Struct Callbacks

pub struct Callbacks { /* private fields */ }

A set of methods that will get called at different states of a Supervisor or Children life.

Example

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 {
                // ...
            }
            // -- Children group stopped.
        })
}).expect("Couldn't create the children group.");

Implementations

impl Callbacks

pub fn new() -> Self

Creates a new instance of Callbacks for Supervisor::with_callbacks or Children::with_callbacks.

Example

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 {
                // ...
            }
            // -- Children group stopped.
        })
}).expect("Couldn't create the children group.");

pub fn with_before_start<C>(self, before_start: C) -> Self

where C: Fn() + Send + Sync + 'static,

Sets the method that will get called before the Supervisor or Children is launched if:

• it was never called before
• or the supervisor of the supervised element using this callback (or the system) decided to restart it and it was already stopped or killed
• or the supervisor of the supervised element using this callback (or the system) decided to restart it and it wasn’t already stopped or killed but did not have a callback defined using with_after_restart

Example

supervisor.children(|children| {
    let callbacks = Callbacks::new()
        .with_before_start(|| println!("Children group started."))
        .with_before_restart(|| println!("Children group restarting."))
        .with_after_restart(|| println!("Children group restarted."))
        .with_after_stop(|| println!("Children group stopped."));

    children
        .with_exec(|ctx| {
            // -- Children group started.
            async move {
                // ...

                // This will stop the children group...
                Ok(())
                // Note that because the children group stopped by itself,
                // if its supervisor restarts it, its `before_start` callback
                // will get called and not `after_restart`.
            }
            // -- Children group stopped.
        })
        .with_callbacks(callbacks)
})

pub fn with_after_start<C>(self, after_start: C) -> Self

where C: Fn() + Send + Sync + 'static,

Sets the method that will get called right after the Supervisor or Children is launched. This method will be called after the child has subscribed to its distributors and dispatchers.

Once the callback has run, the child has caught up it’s message backlog, and is waiting for new messages to process.

Example

supervisor.children(|children| {
    let callbacks = Callbacks::new()
        .with_after_start(|| println!("Children group ready to process messages."));

    children
        .with_exec(|ctx| {
            // -- Children group started.
            // with_after_start called
            async move {
                // ...

                // This will stop the children group...
                Ok(())
                // Note that because the children group stopped by itself,
                // if its supervisor restarts it, its `before_start` callback
                // will get called and not `after_restart`.
            }
            // -- Children group stopped.
        })
        .with_callbacks(callbacks)
})

pub fn with_before_restart<C>(self, before_restart: C) -> Self

where C: Fn() + Send + Sync + 'static,

Sets the method that will get called before the Supervisor or Children is reset if:

• the supervisor of the supervised element using this callback (or the system) decided to restart it and it wasn’t already stopped or killed

Note that if this callback isn’t defined but one was defined using with_after_stop, it will get called instead.

Example

supervisor.children(|children| {
    let callbacks = Callbacks::new()
        .with_before_start(|| println!("Children group started."))
        .with_before_restart(|| println!("Children group restarting."))
        .with_after_restart(|| println!("Children group restarted."))
        .with_after_stop(|| println!("Children group stopped."));

    children
        .with_exec(|ctx| {
            // Once -- Children group started.
            // and then -- Children group restarted.
            async move {
                // ...

                // This will make the children group fault and get
                // restarted by its supervisor...
                Err(())
            }
            // -- Children group restarting.
            // Note that if a `before_restart` wasn't specified for
            // this children group, `after_stop` would get called
            // instead.
        })
        .with_callbacks(callbacks)
})

pub fn with_after_restart<C>(self, after_restart: C) -> Self

where C: Fn() + Send + Sync + 'static,

Sets the method that will get called before the Supervisor or Children is launched if:

• the supervisor of the supervised element using this callback (or the system) decided to restart it and it wasn’t already stopped or killed

Note that if this callback isn’t defined but one was defined using with_before_start, it will get called instead.

Example

supervisor.children(|children| {
    let callbacks = Callbacks::new()
        .with_before_start(|| println!("Children group started."))
        .with_before_restart(|| println!("Children group restarting."))
        .with_after_restart(|| println!("Children group restarted."))
        .with_after_stop(|| println!("Children group stopped."));

    children
        .with_exec(|ctx| {
            // Once -- Children group started.
            // and then -- Children group restarted.
            // Note that if a `after_restart` callback wasn't specified
            // for this children group, `before_restart` would get called
            // instead.
            async move {
                // ...

                // This will make the children group fault and get
                // restarted by its supervisor...
                Err(())
            }
            // -- Children group restarting.
        })
        .with_callbacks(callbacks)
})

pub fn with_after_stop<C>(self, after_stop: C) -> Self

where C: Fn() + Send + Sync + 'static,

Sets the method that will get called after the Supervisor or Children is stopped or killed if:

• the supervisor of the supervised element using this callback (or the system) decided to stop (not restart nor kill) it and it wasn’t already stopped or killed
• or the supervisor or children group using this callback stopped or killed itself or was stopped or killed by a reference to it
• or the supervisor of the supervised element using this callback (or the system) decided to restart it and it wasn’t already stopped or killed but did not have a callback defined using with_before_restart

Example

supervisor.children(|children| {
    let callbacks = Callbacks::new()
        .with_before_start(|| println!("Children group started."))
        .with_before_restart(|| println!("Children group restarting."))
        .with_after_restart(|| println!("Children group restarted."))
        .with_after_stop(|| println!("Children group stopped."));

    children
        .with_exec(|ctx| {
            // -- Children group started.
            async move {
                // ...

                // This will stop the children group...
                Ok(())
            }
            // -- Children group stopped.
            // Note that because the children group stopped by itself,
            // it its supervisor restarts it, its `before_restart` callback
            // will not get called.
        })
        .with_callbacks(callbacks)
})

pub fn has_before_start(&self) -> bool

Returns whether a callback was defined using with_before_start.

Example

let callbacks = Callbacks::new()
    .with_before_start(|| println!("Children group started."));

assert!(callbacks.has_before_start());

pub fn has_before_restart(&self) -> bool

Returns whether a callback was defined using with_before_restart.

Example

let callbacks = Callbacks::new()
    .with_before_restart(|| println!("Children group restarting."));

assert!(callbacks.has_before_restart());

pub fn has_after_restart(&self) -> bool

Returns whether a callback was defined using with_after_restart.

Example

let callbacks = Callbacks::new()
    .with_after_restart(|| println!("Children group restarted."));

assert!(callbacks.has_after_restart());

pub fn has_after_stop(&self) -> bool

Returns whether a callback was defined using with_after_stop.

Example

let callbacks = Callbacks::new()
    .with_after_stop(|| println!("Children group stopped."));

assert!(callbacks.has_after_stop());

Trait Implementations

impl Clone for Callbacks

fn clone(&self) -> Callbacks

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Callbacks

fn fmt(&self, fmt: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Callbacks

fn default() -> Callbacks

Returns the “default value” for a type.