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children.rs
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children.rs
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use crate::broadcast::{Broadcast, Parent, Sender};
use crate::context::{BastionContext, BastionId, ContextState};
use crate::message::{Answer, BastionMessage, Message};
use crate::system::schedule;
use futures::pending;
use futures::poll;
use futures::prelude::*;
use futures::stream::{FuturesOrdered, FuturesUnordered};
use fxhash::FxHashMap;
use lightproc::prelude::*;
use qutex::Qutex;
use std::fmt::{self, Debug, Formatter};
use std::future::Future;
use std::iter::FromIterator;
use std::pin::Pin;
use std::task::{Context, Poll};
struct Init(Box<dyn Fn(BastionContext) -> Exec + Send + Sync>);
struct Exec(Pin<Box<dyn Future<Output = Result<(), ()>> + Send>>);
#[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
///
/// ```
/// # 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<Msg> = 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,
// Messages that were received before the group was
// started. Those will be "replayed" once a start message
// is received.
pre_start_msgs: Vec<BastionMessage>,
started: bool,
}
#[derive(Debug, Clone)]
/// A "reference" to a children group, allowing to communicate
/// with it.
pub struct ChildrenRef {
id: BastionId,
sender: Sender,
children: Vec<ChildRef>,
}
#[derive(Debug)]
pub(crate) struct Child {
bcast: Broadcast,
// The future that this child is executing.
exec: Exec,
// A lock behind which is the child's context state.
// This is used to store the messages that were received
// for the child's associated future to be able to
// retrieve them.
state: Qutex<ContextState>,
// Messages that were received before the child was
// started. Those will be "replayed" once a start message
// is received.
pre_start_msgs: Vec<BastionMessage>,
started: bool,
}
#[derive(Debug, Clone)]
/// A "reference" to an element of a children group, allowing to
/// communicate with it.
pub struct ChildRef {
id: BastionId,
sender: Sender,
}
impl Init {
fn new<C, F>(init: C) -> Self
where
C: Fn(BastionContext) -> F + Send + Sync + 'static,
F: Future<Output = Result<(), ()>> + Send + 'static,
{
let init = Box::new(move |ctx: BastionContext| {
let fut = init(ctx);
let exec = Box::pin(fut);
Exec(exec)
});
Init(init)
}
}
impl Children {
pub(crate) fn new(bcast: Broadcast) -> Self {
let launched = FxHashMap::default();
let init = Init::default();
let redundancy = 1;
let pre_start_msgs = Vec::new();
let started = false;
Children {
bcast,
launched,
init,
redundancy,
pre_start_msgs,
started,
}
}
fn stack(&self) -> ProcStack {
// FIXME: with_pid
ProcStack::default()
}
pub(crate) async fn reset(&mut self, bcast: Broadcast) {
// TODO: stop or kill?
self.kill().await;
self.bcast = bcast;
self.launch_elems();
}
pub(crate) fn id(&self) -> &BastionId {
self.bcast.id()
}
pub(crate) fn bcast(&self) -> &Broadcast {
&self.bcast
}
pub(crate) fn as_ref(&self) -> ChildrenRef {
// TODO: clone or ref?
let id = self.bcast.id().clone();
let sender = self.bcast.sender().clone();
let mut children = Vec::with_capacity(self.launched.len());
for (id, (sender, _)) in &self.launched {
// TODO: clone or ref?
let child = ChildRef::new(id.clone(), sender.clone());
children.push(child);
}
ChildrenRef::new(id, sender, children)
}
/// 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
///
/// ```
/// # use bastion::prelude::*;
/// #
/// # fn main() {
/// # Bastion::init();
/// #
/// Bastion::children(|children| {
/// children.with_exec(|ctx| {
/// async move {
/// // Send and receive messages...
/// let opt_msg: Option<Msg> = 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,
{
self.init = Init::new(init);
self
}
/// Sets the number of 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
///
/// ```
/// # 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();
/// # }
/// ```
pub fn with_redundancy(mut self, redundancy: usize) -> Self {
self.redundancy = redundancy;
self
}
async fn stop(&mut self) {
self.bcast.stop_children();
let launched = self.launched.drain().map(|(_, (_, launched))| launched);
FuturesUnordered::from_iter(launched)
.for_each_concurrent(None, |_| async {})
.await;
}
async fn kill(&mut self) {
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 {}).await;
}
fn stopped(&mut self) {
self.bcast.stopped();
}
fn faulted(&mut self) {
self.bcast.faulted();
}
async fn handle(&mut self, msg: BastionMessage) -> Result<(), ()> {
match msg {
BastionMessage::Start => unreachable!(),
BastionMessage::Stop => {
self.stop().await;
self.stopped();
return Err(());
}
BastionMessage::Kill => {
self.kill().await;
self.stopped();
return Err(());
}
// FIXME
BastionMessage::Deploy(_) => unimplemented!(),
// FIXME
BastionMessage::Prune { .. } => unimplemented!(),
// FIXME
BastionMessage::SuperviseWith(_) => unimplemented!(),
BastionMessage::Message { .. } => {
self.bcast.send_children(msg);
}
BastionMessage::Stopped { id } => {
// FIXME: Err if false?
if self.launched.contains_key(&id) {
self.stop().await;
self.stopped();
return Err(());
}
}
BastionMessage::Faulted { id } => {
// FIXME: Err if false?
if self.launched.contains_key(&id) {
self.kill().await;
self.faulted();
return Err(());
}
}
}
Ok(())
}
async fn run(mut self) -> Self {
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(BastionMessage::Start)) => {
self.started = true;
let msg = BastionMessage::start();
self.bcast.send_children(msg);
let msgs = self.pre_start_msgs.drain(..).collect::<Vec<_>>();
self.pre_start_msgs.shrink_to_fit();
for msg in msgs {
if self.handle(msg).await.is_err() {
return self;
}
}
}
Poll::Ready(Some(msg)) if !self.started => {
self.pre_start_msgs.push(msg);
}
Poll::Ready(Some(msg)) => {
if self.handle(msg).await.is_err() {
return self;
}
}
Poll::Ready(None) => {
// TODO: stop or kill?
self.kill().await;
self.faulted();
return self;
}
Poll::Pending => pending!(),
}
}
}
pub(crate) fn launch_elems(&mut self) {
for _ in 0..self.redundancy {
let parent = Parent::children(self.as_ref());
let bcast = Broadcast::new(parent);
// TODO: clone or ref?
let id = bcast.id().clone();
let sender = bcast.sender().clone();
let child_ref = ChildRef::new(id.clone(), sender.clone());
let children = self.as_ref();
// FIXME
let supervisor = self.bcast.parent().clone().into_supervisor().unwrap();
let state = ContextState::new();
let state = Qutex::new(state);
let ctx =
BastionContext::new(id.clone(), child_ref, children, supervisor, state.clone());
let exec = (self.init.0)(ctx);
self.bcast.register(&bcast);
let child = Child::new(exec, bcast, state);
let launched = child.launch();
self.launched.insert(id.clone(), (sender, launched));
}
}
pub(crate) fn launch(self) -> ProcHandle<Self> {
let stack = self.stack();
let (proc, handle) = LightProc::build(self.run(), schedule, stack);
proc.schedule();
handle
}
}
impl ChildrenRef {
fn new(id: BastionId, sender: Sender, children: Vec<ChildRef>) -> Self {
ChildrenRef {
id,
sender,
children,
}
}
/// Returns a list of [`ChildRef`] referencing the elements
/// of the children group this `ChildrenRef` is referencing.
///
/// # Example
///
/// ```
/// # use bastion::prelude::*;
/// #
/// # fn main() {
/// # Bastion::init();
/// #
/// # let children_ref = Bastion::children(|children| children).unwrap();
/// let elems: &[ChildRef] = children_ref.elems();
/// #
/// # Bastion::start();
/// # Bastion::stop();
/// # Bastion::block_until_stopped();
/// # }
/// ```
///
/// [`ChildRef`]: children/struct.ChildRef.html
pub fn elems(&self) -> &[ChildRef] {
&self.children
}
/// Sends a message to the children group this `ChildrenRef`
/// is referencing which will then send it to all of its
/// elements.
///
/// An alternative would be to use [`elems`] to get all the
/// elements of the group and then send the message to all
/// of them.
///
/// This method returns `()` if it succeeded, or `Err(msg)`
/// otherwise.
///
/// # Arguments
///
/// * `msg` - The message to send.
///
/// # Example
///
/// ```
/// # use bastion::prelude::*;
/// #
/// # fn main() {
/// # Bastion::init();
/// #
/// # let children_ref = Bastion::children(|children| children).unwrap();
/// let msg = "A message containing data.";
/// children_ref.broadcast(msg).expect("Couldn't send the message.");
///
/// # Bastion::children(|children| {
/// # children.with_exec(|ctx: BastionContext| {
/// # async move {
/// // And then in every of the children group's elements' futures...
/// msg! { ctx.recv().await?,
/// ref msg: &'static str => {
/// assert_eq!(msg, &"A message containing data.");
/// };
/// // We are only sending a `&'static str` in this
/// // example, so we know that this won't happen...
/// _: _ => ();
/// }
/// #
/// # Ok(())
/// # }
/// # })
/// # }).unwrap();
/// #
/// # Bastion::start();
/// # Bastion::stop();
/// # Bastion::block_until_stopped();
/// # }
/// ```
///
/// [`elems`]: #method.elems
pub fn broadcast<M: Message>(&self, msg: M) -> Result<(), M> {
let msg = BastionMessage::broadcast(msg);
// FIXME: panics?
self.send(msg).map_err(|err| err.into_msg().unwrap())
}
/// Sends a message to the children group this `ChildrenRef`
/// is referencing to tell it to stop all of its running
/// elements.
///
/// This method returns `()` if it succeeded, or `Err(())`
/// otherwise.
///
/// # Example
///
/// ```
/// # use bastion::prelude::*;
/// #
/// # fn main() {
/// # Bastion::init();
/// #
/// # let children_ref = Bastion::children(|children| children).unwrap();
/// children_ref.stop().expect("Couldn't send the message.");
/// #
/// # Bastion::start();
/// # Bastion::stop();
/// # Bastion::block_until_stopped();
/// # }
/// ```
pub fn stop(&self) -> Result<(), ()> {
let msg = BastionMessage::stop();
self.send(msg).map_err(|_| ())
}
/// Sends a message to the children group this `ChildrenRef`
/// is referencing to tell it to kill all of its running
/// elements.
///
/// This method returns `()` if it succeeded, or `Err(())`
/// otherwise.
///
/// # Example
///
/// ```
/// # use bastion::prelude::*;
/// #
/// # fn main() {
/// # Bastion::init();
/// #
/// # let children_ref = Bastion::children(|children| children).unwrap();
/// children_ref.kill().expect("Couldn't send the message.");
/// #
/// # Bastion::start();
/// # Bastion::stop();
/// # Bastion::block_until_stopped();
/// # }
/// ```
pub fn kill(&self) -> Result<(), ()> {
let msg = BastionMessage::kill();
self.send(msg).map_err(|_| ())
}
pub(crate) fn send(&self, msg: BastionMessage) -> Result<(), BastionMessage> {
self.sender
.unbounded_send(msg)
.map_err(|err| err.into_inner())
}
}
impl Child {
fn new(exec: Exec, bcast: Broadcast, state: Qutex<ContextState>) -> Self {
let pre_start_msgs = Vec::new();
let started = false;
Child {
bcast,
exec,
state,
pre_start_msgs,
started,
}
}
fn stack(&self) -> ProcStack {
let id = self.bcast.id().clone();
// FIXME: panics?
let parent = self.bcast.parent().clone().into_children().unwrap();
// FIXME: with_pid
ProcStack::default().with_after_panic(move || {
// FIXME: clones
let id = id.clone();
let msg = BastionMessage::faulted(id);
// TODO: handle errors
parent.send(msg).ok();
})
}
fn stopped(&mut self) {
self.bcast.stopped();
}
fn faulted(&mut self) {
self.bcast.faulted();
}
async fn handle(&mut self, msg: BastionMessage) -> Result<(), ()> {
match msg {
BastionMessage::Start => unreachable!(),
BastionMessage::Stop | BastionMessage::Kill => {
self.stopped();
return Err(());
}
// FIXME
BastionMessage::Deploy(_) => unimplemented!(),
// FIXME
BastionMessage::Prune { .. } => unimplemented!(),
// FIXME
BastionMessage::SuperviseWith(_) => unimplemented!(),
BastionMessage::Message(msg) => {
let mut state = self.state.clone().lock_async().await.map_err(|_| ())?;
state.push_msg(msg);
}
// FIXME
BastionMessage::Stopped { .. } => unimplemented!(),
// FIXME
BastionMessage::Faulted { .. } => unimplemented!(),
}
Ok(())
}
async fn run(mut self) {
loop {
match poll!(&mut self.bcast.next()) {
// TODO: Err if started == true?
Poll::Ready(Some(BastionMessage::Start)) => {
self.started = true;
let msgs = self.pre_start_msgs.drain(..).collect::<Vec<_>>();
self.pre_start_msgs.shrink_to_fit();
for msg in msgs {
if self.handle(msg).await.is_err() {
return;
}
}
continue;
}
Poll::Ready(Some(msg)) if !self.started => {
self.pre_start_msgs.push(msg);
continue;
}
Poll::Ready(Some(msg)) => {
if self.handle(msg).await.is_err() {
return;
}
continue;
}
Poll::Ready(None) => {
self.faulted();
return;
}
Poll::Pending => (),
}
if !self.started {
pending!();
continue;
}
match poll!(&mut self.exec) {
Poll::Ready(Ok(())) => return self.stopped(),
Poll::Ready(Err(())) => return self.faulted(),
Poll::Pending => (),
}
pending!();
}
}
fn launch(self) -> RecoverableHandle<()> {
let stack = self.stack();
let (proc, handle) = LightProc::recoverable(self.run(), schedule, stack);
proc.schedule();
handle
}
}
impl ChildRef {
fn new(id: BastionId, sender: Sender) -> ChildRef {
ChildRef { id, sender }
}
/// Sends a message to the child this `ChildRef` is referencing.
///
/// This method returns `()` if it succeeded, or `Err(msg)`
/// otherwise.
///
/// # Argument
///
/// * `msg` - The message to send.
///
/// # Example
///
/// ```
/// # use bastion::prelude::*;
/// #
/// # fn main() {
/// # Bastion::init();
/// // The message that will be "told"...
/// const TELL_MSG: &'static str = "A message containing data (tell).";
///
/// # let children_ref =
/// // Create a new child...
/// Bastion::children(|children| {
/// children.with_exec(|ctx: BastionContext| {
/// async move {
/// // ...which will receive the message "told"...
/// msg! { ctx.recv().await?,
/// msg: &'static str => {
/// assert_eq!(msg, TELL_MSG);
/// // Handle the message...
/// };
/// // This won't happen because this example
/// // only "tells" a `&'static str`...
/// _: _ => ();
/// }
///
/// Ok(())
/// }
/// })
/// }).expect("Couldn't create the children group.");
///
/// # let child_ref = &children_ref.elems()[0];
/// // Later, the message is "told" to the child...
/// child_ref.tell(TELL_MSG).expect("Couldn't send the message.");
/// #
/// # Bastion::start();
/// # Bastion::stop();
/// # Bastion::block_until_stopped();
/// # }
/// ```
pub fn tell<M: Message>(&self, msg: M) -> Result<(), M> {
let msg = BastionMessage::tell(msg);
// FIXME: panics?
self.send(msg).map_err(|msg| msg.into_msg().unwrap())
}
/// Sends a message to the child this `ChildRef` is referencing,
/// allowing it to answer.
///
/// This method returns [`Answer`] if it succeeded, or `Err(msg)`
/// otherwise.
///
/// # Argument
///
/// * `msg` - The message to send.
///
/// # Example
///
/// ```
/// # use bastion::prelude::*;
/// #
/// # fn main() {
/// # Bastion::init();
/// // The message that will be "asked"...
/// const ASK_MSG: &'static str = "A message containing data (ask).";
/// // The message the will be "answered"...
/// const ANSWER_MSG: &'static str = "A message containing data (answer).";
///
/// # let children_ref =
/// // Create a new child...
/// Bastion::children(|children| {
/// children.with_exec(|ctx: BastionContext| {
/// async move {
/// // ...which will receive the message asked...
/// msg! { ctx.recv().await?,
/// msg: &'static str =!> {
/// assert_eq!(msg, ASK_MSG);
/// // Handle the message...
///
/// // ...and eventually answer to it...
/// answer!(ANSWER_MSG);
/// };
/// // This won't happen because this example
/// // only "asks" a `&'static str`...
/// _: _ => ();
/// }
///
/// Ok(())
/// }
/// })
/// }).expect("Couldn't create the children group.");
///
/// # Bastion::children(|children| {
/// # children.with_exec(move |ctx: BastionContext| {
/// # let child_ref = children_ref.elems()[0].clone();
/// # async move {
/// // Later, the message is "asked" to the child...
/// let answer: Answer = child_ref.ask(ASK_MSG).expect("Couldn't send the message.");
///
/// // ...and the child's answer is received...
/// msg! { answer.await.expect("Couldn't receive the answer."),
/// msg: &'static str => {
/// assert_eq!(msg, ANSWER_MSG);
/// // Handle the answer...
/// };
/// // This won't happen because this example
/// // only answers a `&'static str`...
/// _: _ => ();
/// }
/// #
/// # Ok(())
/// # }
/// # })
/// # }).unwrap();
/// #
/// # Bastion::start();
/// # Bastion::stop();
/// # Bastion::block_until_stopped();
/// # }
/// ```
///
/// [`Answer`]: message/struct.Answer.html
pub fn ask<M: Message>(&self, msg: M) -> Result<Answer, M> {
let (msg, answer) = BastionMessage::ask(msg);
// FIXME: panics?
self.send(msg).map_err(|msg| msg.into_msg().unwrap())?;
Ok(answer)
}
/// Sends a message to the child this `ChildRef` is referencing
/// to tell it to stop its execution.
///
/// This method returns `()` if it succeeded, or `Err(())`
/// otherwise.
///
/// # Example
///
/// ```
/// # use bastion::prelude::*;
/// #
/// # fn main() {
/// # Bastion::init();
/// #
/// # let children_ref = Bastion::children(|children| children).unwrap();
/// # let child_ref = &children_ref.elems()[0];
/// child_ref.stop().expect("Couldn't send the message.");
/// #
/// # Bastion::start();
/// # Bastion::stop();
/// # Bastion::block_until_stopped();
/// # }
/// ```
pub fn stop(&self) -> Result<(), ()> {
let msg = BastionMessage::stop();
self.send(msg).map_err(|_| ())
}
/// Sends a message to the child this `ChildRef` is referencing
/// to tell it to suicide.
///
/// This method returns `()` if it succeeded, or `Err(())`
/// otherwise.
///
/// # Example
///
/// ```
/// # use bastion::prelude::*;
/// #
/// # fn main() {
/// # Bastion::init();
/// #
/// # let children_ref = Bastion::children(|children| children).unwrap();
/// # let child_ref = &children_ref.elems()[0];
/// child_ref.kill().expect("Couldn't send the message.");
/// #
/// # Bastion::start();
/// # Bastion::stop();
/// # Bastion::block_until_stopped();
/// # }
/// ```
pub fn kill(&self) -> Result<(), ()> {
let msg = BastionMessage::kill();
self.send(msg).map_err(|_| ())
}
pub(crate) fn send(&self, msg: BastionMessage) -> Result<(), BastionMessage> {
self.sender
.unbounded_send(msg)
.map_err(|err| err.into_inner())
}
}
impl Future for Exec {
type Output = Result<(), ()>;
fn poll(self: Pin<&mut Self>, ctx: &mut Context) -> Poll<Self::Output> {
Pin::new(&mut self.get_mut().0).poll(ctx)
}
}
impl Default for Init {
fn default() -> Self {
Init::new(|_| async { Ok(()) })
}
}
impl Debug for Init {
fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
fmt.debug_struct("Init").finish()
}
}
impl Debug for Exec {
fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
fmt.debug_struct("Exec").finish()
}
}