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//! The module with the supervisor and related types.
//!
//! # Supervisor
//!
//! A supervisor supervises an actor and handles any errors it encounters. A
//! supervisor generally does two things; logging of the error and deciding
//! whether to stop or restart the actor. Its advised to keep a supervisor small
//! and simple.
//!
//! When encountering an error it usually means someone has to be notified (to
//! fix it), something often done via logging.
//!
//! Next the supervisor needs to decide if the actor needs to be [stopped] or
//! [restarted]. If the supervisor decides to restart the actor it needs to
//! provide the argument to create a new actor (used in calling the
//! [`NewActor::new`] method).
//!
//! The restarted actor will have the same message inbox as the old (stopped)
//! actor. Note however that if an actor retrieved a message from its inbox, and
//! returned an error when processing it, the new (restarted) actor won't
//! retrieve that message again (messages aren't cloned after all).
//!
//! # Restarting or stopping?
//!
//! Sometimes just restarting an actor is the easiest way to deal with errors.
//! Starting the actor from a clean slate will often allow it to continue
//! processing. However this is not possible in all cases, for example when a
//! new argument can't be provided. For example the `TcpServer` found in the
//! heph-rt. In those cases the supervisor should still log the error
//! encountered.
//!
//! [stopped]: crate::supervisor::SupervisorStrategy::Stop
//! [restarted]: crate::supervisor::SupervisorStrategy::Restart
//!
//! # Actors and sync actors
//!
//! As actors come in two flavours, [regular/asynchronous actors] and
//! [synchronous actors], thus so do the supervisor traits, [`Supervisor`] and
//! [`SyncSupervisor`].
//!
//! [regular/asynchronous actors]: crate::actor::Actor
//! [synchronous actors]: crate::actor::SyncActor
//! [`Supervisor`]: crate::supervisor::Supervisor
//! [`SyncSupervisor`]: crate::supervisor::SyncSupervisor
//!
//!
//! # Provided implementations
//!
//! There are two [`Supervisor`] implementations provided by Heph. First, the
//! [`NoSupervisor`] can be used when the actor never returns an error (i.e.
//! `Result<(), !>` or no return type) and thus doesn't need supervision.
//!
//! Second, the [`restart_supervisor!`] macro, which can be used to easily
//! create a supervisor implementation that restarts the actor.
//!
//! # Examples
//!
//! Supervisor that logs the errors of a badly behaving actor and stops it.
//!
//! ```
//! #![feature(never_type)]
//!
//! use heph::actor;
//! use heph::supervisor::SupervisorStrategy;
//! use heph_rt::spawn::ActorOptions;
//! use heph_rt::{self as rt, ThreadLocal, Runtime};
//! use log::error;
//!
//! fn main() -> Result<(), rt::Error> {
//! // Enable logging so we can see the error message.
//! std_logger::init();
//!
//! let mut runtime = Runtime::new()?;
//! runtime.run_on_workers(|mut runtime_ref| -> Result<(), !> {
//! runtime_ref.spawn_local(supervisor, bad_actor as fn(_) -> _, (), ActorOptions::default());
//! Ok(())
//! })?;
//! runtime.start()
//! }
//!
//! /// The error returned by our actor.
//! struct Error;
//!
//! /// Supervisor that gets called if the actor returns an error.
//! fn supervisor(err: Error) -> SupervisorStrategy<()> {
//! # drop(err); // Silence dead code warnings.
//! error!("Actor encountered an error!");
//! SupervisorStrategy::Stop
//! }
//!
//! /// Our badly behaving actor.
//! async fn bad_actor(_: actor::Context<!, ThreadLocal>) -> Result<(), Error> {
//! Err(Error)
//! }
//! ```
use std::any::Any;
use std::fmt;
use log::warn;
use crate::actor::SyncActor;
use crate::actor::{Actor, NewActor};
/// The supervisor of an [actor].
///
/// For more information about supervisors see the [module documentation], here
/// only the design of the trait is discussed.
///
/// The trait is designed to be generic over the [`NewActor`] implementation
/// (`NA`). This means that the same type can implement supervision for a number
/// of different actors. But a word of caution, supervisors should generally be
/// small and simple, which means that having a different supervisor for each
/// actor is often a good thing.
///
/// The [`restart_supervisor!`] macro can be used to easily create a supervisor
/// implementation that restarts the actor.
///
/// `Supervisor` can be implemented using a simple function if the `NewActor`
/// implementation doesn't return an error (i.e. `NewActor::Error = !`), which
/// is the case for asynchronous functions. See the [module documentation] for
/// an example of this.
///
/// [actor]: crate::actor
/// [module documentation]: crate::supervisor
pub trait Supervisor<NA>
where
NA: NewActor,
{
/// Decide what happens to the actor that returned `error`.
///
/// # Notes
///
/// A restarted actor will immediately will be scheduled run again. This has
/// the benefit that the actor can setup any asynchronous operations without
/// having to wait to be run again.
///
/// However it also has a downside: *it's easy to create create an error and
/// restart loop*. When a supervisor always restarts an actor that always
/// returns an error, we've got an effective loop of restarting and running
/// the actor, the actor crashes and is restarted and run again, etc.
///
/// To avoid creating such an loop limit the amount times an actor can be
/// restarted. Or use the [`restart_supervisor!`] macro to automatically
/// create a supervisor that handles this for you.
fn decide(&mut self, error: <NA::Actor as Actor>::Error) -> SupervisorStrategy<NA::Argument>;
/// Decide what happens when an actor is restarted and the [`NewActor`]
/// implementation returns an `error`.
///
/// Read the documentation of [`decide`] to avoid an *infinite loop*.
///
/// [`decide`]: Supervisor::decide
fn decide_on_restart_error(&mut self, error: NA::Error) -> SupervisorStrategy<NA::Argument>;
/// Method that gets call if an actor fails to restart twice.
///
/// This is only called if [`decide`] returns a restart strategy, the actors
/// fails to restart, after which [`decide_on_restart_error`] is called and
/// also returns a restart strategy and restarting the actor a second time
/// also fails. We will not create an endless loop of restarting failures
/// and instead call this function before stopping the actor (which can't be
/// restarted any more).
///
/// [`decide`]: Supervisor::decide
/// [`decide_on_restart_error`]: Supervisor::decide_on_restart_error
// TODO: a better name.
fn second_restart_error(&mut self, error: NA::Error);
/// Decide what happens to the actor that panicked.
///
/// This is similar to [`Supervisor::decide`], but handles panics instead of
/// errors ([`NewActor::Error`]).
///
/// # Default
///
/// By default this stops the actor as a panic is always unexpected and is
/// generally harder to recover from then an error.
///
/// # Notes
///
/// The panic is always logged using the [panic hook], in addition an error
/// message is printed which states what actor panicked.
///
/// [panic hook]: std::panic::set_hook
fn decide_on_panic(
&mut self,
panic: Box<dyn Any + Send + 'static>,
) -> SupervisorStrategy<NA::Argument> {
drop(panic);
SupervisorStrategy::Stop
}
}
impl<F, NA> Supervisor<NA> for F
where
F: FnMut(<NA::Actor as Actor>::Error) -> SupervisorStrategy<NA::Argument>,
NA: NewActor<Error = !>,
{
fn decide(&mut self, err: <NA::Actor as Actor>::Error) -> SupervisorStrategy<NA::Argument> {
(self)(err)
}
fn decide_on_restart_error(&mut self, _: !) -> SupervisorStrategy<NA::Argument> {
// This can't be called.
SupervisorStrategy::Stop
}
fn second_restart_error(&mut self, _: !) {
// This can't be called.
}
}
/// The strategy to use when handling an error from an actor.
///
/// See the [module documentation] for deciding on whether to restart an or not.
///
/// [module documentation]: index.html#restarting-or-stopping
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
#[non_exhaustive]
pub enum SupervisorStrategy<Arg> {
/// Restart the actor with the provided argument `Arg`.
Restart(Arg),
/// Stop the actor.
Stop,
}
/// Supervisor for [synchronous actors].
///
/// For more information about supervisors see the [module documentation], here
/// only the design of the trait is discussed.
///
/// The trait is designed to be generic over the actor (`A`). This means that
/// the same type can implement supervision for a number of different actors.
/// But a word of caution, supervisors should generally be small and simple,
/// which means that having a different supervisor for each actor is often a
/// good thing.
///
/// `SyncSupervisor` is implemented for any function that takes an error `E` and
/// returns `SupervisorStrategy<Arg>` automatically.
///
/// [synchronous actors]: crate::actor::SyncActor
/// [module documentation]: crate::supervisor
pub trait SyncSupervisor<A>
where
A: SyncActor,
{
/// Decide what happens to the actor that returned `error`.
fn decide(&mut self, error: A::Error) -> SupervisorStrategy<A::Argument>;
}
impl<F, A> SyncSupervisor<A> for F
where
F: FnMut(A::Error) -> SupervisorStrategy<A::Argument>,
A: SyncActor,
{
fn decide(&mut self, err: A::Error) -> SupervisorStrategy<A::Argument> {
(self)(err)
}
}
/// A supervisor implementation for actors that never return an error.
///
/// This supervisor does nothing and can't actually be called, it can only serve
/// as supervisor for actors that never return an error, i.e. actor that use the
/// never type (`!`) as error type.
///
/// # Example
///
/// ```
/// #![feature(never_type)]
///
/// use heph::actor;
/// use heph::supervisor::NoSupervisor;
/// use heph_rt::spawn::ActorOptions;
/// use heph_rt::{self as rt, ThreadLocal, Runtime};
///
/// fn main() -> Result<(), rt::Error> {
/// let mut runtime = Runtime::new()?;
/// runtime.run_on_workers(|mut runtime_ref| -> Result<(), !> {
/// runtime_ref.spawn_local(NoSupervisor, actor as fn(_) -> _, (), ActorOptions::default());
/// Ok(())
/// })?;
/// runtime.start()
/// }
///
/// /// Our actor that never returns an error.
/// async fn actor(ctx: actor::Context<&'static str, ThreadLocal>) {
/// println!("Hello world!");
/// # drop(ctx); // Silence dead code warnings.
/// }
/// ```
#[derive(Copy, Clone, Debug)]
pub struct NoSupervisor;
impl<NA> Supervisor<NA> for NoSupervisor
where
NA: NewActor<Error = !>,
NA::Actor: Actor<Error = !>,
{
fn decide(&mut self, _: !) -> SupervisorStrategy<NA::Argument> {
// This can't be called.
SupervisorStrategy::Stop
}
fn decide_on_restart_error(&mut self, _: !) -> SupervisorStrategy<NA::Argument> {
// This can't be called.
SupervisorStrategy::Stop
}
fn second_restart_error(&mut self, _: !) {
// This can't be called.
}
}
impl<A> SyncSupervisor<A> for NoSupervisor
where
A: SyncActor<Error = !>,
{
fn decide(&mut self, _: !) -> SupervisorStrategy<A::Argument> {
// This can't be called.
SupervisorStrategy::Stop
}
}
/// A supervisor implementation that stops the actor and logs the error.
///
/// This supervisor can be used for quick prototyping or for one off actors that
/// shouldn't be restarted.
///
/// # Example
///
/// ```
/// #![feature(never_type)]
///
/// use heph::actor;
/// use heph::supervisor::StopSupervisor;
/// use heph_rt::spawn::ActorOptions;
/// use heph_rt::{self as rt, ThreadLocal, Runtime};
///
/// fn main() -> Result<(), rt::Error> {
/// let mut runtime = Runtime::new()?;
/// runtime.run_on_workers(|mut runtime_ref| -> Result<(), !> {
/// let supervisor = StopSupervisor::for_actor("print actor");
/// runtime_ref.spawn_local(supervisor, print_actor as fn(_) -> _, (), ActorOptions::default());
/// Ok(())
/// })?;
/// runtime.start()
/// }
///
/// /// Our actor that always returns an error.
/// async fn print_actor(ctx: actor::Context<&'static str, ThreadLocal>) -> Result<(), String> {
/// # drop(ctx); // Silence dead code warnings.
/// println!("Hello world!");
/// Err("oh no! Hit an error".to_string())
/// }
/// ```
#[derive(Copy, Clone, Debug)]
pub struct StopSupervisor(&'static str);
impl StopSupervisor {
/// Create a new `StopSupervisor` for the actor with `actor_name`.
pub const fn for_actor(actor_name: &'static str) -> StopSupervisor {
StopSupervisor(actor_name)
}
}
impl<NA> Supervisor<NA> for StopSupervisor
where
NA: NewActor,
NA::Error: std::fmt::Display,
<NA::Actor as Actor>::Error: fmt::Display,
{
fn decide(&mut self, err: <NA::Actor as Actor>::Error) -> SupervisorStrategy<NA::Argument> {
warn!("{} failed, stopping it: {}", self.0, err);
SupervisorStrategy::Stop
}
fn decide_on_restart_error(&mut self, err: NA::Error) -> SupervisorStrategy<NA::Argument> {
// Shouldn't be called, but it should still have an implementation.
warn!("{} failed to restart, stopping it: {}", self.0, err);
SupervisorStrategy::Stop
}
fn second_restart_error(&mut self, err: NA::Error) {
// Shouldn't be called, but it should still have an implementation.
warn!(
"{} failed to restart a second time, stopping it: {}",
self.0, err
);
}
}
impl<A> SyncSupervisor<A> for StopSupervisor
where
A: SyncActor,
A::Error: std::fmt::Display,
{
fn decide(&mut self, err: A::Error) -> SupervisorStrategy<A::Argument> {
warn!("{} failed, stopping it: {}", self.0, err);
SupervisorStrategy::Stop
}
}
/// Macro to create a supervisor that logs the error and restarts the actor.
///
/// This creates a new type that implements the [`Supervisor`] and
/// [`SyncSupervisor`] traits. The macro accepts the following arguments:
///
/// * Visibility indicator (*optional*), defaults to private (i.e. no
/// indicator).
/// * Name of the new supervisor type.
/// * Log friendly name of the actor, used in logging.
/// * Type of the argument(s) used to restart the actor. Multiple arguments must
/// be in the tuple format (same as for the [`NewActor::Argument`] type).
/// * Maximum number of restarts (*optional*), defaults to 5.
/// * Maximum duration before the restart counter get reset (*optional*),
/// defaults to 5 seconds.
/// * Additional logging message, defaults to nothing extra. This uses normal
/// [rust formatting rules] and is added at the end of the default message,
/// after the error. The `args` keyword gives access to the arguments. See
/// example 7 Restart Supervisor (in the example directory of the source
/// code).
///
/// The new type can be created using the `new` function, e.g.
/// `MySupervisor::new(args)`, see the example below.
///
/// [rust formatting rules]: std::fmt
///
/// # Logged messages
///
/// When the actor failed and is restarted:
///
/// ```text
/// $actor_name failed, restarting it ($left/$max restarts left): ${error}$log_extra
/// # For example, using the supervisor created in the example below.
/// my_actor failed, restarting it (1/2 restarts left): some I/O error: actor arguments (true, 0): (true, 0)
/// ```
///
/// If the actor failed too many times to quickly it will log the following.
///
/// ```text
/// $actor_name failed, stopping it (no restarts left): ${error}$log_extra
/// # For example, using the supervisor created in the example below.
/// my_actor failed, stopping it (no restarts left): some I/O error: actor arguments (true, 0): (true, 0)
/// ```
///
/// Similar messages will be logged if the actor fails to restart.
///
/// # Examples
///
/// The example below shows the simplest usage of the `restart_supervisor`
/// macro. Example 7 Restart Supervisor (in the example directory of the source
/// code) has a more complete example.
///
/// ```
/// use std::time::Duration;
///
/// use heph::restart_supervisor;
///
/// // Creates the `MySupervisor` type.
/// restart_supervisor!(
/// pub // Visibility indicator.
/// MySupervisor, // Name of the supervisor type.
/// "my actor", // Name of the actor.
/// (bool, u32), // Type of the arguments for the actor.
/// 2, // Maximum number of restarts.
/// Duration::from_secs(30), // Maximum duration before the restart counter
/// // get reset, defaults to 5 seconds (optional).
/// // This string is added to the log message after the error. `args`
/// // gives access to the arguments.
/// ": actor arguments {:?} ({}, {})",
/// args,
/// args.0,
/// args.1,
/// );
///
/// // Create a new supervisor.
/// let supervisor = MySupervisor::new(true, 23);
/// # drop(supervisor);
/// ```
#[macro_export]
macro_rules! restart_supervisor {
// No non-optional arguments, unit `NewActor::Argument`.
($vis: vis $supervisor_name: ident, $actor_name: expr $(,)*) => {
$crate::__heph_restart_supervisor_impl!($vis $supervisor_name, $actor_name, (), 5, std::time::Duration::from_secs(5), "",);
};
($vis: vis $supervisor_name: ident, $actor_name: expr, () $(,)*) => {
$crate::__heph_restart_supervisor_impl!($vis $supervisor_name, $actor_name, (), 5, std::time::Duration::from_secs(5), "",);
};
// No non-optional arguments, tuple `NewActor::Argument`.
($vis: vis $supervisor_name: ident, $actor_name: expr, ( $( $arg: ty),* ) $(,)*) => {
$crate::__heph_restart_supervisor_impl!($vis $supervisor_name, $actor_name, ( $( $arg ),* ), 5, std::time::Duration::from_secs(5), "",);
};
// No non-optional arguments, single `NewActor::Argument`.
($vis: vis $supervisor_name: ident, $actor_name: expr, $arg: ty $(,)*) => {
$crate::__heph_restart_supervisor_impl!($vis $supervisor_name, $actor_name, ( $arg ), 5, std::time::Duration::from_secs(5), "",);
};
// No log extra, unit `NewActor::Argument`.
($vis: vis $supervisor_name: ident, $actor_name: expr, (), $max_restarts: expr, $max_duration: expr $(,)*) => {
$crate::__heph_restart_supervisor_impl!($vis $supervisor_name, $actor_name, (), $max_restarts, $max_duration, "",);
};
// No log extra, tuple `NewActor::Argument`.
($vis: vis $supervisor_name: ident, $actor_name: expr, ( $( $arg: ty ),* ), $max_restarts: expr, $max_duration: expr $(,)*) => {
$crate::__heph_restart_supervisor_impl!($vis $supervisor_name, $actor_name, ( $( $arg ),* ), $max_restarts, $max_duration, "",);
};
// No log extra, single `NewActor::Argument`.
($vis: vis $supervisor_name: ident, $actor_name: expr, $arg: ty, $max_restarts: expr, $max_duration: expr $(,)*) => {
$crate::__heph_restart_supervisor_impl!($vis $supervisor_name, $actor_name, ( $arg ), $max_restarts, $max_duration, "",);
};
// All arguments, unit `NewActor::Argument`.
($vis: vis $supervisor_name: ident, $actor_name: expr, (), $max_restarts: expr, $max_duration: expr, $log_extra: expr, $( args $(. $log_arg_field: tt )* ),* $(,)*) => {
$crate::__heph_restart_supervisor_impl!($vis $supervisor_name, $actor_name, (), $max_restarts, $max_duration, $log_extra, $( args $(. $log_arg_field )* ),*);
};
// All arguments, tuple `NewActor::Argument`.
($vis: vis $supervisor_name: ident, $actor_name: expr, ( $( $arg: ty ),* ), $max_restarts: expr, $max_duration: expr, $log_extra: expr, $( args $(. $log_arg_field: tt )* ),* $(,)*) => {
$crate::__heph_restart_supervisor_impl!($vis $supervisor_name, $actor_name, ( $( $arg ),* ), $max_restarts, $max_duration, $log_extra, $( args $(. $log_arg_field )* ),*);
};
// All arguments, single `NewActor::Argument`.
($vis: vis $supervisor_name: ident, $actor_name: expr, $arg: ty, $max_restarts: expr, $max_duration: expr, $log_extra: expr, $( args $(. $log_arg_field: tt )* ),* $(,)*) => {
$crate::__heph_restart_supervisor_impl!($vis $supervisor_name, $actor_name, ( $arg ), $max_restarts, $max_duration, $log_extra, $( args $(. $log_arg_field )* ),*);
};
}
/// Private macro to implement the [`restart_supervisor`].
#[doc(hidden)]
#[macro_export]
macro_rules! __heph_restart_supervisor_impl {
(
$vis: vis
$supervisor_name: ident,
$actor_name: expr,
( $( $arg: ty ),* ),
$max_restarts: expr,
$max_duration: expr,
$log_extra: expr,
$( args $(. $log_arg_field: tt )* ),*
$(,)*
) => {
$crate::__heph_doc!(
std::concat!(
"Supervisor for ", $actor_name, ".\n\n",
"Maximum number of restarts: `", stringify!($max_restarts), "`, ",
"within a duration of: `", stringify!($max_duration), "`.",
),
#[derive(Debug)]
#[allow(unused_qualifications)]
$vis struct $supervisor_name {
/// The number of restarts left.
restarts_left: std::primitive::usize,
/// Time of the last restart.
last_restart: std::option::Option<std::time::Instant>,
/// Arguments used to restart the actor.
args: ( $( $arg ),* ),
}
);
#[allow(unused_qualifications)]
impl $supervisor_name {
/// Maximum number of restarts within a [`Self::MAX_DURATION`] time
/// period before the actor is stopped.
$vis const MAX_RESTARTS: std::primitive::usize = $max_restarts;
/// Maximum duration between errors to be considered of the same
/// cause. If `MAX_DURATION` has elapsed between errors the restart
/// counter gets reset to [`MAX_RESTARTS`].
///
/// [`MAX_RESTARTS`]: Self::MAX_RESTARTS
$vis const MAX_DURATION: std::time::Duration = $max_duration;
$crate::__heph_restart_supervisor_impl!(impl_new $vis $supervisor_name, ( $( $arg ),* ));
}
impl<NA> $crate::supervisor::Supervisor<NA> for $supervisor_name
where
NA: $crate::NewActor<Argument = ( $( $arg ),* )>,
NA::Error: std::fmt::Display,
<NA::Actor as $crate::Actor>::Error: std::fmt::Display,
{
fn decide(&mut self, err: <NA::Actor as $crate::Actor>::Error) -> $crate::SupervisorStrategy<NA::Argument> {
$crate::__heph_restart_supervisor_impl!{decide_impl self, err, $actor_name, $max_restarts, $log_extra, $( args $(. $log_arg_field )* ),*}
}
fn decide_on_restart_error(&mut self, err: NA::Error) -> $crate::SupervisorStrategy<NA::Argument> {
self.last_restart = Some(std::time::Instant::now());
if self.restarts_left >= 1 {
self.restarts_left -= 1;
::log::warn!(
std::concat!($actor_name, " actor failed to restart, trying again ({}/{} restarts left): {}", $log_extra),
self.restarts_left, $max_restarts, err, $( self.args $(. $log_arg_field )* ),*
);
$crate::SupervisorStrategy::Restart(self.args.clone())
} else {
::log::warn!(
std::concat!($actor_name, " actor failed to restart, stopping it (no restarts left): {}", $log_extra),
err, $( self.args $(. $log_arg_field )* ),*
);
$crate::SupervisorStrategy::Stop
}
}
fn second_restart_error(&mut self, err: NA::Error) {
::log::warn!(
std::concat!($actor_name, " actor failed to restart a second time, stopping it: {}", $log_extra),
err, $( self.args $(. $log_arg_field )* ),*
);
}
}
impl<A> $crate::supervisor::SyncSupervisor<A> for $supervisor_name
where
A: $crate::actor::SyncActor<Argument = ( $( $arg ),* )>,
A::Error: std::fmt::Display,
{
fn decide(&mut self, err: A::Error) -> $crate::SupervisorStrategy<A::Argument> {
$crate::__heph_restart_supervisor_impl!{decide_impl self, err, $actor_name, $max_restarts, $log_extra, $( args $(. $log_arg_field )* ),*}
}
}
};
// The `decide` implementation of `Supervisor` and `SyncSupervisor`.
(
decide_impl
$self: ident,
$err: ident,
$actor_name: expr,
$max_restarts: expr,
$log_extra: expr,
$( args $(. $log_arg_field: tt )* ),*
$(,)*
) => {
let now = std::time::Instant::now();
let last_restart = $self.last_restart.replace(now);
// If enough time has passed between the last restart and now we
// reset the `restarts_left` left counter.
if let Some(last_restart) = last_restart {
let duration_since_last_crash = now - last_restart;
if duration_since_last_crash > Self::MAX_DURATION {
$self.restarts_left = Self::MAX_RESTARTS;
}
}
if $self.restarts_left >= 1 {
$self.restarts_left -= 1;
::log::warn!(
std::concat!($actor_name, " failed, restarting it ({}/{} restarts left): {}", $log_extra),
$self.restarts_left, $max_restarts, $err, $( $self.args $(. $log_arg_field )* ),*
);
$crate::SupervisorStrategy::Restart($self.args.clone())
} else {
::log::warn!(
std::concat!($actor_name, " failed, stopping it (no restarts left): {}", $log_extra),
$err, $( $self.args $(. $log_arg_field )* ),*
);
$crate::SupervisorStrategy::Stop
}
};
// TODO: DRY the implementations below.
// Unit (`()`) type as argument.
(impl_new $vis: vis $supervisor_name: ident, ()) => {
$crate::__heph_doc!(
std::concat!("Create a new `", stringify!($supervisor_name), "`."),
#[allow(dead_code)]
$vis const fn new() -> $supervisor_name {
$supervisor_name {
restarts_left: Self::MAX_RESTARTS,
last_restart: None,
args: (),
}
}
);
};
// Single argument.
(impl_new $vis: vis $supervisor_name: ident, ( $arg: ty )) => {
$crate::__heph_doc!(
std::concat!("Create a new `", stringify!($supervisor_name), "`."),
#[allow(dead_code)]
$vis const fn new(arg: $arg) -> $supervisor_name {
$supervisor_name {
restarts_left: Self::MAX_RESTARTS,
last_restart: None,
args: (arg),
}
}
);
};
// Tuple type as argument.
// Tuple of 2.
(impl_new $vis: vis $supervisor_name: ident, ($arg0: ty, $arg1: ty)) => {
$crate::__heph_doc!(
std::concat!("Create a new `", stringify!($supervisor_name), "`."),
#[allow(dead_code)]
$vis const fn new(arg0: $arg0, arg1: $arg1) -> $supervisor_name {
$supervisor_name {
restarts_left: Self::MAX_RESTARTS,
last_restart: None,
args: (arg0, arg1),
}
}
);
};
// Tuple of 3.
(impl_new $vis: vis $supervisor_name: ident, ($arg0: ty, $arg1: ty, $arg2: ty)) => {
$crate::__heph_doc!(
std::concat!("Create a new `", stringify!($supervisor_name), "`."),
#[allow(dead_code)]
$vis const fn new(arg0: $arg0, arg1: $arg1, arg2: $arg2) -> $supervisor_name {
$supervisor_name {
restarts_left: Self::MAX_RESTARTS,
last_restart: None,
args: (arg0, arg1, arg2),
}
}
);
};
// Tuple of 4.
(impl_new $vis: vis $supervisor_name: ident, ($arg0: ty, $arg1: ty, $arg2: ty, $arg3: ty)) => {
$crate::__heph_doc!(
std::concat!("Create a new `", stringify!($supervisor_name), "`."),
#[allow(dead_code)]
$vis const fn new(arg0: $arg0, arg1: $arg1, arg2: $arg2, arg3: $arg3) -> $supervisor_name {
$supervisor_name {
restarts_left: Self::MAX_RESTARTS,
last_restart: None,
args: (arg0, arg1, arg2, arg3),
}
}
);
};
// Tuple of 5.
(impl_new $vis: vis $supervisor_name: ident, ($arg0: ty, $arg1: ty, $arg2: ty, $arg3: ty, $arg4: ty)) => {
$crate::__heph_doc!(
std::concat!("Create a new `", stringify!($supervisor_name), "`."),
#[allow(dead_code)]
$vis const fn new(arg0: $arg0, arg1: $arg1, arg2: $arg2, arg3: $arg3, arg4: $arg4) -> $supervisor_name {
$supervisor_name {
restarts_left: Self::MAX_RESTARTS,
last_restart: None,
args: (arg0, arg1, arg2, arg3, arg4),
}
}
);
};
// Tuple of 6.
(impl_new $vis: vis $supervisor_name: ident, ($arg0: ty, $arg1: ty, $arg2: ty, $arg3: ty, $arg4: ty, $arg5: ty)) => {
$crate::__heph_doc!(
std::concat!("Create a new `", stringify!($supervisor_name), "`."),
#[allow(dead_code)]
$vis const fn new(arg0: $arg0, arg1: $arg1, arg2: $arg2, arg3: $arg3, arg4: $arg4, arg5: $arg5) -> $supervisor_name {
$supervisor_name {
restarts_left: Self::MAX_RESTARTS,
last_restart: None,
args: (arg0, arg1, arg2, arg3, arg4, arg5),
}
}
);
};
// Tuple of 6+.
(impl_new $vis: vis $supervisor_name: ident, ( $( $arg: ty ),* )) => {
$crate::__heph_doc!(
std::concat!("Create a new `", stringify!($supervisor_name), "`."),
#[allow(dead_code)]
$vis const fn new(args: ( $( $arg ),* )) -> $supervisor_name {
$supervisor_name {
restarts_left: Self::MAX_RESTARTS,
last_restart: None,
args,
}
}
);
};
}
/// Helper macro to document type created in [`restart_supervisor`].
#[doc(hidden)]
#[macro_export]
macro_rules! __heph_doc {
($doc: expr, $( $tt: tt )*) => {
#[doc = $doc]
$($tt)*
};
}