ///
/// This method may block. Once it returns, it is guaranteed that all newly /// This method may block. Once it returns, it is guaranteed that all newly
/// processed tasks (if any) have completed. /// processed event (if any) have completed.
pub fn step(&mut self) { pub fn step(&mut self) {
self.step_to_next_bounded(MonotonicTime::MAX); self.step_to_next_bounded(MonotonicTime::MAX);
} }
/// Iteratively advances the simulation time by the specified duration and /// Iteratively advances the simulation time by the specified duration and
/// processes all tasks scheduled up to the target time. /// processes all events scheduled up to the target time.
/// ///
/// This method may block. Once it returns, it is guaranteed that (i) all /// This method may block. Once it returns, it is guaranteed that (i) all
/// tasks scheduled up to the specified target time have completed and (ii) /// events scheduled up to the specified target time have completed and (ii)
/// the final simulation time has been incremented by the specified /// the final simulation time has been incremented by the specified
/// duration. /// duration.
pub fn step_by(&mut self, duration: Duration) { pub fn step_by(&mut self, duration: Duration) {
@ -223,11 +223,11 @@ impl Simulation {
self.step_until_unchecked(target_time); self.step_until_unchecked(target_time);
} }
/// Iteratively advances the simulation time and processes all tasks /// Iteratively advances the simulation time and processes all events
/// scheduled up to the specified target time. /// scheduled up to the specified target time.
/// ///
/// This method may block. Once it returns, it is guaranteed that (i) all /// This method may block. Once it returns, it is guaranteed that (i) all
/// tasks scheduled up to the specified target time have completed and (ii) /// events scheduled up to the specified target time have completed and (ii)
/// the final simulation time matches the target time. /// the final simulation time matches the target time.
pub fn step_until(&mut self, target_time: MonotonicTime) -> Result<(), ScheduledTimeError<()>> { pub fn step_until(&mut self, target_time: MonotonicTime) -> Result<(), ScheduledTimeError<()>> {
if self.time.read() >= target_time { if self.time.read() >= target_time {
@ -244,13 +244,13 @@ impl Simulation {
/// ///
/// Events scheduled for the same time and targeting the same model are /// Events scheduled for the same time and targeting the same model are
/// guaranteed to be processed according to the scheduling order. /// guaranteed to be processed according to the scheduling order.
pub fn schedule_in<M, F, T, S>( pub fn schedule_event_in<M, F, T, S>(
&mut self, &mut self,
duration: Duration, duration: Duration,
func: F, func: F,
arg: T, arg: T,
address: impl Into<Address<M>>, address: impl Into<Address<M>>,
) -> Result<SchedulerKey, ScheduledTimeError<T>> ) -> Result<(), ScheduledTimeError<T>>
where where
M: Model, M: Model,
F: for<'a> InputFn<'a, M, T, S>, F: for<'a> InputFn<'a, M, T, S>,
@ -261,7 +261,36 @@ impl Simulation {
} }
let time = self.time.read() + duration; let time = self.time.read() + duration;
let schedule_key = time::schedule_event_at_unchecked( time::schedule_event_at_unchecked(time, func, arg, address.into().0, &self.scheduler_queue);
Ok(())
}
/// Schedules an event at the lapse of the specified duration and returns an
/// event key.
///
/// An error is returned if the specified duration is null.
///
/// Events scheduled for the same time and targeting the same model are
/// guaranteed to be processed according to the scheduling order.
pub fn schedule_keyed_event_in<M, F, T, S>(
&mut self,
duration: Duration,
func: F,
arg: T,
address: impl Into<Address<M>>,
) -> Result<EventKey, ScheduledTimeError<T>>
where
M: Model,
F: for<'a> InputFn<'a, M, T, S>,
T: Send + Clone + 'static,
{
if duration.is_zero() {
return Err(ScheduledTimeError(arg));
}
let time = self.time.read() + duration;
let event_key = time::schedule_keyed_event_at_unchecked(
time, time,
func, func,
arg, arg,
@ -269,7 +298,7 @@ impl Simulation {
&self.scheduler_queue, &self.scheduler_queue,
); );
Ok(schedule_key) Ok(event_key)
} }
/// Schedules an event at a future time. /// Schedules an event at a future time.
@ -279,13 +308,13 @@ impl Simulation {
/// ///
/// Events scheduled for the same time and targeting the same model are /// Events scheduled for the same time and targeting the same model are
/// guaranteed to be processed according to the scheduling order. /// guaranteed to be processed according to the scheduling order.
pub fn schedule_at<M, F, T, S>( pub fn schedule_event_at<M, F, T, S>(
&mut self, &mut self,
time: MonotonicTime, time: MonotonicTime,
func: F, func: F,
arg: T, arg: T,
address: impl Into<Address<M>>, address: impl Into<Address<M>>,
) -> Result<SchedulerKey, ScheduledTimeError<T>> ) -> Result<(), ScheduledTimeError<T>>
where where
M: Model, M: Model,
F: for<'a> InputFn<'a, M, T, S>, F: for<'a> InputFn<'a, M, T, S>,
@ -294,7 +323,34 @@ impl Simulation {
if self.time.read() >= time { if self.time.read() >= time {
return Err(ScheduledTimeError(arg)); return Err(ScheduledTimeError(arg));
} }
let schedule_key = time::schedule_event_at_unchecked( time::schedule_event_at_unchecked(time, func, arg, address.into().0, &self.scheduler_queue);
Ok(())
}
/// Schedules an event at a future time and returns an event key.
///
/// An error is returned if the specified time is not in the future of the
/// current simulation time.
///
/// Events scheduled for the same time and targeting the same model are
/// guaranteed to be processed according to the scheduling order.
pub fn schedule_keyed_event_at<M, F, T, S>(
&mut self,
time: MonotonicTime,
func: F,
arg: T,
address: impl Into<Address<M>>,
) -> Result<EventKey, ScheduledTimeError<T>>
where
M: Model,
F: for<'a> InputFn<'a, M, T, S>,
T: Send + Clone + 'static,
{
if self.time.read() >= time {
return Err(ScheduledTimeError(arg));
}
let event_key = time::schedule_keyed_event_at_unchecked(
time, time,
func, func,
arg, arg,
@ -302,16 +358,7 @@ impl Simulation {
&self.scheduler_queue, &self.scheduler_queue,
); );
Ok(schedule_key) Ok(event_key)
}
/// Cancels an event with a scheduled time in the future of the current
/// simulation time.
///
/// If the corresponding event was already executed, or if it is scheduled
/// for the current simulation time, an error is returned.
pub fn cancel(&self, scheduler_key: SchedulerKey) -> Result<(), CancellationError> {
time::cancel_scheduled(scheduler_key, &self.scheduler_queue)
} }
/// Sends and processes an event, blocking until completion. /// Sends and processes an event, blocking until completion.
@ -387,72 +434,84 @@ impl Simulation {
reply_reader.try_read().map_err(|_| QueryError {}) reply_reader.try_read().map_err(|_| QueryError {})
} }
/// Advances simulation time to that of the next scheduled task if its /// Advances simulation time to that of the next scheduled event if its
/// scheduling time does not exceed the specified bound, processing that /// scheduling time does not exceed the specified bound, processing that
/// task as well as all other tasks scheduled for the same time. /// event as well as all other events scheduled for the same time.
/// ///
/// If at least one task was found that satisfied the time bound, the /// If at least one event was found that satisfied the time bound, the
/// corresponding new simulation time is returned. /// corresponding new simulation time is returned.
fn step_to_next_bounded(&mut self, upper_time_bound: MonotonicTime) -> Option<MonotonicTime> { fn step_to_next_bounded(&mut self, upper_time_bound: MonotonicTime) -> Option<MonotonicTime> {
let mut scheduler_queue = self.scheduler_queue.lock().unwrap(); // Closure returning the next key which time stamp is no older than the
// upper bound, if any. Cancelled events are discarded.
let mut current_key = match scheduler_queue.peek_key() { let get_next_key = |scheduler_queue: &mut MutexGuard<SchedulerQueue>| {
Some(&k) if k.0 <= upper_time_bound => k, loop {
_ => return None, match scheduler_queue.peek() {
Some((&k, t)) if k.0 <= upper_time_bound => {
if !t.is_cancelled() {
break Some(k);
}
// Discard cancelled events.
scheduler_queue.pull();
}
_ => break None,
}
}
}; };
// Set the simulation time to that of the next scheduled task // Move to the next scheduled time.
let mut scheduler_queue = self.scheduler_queue.lock().unwrap();
let mut current_key = get_next_key(&mut scheduler_queue)?;
self.time.write(current_key.0); self.time.write(current_key.0);
loop { loop {
let task = scheduler_queue.pull().unwrap().1; let event = scheduler_queue.pull().unwrap().1;
let mut next_key = scheduler_queue.peek_key(); let mut next_key = get_next_key(&mut scheduler_queue);
if next_key != Some(&current_key) { if next_key != Some(current_key) {
// Since there are no other tasks targeting the same mailbox // Since there are no other events targeting the same mailbox
// and the same time, the task is spawned immediately. // and the same time, the event is spawned immediately.
self.executor.spawn_and_forget(Box::into_pin(task)); self.executor.spawn_and_forget(Box::into_pin(event));
} else { } else {
// To ensure that their relative order of execution is // To ensure that their relative order of execution is
// preserved, all tasks targeting the same mailbox are // preserved, all event targeting the same mailbox are executed
// concatenated into a single future. // sequentially within a single compound future.
let mut task_sequence = SeqFuture::new(); let mut event_sequence = SeqFuture::new();
task_sequence.push(Box::into_pin(task)); event_sequence.push(Box::into_pin(event));
loop { loop {
let task = scheduler_queue.pull().unwrap().1; let event = scheduler_queue.pull().unwrap().1;
task_sequence.push(Box::into_pin(task)); event_sequence.push(Box::into_pin(event));
next_key = scheduler_queue.peek_key(); next_key = get_next_key(&mut scheduler_queue);
if next_key != Some(&current_key) { if next_key != Some(current_key) {
break; break;
} }
} }
// Spawn a parent task that sequentially polls all sub-tasks. // Spawn a parent event that sequentially polls all events
self.executor.spawn_and_forget(task_sequence); // targeting the same mailbox.
self.executor.spawn_and_forget(event_sequence);
} }
match next_key { current_key = match next_key {
// If the next task is scheduled at the same time, update the key and continue. // If the next event is scheduled at the same time, update the
Some(k) if k.0 == current_key.0 => { // key and continue.
current_key = *k; Some(k) if k.0 == current_key.0 => k,
} // Otherwise wait until all events have completed and return.
// Otherwise wait until all tasks have completed and return.
_ => { _ => {
drop(scheduler_queue); // make sure the queue's mutex is unlocked. drop(scheduler_queue); // make sure the queue's mutex is released.
self.executor.run(); self.executor.run();
return Some(current_key.0); return Some(current_key.0);
} }
} };
} }
} }
/// Iteratively advances simulation time and processes all tasks scheduled /// Iteratively advances simulation time and processes all events scheduled
/// up to the specified target time. /// up to the specified target time.
/// ///
/// Once the method returns it is guaranteed that (i) all tasks scheduled up /// Once the method returns it is guaranteed that (i) all events scheduled
/// to the specified target time have completed and (ii) the final /// up to the specified target time have completed and (ii) the final
/// simulation time matches the target time. /// simulation time matches the target time.
/// ///
/// This method does not check whether the specified time lies in the future /// This method does not check whether the specified time lies in the future
@ -462,7 +521,7 @@ impl Simulation {
match self.step_to_next_bounded(target_time) { match self.step_to_next_bounded(target_time) {
// The target time was reached exactly. // The target time was reached exactly.
Some(t) if t == target_time => return, Some(t) if t == target_time => return,
// No tasks are scheduled before or at the target time. // No events are scheduled before or at the target time.
None => { None => {
// Update the simulation time. // Update the simulation time.
self.time.write(target_time); self.time.write(target_time);

8
asynchronix/src/time.rs
View File

@ -31,7 +31,7 @@
//! //!
//! // Sets an alarm [input port]. //! // Sets an alarm [input port].
//! pub fn set(&mut self, setting: MonotonicTime, scheduler: &Scheduler<Self>) { //! pub fn set(&mut self, setting: MonotonicTime, scheduler: &Scheduler<Self>) {
//! if scheduler.schedule_at(setting, Self::ring, ()).is_err() { //! if scheduler.schedule_event_at(setting, Self::ring, ()).is_err() {
//! println!("The alarm clock can only be set for a future time"); //! println!("The alarm clock can only be set for a future time");
//! } //! }
//! } //! }
@ -50,5 +50,7 @@ mod scheduler;
pub(crate) use monotonic_time::TearableAtomicTime; pub(crate) use monotonic_time::TearableAtomicTime;
pub use monotonic_time::{MonotonicTime, SystemTimeError}; pub use monotonic_time::{MonotonicTime, SystemTimeError};
pub(crate) use scheduler::{cancel_scheduled, schedule_event_at_unchecked, SchedulerQueue}; pub(crate) use scheduler::{
pub use scheduler::{CancellationError, ScheduledTimeError, Scheduler, SchedulerKey}; schedule_event_at_unchecked, schedule_keyed_event_at_unchecked, SchedulerQueue,
};
pub use scheduler::{EventKey, ScheduledTimeError, Scheduler};

393
asynchronix/src/time/scheduler.rs
View File

@ -3,20 +3,23 @@
use std::error::Error; use std::error::Error;
use std::fmt; use std::fmt;
use std::future::Future; use std::future::Future;
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::{Arc, Mutex}; use std::sync::{Arc, Mutex};
use std::task::{Context, Poll};
use std::time::Duration; use std::time::Duration;
use pin_project_lite::pin_project;
use recycle_box::{coerce_box, RecycleBox}; use recycle_box::{coerce_box, RecycleBox};
use crate::channel::{ChannelId, Sender}; use crate::channel::{ChannelId, Sender};
use crate::model::{InputFn, Model}; use crate::model::{InputFn, Model};
use crate::time::{MonotonicTime, TearableAtomicTime}; use crate::time::{MonotonicTime, TearableAtomicTime};
use crate::util::priority_queue::{self, PriorityQueue}; use crate::util::priority_queue::PriorityQueue;
use crate::util::sync_cell::SyncCellReader; use crate::util::sync_cell::SyncCellReader;
/// Shorthand for the scheduler queue type. /// Shorthand for the scheduler queue type.
pub(crate) type SchedulerQueue = pub(crate) type SchedulerQueue =
PriorityQueue<(MonotonicTime, ChannelId), Box<dyn Future<Output = ()> + Send>>; PriorityQueue<(MonotonicTime, ChannelId), Box<dyn EventFuture<Output = ()> + Send>>;
/// A local scheduler for models. /// A local scheduler for models.
/// ///
@ -65,8 +68,8 @@ pub(crate) type SchedulerQueue =
/// let greeting = format!("Hello, this message was scheduled at: /// let greeting = format!("Hello, this message was scheduled at:
/// {:?}.", time); /// {:?}.", time);
/// ///
/// if let Err(err) = scheduler.schedule_in(delay, Self::send_msg, greeting) { /// if let Err(err) = scheduler.schedule_event_in(delay, Self::send_msg, greeting) {
/// // ^^^^^^^^ scheduled method /// // ^^^^^^^^ scheduled method
/// // The duration was zero, so greet right away. /// // The duration was zero, so greet right away.
/// let greeting = err.0; /// let greeting = err.0;
/// self.msg_out.send(greeting).await; /// self.msg_out.send(greeting).await;
@ -144,19 +147,19 @@ impl<M: Model> Scheduler<M> {
/// ///
/// // Schedule this method again in 1s with an incremented counter. /// // Schedule this method again in 1s with an incremented counter.
/// scheduler /// scheduler
/// .schedule_in(Duration::from_secs(1), Self::trigger, counter + 1) /// .schedule_event_in(Duration::from_secs(1), Self::trigger, counter + 1)
/// .unwrap(); /// .unwrap();
/// } /// }
/// } /// }
/// ///
/// impl Model for PeriodicLogger {} /// impl Model for PeriodicLogger {}
/// ``` /// ```
pub fn schedule_in<F, T, S>( pub fn schedule_event_in<F, T, S>(
&self, &self,
duration: Duration, duration: Duration,
func: F, func: F,
arg: T, arg: T,
) -> Result<SchedulerKey, ScheduledTimeError<T>> ) -> Result<(), ScheduledTimeError<T>>
where where
F: for<'a> InputFn<'a, M, T, S>, F: for<'a> InputFn<'a, M, T, S>,
T: Send + Clone + 'static, T: Send + Clone + 'static,
@ -166,10 +169,70 @@ impl<M: Model> Scheduler<M> {
} }
let time = self.time() + duration; let time = self.time() + duration;
let sender = self.sender.clone(); let sender = self.sender.clone();
let schedule_key = schedule_event_at_unchecked(time, func, arg, sender, &self.scheduler_queue);
schedule_event_at_unchecked(time, func, arg, sender, &self.scheduler_queue);
Ok(schedule_key) Ok(())
}
/// Schedules an event at the lapse of the specified duration and returns an
/// event key.
///
/// An error is returned if the specified duration is null.
///
/// # Examples
///
/// ```
/// use std::time::Duration;
/// use std::future::Future;
/// use asynchronix::model::Model;
/// use asynchronix::time::{EventKey, Scheduler};
///
/// // A model that logs the value of a counter every second after being
/// // triggered the first time until logging is stopped.
/// pub struct PeriodicLogger {
/// event_key: Option<EventKey>
/// }
///
/// impl PeriodicLogger {
/// // Triggers the logging of a timestamp every second [input port].
/// pub fn trigger(&mut self, counter: u64, scheduler: &Scheduler<Self>) {
/// self.stop();
/// println!("counter: {}", counter);
///
/// // Schedule this method again in 1s with an incremented counter.
/// let event_key = scheduler
/// .schedule_keyed_event_in(Duration::from_secs(1), Self::trigger, counter + 1)
/// .unwrap();
/// self.event_key = Some(event_key);
/// }
///
/// // Cancels the logging of timestamps.
/// pub fn stop(&mut self) {
/// self.event_key.take().map(|k| k.cancel_event());
/// }
/// }
///
/// impl Model for PeriodicLogger {}
/// ```
pub fn schedule_keyed_event_in<F, T, S>(
&self,
duration: Duration,
func: F,
arg: T,
) -> Result<EventKey, ScheduledTimeError<T>>
where
F: for<'a> InputFn<'a, M, T, S>,
T: Send + Clone + 'static,
{
if duration.is_zero() {
return Err(ScheduledTimeError(arg));
}
let time = self.time() + duration;
let sender = self.sender.clone();
let event_key =
schedule_keyed_event_at_unchecked(time, func, arg, sender, &self.scheduler_queue);
Ok(event_key)
} }
/// Schedules an event at a future time. /// Schedules an event at a future time.
@ -183,7 +246,7 @@ impl<M: Model> Scheduler<M> {
/// use asynchronix::model::Model; /// use asynchronix::model::Model;
/// use asynchronix::time::{MonotonicTime, Scheduler}; /// use asynchronix::time::{MonotonicTime, Scheduler};
/// ///
/// // An alarm clock model. /// // An alarm clock.
/// pub struct AlarmClock { /// pub struct AlarmClock {
/// msg: String /// msg: String
/// } /// }
@ -196,7 +259,7 @@ impl<M: Model> Scheduler<M> {
/// ///
/// // Sets an alarm [input port]. /// // Sets an alarm [input port].
/// pub fn set(&mut self, setting: MonotonicTime, scheduler: &Scheduler<Self>) { /// pub fn set(&mut self, setting: MonotonicTime, scheduler: &Scheduler<Self>) {
/// if scheduler.schedule_at(setting, Self::ring, ()).is_err() { /// if scheduler.schedule_event_at(setting, Self::ring, ()).is_err() {
/// println!("The alarm clock can only be set for a future time"); /// println!("The alarm clock can only be set for a future time");
/// } /// }
/// } /// }
@ -209,12 +272,12 @@ impl<M: Model> Scheduler<M> {
/// ///
/// impl Model for AlarmClock {} /// impl Model for AlarmClock {}
/// ``` /// ```
pub fn schedule_at<F, T, S>( pub fn schedule_event_at<F, T, S>(
&self, &self,
time: MonotonicTime, time: MonotonicTime,
func: F, func: F,
arg: T, arg: T,
) -> Result<SchedulerKey, ScheduledTimeError<T>> ) -> Result<(), ScheduledTimeError<T>>
where where
F: for<'a> InputFn<'a, M, T, S>, F: for<'a> InputFn<'a, M, T, S>,
T: Send + Clone + 'static, T: Send + Clone + 'static,
@ -223,20 +286,77 @@ impl<M: Model> Scheduler<M> {
return Err(ScheduledTimeError(arg)); return Err(ScheduledTimeError(arg));
} }
let sender = self.sender.clone(); let sender = self.sender.clone();
let schedule_key = schedule_event_at_unchecked(time, func, arg, sender, &self.scheduler_queue);
schedule_event_at_unchecked(time, func, arg, sender, &self.scheduler_queue);
Ok(schedule_key) Ok(())
} }
/// Cancels an event with a scheduled time in the future of the current /// Schedules an event at a future time and returns an event key.
/// simulation time.
/// ///
/// If the corresponding event was already executed, or if it is scheduled /// An error is returned if the specified time is not in the future of the
/// for the current simulation time but was not yet executed, an error is /// current simulation time.
/// returned. ///
pub fn cancel(&self, scheduler_key: SchedulerKey) -> Result<(), CancellationError> { /// # Examples
cancel_scheduled(scheduler_key, &self.scheduler_queue) ///
/// ```
/// use asynchronix::model::Model;
/// use asynchronix::time::{EventKey, MonotonicTime, Scheduler};
///
/// // An alarm clock that can be cancelled.
/// pub struct AlarmClock {
/// msg: String,
/// event_key: Option<EventKey>,
/// }
///
/// impl AlarmClock {
/// // Creates a new alarm clock.
/// pub fn new(msg: String) -> Self {
/// Self {
/// msg,
/// event_key: None
/// }
/// }
///
/// // Sets an alarm [input port].
/// pub fn set(&mut self, setting: MonotonicTime, scheduler: &Scheduler<Self>) {
/// self.cancel();
/// match scheduler.schedule_keyed_event_at(setting, Self::ring, ()) {
/// Ok(event_key) => self.event_key = Some(event_key),
/// Err(_) => println!("The alarm clock can only be set for a future time"),
/// };
/// }
///
/// // Cancels the current alarm, if any.
/// pub fn cancel(&mut self) {
/// self.event_key.take().map(|k| k.cancel_event());
/// }
///
/// // Rings the alarm [private input port].
/// fn ring(&mut self) {
/// println!("{}", self.msg);
/// }
/// }
///
/// impl Model for AlarmClock {}
/// ```
pub fn schedule_keyed_event_at<F, T, S>(
&self,
time: MonotonicTime,
func: F,
arg: T,
) -> Result<EventKey, ScheduledTimeError<T>>
where
F: for<'a> InputFn<'a, M, T, S>,
T: Send + Clone + 'static,
{
if self.time() >= time {
return Err(ScheduledTimeError(arg));
}
let sender = self.sender.clone();
let event_key =
schedule_keyed_event_at_unchecked(time, func, arg, sender, &self.scheduler_queue);
Ok(event_key)
} }
} }
@ -246,15 +366,61 @@ impl<M: Model> fmt::Debug for Scheduler<M> {
} }
} }
/// Unique identifier for a scheduled event. /// Handle to a scheduled event.
/// ///
/// A `SchedulerKey` can be used to cancel a future event. /// An `EventKey` can be used to cancel a future event.
#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)] #[derive(Clone, Debug)]
pub struct SchedulerKey(priority_queue::InsertKey); pub struct EventKey {
state: Arc<AtomicUsize>,
}
impl SchedulerKey { impl EventKey {
pub(crate) fn new(key: priority_queue::InsertKey) -> Self { const IS_PENDING: usize = 0;
Self(key) const IS_CANCELLED: usize = 1;
const IS_PROCESSED: usize = 2;
/// Creates a key for a pending event.
pub(crate) fn new() -> Self {
Self {
state: Arc::new(AtomicUsize::new(Self::IS_PENDING)),
}
}
/// Checks whether the event was cancelled.
pub(crate) fn event_is_cancelled(&self) -> bool {
self.state.load(Ordering::Relaxed) == Self::IS_CANCELLED
}
/// Marks the event as processed.
///
/// If the event cannot be processed because it was cancelled, `false` is
/// returned.
pub(crate) fn process_event(self) -> bool {
match self.state.compare_exchange(
Self::IS_PENDING,
Self::IS_PROCESSED,
Ordering::Relaxed,
Ordering::Relaxed,
) {
Ok(_) => true,
Err(s) => s == Self::IS_PROCESSED,
}
}
/// Cancels the associated event if possible.
///
/// If the event cannot be cancelled because it was already processed,
/// `false` is returned.
pub fn cancel_event(self) -> bool {
match self.state.compare_exchange(
Self::IS_PENDING,
Self::IS_CANCELLED,
Ordering::Relaxed,
Ordering::Relaxed,
) {
Ok(_) => true,
Err(s) => s == Self::IS_CANCELLED,
}
} }
} }
@ -274,21 +440,6 @@ impl<T> fmt::Display for ScheduledTimeError<T> {
impl<T: fmt::Debug> Error for ScheduledTimeError<T> {} impl<T: fmt::Debug> Error for ScheduledTimeError<T> {}
/// Error returned when the cancellation of a scheduler event is unsuccessful.
#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub struct CancellationError {}
impl fmt::Display for CancellationError {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(
fmt,
"the scheduler key should belong to an event or command scheduled in the future of the current simulation time"
)
}
}
impl Error for CancellationError {}
/// Schedules an event at a future time. /// Schedules an event at a future time.
/// ///
/// This method does not check whether the specified time lies in the future /// This method does not check whether the specified time lies in the future
@ -299,8 +450,7 @@ pub(crate) fn schedule_event_at_unchecked<M, F, T, S>(
arg: T, arg: T,
sender: Sender<M>, sender: Sender<M>,
scheduler_queue: &Mutex<SchedulerQueue>, scheduler_queue: &Mutex<SchedulerQueue>,
) -> SchedulerKey ) where
where
M: Model, M: Model,
F: for<'a> InputFn<'a, M, T, S>, F: for<'a> InputFn<'a, M, T, S>,
T: Send + Clone + 'static, T: Send + Clone + 'static,
@ -321,26 +471,143 @@ where
) )
.await; .await;
}; };
let fut = Box::new(UnkeyedEventFuture::new(fut));
let mut scheduler_queue = scheduler_queue.lock().unwrap(); let mut scheduler_queue = scheduler_queue.lock().unwrap();
let insert_key = scheduler_queue.insert((time, channel_id), Box::new(fut)); scheduler_queue.insert((time, channel_id), fut);
SchedulerKey::new(insert_key)
} }
/// Cancels an event or command with a scheduled time in the future of the /// Schedules an event at a future time, returning an event key.
/// current simulation time.
/// ///
/// If the corresponding event or command was already executed, or if it is /// This method does not check whether the specified time lies in the future
/// scheduled for the current simulation time, an error is returned. /// of the current simulation time.
pub(crate) fn cancel_scheduled( pub(crate) fn schedule_keyed_event_at_unchecked<M, F, T, S>(
scheduler_key: SchedulerKey, time: MonotonicTime,
func: F,
arg: T,
sender: Sender<M>,
scheduler_queue: &Mutex<SchedulerQueue>, scheduler_queue: &Mutex<SchedulerQueue>,
) -> Result<(), CancellationError> { ) -> EventKey
let mut scheduler_queue = scheduler_queue.lock().unwrap(); where
if scheduler_queue.delete(scheduler_key.0) { M: Model,
return Ok(()); F: for<'a> InputFn<'a, M, T, S>,
} T: Send + Clone + 'static,
{
let channel_id = sender.channel_id();
Err(CancellationError {}) let event_key = EventKey::new();
let local_event_key = event_key.clone();
let fut = async move {
let _ = sender
.send(
move |model: &mut M,
scheduler,
recycle_box: RecycleBox<()>|
-> RecycleBox<dyn Future<Output = ()> + Send + '_> {
let fut = async move {
if local_event_key.process_event() {
func.call(model, arg, scheduler).await;
}
};
coerce_box!(RecycleBox::recycle(recycle_box, fut))
},
)
.await;
};
// Implementation note: we end up with two atomic references to the event
// key stored inside the event future: one was moved above to the future
// itself and the other one is created below via cloning and stored
// separately in the `KeyedEventFuture`. This is not ideal as we could
// theoretically spare on atomic reference counting by storing a single
// reference, but this would likely require some tricky `unsafe`, not least
// because the inner future sent to the mailbox outlives the
// `KeyedEventFuture`.
let fut = Box::new(KeyedEventFuture::new(fut, event_key.clone()));
let mut scheduler_queue = scheduler_queue.lock().unwrap();
scheduler_queue.insert((time, channel_id), fut);
event_key
}
/// The future of an event which scheduling may be cancelled by the user.
pub(crate) trait EventFuture: Future {
/// Whether the scheduling of this event was cancelled.
fn is_cancelled(&self) -> bool;
}
pin_project! {
/// Future associated to a regular event that cannot be cancelled.
pub(crate) struct UnkeyedEventFuture<F> {
#[pin]
fut: F,
}
}
impl<F> UnkeyedEventFuture<F> {
/// Creates a new `EventFuture`.
pub(crate) fn new(fut: F) -> Self {
Self { fut }
}
}
impl<F> Future for UnkeyedEventFuture<F>
where
F: Future,
{
type Output = F::Output;
#[inline(always)]
fn poll(self: std::pin::Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
self.project().fut.poll(cx)
}
}
impl<F> EventFuture for UnkeyedEventFuture<F>
where
F: Future,
{
fn is_cancelled(&self) -> bool {
false
}
}
pin_project! {
/// Future associated to a keyed event that can be cancelled.
pub(crate) struct KeyedEventFuture<F> {
event_key: EventKey,
#[pin]
fut: F,
}
}
impl<F> KeyedEventFuture<F> {
/// Creates a new `EventFuture`.
pub(crate) fn new(fut: F, event_key: EventKey) -> Self {
Self { event_key, fut }
}
}
impl<F> Future for KeyedEventFuture<F>
where
F: Future,
{
type Output = F::Output;
#[inline(always)]
fn poll(self: std::pin::Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
self.project().fut.poll(cx)
}
}
impl<F> EventFuture for KeyedEventFuture<F>
where
F: Future,
{
fn is_cancelled(&self) -> bool {
self.event_key.event_is_cancelled()
}
} }

38
asynchronix/src/util/futures.rs
View File

@ -4,6 +4,8 @@
use std::future::Future; use std::future::Future;
use std::pin::Pin; use std::pin::Pin;
use std::sync::atomic::AtomicBool;
use std::sync::Arc;
use std::task::{Context, Poll}; use std::task::{Context, Poll};
/// An owned future which sequentially polls a collection of futures. /// An owned future which sequentially polls a collection of futures.
@ -51,3 +53,39 @@ impl<F: Future + Unpin> Future for SeqFuture<F> {
Poll::Pending Poll::Pending
} }
} }
trait RevocableFuture: Future {
fn is_revoked() -> bool;
}
struct NeverRevokedFuture<F> {
inner: F,
}
impl<F: Future> NeverRevokedFuture<F> {
fn new(fut: F) -> Self {
Self { inner: fut }
}
}
impl<T: Future> Future for NeverRevokedFuture<T> {
type Output = T::Output;
#[inline(always)]
fn poll(
self: std::pin::Pin<&mut Self>,
cx: &mut std::task::Context<'_>,
) -> std::task::Poll<Self::Output> {
unsafe { self.map_unchecked_mut(|s| &mut s.inner).poll(cx) }
}
}
impl<T: Future> RevocableFuture for NeverRevokedFuture<T> {
fn is_revoked() -> bool {
false
}
}
struct ConcurrentlyRevocableFuture<F> {
inner: F,
is_revoked: Arc<AtomicBool>,
}

686
asynchronix/src/util/priority_queue.rs
View File

@ -1,52 +1,60 @@
//! Associative priority queue. //! Associative priority queue.
#![allow(unused)] use std::cmp::{Eq, Ord, Ordering, PartialOrd};
use std::collections::BinaryHeap;
use std::mem; /// A key-value pair ordered by keys in inverse order, with epoch-based ordering
/// for equal keys.
struct Item<K, V>
where
K: Ord,
{
key: K,
value: V,
epoch: u64,
}
/// An associative container optimized for extraction of the value with the impl<K, V> Ord for Item<K, V>
/// lowest key and deletion of arbitrary key-value pairs. where
K: Ord,
{
fn cmp(&self, other: &Self) -> Ordering {
self.key
.cmp(&other.key)
.then_with(|| self.epoch.cmp(&other.epoch))
.reverse()
}
}
impl<K, V> PartialOrd for Item<K, V>
where
K: Ord,
{
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl<K, V> Eq for Item<K, V> where K: Ord {}
impl<K, V> PartialEq for Item<K, V>
where
K: Ord,
{
fn eq(&self, other: &Self) -> bool {
(self.key == other.key) && (self.epoch == other.epoch)
}
}
/// An associative container optimized for extraction of the key-value pair with
/// the lowest key, based on a binary heap.
/// ///
/// This implementation has the same theoretical complexity for insert and pull /// The insertion order of equal keys is preserved, with FIFO ordering.
/// operations as a conventional array-based binary heap but does differ from
/// the latter in some important aspects:
///
/// - elements can be deleted in *O*(log(*N*)) time rather than *O*(*N*) time
/// using a unique index returned at insertion time.
/// - same-key elements are guaranteed to be pulled in FIFO order,
///
/// Under the hood, the priority queue relies on a binary heap cross-indexed
/// with values stored in a slab allocator. Each item of the binary heap
/// contains an index pointing to the associated slab-allocated node, as well as
/// the user-provided key. Each slab node contains the value associated to the
/// key and a back-pointing index to the binary heap. The heap items also
/// contain a unique epoch which allows same-key nodes to be sorted by insertion
/// order. The epoch is used as well to build unique indices that enable
/// efficient deletion of arbitrary key-value pairs.
///
/// The slab-based design is what makes *O*(log(*N*)) deletion possible, but it
/// does come with some trade-offs:
///
/// - its memory footprint is higher because it needs 2 extra pointer-sized
/// indices for each element to cross-index the heap and the slab,
/// - its computational footprint is higher because of the extra cost associated
/// with random slab access; that being said, array-based binary heaps are not
/// extremely cache-friendly to start with so unless the slab becomes very
/// fragmented, this is not expected to introduce more than a reasonable
/// constant-factor penalty compared to a conventional binary heap.
///
/// The computational penalty is partially offset by the fact that the value
/// never needs to be moved from the moment it is inserted until it is pulled.
///
/// Note that the `Copy` bound on they keys could be lifted but this would make
/// the implementation slightly less efficient unless `unsafe` is used.
pub(crate) struct PriorityQueue<K, V> pub(crate) struct PriorityQueue<K, V>
where where
K: Copy + Clone + Ord, K: Ord,
{ {
heap: Vec<Item<K>>, heap: BinaryHeap<Item<K, V>>,
slab: Vec<Node<V>>,
first_free_node: Option<usize>,
next_epoch: u64, next_epoch: u64,
} }
@ -54,81 +62,23 @@ impl<K: Copy + Ord, V> PriorityQueue<K, V> {
/// Creates an empty `PriorityQueue`. /// Creates an empty `PriorityQueue`.
pub(crate) fn new() -> Self { pub(crate) fn new() -> Self {
Self { Self {
heap: Vec::new(), heap: BinaryHeap::new(),
slab: Vec::new(),
first_free_node: None,
next_epoch: 0, next_epoch: 0,
} }
} }
/// Creates an empty `PriorityQueue` with at least the specified capacity. /// Inserts a new key-value pair.
pub(crate) fn with_capacity(capacity: usize) -> Self {
Self {
heap: Vec::with_capacity(capacity),
slab: Vec::with_capacity(capacity),
first_free_node: None,
next_epoch: 0,
}
}
/// Returns the number of key-value pairs in the priority queue.
pub(crate) fn len(&self) -> usize {
self.heap.len()
}
/// Inserts a new key-value pair and returns a unique insertion key.
/// ///
/// This operation has *O*(log(*N*)) amortized worse-case theoretical /// This operation has *O*(log(*N*)) amortized worse-case theoretical
/// complexity and *O*(1) amortized theoretical complexity for a /// complexity and *O*(1) amortized theoretical complexity for a
/// sufficiently random heap. /// sufficiently random heap.
pub(crate) fn insert(&mut self, key: K, value: V) -> InsertKey { pub(crate) fn insert(&mut self, key: K, value: V) {
// Build a unique key from the user-provided key and a unique epoch. // Build an element from the user-provided key-value and a unique epoch.
let epoch = self.next_epoch; let epoch = self.next_epoch;
assert_ne!(epoch, u64::MAX); assert_ne!(epoch, u64::MAX);
self.next_epoch += 1; self.next_epoch += 1;
let unique_key = UniqueKey { key, epoch }; let item = Item { key, value, epoch };
self.heap.push(item);
// Add a new node to the slab, either by re-using a free node or by
// appending a new one.
let slab_idx = match self.first_free_node {
Some(idx) => {
self.first_free_node = self.slab[idx].unwrap_next_free_node();
self.slab[idx] = Node::HeapNode(HeapNode {
value,
heap_idx: 0, // temporary value overridden in `sift_up`
});
idx
}
None => {
let idx = self.slab.len();
self.slab.push(Node::HeapNode(HeapNode {
value,
heap_idx: 0, // temporary value overridden in `sift_up`
}));
idx
}
};
// Add a new node at the bottom of the heap.
let heap_idx = self.heap.len();
self.heap.push(Item {
key: unique_key, // temporary value overridden in `sift_up`
slab_idx: 0, // temporary value overridden in `sift_up`
});
// Sift up the new node.
self.sift_up(
Item {
key: unique_key,
slab_idx,
},
heap_idx,
);
InsertKey { slab_idx, epoch }
} }
/// Pulls the value with the lowest key. /// Pulls the value with the lowest key.
@ -138,26 +88,7 @@ impl<K: Copy + Ord, V> PriorityQueue<K, V> {
/// ///
/// This operation has *O*(log(N)) non-amortized theoretical complexity. /// This operation has *O*(log(N)) non-amortized theoretical complexity.
pub(crate) fn pull(&mut self) -> Option<(K, V)> { pub(crate) fn pull(&mut self) -> Option<(K, V)> {
let item = self.heap.first()?; let Item { key, value, .. } = self.heap.pop()?;
let top_slab_idx = item.slab_idx;
let key = item.key.key;
// Free the top node, extracting its value.
let value = mem::replace(
&mut self.slab[top_slab_idx],
Node::FreeNode(FreeNode {
next: self.first_free_node,
}),
)
.unwrap_value();
self.first_free_node = Some(top_slab_idx);
// Sift the last node at the bottom of the heap from the top of the heap.
let last_item = self.heap.pop().unwrap();
if last_item.slab_idx != top_slab_idx {
self.sift_down(last_item, 0);
}
Some((key, value)) Some((key, value))
} }
@ -165,497 +96,48 @@ impl<K: Copy + Ord, V> PriorityQueue<K, V> {
/// Peeks a reference to the key-value pair with the lowest key, leaving it /// Peeks a reference to the key-value pair with the lowest key, leaving it
/// in the queue. /// in the queue.
/// ///
/// If there are several equal lowest keys, a reference to the key-value /// If there are several equal lowest keys, references to the key-value pair
/// pair which was inserted first is returned. /// which was inserted first is returned.
/// ///
/// This operation has *O*(1) non-amortized theoretical complexity. /// This operation has *O*(1) non-amortized theoretical complexity.
pub(crate) fn peek(&self) -> Option<(&K, &V)> { pub(crate) fn peek(&self) -> Option<(&K, &V)> {
let item = self.heap.first()?; let Item {
let top_slab_idx = item.slab_idx; ref key, ref value, ..
let key = &item.key.key; } = self.heap.peek()?;
let value = self.slab[top_slab_idx].unwrap_value_ref();
Some((key, value)) Some((key, value))
} }
/// Peeks a reference to the lowest key, leaving it in the queue.
///
/// If there are several equal lowest keys, a reference to the key which was
/// inserted first is returned.
///
/// This operation has *O*(1) non-amortized theoretical complexity.
pub(crate) fn peek_key(&self) -> Option<&K> {
let item = self.heap.first()?;
Some(&item.key.key)
}
/// Delete the key-value pair associated to the provided insertion key if it
/// is still in the queue.
///
/// Using an insertion key returned from another `PriorityQueue` is a logic
/// error and could result in the deletion of an arbitrary key-value pair.
///
/// This method returns `true` if the pair was indeed in the queue and
/// `false` otherwise.
///
/// This operation has guaranteed *O*(log(*N*)) theoretical complexity.
pub(crate) fn delete(&mut self, insert_key: InsertKey) -> bool {
// Check that (i) there is a node at this index, (ii) this node is in
// the heap and (iii) this node has the correct epoch.
let slab_idx = insert_key.slab_idx;
let heap_idx = if let Some(Node::HeapNode(node)) = self.slab.get(slab_idx) {
let heap_idx = node.heap_idx;
if self.heap[heap_idx].key.epoch != insert_key.epoch {
return false;
}
heap_idx
} else {
return false;
};
// If the last item of the heap is not the one to be deleted, sift it up
// or down as appropriate starting from the vacant spot.
let last_item = self.heap.pop().unwrap();
if let Some(item) = self.heap.get(heap_idx) {
if last_item.key < item.key {
self.sift_up(last_item, heap_idx);
} else {
self.sift_down(last_item, heap_idx);
}
}
// Free the deleted node in the slab.
self.slab[slab_idx] = Node::FreeNode(FreeNode {
next: self.first_free_node,
});
self.first_free_node = Some(slab_idx);
true
}
/// Take a heap item and, starting at `heap_idx`, move it up the heap while
/// a parent has a larger key.
#[inline]
fn sift_up(&mut self, item: Item<K>, heap_idx: usize) {
let mut child_heap_idx = heap_idx;
let key = &item.key;
while child_heap_idx != 0 {
let parent_heap_idx = (child_heap_idx - 1) / 2;
// Stop when the key is larger or equal to the parent's.
if key >= &self.heap[parent_heap_idx].key {
break;
}
// Move the parent down one level.
self.heap[child_heap_idx] = self.heap[parent_heap_idx];
let parent_slab_idx = self.heap[parent_heap_idx].slab_idx;
*self.slab[parent_slab_idx].unwrap_heap_index_mut() = child_heap_idx;
// Stop when the key is larger or equal to the parent's.
if key >= &self.heap[parent_heap_idx].key {
break;
}
// Make the former parent the new child.
child_heap_idx = parent_heap_idx;
}
// Move the original item to the current child.
self.heap[child_heap_idx] = item;
*self.slab[item.slab_idx].unwrap_heap_index_mut() = child_heap_idx;
}
/// Take a heap item and, starting at `heap_idx`, move it down the heap
/// while a child has a smaller key.
#[inline]
fn sift_down(&mut self, item: Item<K>, heap_idx: usize) {
let mut parent_heap_idx = heap_idx;
let mut child_heap_idx = 2 * parent_heap_idx + 1;
let key = &item.key;
while child_heap_idx < self.heap.len() {
// If the sibling exists and has a smaller key, make it the
// candidate for swapping.
if let Some(other_child) = self.heap.get(child_heap_idx + 1) {
child_heap_idx += (self.heap[child_heap_idx].key > other_child.key) as usize;
}
// Stop when the key is smaller or equal to the child with the smallest key.
if key <= &self.heap[child_heap_idx].key {
break;
}
// Move the child up one level.
self.heap[parent_heap_idx] = self.heap[child_heap_idx];
let child_slab_idx = self.heap[child_heap_idx].slab_idx;
*self.slab[child_slab_idx].unwrap_heap_index_mut() = parent_heap_idx;
// Make the child the new parent.
parent_heap_idx = child_heap_idx;
child_heap_idx = 2 * parent_heap_idx + 1;
}
// Move the original item to the current parent.
self.heap[parent_heap_idx] = item;
*self.slab[item.slab_idx].unwrap_heap_index_mut() = parent_heap_idx;
}
}
/// Data related to a single key-value pair stored in the heap.
#[derive(Copy, Clone)]
struct Item<K: Copy> {
// A unique key by which the heap is sorted.
key: UniqueKey<K>,
// An index pointing to the corresponding node in the slab.
slab_idx: usize,
}
/// Data related to a single key-value pair stored in the slab.
enum Node<V> {
FreeNode(FreeNode),
HeapNode(HeapNode<V>),
}
impl<V> Node<V> {
/// Unwraps the `FreeNode::next` field.
fn unwrap_next_free_node(&self) -> Option<usize> {
match self {
Self::FreeNode(n) => n.next,
_ => panic!("the node was expected to be a free node"),
}
}
/// Unwraps the `HeapNode::value` field.
fn unwrap_value(self) -> V {
match self {
Self::HeapNode(n) => n.value,
_ => panic!("the node was expected to be a heap node"),
}
}
/// Unwraps the `HeapNode::value` field.
fn unwrap_value_ref(&self) -> &V {
match self {
Self::HeapNode(n) => &n.value,
_ => panic!("the node was expected to be a heap node"),
}
}
/// Unwraps a mutable reference to the `HeapNode::heap_idx` field.
fn unwrap_heap_index_mut(&mut self) -> &mut usize {
match self {
Self::HeapNode(n) => &mut n.heap_idx,
_ => panic!("the node was expected to be a heap node"),
}
}
}
/// A node that is no longer in the binary heap.
struct FreeNode {
// An index pointing to the next free node, if any.
next: Option<usize>,
}
/// A node currently in the binary heap.
struct HeapNode<V> {
// The value associated to this node.
value: V,
// Index of the node in the heap.
heap_idx: usize,
}
/// A unique insertion key that can be used for key-value pair deletion.
#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
pub(crate) struct InsertKey {
// An index pointing to a node in the slab.
slab_idx: usize,
// The epoch when the node was inserted.
epoch: u64,
}
/// A unique key made of the user-provided key complemented by a unique epoch.
///
/// Implementation note: `UniqueKey` automatically derives `PartialOrd`, which
/// implies that lexicographic order between `key` and `epoch` must be preserved
/// to make sure that `key` has a higher sorting priority than `epoch`.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
struct UniqueKey<K: Copy + Clone> {
/// The user-provided key.
key: K,
/// A unique epoch that indicates the insertion date.
epoch: u64,
} }
#[cfg(all(test, not(asynchronix_loom)))] #[cfg(all(test, not(asynchronix_loom)))]
mod tests { mod tests {
use std::fmt::Debug;
use super::*; use super::*;
enum Op<K, V> {
Insert(K, V),
InsertAndMark(K, V),
Pull(Option<(K, V)>),
DeleteMarked(bool),
}
fn check<K: Copy + Clone + Ord + Debug, V: Eq + Debug>(
operations: impl Iterator<Item = Op<K, V>>,
) {
let mut queue = PriorityQueue::new();
let mut marked = None;
for op in operations {
match op {
Op::Insert(key, value) => {
queue.insert(key, value);
}
Op::InsertAndMark(key, value) => {
marked = Some(queue.insert(key, value));
}
Op::Pull(kv) => {
assert_eq!(queue.pull(), kv);
}
Op::DeleteMarked(success) => {
assert_eq!(
queue.delete(marked.take().expect("no item was marked for deletion")),
success
)
}
}
}
}
#[test] #[test]
fn priority_queue_smoke() { fn priority_smoke() {
let operations = [ let mut q = PriorityQueue::new();
Op::Insert(5, 'a'),
Op::Insert(2, 'b'),
Op::Insert(3, 'c'),
Op::Insert(4, 'd'),
Op::Insert(9, 'e'),
Op::Insert(1, 'f'),
Op::Insert(8, 'g'),
Op::Insert(0, 'h'),
Op::Insert(7, 'i'),
Op::Insert(6, 'j'),
Op::Pull(Some((0, 'h'))),
Op::Pull(Some((1, 'f'))),
Op::Pull(Some((2, 'b'))),
Op::Pull(Some((3, 'c'))),
Op::Pull(Some((4, 'd'))),
Op::Pull(Some((5, 'a'))),
Op::Pull(Some((6, 'j'))),
Op::Pull(Some((7, 'i'))),
Op::Pull(Some((8, 'g'))),
Op::Pull(Some((9, 'e'))),
];
check(operations.into_iter()); q.insert(5, 'e');
} q.insert(2, 'y');
q.insert(1, 'a');
q.insert(3, 'c');
q.insert(2, 'z');
q.insert(4, 'd');
q.insert(2, 'x');
#[test] assert_eq!(q.peek(), Some((&1, &'a')));
fn priority_queue_interleaved() { assert_eq!(q.pull(), Some((1, 'a')));
let operations = [ assert_eq!(q.peek(), Some((&2, &'y')));
Op::Insert(2, 'a'), assert_eq!(q.pull(), Some((2, 'y')));
Op::Insert(7, 'b'), assert_eq!(q.peek(), Some((&2, &'z')));
Op::Insert(5, 'c'), assert_eq!(q.pull(), Some((2, 'z')));
Op::Pull(Some((2, 'a'))), assert_eq!(q.peek(), Some((&2, &'x')));
Op::Insert(4, 'd'), assert_eq!(q.pull(), Some((2, 'x')));
Op::Pull(Some((4, 'd'))), assert_eq!(q.peek(), Some((&3, &'c')));
Op::Insert(8, 'e'), assert_eq!(q.pull(), Some((3, 'c')));
Op::Insert(2, 'f'), assert_eq!(q.peek(), Some((&4, &'d')));
Op::Pull(Some((2, 'f'))), assert_eq!(q.pull(), Some((4, 'd')));
Op::Pull(Some((5, 'c'))), assert_eq!(q.peek(), Some((&5, &'e')));
Op::Pull(Some((7, 'b'))), assert_eq!(q.pull(), Some((5, 'e')));
Op::Insert(5, 'g'),
Op::Insert(3, 'h'),
Op::Pull(Some((3, 'h'))),
Op::Pull(Some((5, 'g'))),
Op::Pull(Some((8, 'e'))),
Op::Pull(None),
];
check(operations.into_iter());
}
#[test]
fn priority_queue_equal_keys() {
let operations = [
Op::Insert(4, 'a'),
Op::Insert(1, 'b'),
Op::Insert(3, 'c'),
Op::Pull(Some((1, 'b'))),
Op::Insert(4, 'd'),
Op::Insert(8, 'e'),
Op::Insert(3, 'f'),
Op::Pull(Some((3, 'c'))),
Op::Pull(Some((3, 'f'))),
Op::Pull(Some((4, 'a'))),
Op::Insert(8, 'g'),
Op::Pull(Some((4, 'd'))),
Op::Pull(Some((8, 'e'))),
Op::Pull(Some((8, 'g'))),
Op::Pull(None),
];
check(operations.into_iter());
}
#[test]
fn priority_queue_delete_valid() {
let operations = [
Op::Insert(8, 'a'),
Op::Insert(1, 'b'),
Op::Insert(3, 'c'),
Op::InsertAndMark(3, 'd'),
Op::Insert(2, 'e'),
Op::Pull(Some((1, 'b'))),
Op::Insert(4, 'f'),
Op::DeleteMarked(true),
Op::Insert(5, 'g'),
Op::Pull(Some((2, 'e'))),
Op::Pull(Some((3, 'c'))),
Op::Pull(Some((4, 'f'))),
Op::Pull(Some((5, 'g'))),
Op::Pull(Some((8, 'a'))),
Op::Pull(None),
];
check(operations.into_iter());
}
#[test]
fn priority_queue_delete_invalid() {
let operations = [
Op::Insert(0, 'a'),
Op::Insert(7, 'b'),
Op::InsertAndMark(2, 'c'),
Op::Insert(4, 'd'),
Op::Pull(Some((0, 'a'))),
Op::Insert(2, 'e'),
Op::Pull(Some((2, 'c'))),
Op::Insert(4, 'f'),
Op::DeleteMarked(false),
Op::Pull(Some((2, 'e'))),
Op::Pull(Some((4, 'd'))),
Op::Pull(Some((4, 'f'))),
Op::Pull(Some((7, 'b'))),
Op::Pull(None),
];
check(operations.into_iter());
}
#[test]
fn priority_queue_fuzz() {
use std::cell::Cell;
use std::collections::BTreeMap;
use crate::util::rng::Rng;
// Number of fuzzing operations.
const ITER: usize = if cfg!(miri) { 1000 } else { 10_000_000 };
// Inclusive upper bound for randomly generated keys.
const MAX_KEY: u64 = 99;
// Probabilistic weight of each of the 4 operations.
//
// The weight for pull values should probably stay close to the sum of
// the two insertion weights to prevent queue size runaway.
const INSERT_WEIGHT: u64 = 5;
const INSERT_AND_MARK_WEIGHT: u64 = 1;
const PULL_WEIGHT: u64 = INSERT_WEIGHT + INSERT_AND_MARK_WEIGHT;
const DELETE_MARKED_WEIGHT: u64 = 1;
// Defines 4 basic operations on the priority queue, each of them being
// performed on both the tested implementation and on a shadow queue
// implemented with a `BTreeMap`. Any mismatch between the outcomes of
// pull and delete operations between the two queues triggers a panic.
let epoch: Cell<usize> = Cell::new(0);
let marked: Cell<Option<InsertKey>> = Cell::new(None);
let shadow_marked: Cell<Option<(u64, usize)>> = Cell::new(None);
let insert_fn = |queue: &mut PriorityQueue<u64, u64>,
shadow_queue: &mut BTreeMap<(u64, usize), u64>,
key,
value| {
queue.insert(key, value);
shadow_queue.insert((key, epoch.get()), value);
epoch.set(epoch.get() + 1);
};
let insert_and_mark_fn = |queue: &mut PriorityQueue<u64, u64>,
shadow_queue: &mut BTreeMap<(u64, usize), u64>,
key,
value| {
marked.set(Some(queue.insert(key, value)));
shadow_queue.insert((key, epoch.get()), value);
shadow_marked.set(Some((key, epoch.get())));
epoch.set(epoch.get() + 1);
};
let pull_fn = |queue: &mut PriorityQueue<u64, u64>,
shadow_queue: &mut BTreeMap<(u64, usize), u64>| {
let value = queue.pull();
let shadow_value = match shadow_queue.iter().next() {
Some((&unique_key, &value)) => {
shadow_queue.remove(&unique_key);
Some((unique_key.0, value))
}
None => None,
};
assert_eq!(value, shadow_value);
};
let delete_marked_fn =
|queue: &mut PriorityQueue<u64, u64>,
shadow_queue: &mut BTreeMap<(u64, usize), u64>| {
let success = match marked.take() {
Some(delete_key) => Some(queue.delete(delete_key)),
None => None,
};
let shadow_success = match shadow_marked.take() {
Some(delete_key) => Some(shadow_queue.remove(&delete_key).is_some()),
None => None,
};
assert_eq!(success, shadow_success);
};
// Fuzz away.
let mut queue = PriorityQueue::new();
let mut shadow_queue = BTreeMap::new();
let rng = Rng::new(12345);
const TOTAL_WEIGHT: u64 =
INSERT_WEIGHT + INSERT_AND_MARK_WEIGHT + PULL_WEIGHT + DELETE_MARKED_WEIGHT;
for _ in 0..ITER {
// Randomly choose one of the 4 possible operations, respecting the
// probability weights.
let mut op = rng.gen_bounded(TOTAL_WEIGHT);
if op < INSERT_WEIGHT {
let key = rng.gen_bounded(MAX_KEY + 1);
let val = rng.gen();
insert_fn(&mut queue, &mut shadow_queue, key, val);
continue;
}
op -= INSERT_WEIGHT;
if op < INSERT_AND_MARK_WEIGHT {
let key = rng.gen_bounded(MAX_KEY + 1);
let val = rng.gen();
insert_and_mark_fn(&mut queue, &mut shadow_queue, key, val);
continue;
}
op -= INSERT_AND_MARK_WEIGHT;
if op < PULL_WEIGHT {
pull_fn(&mut queue, &mut shadow_queue);
continue;
}
delete_marked_fn(&mut queue, &mut shadow_queue);
}
} }
} }