Struct stakker::Cx

pub struct Cx<'a, A: 'static> { /* fields omitted */ }

Context for an actor call

Gives access to Core through auto-deref or *cx. Also allows stopping the actor with stop! (successful termination) and aborting the actor with fail! (failure with an error). A reference to the current actor is available through Cx::this.

Implementations

impl<'a, A> Cx<'a, A>

pub fn this(&self) -> &Actor<A>

Borrow the current actor reference temporarily. If you need a longer-lived reference to the actor, then clone the result of this call.

pub fn id(&self) -> LogID

Get the logging-ID of the current actor. If the logger feature isn't enabled, returns 0.

pub fn stop(&mut self)

Indicate successful termination of the actor. As soon as the currently-running actor call finishes, the actor will be terminated. Actor state will be dropped, and any further calls to this actor will be discarded. The termination status is passed back to the StopCause handler provided when the actor was created.

pub fn fail(&mut self, e: impl Error + 'static)

Indicate failure of the actor. As soon as the currently-running actor call finishes, the actor will be terminated. Actor state will be dropped, and any further calls to this actor will be discarded. The termination status is passed back to the StopCause handler provided when the actor was created.

fail! provides a convenient interface to this method.

pub fn fail_str(&mut self, e: &'static str)

Indicate failure of the actor. As soon as the currently-running actor call finishes, the actor will be terminated. Actor state will be dropped, and any further calls to this actor will be discarded. The termination status is passed back to the StopCause handler provided when the actor was created.

fail! provides a convenient interface to this method.

pub fn fail_string(&mut self, e: impl Into<String>)

Indicate failure of the actor. As soon as the currently-running actor call finishes, the actor will be terminated. Actor state will be dropped, and any further calls to this actor will be discarded. The termination status is passed back to the StopCause handler provided when the actor was created.

fail! provides a convenient interface to this method.

pub fn access_actor(&self) -> &Actor<A>

Used in macros to get an Actor reference

pub fn access_log_id(&self) -> LogID

Used in macros to get the actor's logging-ID. If the logger feature isn't enabled, returns 0.

Methods from Deref<Target = Core>

pub fn now(&self) -> Instant

Our view of the current time. Actors should use this in preference to Instant::now() for speed and in order to work in virtual time.

pub fn systime(&self) -> SystemTime

Get the current SystemTime. Normally this returns the same as SystemTime::now(), but if running in virtual time, it would return the virtual SystemTime instead (as provided to Stakker::set_systime by the virtual time main loop). Note that this time is not suitable for timing things, as it may go backwards if the user or a system process adjusts the clock. It is just useful for showing or recording "human time" for the user, and for recording times that are meaningful on a longer scale, e.g. from one run of a process to the next.

pub fn defer(&mut self, f: impl FnOnce(&mut Stakker) + 'static)

Defer an operation to be executed later. It is put on the main queue, and run as soon all operations preceding it have been executed.

pub fn lazy(&mut self, f: impl FnOnce(&mut Stakker) + 'static)

Defer an operation to executed soon, but lazily. It goes onto a lower priority queue executed once the normal defer queue has been completely cleared (including any further deferred items added whilst clearing that queue). This can be used for flushing data generated in this batch of processing, for example.

pub fn idle(&mut self, f: impl FnOnce(&mut Stakker) + 'static)

Defer an operation to be executed when this process next becomes idle, i.e. when all other queues are empty and there is no I/O to process. This can be used to implement backpressure on incoming streams, i.e. only fetch more data once there is nothing else left to do.

pub fn after(
    &mut self,
    dur: Duration,
    f: impl FnOnce(&mut Stakker) + 'static
) -> FixedTimerKey

Delay an operation to be executed after a duration has passed. This is the same as adding it as a fixed timer. Returns a key that can be used to delete the timer.

pub fn timer_add(
    &mut self,
    expiry: Instant,
    f: impl FnOnce(&mut Stakker) + 'static
) -> FixedTimerKey

Add a fixed timer that expires at the given time. Returns a key that can be used to delete the timer.

pub fn timer_del(&mut self, key: FixedTimerKey) -> bool

Delete a fixed timer. Returns true on success, false if timer no longer exists (i.e. it expired or was deleted)

pub fn timer_max_add(
    &mut self,
    expiry: Instant,
    f: impl FnOnce(&mut Stakker) + 'static
) -> MaxTimerKey

Add a "Max" timer, which expires at the greatest (latest) expiry time provided. See MaxTimerKey for the characteristics of this timer. Returns a key that can be used to delete or modify the timer.

See also the timer_max! macro, which may be more convenient as it combines Core::timer_max_add and Core::timer_max_upd.

pub fn timer_max_upd(&mut self, key: MaxTimerKey, expiry: Instant) -> bool

Update a "Max" timer with a new expiry time. It will be used as the new expiry time only if it is greater than the current expiry time. This call is designed to be very cheap to call frequently.

Returns true on success, false if timer no longer exists (i.e. it expired or was deleted)

See also the timer_max! macro, which may be more convenient as it combines Core::timer_max_add and Core::timer_max_upd.

pub fn timer_max_del(&mut self, key: MaxTimerKey) -> bool

Delete a "Max" timer. Returns true on success, false if timer no longer exists (i.e. it expired or was deleted)

pub fn timer_max_active(&mut self, key: MaxTimerKey) -> bool

Check whether a "Max" timer is active. Returns true if it exists and is active, false if it expired or was deleted or never existed

pub fn timer_min_add(
    &mut self,
    expiry: Instant,
    f: impl FnOnce(&mut Stakker) + 'static
) -> MinTimerKey

Add a "Min" timer, which expires at the smallest (earliest) expiry time provided. See MinTimerKey for the characteristics of this timer. Returns a key that can be used to delete or modify the timer.

See also the timer_min! macro, which may be more convenient as it combines Core::timer_min_add and Core::timer_min_upd.

pub fn timer_min_upd(&mut self, key: MinTimerKey, expiry: Instant) -> bool

Update a "Min" timer with a new expiry time. It will be used as the new expiry time only if it is earlier than the current expiry time. This call is designed to be very cheap to call frequently, so long as the change is within the wiggle-room allowed. Otherwise it causes the working timer to be deleted and added again, readjusting the wiggle-room accordingly.

Returns true on success, false if timer no longer exists (i.e. it expired or was deleted)

See also the timer_min! macro, which may be more convenient as it combines Core::timer_min_add and Core::timer_min_upd.

pub fn timer_min_del(&mut self, key: MinTimerKey) -> bool

Delete a "Min" timer. Returns true on success, false if timer no longer exists (i.e. it expired or was deleted)

pub fn timer_min_active(&mut self, key: MinTimerKey) -> bool

Check whether a "Min" timer is active. Returns true if it exists and is active, false if it expired or was deleted or never existed

pub fn anymap_set<T: Clone + 'static>(&mut self, val: T)

Put a value into the anymap. This can be accessed using the Core::anymap_get or Core::anymap_try_get call. An anymap can store one value for each type (see crate anymap). The value must implement Clone, i.e. it must act something like an Rc or else be copyable data.

This is intended to be used for storing certain global instances which actors may need to get hold of, for example an access-point for the I/O poll implementation that Stakker is running under.

pub fn anymap_get<T: Clone + 'static>(&mut self) -> T

Gets a clone of a value from the Stakker anymap. This is intended to be used to access certain global instances, for example the I/O poll implementation that this Stakker is running inside. Panics if the value is not found.

pub fn anymap_try_get<T: Clone + 'static>(&mut self) -> Option<T>

Tries to get a clone of a value from the Stakker anymap. This is intended to be used to access certain global instances, for example the I/O poll implementation that this Stakker is running inside. Returns None if the value is missing.

pub fn shutdown(&mut self, cause: StopCause)

Request that the event loop terminate. For this to work, the event loop must check Core::not_shutdown each time through the loop. See also the ret_shutdown! macro which can be used as the StopCause handler for an actor, to shut down the event loop when that actor terminates. The event loop code can obtain the StopCause using Core::shutdown_reason.

pub fn not_shutdown(&self) -> bool

Should the event loop continue running? Returns true if there is no active shutdown in progress.

pub fn shutdown_reason(&mut self) -> Option<StopCause>

Get the reason for shutdown, if shutdown was requested. After calling this, the shutdown flag is cleared, i.e. Core::not_shutdown will return false and the event loop could continue to run.

pub fn deferrer(&self) -> Deferrer

Get a new Deferrer instance which can be used to defer calls to the main queue from contexts in the same thread which don't have access to Core, for example drop handlers.

pub fn waker(&mut self, cb: impl FnMut(&mut Stakker, bool) + 'static) -> Waker

Register a wake handler callback, and obtain a Waker instance which can be passed to another thread. The wake handler will always be executed in the main thread. When Waker::wake is called in another thread, a wake-up is scheduled to occur in the main thread, using the wake-up mechanism provided by the I/O poller. Then when that wake-up is received, the corresponding wake handler is executed. Note that this is efficient -- if many wake handlers are scheduled around the same time, they share the same main thread wake-up.

The wake handler is called in the main thread with arguments of (stakker, deleted). Note that there is a small chance of a spurious wake call happening occasionally, so the wake handler code must be ready for that. If deleted is true then the Waker was dropped, and this wake handler is also just about to be dropped.

This call panics if no I/O poller has yet set up a waker using Stakker::set_poll_waker.

pub fn share_rw2<'a, T, U>(
    &'a mut self,
    s1: &'a Share<T>,
    s2: &'a Share<U>
) -> (&'a mut T, &'a mut U)

Borrow two Share instances mutably at the same time. This will panic if they are the same instance.

pub fn share_rw3<'a, T, U, V>(
    &'a mut self,
    s1: &'a Share<T>,
    s2: &'a Share<U>,
    s3: &'a Share<V>
) -> (&'a mut T, &'a mut U, &'a mut V)

Borrow three Share instances mutably at the same time. This will panic if any two are the same instance.

pub fn log(
    &mut self,
    id: LogID,
    level: LogLevel,
    target: &str,
    fmt: Arguments<'_>,
    kvscan: impl Fn(&mut dyn LogVisitor)
)

Log a log-record to the current logger, if one is active and if the log-level is enabled. Otherwise it is ignored. id should be the logging-ID (obtained from actor.id() or cx.id() or core.log_span_open() for non-actor spans) or 0 if the log-record doesn't belong to any span.

Normally you would use a macro provided by an external crate which wraps this call.

pub fn log_check(&self, level: LogLevel) -> bool

Check whether a log-record with the given LogLevel should be logged

pub fn log_span_open(
    &mut self,
    tag: &str,
    parent_id: LogID,
    kvscan: impl Fn(&mut dyn LogVisitor)
) -> LogID

Allocate a new logging-ID and write an Open record to the logger. tag will be included as the record's text, and should indicate what kind of span it is, e.g. the type name for an actor. This should be the tag for the record, and would not normally contain any dynamic information. If parent_id is non-zero, then a parent key will be added with that value. kvscan will be called to add any other key-value pairs as required, which is where the dynamic information should go.

This is used by actors on startup to allocate a logging-ID for the span of the actor's lifetime. However other code that needs to do logging within a certain identifiable span can also make use of this call. Where possible, relate this new span to another span using parent_id. Use Core::log_span_close when the span is complete.

In the unlikely event that a program allocates 2^64 logging IDs, the IDs will wrap around to 1 again. If this is likely to cause a problem downstream, the logger implementation should detect this and warn or terminate as appropriate.

pub fn log_span_close(
    &mut self,
    id: LogID,
    fmt: Arguments<'_>,
    kvscan: impl Fn(&mut dyn LogVisitor)
)

Write a Close record to the logger

fmt is a message which may give more information, e.g. the error message in the case of a failure. kvscan will be called to add key-value pairs to the record.

pub fn access_core(&mut self) -> &mut Core

Used in macros to get a Core reference

pub fn access_deferrer(&self) -> &Deferrer

Used in macros to get a Deferrer reference

pub fn access_log_id(&self) -> LogID

Used in macros to get the LogID in case this is an actor. Since it isn't, this call returns 0.

Trait Implementations

impl<'a, A> Deref for Cx<'a, A>

type Target = Core

The resulting type after dereferencing.

fn deref(&self) -> &Core

Dereferences the value.

impl<'a, A> DerefMut for Cx<'a, A>

fn deref_mut(&mut self) -> &mut Core

Mutably dereferences the value.