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//! Implements actors and related types of Maxim. //! //! These are the core components that make up the features of Maxim. The actor model is //! designed to allow the user maximum flexibility. The actors can skip messages if they choose, //! enabling them to work as a *finite state machine* without having to move messages around. Actors //! are created by calling `system::spawn().with()` with any kind of function or closure that //! implements the `Processor` trait. use crate::message::ActorMessage; use crate::prelude::*; use futures::{FutureExt, Stream}; use log::{debug, error, trace, warn}; #[cfg(feature = "actor-pool")] use rand::{ distributions::{Distribution, Uniform}, SeedableRng, }; #[cfg(feature = "actor-pool")] use rand_xoshiro::Xoshiro256Plus; use secc::*; use serde::de::Deserializer; use serde::ser::Serializer; use serde::{Deserialize, Serialize}; use std::cell::UnsafeCell; use std::fmt::Debug; use std::future::Future; use std::hash::{Hash, Hasher}; use std::marker::{Send, Sync}; use std::panic::{catch_unwind, AssertUnwindSafe}; use std::pin::Pin; use std::ptr; use std::sync::atomic::{AtomicBool, Ordering}; use std::sync::Arc; use std::task::Poll; use std::time::Duration; use uuid::Uuid; /// Status of the message and potentially the actor as a resulting from processing a message /// with the actor. #[derive(Debug, Eq, PartialEq, Serialize, Deserialize)] pub enum Status { /// The message was processed and can be removed from the channel. Note that this doesn't /// necessarily mean that anything was done with the message, just that it can be removed. /// It is up to the actor to decide what, if anything, to do with the message. Done, /// The message was skipped and should remain in the channel. Once a message is skipped a skip /// cursor will be created in the actor's message channel which will act as the actual head /// of the channel until an [`Status::Reset`] is returned from an actor's processor. /// This enables an actor to skip messages while working on a process and then clear the skip /// cursor and resume normal processing. This functionality is critical for actors that /// implement a finite state machine. Skip, /// Marks the message as processed and clears the skip cursor on the channel. A skip cursor /// is present when a message has been skipped by an actor returning [`Status::Skip`] /// from a call to the actor's message processor. If no skip cursor is set than this status /// is semantically the same as [`Status::Done`]. Reset, /// Returned from an actor when the actor wants the system to stop the actor. When this status /// is returned the actor's [`Aid`] will no longer send any messages and the actor /// instance itself will be removed from the actors table in the [`ActorSystem`]. The user is /// advised to do any cleanup needed before returning [`Status::Stop`]. Stop, } impl Status { /// Ergonomic shortcut for writing `(state, Status::Done)` pub fn done<T>(state: T) -> (T, Status) { (state, Status::Done) } /// Ergonomic shortcut for writing `(state, Status::Skip)` pub fn skip<T>(state: T) -> (T, Status) { (state, Status::Skip) } /// Ergonomic shortcut for writing `(state, Status::Reset)` pub fn reset<T>(state: T) -> (T, Status) { (state, Status::Reset) } /// Ergonomic shortcut for writing `(state, Status::Stop)` pub fn stop<T>(state: T) -> (T, Status) { (state, Status::Stop) } } /// Errors returned by the Aid #[derive(Debug, PartialEq, Eq, Serialize, Deserialize)] pub enum AidError { /// This error is returned when a message cannot be converted to bincode. This will happen if /// the message is not Serde serializable and the user has not implemented ActorMessage to /// provide the correct implementation. CantConvertToBincode, /// This error is returned when a message cannot be converted from bincode. This will happen /// if the message is not Serde serializable and the user has not implemented ActorMessage to /// provide the correct implementation. CantConvertFromBincode, /// Error sent when attempting to send to an actor that has already been stopped. A stopped /// actor cannot accept any more messages and is shut down. The holder of an [`Aid`] to /// a stopped actor should throw the [`Aid`] away as the actor can never be started again. ActorAlreadyStopped, /// Error returned when an Aid is not local and a user is trying to do operations that /// only work on local Aid instances. AidNotLocal, /// Used when unable to send to an actor's message channel within the scheduled timeout /// configured in the actor system. This could result from the actor's channel being too /// small to accommodate the message flow, the lack of thread count to process messages fast /// enough to keep up with the flow or something wrong with the actor itself that it is /// taking too long to clear the messages. SendTimedOut(Aid), /// Used when unable to schedule the actor for work in the work channel. This could be a /// result of having a work channel that is too small to accommodate the number of actors /// being concurrently scheduled, not enough threads to process actors in the channel fast /// enough or simply an actor that misbehaves, causing dispatcher threads to take a lot of /// time or not finish at all. UnableToSchedule, } impl std::fmt::Display for AidError { fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { write!(f, "{:?}", self) } } impl std::error::Error for AidError {} /// An enum that holds a sender for an actor. /// /// An [`Aid`] uses the sender to send messages to the destination actor. Messages that are /// sent to actors running on this actor system are wrapped in an Arc for efficiency. enum ActorSender { /// A sender used for sending messages to actors running on the same actor system. Local { /// Holds a boolean to indicate if the actor is stopped. A stopped actor will no longer /// accept further messages to be sent. stopped: AtomicBool, /// The send side of the actor's message channel. sender: SeccSender<Message>, /// The reference to the local [`ActorSystem`] that the `aid` is on. system: ActorSystem, }, /// A sender that is used when an actor is on another actor system. Messages are wrapped in a /// [`WireMessage`] struct and it will be up to the cluster implementation to get the messages /// to the remote system. Remote { sender: SeccSender<WireMessage> }, } impl std::fmt::Debug for ActorSender { fn fmt(&self, formatter: &'_ mut std::fmt::Formatter) -> std::fmt::Result { write!( formatter, "{}", match *self { ActorSender::Local { .. } => "ActorSender::Local", ActorSender::Remote { .. } => "ActorSender::Remote", } ) } } /// The inner data of an [`Aid`]. /// /// This is kept separate to make serialization possible without duplicating all of the data /// associated with the [`Aid`]. It also makes it easier when cloning and referring to an /// `aid` as the user doesnt have to put `Arc<Aid>` all over their code. struct AidData { /// See [`Aid::uuid()`] uuid: Uuid, /// See [`Aid::system_uuid()`] system_uuid: Uuid, /// See [`Aid::name()`] name: Option<String>, /// The handle to the sender side for the actor's message channel. sender: ActorSender, } /// A helper type to make [`Aid`] serialization cleaner. #[derive(Serialize, Deserialize)] struct AidSerializedForm { uuid: Uuid, system_uuid: Uuid, name: Option<String>, } /// Encapsulates an Actor ID and is used to send messages to the actor. /// /// This is a unique reference to the actor within the entire cluster and can be used to send /// messages to the actor regardless of location. The [`Aid`] does the heavy lifting of /// deciding where the actor is and sending the message. However it is important that the user at /// least has some notion of where the actor is for developing an efficient actor architecture. /// This `aid` can also be serialized to a remote system and then back to the system hosting the /// actor without issue. Often `Aid`s are passed around an actor system so this is a common /// use case. #[derive(Clone)] pub struct Aid { /// Holds the actual data for the [`Aid`]. data: Arc<AidData>, } impl Serialize for Aid { fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where S: Serializer, { let serialized_form = AidSerializedForm { uuid: self.uuid(), system_uuid: self.system_uuid(), name: self.name(), }; serialized_form.serialize(serializer) } } impl<'de> Deserialize<'de> for Aid { fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: Deserializer<'de>, { let serialized_form = AidSerializedForm::deserialize(deserializer)?; let system = ActorSystem::current(); // We will look up the aid in the actor system and return a clone to the caller if found; // otherwise the Aid must be a on a remote actor system. match system.find_aid_by_uuid(&serialized_form.uuid) { Some(aid) => Ok(aid), None => { if serialized_form.system_uuid == system.uuid() { // This could happen if you get an Aid to an actor that has already been // stopped and then attempt to deserialize it. Err(serde::de::Error::custom(format!( "{:?}:{} system uuid matches but the uuid was not found.", serialized_form.name, serialized_form.uuid, ))) } else if let Some(sender) = system.remote_sender(&serialized_form.system_uuid) { // This serialized Aid is on another actor system so we will create a remote // sender for the Aid and return the result. Ok(Aid { data: Arc::new(AidData { uuid: serialized_form.uuid, system_uuid: serialized_form.system_uuid, name: serialized_form.name, sender: ActorSender::Remote { sender }, }), }) } else { // This can happen if you get an Aid to deserialize that is on another actor // system but the other actor system has been disconnected. Err(serde::de::Error::custom(format!( "{:?}:{} Unable to find a connection for remote system.", serialized_form.name, serialized_form.uuid, ))) } } } } } impl std::cmp::PartialEq for Aid { fn eq(&self, other: &Self) -> bool { self.data.uuid == other.data.uuid && self.data.system_uuid == other.data.system_uuid } } impl std::cmp::Eq for Aid {} impl std::cmp::PartialOrd for Aid { fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> { use std::cmp::Ordering; // Order by name, then by system, then by uuid. Also, sort `None` names before others. match (&self.data.name, &other.data.name) { (None, Some(_)) => Some(Ordering::Less), (Some(_), None) => Some(Ordering::Greater), (Some(a), Some(b)) if a != b => Some(a.cmp(b)), (_, _) => { // Names are equal, either both `None` or `Some(thing)` where `thing1 == thing2` // so we impose a secondary order by system uuid. match self.data.system_uuid.cmp(&other.data.system_uuid) { Ordering::Equal => Some(self.data.uuid.cmp(&other.data.uuid)), x => Some(x), } } } } } impl std::cmp::Ord for Aid { fn cmp(&self, other: &Self) -> std::cmp::Ordering { self.partial_cmp(other) .expect("Aid::partial_cmp() returned None; can't happen") } } impl Aid { /// Attempts to send a message to the actor with the given [`Aid`] and returns /// `std::Result::Ok` when the send was successful or a `std::Result::Err<MaximError>` /// if something went wrong with the send. Note that if a user just calls `send(msg).unwrap()`, /// a panic could take down the dispatcher thread and thus eventually hang the process. /// /// # Examples /// ``` /// use maxim::prelude::*; /// use std::sync::Arc; /// use std::time::Duration; /// /// let system = ActorSystem::create(ActorSystemConfig::default().thread_pool_size(2)); /// /// let aid = system /// .spawn() /// .with( /// 0 as usize, /// |state: usize, context: Context, message: Message| async move { /// if let Some(_) = message.content_as::<i32>() { /// context.system.trigger_shutdown(); /// } /// Ok(Status::done(state)) /// }, /// ) /// .unwrap(); /// /// match aid.send(Message::new(11)) { /// Ok(_) => println!("OK Then!"), /// Err(e) => println!("Ooops {:?}", e), /// } /// /// system.await_shutdown(None); /// ``` pub fn send(&self, message: Message) -> Result<(), AidError> { match &self.data.sender { ActorSender::Local { stopped, sender, system, } => { if stopped.load(Ordering::Relaxed) { Err(AidError::ActorAlreadyStopped) } else { match sender.send_await_timeout(message, system.config().send_timeout) { Ok(_) => { if sender.receivable() == 1 { system.schedule(self.clone()); }; Ok(()) } Err(_) => Err(AidError::SendTimedOut(self.clone())), } } } ActorSender::Remote { sender } => { sender .send_await(WireMessage::ActorMessage { actor_uuid: self.data.uuid, system_uuid: self.data.system_uuid, message, }) .unwrap(); Ok(()) } } } /// Shortcut for calling `send(Message::from_arc(arc))` This method will internally wrap the /// `Arc` passed into a `Message` and try to send it. Note that using this method is much /// more efficient than `send_new` if you want to send an `Arc` that you already have. /// The `Arc` sent will be transferred to the ownership of the `Aid`. /// /// ``` /// use maxim::prelude::*; /// use std::sync::Arc; /// use std::time::Duration; /// /// let system = ActorSystem::create(ActorSystemConfig::default().thread_pool_size(2)); /// /// let aid = system /// .spawn() /// .with( /// 0 as usize, /// |state: usize, context: Context, message: Message| async move { /// if let Some(_) = message.content_as::<i32>() { /// context.system.trigger_shutdown(); /// } /// Ok(Status::done(state)) /// }, /// ) /// .unwrap(); /// /// let arc = Arc::new(11 as i32); /// match aid.send_arc(arc.clone()) { /// Ok(_) => println!("OK Then!"), /// Err(e) => println!("Ooops {:?}", e), /// } /// /// system.await_shutdown(None); /// ``` pub fn send_arc<T>(&self, value: Arc<T>) -> Result<(), AidError> where T: 'static + ActorMessage, { self.send(Message::from_arc(value)) } /// Shortcut for calling `send(Message::new(value))` This method will internally wrap /// whatever it is passed into a `Message` and try to send it. This method would not be /// appropriate if you want to re-send a message as it would wrap the message again with the /// same result as if the the code called `aid.send(Message::new(Message::new(value)))`. /// If the code wishes to resend a message it should just call just call `send(msg)`. /// /// ``` /// use maxim::prelude::*; /// use std::sync::Arc; /// use std::time::Duration; /// /// let system = ActorSystem::create(ActorSystemConfig::default().thread_pool_size(2)); /// /// let aid = system /// .spawn() /// .with( /// 0 as usize, /// |state: usize, context: Context, message: Message| async move { /// if let Some(_) = message.content_as::<i32>() { /// context.system.trigger_shutdown(); /// } /// Ok(Status::done(state)) /// }, /// ) /// .unwrap(); /// /// match aid.send_new(11) { /// Ok(_) => println!("OK Then!"), /// Err(e) => println!("Ooops {:?}", e), /// } /// /// system.await_shutdown(None); /// ``` pub fn send_new<T>(&self, value: T) -> Result<(), AidError> where T: 'static + ActorMessage, { self.send(Message::new(value)) } /// Schedules the given message to be sent after a minimum of the specified duration. Note /// that Maxim doesn't guarantee that the message will be sent on exactly now + duration but /// rather that _at least_ the duration will pass before the message is sent to the actor. /// Maxim will try to send as close as possible without going under the amount but precise /// timing should not be depended on. This method will return an `Err` if the actor has been /// stopped or `Ok` if the message was scheduled to be sent. If the actor is stopped before /// the duration passes then the scheduled message will never get to the actor. /// /// # Examples /// ``` /// use maxim::prelude::*; /// use std::sync::Arc; /// use std::time::Duration; /// /// let system = ActorSystem::create(ActorSystemConfig::default().thread_pool_size(2)); /// /// let aid = system /// .spawn() /// .with( /// 0 as usize, /// |state: usize, context: Context, message: Message| async move { /// if let Some(_) = message.content_as::<i32>() { /// context.system.trigger_shutdown(); /// } /// Ok(Status::done(state)) /// }, /// ) /// .unwrap(); /// /// match aid.send_after(Message::new(11), Duration::from_millis(1)) { /// Ok(_) => println!("OK Then!"), /// Err(e) => println!("Ooops {:?}", e), /// } /// /// system.await_shutdown(None); /// ``` pub fn send_after(&self, message: Message, duration: Duration) -> Result<(), AidError> { match &self.data.sender { ActorSender::Local { stopped, system, .. } => { if stopped.load(Ordering::Relaxed) { Err(AidError::ActorAlreadyStopped) } else { system.send_after(message, self.clone(), duration); Ok(()) } } ActorSender::Remote { sender } => { if let Err(err) = sender.send_await(WireMessage::DelayedActorMessage { duration, actor_uuid: self.data.uuid, system_uuid: self.data.system_uuid, message, }) { // Right now, this is the full extent of errors, but if that should change, it // should create a compiler error. return match err { SeccErrors::Full(_) | SeccErrors::Empty => Ok(()), }; } Ok(()) } } } /// Shortcut for calling `send_after(Message::from_arc(arc))` This method will internally /// wrap the `Arc` passed into a `Message` and try to send it. Note that using this method is /// much more efficient than `send_new_after` if you want to send an `Arc` that you already /// have. /// /// # Examples /// ``` /// use maxim::prelude::*; /// use std::sync::Arc; /// use std::time::Duration; /// /// let system = ActorSystem::create(ActorSystemConfig::default().thread_pool_size(2)); /// /// let aid = system /// .spawn() /// .with( /// 0 as usize, /// |state: usize, context: Context, message: Message| async move { /// if let Some(_) = message.content_as::<i32>() { /// context.system.trigger_shutdown(); /// } /// Ok(Status::done(state)) /// }, /// ) /// .unwrap(); /// /// let arc = Arc::new(11); /// match aid.send_arc_after(arc.clone(), Duration::from_millis(1)) { /// Ok(_) => println!("OK Then!"), /// Err(e) => println!("Ooops {:?}", e), /// } /// /// system.await_shutdown(None); /// ``` pub fn send_arc_after<T>(&self, value: Arc<T>, duration: Duration) -> Result<(), AidError> where T: 'static + ActorMessage, { self.send_after(Message::from_arc(value), duration) } /// Shortcut for calling `send_after(Message::new(value))` This method will internally wrap /// whatever it is passed into a `Message` and try to send it. This method would not be /// appropriate if you want to re-send a message as it would wrap the message again with the /// same result as if the the code called `aid.send_after(Message::new(Message::new(value)))`. /// If the code wishes to resend a message it should just call just call `send(msg)`. /// /// # Examples /// ``` /// use maxim::prelude::*; /// use std::sync::Arc; /// use std::time::Duration; /// /// let system = ActorSystem::create(ActorSystemConfig::default().thread_pool_size(2)); /// /// let aid = system /// .spawn() /// .with( /// 0 as usize, /// |state: usize, context: Context, message: Message| async move { /// if let Some(_) = message.content_as::<i32>() { /// context.system.trigger_shutdown(); /// } /// Ok(Status::done(state)) /// }, /// ) /// .unwrap(); /// /// match aid.send_new_after(11, Duration::from_millis(1)) { /// Ok(_) => println!("OK Then!"), /// Err(e) => println!("Ooops {:?}", e), /// } /// /// system.await_shutdown(None); /// ``` pub fn send_new_after<T>(&self, value: T, duration: Duration) -> Result<(), AidError> where T: 'static + ActorMessage, { self.send_after(Message::new(value), duration) } /// The unique UUID for this actor within the entire cluster. The UUID for an [`Aid`] /// is generated with a v4 random UUID so the chances of collision are not worth considering. #[inline] pub fn uuid(&self) -> Uuid { self.data.uuid } /// The unique UUID for the actor system that this actor lives on. As with `uuid` this value /// is a v4 UUID and so the chances of two systems having the same uuid is inconsequential. #[inline] pub fn system_uuid(&self) -> Uuid { self.data.system_uuid } /// The name of the actor as assigned by the user at spawn time if any. Note that this name /// is guaranteed to be unique only within the actor system in which the actor was spawned; /// no guarantees are made that the name will be unique within a cluster of actor systems. #[inline] pub fn name(&self) -> Option<String> { self.data.name.clone() } /// Returns the name assigned to the Aid if it is not a `None` and otherwise returns the /// uuid of the actor as a string. #[inline] pub fn name_or_uuid(&self) -> String { match &self.data.name { Some(value) => value.to_string(), None => self.data.uuid.to_string(), } } /// Determines if this actor lives on the local actor system or another system in the same /// process. Actors that are local to each other can exchange large amounts of data /// efficiently through passing [`Arc`]s. #[inline] pub fn is_local(&self) -> bool { if let ActorSender::Local { .. } = self.data.sender { true } else { false } } /// Determines how many messages the actor with the [`Aid`] has been sent. This method works only /// for local [`Aid`]s, remote [`Aid`]s will return an error if this is called. pub fn sent(&self) -> Result<usize, AidError> { match &self.data.sender { ActorSender::Local { sender, .. } => Ok(sender.sent()), _ => Err(AidError::AidNotLocal), } } /// Determines how many messages the actor with the [`Aid`] has received. This method works only /// for local [`Aid`]s, remote [`Aid`]s will return an error if this is called. pub fn received(&self) -> Result<usize, AidError> { match &self.data.sender { ActorSender::Local { sender, .. } => Ok(sender.received()), _ => Err(AidError::AidNotLocal), } } /// Marks the actor referenced by the [`Aid`] as stopped and puts mechanisms in place to /// cause no more messages to be sent to the actor. Note that once stopped, an [`Aid`] can /// never be started again. Note that this is `pub(crate)` because the user should be sending /// `SystemMsg::Stop` to actors or, at worst, calling `ActorSystem::stop()` to stop an actor. pub(crate) fn stop(&self) -> Result<(), AidError> { match &self.data.sender { ActorSender::Local { stopped, .. } => { trace!("Stopping local Actor"); stopped.fetch_or(true, Ordering::AcqRel); Ok(()) } _ => Err(AidError::AidNotLocal), } } /// Checks to see if the left and right aid actually point at the exact same actor. pub fn ptr_eq(left: &Aid, right: &Aid) -> bool { Arc::ptr_eq(&left.data, &right.data) } } impl AidPool for Aid { /// See [`Aid::send`] #[inline] fn send(&mut self, message: Message) -> Result<(), AidError> { Aid::send(self, message) } /// See [`Aid::send_arc`] #[inline] fn send_arc<T>(&mut self, value: Arc<T>) -> Result<(), AidError> where T: 'static + ActorMessage, { Aid::send_arc(self, value) } /// See [`Aid::send_new`] #[inline] fn send_new<T>(&mut self, value: T) -> Result<(), AidError> where T: 'static + ActorMessage, { Aid::send_new(self, value) } /// See [`Aid::send_after`] #[inline] fn send_after(&mut self, message: Message, duration: Duration) -> Result<(), AidError> { Aid::send_after(self, message, duration) } /// See [`Aid::send_arc_after`] #[inline] fn send_arc_after<T>(&mut self, value: Arc<T>, duration: Duration) -> Result<(), AidError> where T: 'static + ActorMessage, { Aid::send_arc_after(self, value, duration) } /// See [`Aid::send_new_after`] #[inline] fn send_new_after<T>(&mut self, value: T, duration: Duration) -> Result<(), AidError> where T: 'static + ActorMessage, { Aid::send_new_after(self, value, duration) } } impl std::fmt::Debug for Aid { fn fmt(&self, formatter: &'_ mut std::fmt::Formatter) -> std::fmt::Result { write!( formatter, "Aid{{id: {}, system_uuid: {}, name: {:?}, is_local: {}}}", self.data.uuid.to_string(), self.data.system_uuid.to_string(), self.data.name, self.is_local() ) } } impl std::fmt::Display for Aid { fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { match &self.data.name { Some(name) => write!(f, "{}:{}", name, self.data.uuid), None => write!(f, "{}", self.data.uuid), } } } impl Hash for Aid { fn hash<H: Hasher>(&self, state: &'_ mut H) { self.data.uuid.hash(state); self.data.system_uuid.hash(state); } } /// Represents a pool of actor ids in which you don't care *which* actor recieves a /// message. /// /// When a message is sent to a pool, only one actor in the pool will receive the message. Different /// [`AidPool`] implementations may have different ways of determining which actor to send a message /// to. The implmentation may send a message to a random actor or it may go in order, for example. /// /// [`Aid`]'s also implement [`AidPool`] so an [`Aid`] can be used wherever a generic [`AidPool`] is /// expected. pub trait AidPool { /// See [`Aid::send`] fn send(&mut self, message: Message) -> Result<(), AidError>; /// See [`Aid::send_arc`] fn send_arc<T>(&mut self, value: Arc<T>) -> Result<(), AidError> where T: 'static + ActorMessage; /// See [`Aid::send_new`] fn send_new<T>(&mut self, value: T) -> Result<(), AidError> where T: 'static + ActorMessage; /// See [`Aid::send_after`] fn send_after(&mut self, message: Message, duration: Duration) -> Result<(), AidError>; /// See [`Aid::send_arc_after`] fn send_arc_after<T>(&mut self, value: Arc<T>, duration: Duration) -> Result<(), AidError> where T: 'static + ActorMessage; /// See [`Aid::send_new_after`] fn send_new_after<T>(&mut self, value: T, duration: Duration) -> Result<(), AidError> where T: 'static + ActorMessage; } /// A helper trait that is simply an AidPool that can be passed between actors, i.e. it is /// `Sync + Send + Clone + 'static`. This is useful when you want to make a function generic over /// [`AidPool`] but you need to be able to give the poool to actor. pub trait SyncAidPool: AidPool + Sync + Send + Clone + 'static {} // Auto implement SyncAidPool for complying [`AidPool`]s impl<T: AidPool + Sync + Send + Clone + 'static> SyncAidPool for T {} /// An [`AidPool`] that sends messages to a random [`Aid`] in the pool. #[derive(Debug)] #[cfg(feature = "actor-pool")] pub struct RandomAidPool { /// The list of contained [`Aid`]s aids: Vec<Aid>, /// The random number generator used to pick a random [`Aid`] rng: Xoshiro256Plus, /// The uniform range for generating random numbers withing the range of available /// [`Aid`]s. uniform: Uniform<usize>, } #[cfg(feature = "actor-pool")] impl RandomAidPool { /// Create a [`RandomAidPool`] from a vector of [`Aid`]s pub fn new(aids: Vec<Aid>) -> Self { let len = aids.len(); RandomAidPool { aids, rng: Xoshiro256Plus::seed_from_u64(0), uniform: Uniform::from(0..len), } } } #[cfg(feature = "actor-pool")] impl AidPool for RandomAidPool { /// See [`Aid::send`] #[inline] fn send(&mut self, message: Message) -> Result<(), AidError> { self.aids[self.uniform.sample(&mut self.rng)].send(message) } /// See [`Aid::send_arc`] #[inline] fn send_arc<T>(&mut self, value: Arc<T>) -> Result<(), AidError> where T: 'static + ActorMessage, { self.aids[self.uniform.sample(&mut self.rng)].send_arc(value) } /// See [`Aid::send_new`] #[inline] fn send_new<T>(&mut self, value: T) -> Result<(), AidError> where T: 'static + ActorMessage, { self.aids[self.uniform.sample(&mut self.rng)].send_new(value) } /// See [`Aid::send_after`] #[inline] fn send_after(&mut self, message: Message, duration: Duration) -> Result<(), AidError> { self.aids[self.uniform.sample(&mut self.rng)].send_after(message, duration) } /// See [`Aid::send_arc_after`] #[inline] fn send_arc_after<T>(&mut self, value: Arc<T>, duration: Duration) -> Result<(), AidError> where T: 'static + ActorMessage, { self.aids[self.uniform.sample(&mut self.rng)].send_arc_after(value, duration) } /// See [`Aid::send_new_after`] #[inline] fn send_new_after<T>(&mut self, value: T, duration: Duration) -> Result<(), AidError> where T: 'static + ActorMessage, { self.aids[self.uniform.sample(&mut self.rng)].send_new_after(value, duration) } } #[cfg(feature = "actor-pool")] impl From<Vec<Aid>> for RandomAidPool { fn from(aids: Vec<Aid>) -> Self { Self::new(aids) } } #[cfg(feature = "actor-pool")] impl Into<Vec<Aid>> for RandomAidPool { fn into(self) -> Vec<Aid> { self.aids } } #[cfg(feature = "actor-pool")] impl Clone for RandomAidPool { fn clone(&self) -> Self { // Jump the rng to prevent colliding random numbers from this cloned pool let mut new_rng = self.rng.clone(); new_rng.jump(); RandomAidPool { aids: self.aids.clone(), rng: new_rng, uniform: self.uniform, } } } /// A context that is passed to the processor to give immutable access to elements of the actor /// system to the implementor of an actor's processor. #[derive(Clone, Debug)] pub struct Context { pub aid: Aid, pub system: ActorSystem, } impl std::fmt::Display for Context { fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { write!( f, "Context{{aid: {}, system: {}}}", self.aid.uuid(), self.system.uuid() ) } } /// A type for a function that processes messages for an actor. /// /// This will be passed to a spawn function to specify the function used for managing the state of /// the actor based on the messages passed to the actor. The processor should return the status of /// the actor, as well as the potentially modified state. If the actor returns `Err` then it will be /// stopped as if the actor had returned `Stop`. The processor takes three arguments: /// * `state` - The current state of the actor. /// * `context` - The immutable context for this actor and its system. /// * `message` - The current message to process. /// The actor must return the state on success as a `(State, Status)` tuple. See [`Status`] for /// helper methods for returns. pub trait Processor<S: Send + Sync, R: Future<Output = ActorResult<S>> + Send + 'static>: (FnMut(S, Context, Message) -> R) + Send + Sync { } // Allows any static function or closure, to be used as a Processor. impl<F, S, R> Processor<S, R> for F where S: Send + Sync, R: Future<Output = ActorResult<S>> + Send + 'static, F: (FnMut(S, Context, Message) -> R) + Send + Sync + 'static, { } pub(crate) type HandlerFuture = Pin<Box<dyn Future<Output = Result<Status, StdError>> + Send + 'static>>; /// This is the internal type for the handler that will manage the state for the actor using the /// user-provided message processor. pub(crate) trait Handler: (FnMut(Context, Message) -> HandlerFuture) + Send + Sync + 'static { } // Allows any static function or closure, to be used as a Handler. impl<F> Handler for F where F: (FnMut(Context, Message) -> HandlerFuture) + Send + Sync + 'static {} /// A builder that can be used to create and spawn an actor. To get a builder, the user would ask /// the actor system to create one using `system.spawn()` and then to spawn the actor by means of /// the the `with` method on the builder. See [`ActorSystem::spawn`] for more information. #[derive(Clone)] pub struct ActorBuilder { /// The System that the actor builder was created on. pub(crate) system: ActorSystem, /// The optional name of the actor which defaults to `None` meaning the actor will be unnamed. pub name: Option<String>, /// The size of the message channel for the actor which defaults to `None`; meaning the /// default for the actor system will be used for the message channel. pub channel_size: Option<u16>, } impl ActorBuilder { /// Completes the spawning of the the actor configured with this builder on the system, /// consuming the builder in the process and using the provided state and handler. See /// `ActorSystem::spawn` for more information and examples. /// // FIXME Consider implementing `using` to spawn a stateless actor. pub fn with<F, S, R>(self, state: S, processor: F) -> Result<Aid, SystemError> where S: Send + Sync + 'static, R: Future<Output = ActorResult<S>> + Send + 'static, F: Processor<S, R> + 'static, { let (actor, stream) = Actor::new(self.system.clone(), &self, state, processor); debug!("Actor created: {}", actor.context.aid.uuid()); self.system.register_actor(actor, stream) } /// Set the name of the actor to the given string. pub fn name(mut self, name: impl Into<String>) -> Self { self.name = Some(name.into()); self } /// Set the size of the channel to the given value instead of the default for the actor system /// that the actor is spawned on. Note that passing a value less than 1 will cause a panic and /// there would be little reason to do so anyway. pub fn channel_size(mut self, size: u16) -> Self { assert!(size > 0); self.channel_size = Some(size); self } } /// A builder than can be used to spawn an actor pool.Uniform /// /// See [`ActorBuilder`]. #[cfg(feature = "actor-pool")] pub struct ActorPoolBuilder { /// The actor builder used to build the actors in the pool builder: ActorBuilder, /// The number of actors to build in the pool count: usize, } #[cfg(feature = "actor-pool")] impl ActorPoolBuilder { /// Create a new [`ActorPoolBuilder`] from a normal [`ActorBuilder`]. pub fn new(builder: ActorBuilder, count: usize) -> Self { ActorPoolBuilder { builder, count } } /// See [`ActorBuilder::with`] pub fn with<F, S, R, P>(self, state: S, processor: F) -> Result<P, SystemError> where S: Clone + Send + Sync + 'static, R: Future<Output = ActorResult<S>> + Send + 'static, F: Processor<S, R> + Clone + 'static, P: AidPool + From<Vec<Aid>>, { let mut aids = Vec::with_capacity(self.count); for i in 0..self.count { // Clone the builder let mut b = self.builder.clone(); // Add index as name suffix b.name = b.name.map(|name| format!("{}_{}", name, i)); // Add aid to list aids.push(b.with(state.clone(), processor.clone())?) } // Return an `AidPool` from the list of `Aid`s Ok(P::from(aids)) } /// Set the base name for the actors created in this pool. /// /// The name will be suffixed with "_{index}" to make the name unique. For example, if you /// set the name to "worker" and there were 3 actors in the pool, you would end up with the /// actors with the names: "worker_0", "worker_1", "worker_2". pub fn name(mut self, name: impl Into<String>) -> Self { self.builder = self.builder.name(name); self } /// See [`ActorBuilder::channel_size`] pub fn channel_size(mut self, size: u16) -> Self { self.builder = self.builder.channel_size(size); self } } pub(crate) struct ActorStream { /// The context data for the actor containing the [`Aid`] as well as other immutable data. pub context: Context, /// Receiver for the actor's message channel. receiver: SeccReceiver<Message>, /// An async function processing a message sent to the actor, wrapped in a closure to /// erase the state type that the actor is managing. The inner state is Arc<Mutex>'d to /// ensure the Actor is synchronous in relation to itself. handler: Box<dyn Handler>, /// The pending result of the current handler invocation. pending: Option<HandlerFuture>, /// Set to true when the stream receives SystemMsg::Stop stopping: bool, } /// The implementation of the actor in the system. Please see overview and library documentation /// for more detail. pub(crate) struct Actor { /// The context data for the actor containing the `aid` as well as other immutable data. pub context: Context, } /// This is exclusively used in contexts we can be more than confident are safe. /// This is required for holding onto the Actor State. #[repr(transparent)] struct SendSyncPointer<T>(*mut T); /// This is exclusively used in contexts we can be more than confident are safe. /// This is required for holding onto the Actor State. #[repr(transparent)] struct SendSyncUnsafeCell<T>(UnsafeCell<T>); unsafe impl<T> Send for SendSyncPointer<T> {} unsafe impl<T> Sync for SendSyncPointer<T> {} unsafe impl<T> Send for SendSyncUnsafeCell<T> {} unsafe impl<T> Sync for SendSyncUnsafeCell<T> {} impl Actor { /// Creates a new actor on the given actor system with the given processor function. The user /// will pass the initial state of the actor as well as the processor that will be used to /// process messages sent to the actor. pub(crate) fn new<F, S, R>( system: ActorSystem, builder: &ActorBuilder, state: S, mut processor: F, ) -> (Arc<Actor>, ActorStream) where S: Send + Sync + 'static, R: Future<Output = ActorResult<S>> + Send + 'static, F: Processor<S, R> + 'static, { let (sender, receiver) = secc::create::<Message>( builder .channel_size .unwrap_or(system.config().message_channel_size), Duration::from_millis(10), ); // The sender will be put inside the actor id. let aid = Aid { data: Arc::new(AidData { uuid: Uuid::new_v4(), system_uuid: system.uuid(), name: builder.name.clone(), sender: ActorSender::Local { system: system.clone(), stopped: AtomicBool::new(false), sender, }, }), }; // Here we wrap the state in an UnsafeCell so we can do more performant retention of state. // While it might normally be prudent to have the unsafe block encompass the code that keeps // the safe guarantees, that isn't possible here as the guarantees are the same that keep // the Actor Model sound, and are stretched across multiple parts of the infrastructure. If // the unsoundness of this were to leak, there would be problems beyond this one UnsafeCell. let state_box = SendSyncUnsafeCell(UnsafeCell::new(Some(state))); let handler = Box::new(move |ctx: Context, msg: Message| { let state = SendSyncPointer(state_box.0.get()); let s = unsafe { (*state.0).take() }.expect("State cell was empty"); let future = catch_unwind(AssertUnwindSafe(|| (processor)(s, ctx, msg))); async move { match future { Ok(future) => match AssertUnwindSafe(future).catch_unwind().await { Ok(x) => x, Err(panic) => { warn!("Actor panicked! Catching as error"); Err(Panic::from(panic).into()) } }, Err(err) => { warn!("Actor panicked! Catching as error"); Err(Panic::from(err).into()) } } .map(|(s, status)| { unsafe { ptr::write(state.0, Some(s)) }; status }) } .boxed() }); // This is the receiving side of the actor which holds the processor wrapped in the // handler type. let context = Context { aid, system }; let actor = Actor { context: context.clone(), }; let stream = ActorStream { context, receiver, handler, pending: None, stopping: false, }; (Arc::new(actor), stream) } } impl ActorStream { /// This takes the result and executes the subsequent steps in respect to the result. Namely, /// handling the Actor's message channel and informing the ActorSystem of errors. Returns /// whether the Actor is stopping or not. pub(crate) fn handle_result(&self, result: Result<Status, StdError>) -> bool { let mut stopping = false; match result { Ok(Status::Done) => { trace!( "Actor {} finished processing a message", self.context.aid.uuid() ); self.receiver.pop().unwrap() } Ok(Status::Skip) => { trace!( "Actor {} skipped processing a message", self.context.aid.uuid() ); self.receiver.skip().unwrap() } Ok(Status::Reset) => { trace!( "Actor {} finished processing a message and reset the cursor", self.context.aid.uuid() ); self.receiver.pop().unwrap(); self.receiver.reset_skip().unwrap(); } Ok(Status::Stop) => { debug!("Actor \"{}\" stopping", self.context.aid.name_or_uuid()); self.receiver.pop().unwrap(); self.context .system .internal_stop_actor(&self.context.aid, None); stopping = true; } Err(e) => { self.receiver.pop().unwrap(); error!( "[{}] returned an error when processing: {}", self.context.aid, &e ); self.context .system .internal_stop_actor(&self.context.aid, e); stopping = true; } } stopping } fn overwrite_on_stop(&self, result: Result<Status, StdError>) -> Result<Status, StdError> { if self.stopping { result.map(|_| Status::Stop) } else { result } } } /// The meat of the Actor's handling impl Stream for ActorStream { type Item = Result<Status, StdError>; fn poll_next( mut self: Pin<&mut Self>, cx: &mut std::task::Context<'_>, ) -> Poll<Option<Self::Item>> { trace!("Actor {} is being polled", self.context.aid.name_or_uuid()); // If we have a pending future, that's what we poll. if let Some(pending) = self.pending.as_mut() { // Poll, ensure we respect stopping condition. let poll = pending .as_mut() .poll(cx) .map(|r| Some(self.overwrite_on_stop(r))); if let Poll::Pending = &poll { trace!("Actor {} is pending", self.context.aid.uuid()); } else { drop(self.pending.take()); } poll } else { // Are we stopped? If so, we should not have been polled, panic. This is only acceptable // because it means a bug in the Executor or Reactor. if self.stopping { panic!("Stopped ActorStream was polled after stopping. Please open a bug report.") } // Else, we go for another. match self.receiver.peek() { Ok(msg) => { // We're stopping after this future, mark as such if let Some(m) = msg.content_as::<SystemMsg>() { if let SystemMsg::Stop = *m { trace!("Actor {} received stop message", self.context.aid.uuid()); self.stopping = true; } } // Get the next future let ctx = self.context.clone(); let mut future = (&mut self.handler)(ctx, msg); // Just. give it a ~~wave~~ poll!! match future.as_mut().poll(cx) { Poll::Ready(r) => Poll::Ready(Some(self.overwrite_on_stop(r))), Poll::Pending => { trace!("Actor {} is pending", self.context.aid.uuid()); self.pending = Some(future); Poll::Pending } } } Err(err) => match err { // Ready(None) is standard for "Stream is depleted". The stream is effectively // monadic around the message queue, so if the channel is depleted, the stream // is as well. `Full` is non-contextual. // // While this is exhaustive, we're avoiding a catchall to in anticipation of // future Secc errors we would *want* to handle. SeccErrors::Empty | SeccErrors::Full(_) => { trace!( "Actor `{}` has no more messages, return to sleep", self.context.aid.name_or_uuid() ); Poll::Ready(None) } }, } } } } #[cfg(test)] mod tests { use super::*; use crate::tests::*; use log::*; use std::thread; use std::time::Instant; /// This is identical to the documentation but here so that its formatted by rust and we can /// copy paste this into the docs. It's also easier to debug here. #[test] fn test_send_examples() { let system = ActorSystem::create(ActorSystemConfig::default().thread_pool_size(2)); let aid = system .spawn() .with((), |_: (), context: Context, message: Message| async move { if let Some(_) = message.content_as::<i32>() { context.system.trigger_shutdown(); } Ok(Status::done(())) }) .unwrap(); match aid.send(Message::new(11)) { Ok(_) => info!("OK Then!"), Err(e) => info!("Ooops {:?}", e), } system.await_shutdown(None); } /// Tests that unserializable messages can be sent locally. #[test] fn test_send_unserializable() { use std::time::Duration; let system = ActorSystem::create(ActorSystemConfig::default().thread_pool_size(2)); // We declare a message type that we know is unserializable and then we implement the // `ActorMessage` with the default methods which error on attempting to serialize. Note // that this could be used for sending any unserialized type in other libs by simply // wrapping that value in a user-made struct. struct Foo {} impl ActorMessage for Foo {} assert!(Foo {}.to_bincode().is_err()); assert!(Foo::from_bincode(&vec![1, 2, 3]).is_err()); let aid = system .spawn() .with( (), move |_state: (), context: Context, message: Message| async move { if let Some(_) = message.content_as::<Foo>() { context.system.trigger_shutdown(); } Ok(Status::done(())) }, ) .unwrap(); aid.send(Message::new(Foo {})).unwrap(); await_received(&aid, 2, 1000).unwrap(); system.await_shutdown(Duration::from_millis(1000)); } /// This test verifies that an actor's functions that retrieve basic info are working for /// unnamed actors. #[test] fn test_basic_info_unnamed() { init_test_log(); let system = ActorSystem::create(ActorSystemConfig::default().thread_pool_size(2)); let aid = system.spawn().with((), simple_handler).unwrap(); await_received(&aid, 1, 1000).unwrap(); assert_eq!(system.uuid(), aid.data.system_uuid); assert_eq!(aid.data.system_uuid, aid.system_uuid()); assert_eq!(aid.data.uuid, aid.uuid()); assert_eq!(None, aid.data.name); assert_eq!(aid.data.name, aid.name()); system.trigger_and_await_shutdown(None); } /// This test verifies that an actor's functions that retrieve basic info are working for /// named actors. #[test] fn test_basic_info_named() { init_test_log(); let system = ActorSystem::create(ActorSystemConfig::default().thread_pool_size(2)); let aid = system.spawn().name("A").with((), simple_handler).unwrap(); await_received(&aid, 1, 1000).unwrap(); assert_eq!(system.uuid(), aid.data.system_uuid); assert_eq!(aid.data.system_uuid, aid.system_uuid()); assert_eq!(aid.data.uuid, aid.uuid()); assert_eq!(Some("A".to_string()), aid.data.name); assert_eq!(aid.data.name, aid.name()); system.trigger_and_await_shutdown(None); } /// Tests serialization and deserialization of `Aid`s. This verifies that deserialized /// `aid`s on the same actor system should just be the same `aid` as well as the fact that /// when deserialized on other actor systems the `aid`'s sender should be a remote aid. /// /// FIXME (Issue #70) Return error when deserializing an Aid if a remote is not connected /// instead of panic. #[test] fn test_aid_serialization() { let system = ActorSystem::create(ActorSystemConfig::default().thread_pool_size(2)); let aid1 = system.spawn().with((), simple_handler).unwrap(); system.init_current(); // Required by Aid serialization. // This check forces the test to break here if someone changes the default. match aid1.data.sender { ActorSender::Local { .. } => (), _ => panic!("The sender should be `Local`"), } let aid1_serialized = bincode::serialize(&aid1).unwrap(); let aid1_deserialized: Aid = bincode::deserialize(&aid1_serialized).unwrap(); // In this case the resulting Aid should be identical to the serialized one because // we have the same actor system in a thread-local. assert!(Aid::ptr_eq(&aid1, &aid1_deserialized)); // Spawn an actor and serialize the value but then stop the actor and try and deserialize // and we should get an error. let aid2 = system.spawn().with((), simple_handler).unwrap(); let aid2_serialized = bincode::serialize(&aid2).unwrap(); system.stop_actor(&aid2); let aid2_deserialized = bincode::deserialize::<Aid>(&aid2_serialized); assert!(aid2_deserialized.is_err()); // If we deserialize on another actor system in another thread it should be a remote aid. let handle = thread::spawn(move || { let system2 = ActorSystem::create(ActorSystemConfig::default().thread_pool_size(2)); system2.init_current(); // Connect the systems so the remote channel can be used. ActorSystem::connect_with_channels(&system, &system2); let deserialized: Aid = bincode::deserialize(&aid1_serialized).unwrap(); match deserialized.data.sender { ActorSender::Remote { .. } => { assert_eq!(aid1.uuid(), deserialized.uuid()); assert_eq!(aid1.system_uuid(), deserialized.system_uuid()); assert_eq!(aid1.name(), deserialized.name()); } _ => panic!( "The sender should be `Remote` but was {:?}", aid1.data.sender ), } // Disconnecting the remote then attempting to deserialize the Aid should result in a // deserialization error. system2.disconnect(aid1.system_uuid()).unwrap(); let aid1_deserialized = bincode::deserialize::<Aid>(&aid1_serialized); assert!(aid1_deserialized.is_err()); }); handle.join().unwrap(); } /// Tests that an Aid can be used as a message alone and inside another value. #[test] fn test_aid_as_message() { init_test_log(); let system = ActorSystem::create(ActorSystemConfig::default().thread_pool_size(2)); let tracker = AssertCollect::new(); let t = tracker.clone(); #[derive(Serialize, Deserialize)] enum Op { Aid(Aid), } let aid = system .spawn() .with( t, |t: AssertCollect, context: Context, message: Message| async move { if let Some(msg) = message.content_as::<Aid>() { t.assert(Aid::ptr_eq(&context.aid, &msg), "Aid mutated in transit"); } else if let Some(msg) = message.content_as::<Op>() { match &*msg { Op::Aid(a) => { t.assert(Aid::ptr_eq(&context.aid, &a), "Aid mutated in transit") } } } Ok(Status::done(t)) }, ) .unwrap(); // Send a message to the actor. aid.send_new(aid.clone()).unwrap(); aid.send_new(Op::Aid(aid.clone())).unwrap(); // Wait for the Start and our message to get there because test is asynchronous. await_received(&aid, 2, 1000).unwrap(); system.trigger_and_await_shutdown(None); tracker.collect(); } /// Tests that messages cannot be sent to an `aid` for an actor that has been stopped. #[test] fn test_cant_send_to_stopped() { let system = ActorSystem::create(ActorSystemConfig::default().thread_pool_size(2)); let aid = system.spawn().with((), simple_handler).unwrap(); system.stop_actor(&aid); assert_eq!(false, system.is_actor_alive(&aid)); // Make sure that the actor is actually stopped and can't get more messages. match aid.send(Message::new(42 as i32)) { Err(AidError::ActorAlreadyStopped) => assert!(true), // all OK! Ok(_) => panic!("Expected the actor to be shut down!"), Err(e) => panic!("Unexpected error: {:?}", e), } } /// Tests that an actor that returns stop is actually stopped by the system. #[test] fn test_actor_returns_stop() { init_test_log(); let system = ActorSystem::create(ActorSystemConfig::default().thread_pool_size(2)); let tracker = AssertCollect::new(); let t = tracker.clone(); let aid = system .spawn() .with( t, |t: AssertCollect, _: Context, message: Message| async move { if let Some(_msg) = message.content_as::<i32>() { Ok(Status::stop(t)) } else if let Some(msg) = message.content_as::<SystemMsg>() { match &*msg { SystemMsg::Start => Ok(Status::done(t)), m => t.panic(format!("unexpected message: {:?}", m)), } } else { t.panic("Unknown Message received") } }, ) .unwrap(); // Send a message to the actor. assert_eq!(true, system.is_actor_alive(&aid)); aid.send_new(11 as i32).unwrap(); await_received(&aid, 2, 1000).unwrap(); // Remember they always get `Start` as well! let max = Duration::from_millis(200); let start = Instant::now(); loop { if !system.is_actor_alive(&aid) { break; } else if max < Instant::elapsed(&start) { panic!("Timed out waiting for actor to stop!"); } sleep(1); } system.trigger_and_await_shutdown(None); tracker.collect(); } /// Tests that an actor cannot override the processing of a `Stop` message by returning a /// different `Status` variant other than `Stop`. #[test] fn test_actor_cannot_override_stop() { init_test_log(); let system = ActorSystem::create(ActorSystemConfig::default().thread_pool_size(2)); let tracker = AssertCollect::new(); let t = tracker.clone(); // FIXME (Issue #63) Create a processor type that doesn't use state. let aid = system .spawn() .with( t, |t: AssertCollect, _: Context, message: Message| async move { if let Some(msg) = message.content_as::<SystemMsg>() { match &*msg { SystemMsg::Start => Ok(Status::done(t)), SystemMsg::Stop => Ok(Status::done(t)), m => t.panic(format!("unexpected message: {:?}", m)), } } else { t.panic("Unknown Message received") } }, ) .unwrap(); // Send a message to the actor. assert_eq!(true, system.is_actor_alive(&aid)); aid.send_new(SystemMsg::Stop).unwrap(); await_received(&aid, 2, 1000).unwrap(); // Remember they always get `Start` as well! let max = Duration::from_millis(200); let start = Instant::now(); loop { if !system.is_actor_alive(&aid) { break; } else if max < Instant::elapsed(&start) { panic!("Timed out waiting for actor to stop!"); } sleep(1); } system.trigger_and_await_shutdown(None); tracker.collect(); } }