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bastion/src/bastion/src/children.rs

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//!
//! Children are a group of child supervised under a supervisor
use crate::broadcast::{Broadcast, Parent, Sender};
use crate::callbacks::{CallbackType, Callbacks};
use crate::child::{Child, Init};
use crate::child_ref::ChildRef;
use crate::children_ref::ChildrenRef;
use crate::context::{BastionContext, BastionId, ContextState};
use crate::dispatcher::Dispatcher;
use crate::envelope::Envelope;
use crate::message::BastionMessage;
use crate::path::BastionPathElement;
use crate::system::SYSTEM;
use bastion_executor::pool;
use futures::pending;
use futures::poll;
use futures::prelude::*;
use futures::stream::FuturesOrdered;
use fxhash::FxHashMap;
use lightproc::prelude::*;
use qutex::Qutex;
use std::fmt::Debug;
use std::future::Future;
use std::pin::Pin;
use std::sync::Arc;
use std::task::Poll;
#[derive(Debug)]
/// A children group that will contain a defined number of
/// elements (set with [`with_redundancy`] or `1` by default)
/// all running a future (returned by the closure that is set
/// with [`with_exec`]).
///
/// When an element of the group stops or panics, all the
/// elements will be stopped as well and the group's supervisor
/// will receive a notice that a stop or panic occurred (note
/// that if a panic occurred, the supervisor will restart the
/// children group and eventually some of its other children,
/// depending on its [`SupervisionStrategy`]).
///
/// # Example
///
/// ```rust
/// # use bastion::prelude::*;
/// #
/// # fn main() {
/// # Bastion::init();
/// #
/// let children_ref: ChildrenRef = Bastion::children(|children| {
/// // Configure the children group...
/// children.with_exec(|ctx: BastionContext| {
/// async move {
/// // Send and receive messages...
/// let opt_msg: Option<SignedMessage> = ctx.try_recv().await;
/// // ...and return `Ok(())` or `Err(())` when you are done...
/// Ok(())
///
/// // Note that if `Err(())` was returned, the supervisor would
/// // restart the children group.
/// }
/// })
/// // ...and return it.
/// }).expect("Couldn't create the children group.");
/// #
/// # Bastion::start();
/// # Bastion::stop();
/// # Bastion::block_until_stopped();
/// # }
/// ```
///
/// [`with_redundancy`]: #method.with_redundancy
/// [`with_exec`]: #method.with_exec
/// [`SupervisionStrategy`]: supervisor/enum.SupervisionStrategy.html
pub struct Children {
bcast: Broadcast,
// The currently launched elements of the group.
launched: FxHashMap<BastionId, (Sender, RecoverableHandle<()>)>,
// The closure returning the future that will be used by
// every element of the group.
init: Init,
redundancy: usize,
// The callbacks called at the group's different lifecycle
// events.
callbacks: Callbacks,
// Messages that were received before the group was
// started. Those will be "replayed" once a start message
// is received.
pre_start_msgs: Vec<Envelope>,
started: bool,
// List of dispatchers attached to each actor in the group.
dispatchers: Vec<Arc<Box<Dispatcher>>>,
// The name of children
name: Option<String>,
}
impl Children {
pub(crate) fn new(bcast: Broadcast) -> Self {
debug!("Children({}): Initializing.", bcast.id());
let launched = FxHashMap::default();
let init = Init::default();
let redundancy = 1;
let callbacks = Callbacks::new();
let pre_start_msgs = Vec::new();
let started = false;
let dispatchers = Vec::new();
let name = None;
Children {
bcast,
launched,
init,
redundancy,
callbacks,
pre_start_msgs,
started,
dispatchers,
name,
}
}
fn stack(&self) -> ProcStack {
trace!("Children({}): Creating ProcStack.", self.id());
// FIXME: with_pid
ProcStack::default()
}
/// Returns this children group's identifier.
///
/// Note that the children group's identifier is reset when it
/// is restarted.
///
/// # Example
///
/// ```rust
/// # use bastion::prelude::*;
/// #
/// # fn main() {
/// # Bastion::init();
/// #
/// Bastion::children(|children| {
/// let children_id: &BastionId = children.id();
/// // ...
/// # children
/// }).expect("Couldn't create the children group.");
/// #
/// # Bastion::start();
/// # Bastion::stop();
/// # Bastion::block_until_stopped();
/// # }
/// ```
pub fn id(&self) -> &BastionId {
self.bcast.id()
}
pub(crate) fn bcast(&self) -> &Broadcast {
&self.bcast
}
pub(crate) fn callbacks(&self) -> &Callbacks {
&self.callbacks
}
pub(crate) fn name(&self) -> String {
if let Some(name) = &self.name {
name.clone()
} else {
"__Anonymous__".into()
}
}
pub(crate) fn as_ref(&self) -> ChildrenRef {
trace!(
"Children({}): Creating new ChildrenRef({}).",
self.id(),
self.id()
);
// TODO: clone or ref?
let id = self.bcast.id().clone();
let sender = self.bcast.sender().clone();
let path = self.bcast.path().clone();
let mut children = Vec::with_capacity(self.launched.len());
for (id, (sender, _)) in &self.launched {
trace!("Children({}): Creating new ChildRef({}).", self.id(), id);
// TODO: clone or ref?
let child = ChildRef::new(id.clone(), sender.clone(), self.name(), path.clone());
children.push(child);
}
let dispatchers = self
.dispatchers
.iter()
.map(|dispatcher| dispatcher.dispatcher_type())
.collect();
ChildrenRef::new(id, sender, path, children, dispatchers)
}
/// Sets the name of this children group.
pub fn with_name(mut self, name: impl Into<String>) -> Self {
self.name = Some(name.into());
self
}
/// Sets the closure taking a [`BastionContext`] and returning a
/// [`Future`] that will be used by every element of this children
/// group.
///
/// When a new element is started, it will be assigned a new context,
/// pass it to the `init` closure and poll the returned future until
/// it stops, panics or another element of the group stops or panics.
///
/// The returned future's output should be `Result<(), ()>`.
///
/// # Arguments
///
/// * `init` - The closure taking a [`BastionContext`] and returning
/// a [`Future`] that will be used by every element of this
/// children group.
///
/// # Example
///
/// ```rust
/// # use bastion::prelude::*;
/// #
/// # fn main() {
/// # Bastion::init();
/// #
/// Bastion::children(|children| {
/// children.with_exec(|ctx| {
/// async move {
/// // Send and receive messages...
/// let opt_msg: Option<SignedMessage> = ctx.try_recv().await;
/// // ...and return `Ok(())` or `Err(())` when you are done...
/// Ok(())
///
/// // Note that if `Err(())` was returned, the supervisor would
/// // restart the children group.
/// }
/// })
/// }).expect("Couldn't create the children group.");
/// #
/// # Bastion::start();
/// # Bastion::stop();
/// # Bastion::block_until_stopped();
/// # }
/// ```
pub fn with_exec<I, F>(mut self, init: I) -> Self
where
I: Fn(BastionContext) -> F + Send + Sync + 'static,
F: Future<Output = Result<(), ()>> + Send + 'static,
{
trace!("Children({}): Setting exec closure.", self.id());
self.init = Init::new(init);
self
}
/// Sets the number of elements this children group will
/// contain. Each element will call the closure passed in
/// [`with_exec`] and run the returned future until it stops,
/// panics or another element in the group stops or panics.
///
/// The default number of elements a children group contains is `1`.
///
/// # Arguments
///
/// * `redundancy` - The number of elements this group will contain.
///
/// # Example
///
/// ```rust
/// # use bastion::prelude::*;
/// #
/// # fn main() {
/// # Bastion::init();
/// #
/// Bastion::children(|children| {
/// // Note that "1" is the default number of elements.
/// children.with_redundancy(1)
/// }).expect("Couldn't create the children group.");
/// #
/// # Bastion::start();
/// # Bastion::stop();
/// # Bastion::block_until_stopped();
/// # }
/// ```
///
/// [`with_exec`]: #method.with_exec
pub fn with_redundancy(mut self, redundancy: usize) -> Self {
trace!(
"Children({}): Setting redundancy: {}",
self.id(),
redundancy
);
if redundancy == std::usize::MIN {
self.redundancy = redundancy.saturating_add(1);
} else {
self.redundancy = redundancy;
}
self
}
/// Appends each supervised element to the declared dispatcher.
///
/// By default supervised elements aren't added to any of dispatcher.
///
/// # Arguments
///
/// * `redundancy` - An instance of struct that implements the
/// [`DispatcherHandler`] trait.
///
/// # Example
///
/// ```rust
/// # use bastion::prelude::*;
/// #
/// # fn main() {
/// # Bastion::init();
/// #
/// Bastion::children(|children| {
/// children
/// .with_dispatcher(
/// Dispatcher::with_type(DispatcherType::Named("CustomGroup".to_string()))
/// )
/// }).expect("Couldn't create the children group.");
/// #
/// # Bastion::start();
/// # Bastion::stop();
/// # Bastion::block_until_stopped();
/// # }
/// ```
/// [`DispatcherHandler`]: ../dispatcher/trait.DispatcherHandler.html
pub fn with_dispatcher(mut self, dispatcher: Dispatcher) -> Self {
self.dispatchers.push(Arc::new(Box::new(dispatcher)));
self
}
/// Sets the callbacks that will get called at this children group's
/// different lifecycle events.
///
/// See [`Callbacks`]'s documentation for more information about the
/// different callbacks available.
///
/// # Arguments
///
/// * `callbacks` - The callbacks that will get called for this
/// children group.
///
/// # Example
///
/// ```rust
/// # use bastion::prelude::*;
/// #
/// # fn main() {
/// # Bastion::init();
/// #
/// Bastion::children(|children| {
/// let callbacks = Callbacks::new()
/// .with_before_start(|| println!("Children group started."))
/// .with_after_stop(|| println!("Children group stopped."));
///
/// children
/// .with_callbacks(callbacks)
/// .with_exec(|ctx| {
/// // -- Children group started.
/// async move {
/// // ...
/// # Ok(())
/// }
/// // -- Children group stopped.
/// })
/// }).expect("Couldn't create the children group.");
/// #
/// # Bastion::start();
/// # Bastion::stop();
/// # Bastion::block_until_stopped();
/// # }
/// ```
///
/// [`Callbacks`]: struct.Callbacks.html
pub fn with_callbacks(mut self, callbacks: Callbacks) -> Self {
trace!(
"Children({}): Setting callbacks: {:?}",
self.id(),
callbacks
);
self.callbacks = callbacks;
self
}
async fn kill(&mut self) {
debug!("Children({}): Killing.", self.id());
self.bcast.kill_children();
let mut children = FuturesOrdered::new();
for (_, (_, launched)) in self.launched.drain() {
launched.cancel();
children.push(launched);
}
children
.for_each_concurrent(None, |_| async {
trace!("Children({}): Unknown child stopped.", self.id());
})
.await;
}
fn stopped(&mut self) {
debug!("Children({}): Stopped.", self.id());
self.remove_dispatchers();
self.bcast.stopped();
}
fn faulted(&mut self) {
debug!("Children({}): Faulted.", self.id());
self.remove_dispatchers();
self.bcast.faulted();
}
async fn kill_children(&mut self) -> Result<(), ()> {
self.kill().await;
self.stopped();
Err(())
}
async fn stop_children(&mut self) -> Result<(), ()> {
self.kill().await;
self.stopped();
Err(())
}
async fn handle_stopped_child(&mut self, id: &BastionId) -> Result<(), ()> {
// FIXME: Err if false?
if self.launched.contains_key(&id) {
debug!("Children({}): Child({}) stopped.", self.id(), id);
self.drop_child(id);
let msg = BastionMessage::finished_child(id.clone(), self.bcast.id().clone());
let env = Envelope::new(msg, self.bcast.path().clone(), self.bcast.sender().clone());
self.bcast.send_parent(env).ok();
}
Ok(())
}
async fn handle_faulted_child(&mut self, id: &BastionId) -> Result<(), ()> {
// FIXME: Err if false?
if self.launched.contains_key(id) {
warn!("Children({}): Child({}) faulted.", self.id(), id);
self.kill().await;
self.faulted();
return Err(());
}
Ok(())
}
fn request_restarting_child(&mut self, id: &BastionId, parent_id: &BastionId) {
if parent_id == self.bcast.id() && self.launched.contains_key(id) {
let parent_id = self.bcast.id().clone();
let msg = BastionMessage::restart_required(id.clone(), parent_id);
let env = Envelope::new(msg, self.bcast.path().clone(), self.bcast.sender().clone());
self.bcast.send_parent(env).ok();
}
}
fn restart_child(&mut self, old_id: &BastionId, old_state: &Qutex<Pin<Box<ContextState>>>) {
let parent = Parent::children(self.as_ref());
let bcast = Broadcast::new(parent, BastionPathElement::Child(old_id.clone()));
let id = bcast.id().clone();
let sender = bcast.sender().clone();
let path = bcast.path().clone();
let child_ref = ChildRef::new(id.clone(), sender.clone(), self.name(), path);
let children = self.as_ref();
let supervisor = self.bcast.parent().clone().into_supervisor();
let state = Qutex::new(Box::pin(ContextState::new()));
let ctx = BastionContext::new(
id.clone(),
child_ref.clone(),
children,
supervisor,
state.clone(),
);
let exec = (self.init.0)(ctx);
self.bcast.register(&bcast);
let msg = BastionMessage::set_state(old_state.clone());
let env = Envelope::new(msg, self.bcast.path().clone(), self.bcast.sender().clone());
self.bcast.send_child(&id, env);
let msg = BastionMessage::apply_callback(CallbackType::AfterRestart);
let env = Envelope::new(msg, self.bcast.path().clone(), self.bcast.sender().clone());
self.bcast.send_child(&id, env);
let msg = BastionMessage::start();
let env = Envelope::new(msg, self.bcast.path().clone(), self.bcast.sender().clone());
self.bcast.send_child(&id, env);
debug!("Children({}): Restarting Child({}).", self.id(), bcast.id());
let callbacks = self.callbacks.clone();
let child = Child::new(exec, callbacks, bcast, state, child_ref);
debug!(
"Children({}): Launching faulted Child({}).",
self.id(),
child.id(),
);
let id = child.id().clone();
let launched = child.launch();
self.launched.insert(id, (sender, launched));
}
fn drop_child(&mut self, id: &BastionId) {
debug!(
"Children({}): Dropping Child({:?}): reached restart limits.",
self.id(),
id,
);
self.launched.remove_entry(id);
}
async fn handle(&mut self, envelope: Envelope) -> Result<(), ()> {
match envelope {
Envelope {
msg: BastionMessage::Start,
..
} => unreachable!(),
Envelope {
msg: BastionMessage::Stop,
..
} => self.stop_children().await?,
Envelope {
msg: BastionMessage::Kill,
..
} => self.kill_children().await?,
// FIXME
Envelope {
msg: BastionMessage::Deploy(_),
..
} => unimplemented!(),
// FIXME
Envelope {
msg: BastionMessage::Prune { .. },
..
} => unimplemented!(),
// FIXME
Envelope {
msg: BastionMessage::SuperviseWith(_),
..
} => unimplemented!(),
Envelope {
msg: BastionMessage::ApplyCallback { .. },
..
} => unreachable!(),
Envelope {
msg: BastionMessage::InstantiatedChild { .. },
..
} => unreachable!(),
Envelope {
msg: BastionMessage::Message(ref message),
..
} => {
debug!(
"Children({}): Broadcasting a message: {:?}",
self.id(),
message
);
self.bcast.send_children(envelope);
}
Envelope {
msg: BastionMessage::RestartRequired { id, parent_id },
..
} => self.request_restarting_child(&id, &parent_id),
Envelope {
msg: BastionMessage::FinishedChild { .. },
..
} => unreachable!(),
Envelope {
msg: BastionMessage::RestartSubtree,
..
} => unreachable!(),
Envelope {
msg: BastionMessage::RestoreChild { id, state },
..
} => self.restart_child(&id, &state),
Envelope {
msg: BastionMessage::DropChild { id },
..
} => self.drop_child(&id),
Envelope {
msg: BastionMessage::SetState { .. },
..
} => unreachable!(),
Envelope {
msg: BastionMessage::Stopped { id },
..
} => self.handle_stopped_child(&id).await?,
Envelope {
msg: BastionMessage::Faulted { id },
..
} => self.handle_faulted_child(&id).await?,
}
Ok(())
}
async fn initialize(&mut self) -> Result<(), ()> {
trace!(
"Children({}): Received a new message (started=false): {:?}",
self.id(),
BastionMessage::Start
);
debug!("Children({}): Starting.", self.id());
self.started = true;
let msg = BastionMessage::start();
let env = Envelope::new(msg, self.bcast.path().clone(), self.bcast.sender().clone());
self.bcast.send_children(env);
let msgs = self.pre_start_msgs.drain(..).collect::<Vec<_>>();
self.pre_start_msgs.shrink_to_fit();
debug!(
"Children({}): Replaying messages received before starting.",
self.id()
);
for msg in msgs {
trace!("Children({}): Replaying message: {:?}", self.id(), msg);
if self.handle(msg).await.is_err() {
return Err(());
}
}
Ok(())
}
async fn run(mut self) -> Self {
debug!("Children({}): Launched.", self.id());
loop {
for (_, launched) in self.launched.values_mut() {
let _ = poll!(launched);
}
match poll!(&mut self.bcast.next()) {
// TODO: Err if started == true?
Poll::Ready(Some(Envelope {
msg: BastionMessage::Start,
..
})) => {
if self.initialize().await.is_err() {
return self;
}
}
Poll::Ready(Some(msg)) if !self.started => {
trace!(
"Children({}): Received a new message (started=false): {:?}",
self.id(),
msg
);
self.pre_start_msgs.push(msg);
}
Poll::Ready(Some(msg)) => {
trace!(
"Children({}): Received a new message (started=true): {:?}",
self.id(),
msg
);
if self.handle(msg).await.is_err() {
return self;
}
}
// NOTE: because `Broadcast` always holds both a `Sender` and
// `Receiver` of the same channel, this would only be
// possible if the channel was closed, which never happens.
Poll::Ready(None) => unreachable!(),
Poll::Pending => pending!(),
}
}
}
pub(crate) fn launch_elems(&mut self) {
debug!("Children({}): Launching elements.", self.id());
let name = self.name();
for _ in 0..self.redundancy {
let parent = Parent::children(self.as_ref());
let bcast = Broadcast::new(parent, BastionPathElement::Child(BastionId::new()));
// TODO: clone or ref?
let id = bcast.id().clone();
let sender = bcast.sender().clone();
let path = bcast.path().clone();
let child_ref = ChildRef::new(id.clone(), sender.clone(), name.clone(), path);
let children = self.as_ref();
let supervisor = self.bcast.parent().clone().into_supervisor();
let state = Qutex::new(Box::pin(ContextState::new()));
let ctx = BastionContext::new(
id.clone(),
child_ref.clone(),
children,
supervisor,
state.clone(),
);
let exec = (self.init.0)(ctx);
let parent_id = self.bcast.id().clone();
let msg = BastionMessage::instantiated_child(parent_id, id.clone(), state.clone());
let env = Envelope::new(msg, self.bcast.path().clone(), self.bcast.sender().clone());
self.bcast.send_parent(env).ok();
self.bcast.register(&bcast);
debug!(
"Children({}): Initializing Child({}).",
self.id(),
bcast.id()
);
let callbacks = self.callbacks.clone();
let child = Child::new(exec, callbacks, bcast, state, child_ref);
debug!("Children({}): Launching Child({}).", self.id(), child.id());
let id = child.id().clone();
let launched = child.launch();
self.launched.insert(id, (sender, launched));
}
}
pub(crate) fn launch(self) -> RecoverableHandle<Self> {
debug!("Children({}): Launching.", self.id());
let stack = self.stack();
pool::spawn(self.run(), stack)
}
/// Registers all declared local dispatchers in the global dispatcher.
pub(crate) fn register_dispatchers(&self) {
let global_dispatcher = SYSTEM.dispatcher();
for dispatcher in self.dispatchers.iter() {
global_dispatcher.register_dispatcher(dispatcher)
}
}
/// Removes all declared local dispatchers from the global dispatcher.
pub(crate) fn remove_dispatchers(&self) {
let global_dispatcher = SYSTEM.dispatcher();
for dispatcher in self.dispatchers.iter() {
global_dispatcher.remove_dispatcher(dispatcher)
}
}
}
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