1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855
use crate::queue::FnOnceQueue;
use crate::rc::ActorRc;
use crate::{ret, ret_some_do, Core, Deferrer, LogID, Ret, Stakker};
use slab::Slab;
use std::error::Error;
use std::fmt;
use std::ops::{Deref, DerefMut};
/// An owning ref-counting reference to an actor
///
/// This not only keeps a reference to the actor, but it will also
/// automatically terminate the actor when the last owning reference
/// is dropped. This dereferences to a normal [`Actor`] reference, so
/// when `.clone()` is called on it, a normal non-owning reference
/// results. To get another owning reference, use `.owned()`.
///
/// [`Actor`]: struct.Actor.html
pub struct ActorOwn<A: 'static> {
actor: Actor<A>,
}
impl<A: 'static> ActorOwn<A> {
/// Create a new uninitialised actor of the given type. This is
/// in the **Prep** state. The reference can be cloned and passed
/// around and used to create [`Fwd`] or [`Ret`] instances.
/// However all calls to the actor will be delayed until the actor
/// moves into the **Ready** state.
///
/// `notify` is the [`StopCause`] return, which is called when the
/// actor terminates. `parent_id` is the logging-ID of the parent
/// actor if known, or else 0.
///
/// See macros [`actor!`] and [`actor_new!`] for help with
/// creating and initialising actors.
///
/// [`Fwd`]: struct.Fwd.html
/// [`Ret`]: struct.Ret.html
/// [`StopCause`]: enum.StopCause.html
/// [`actor!`]: macro.actor.html
/// [`actor_new!`]: macro.actor_new.html
#[inline]
pub fn new(core: &mut Core, notify: Ret<StopCause>, parent_id: LogID) -> ActorOwn<A> {
Self::construct(Actor {
rc: ActorRc::new(core, Some(notify), parent_id),
})
}
fn construct(actor: Actor<A>) -> Self {
actor.rc.strong_inc();
Self { actor }
}
/// Create an additional owning reference to this actor. When the
/// last owning reference is dropped, the actor is terminated,
/// even when there are other references active.
pub fn owned(&self) -> ActorOwn<A> {
ActorOwn::construct(self.actor.clone())
}
/// Kill actor, moving to **Zombie** state and dropping the
/// contained actor `Self` value. The actor can never return from
/// the **Zombie** state. The provided error is used to generate
/// an `StopCause::Killed` instance, which is passed to the
/// [`StopCause`] handler set up when the actor was created.
///
/// [`StopCause`]: enum.StopCause.html
pub fn kill(&self, s: &mut Stakker, err: Box<dyn Error>) {
self.actor.terminate(s, StopCause::Killed(err));
}
/// Kill actor, moving to **Zombie** state and dropping the
/// contained actor `Self` value. The actor can never return from
/// the **Zombie** state. The provided error string is used to
/// generate an `StopCause::Killed` instance, which is passed to
/// the [`StopCause`] handler set up when the actor was created.
///
/// [`StopCause`]: enum.StopCause.html
pub fn kill_str(&self, s: &mut Stakker, err: &'static str) {
self.actor
.terminate(s, StopCause::Killed(Box::new(StrError(err))));
}
/// Kill actor, moving to **Zombie** state and dropping the
/// contained actor `Self` value. The actor can never return from
/// the **Zombie** state. The provided error string is used to
/// generate an `StopCause::Killed` instance, which is passed to
/// the [`StopCause`] handler set up when the actor was created.
///
/// [`StopCause`]: enum.StopCause.html
pub fn kill_string(&self, s: &mut Stakker, err: impl Into<String>) {
self.actor
.terminate(s, StopCause::Killed(Box::new(StringError(err.into()))));
}
/// Convert into an anonymous owning reference. See
/// [`ActorOwnAnon`].
///
/// [`ActorOwnAnon`]: struct.ActorOwnAnon.html
pub fn anon(self) -> ActorOwnAnon {
ActorOwnAnon::new(self)
}
}
impl<A: 'static> Deref for ActorOwn<A> {
type Target = Actor<A>;
fn deref(&self) -> &Actor<A> {
&self.actor
}
}
impl<A: 'static> DerefMut for ActorOwn<A> {
fn deref_mut(&mut self) -> &mut Actor<A> {
&mut self.actor
}
}
impl<A: 'static> Drop for ActorOwn<A> {
fn drop(&mut self) {
let went_to_zero = self.actor.rc.strong_dec();
if went_to_zero {
let actor = self.actor.clone();
self.actor
.defer(move |s| actor.terminate(s, StopCause::Dropped));
}
}
}
/// An owning ref-counting reference to an anonymous actor
///
/// The purpose of this is to allow owning any one of a class of other
/// actors without knowing the exact type. The only operation this
/// supports is dropping an owning reference to an actor when this
/// value is dropped. It can be used in combination with a [`Fwd`]
/// instance to support plugging a variety of different actors into a
/// standard interface, without needing traits. As an alternative,
/// see [`actor_of_trait!`].
///
/// Example, using [`ActorOwn::anon`] to create the anonymous
/// reference:
///
/// ```
/// # use stakker::*;
/// # use std::time::Instant;
/// struct Cat;
/// impl Cat {
/// fn init(_: CX![]) -> Option<Self> {
/// Some(Self)
/// }
/// fn sound(&mut self, _: CX![]) {
/// println!("Miaow");
/// }
/// }
///
/// struct Dog;
/// impl Dog {
/// fn init(_: CX![]) -> Option<Self> {
/// Some(Self)
/// }
/// fn sound(&mut self, _: CX![]) {
/// println!("Woof");
/// }
/// }
///
/// // This function doesn't know whether it's getting a cat or a dog,
/// // but it can still call it and drop it when it has finished
/// pub fn call_and_drop(sound: Fwd<()>, own: ActorOwnAnon) {
/// fwd!([sound]);
/// }
///
/// let mut stakker = Stakker::new(Instant::now());
/// let s = &mut stakker;
///
/// let cat = actor!(s, Cat::init(), ret_nop!());
/// call_and_drop(fwd_to!([cat], sound() as ()), cat.anon());
///
/// let dog = actor!(s, Dog::init(), ret_nop!());
/// call_and_drop(fwd_to!([dog], sound() as ()), dog.anon());
///
/// s.run(Instant::now(), false);
/// ```
///
/// [`ActorOwn::anon`]: struct.ActorOwn.html#method.anon
/// [`Fwd`]: struct.Fwd.html
/// [`actor_of_trait!`]: macro.actor_of_trait.html
#[allow(dead_code)]
pub struct ActorOwnAnon(Box<dyn ActorOwnAnonTrait>);
trait ActorOwnAnonTrait {}
impl<T: 'static> ActorOwnAnonTrait for ActorOwn<T> {}
impl ActorOwnAnon {
pub fn new<T: 'static>(actorown: ActorOwn<T>) -> Self {
Self(Box::new(actorown))
}
}
/// A ref-counting reference to an actor
///
/// This may be cloned to get another reference to the same actor.
///
/// # Example implementation of an minimal actor
///
/// ```
///# use stakker::{call, Cx, CX, Ret, ret};
/// struct Light {
/// on: bool,
/// }
/// impl Light {
/// pub fn init(_cx: CX![], on: bool) -> Option<Self> {
/// Some(Self { on })
/// }
/// pub fn set(&mut self, _cx: CX![], on: bool) {
/// self.on = on;
/// }
/// pub fn get(&self, cx: CX![], ret: Ret<bool>) {
/// ret!([ret], self.on);
/// }
/// }
/// ```
///
/// # Internal state of an actor
///
/// An actor may be in one of three states: **Prep**, **Ready** or
/// **Zombie**. This is independent of whether there are still
/// references to it. The actor only has a `self` value in the
/// **Ready** state.
///
///
/// # Lifecycle of an actor
///
/// **"Prep" state**: As soon as [`ActorOwn::new`] returns, the actor
/// exists and is in the **Prep** state. It has an actor reference,
/// but it does not yet have a `self` value. It is possible to create
/// [`Fwd`] or [`Ret`] instances referring to methods in this actor,
/// and to pass the actor reference to other actors. However any
/// normal actor calls will be queued up until the actor becomes
/// ready. The only calls that are permitted on the actor in the
/// **Prep** state are calls to static methods with the signature `fn
/// method(cx: CX![], ...) -> Option<Self>`.
///
/// An actor call should be made to one of the static methods on the
/// actor to start the process of initialising it. Initialisation may
/// be immediate, or it may start an asynchronous process (for
/// example, making a connection to a remote server). Each call to a
/// static method may schedule callbacks to other static methods.
/// Eventually, one of these methods should either return
/// `Some(value)` or else fail the actor.
///
/// **"Ready" state**: As soon as a `Self` value is returned from a
/// **Prep** method, this is installed as the actor's `self` value,
/// and the actor moves to the **Ready** state. Any calls to the
/// actor that were queued up whilst it was in the **Prep** state are
/// flushed and executed at this point. Whilst in the **Ready**
/// state, the actor can only execute calls to methods with the
/// signatures `fn method(&mut self, cx: CX![], ...)` or `fn
/// method(&self, cx: CX![], ...)`. Any **Prep**-style calls that
/// occur will be dropped. Now deferred calls from timers or other
/// actors will execute immediately on reaching the front of the
/// queue. This is the normal operating mode of the actor.
///
/// **"Zombie" state**: The **Zombie** state can be entered for
/// various reasons. The first is normal shutdown of the actor
/// through the [`Cx::stop`] method. The second is failure of the
/// actor through the [`Cx::fail`], [`Cx::fail_str`] or
/// [`Cx::fail_string`] methods. The third is through being killed
/// externally through the [`ActorOwn::kill`], [`ActorOwn::kill_str`]
/// or [`ActorOwn::kill_string`] methods. The fourth is through the
/// last owning reference to the actor being dropped. Termination of
/// the actor is notified to the [`StopCause`] handler provided to the
/// [`ActorOwn::new`] method when the actor was created.
///
/// Once an actor is a **Zombie** it never leaves that state. The
/// `self` value is dropped and all resources are released.
/// References remain valid until the last reference is dropped, but
/// the [`Actor::is_zombie`] method will return true. Any calls
/// queued for the actor will be dropped. (Note that if you need to
/// have a very long-lived actor but you also need to restart the
/// actor on failure, consider having one actor wrap another.)
///
///
/// # Ownership of an actor and automatic termination on drop
///
/// There are two forms of reference to an actor: [`ActorOwn`]
/// instances are strong references, and [`Actor`], [`Fwd`] and
/// [`Ret`] instances are weak references. When the last [`ActorOwn`]
/// reference is dropped, the actor will be terminated automatically.
/// After termination, the actor `self` state data is dropped, but the
/// actor stays in memory in the **Zombie** state until the final weak
/// references are dropped.
///
/// The normal approach is to use [`ActorOwn`] references to control
/// the termination of the actor. If the actor relationships are
/// designed such that there can be no cycles in the [`ActorOwn`]
/// graph (e.g. it will always be a simple tree), then cleanup is safe
/// and straightforward even in the presence of [`Actor`], [`Fwd`] or
/// [`Ret`] reference cycles. Everything will be cleaned up correctly
/// by simply dropping things when they are no longer required. This
/// means that when an actor fails with [`fail!`], all of its child
/// actors will automatically be terminated too.
///
/// This also handles the case where many actors hold owning
/// references to a common shared actor. The common actor will only
/// be terminated when the last [`ActorOwn`] reference is dropped.
///
/// However if the situation doesn't fit the "no cyclic owning
/// references" model (i.e. ownership cannot be represented as a
/// directed-acyclic-graph), then other termination strategies are
/// possible, since an actor can be terminated externally using a
/// [`kill!`] operation. This would normally be a design decision to
/// solve some particularly difficult problem, and in this case the
/// coder must ensure proper cleanup occurs using [`kill!`] instead of
/// simply relying on drop.
///
/// [`Actor::is_zombie`]: struct.Actor.html#method.is_zombie
/// [`ActorOwn::kill_str`]: struct.ActorOwn.html#method.kill_str
/// [`ActorOwn::kill_string`]: struct.ActorOwn.html#method.kill_string
/// [`ActorOwn::kill`]: struct.ActorOwn.html#method.kill
/// [`ActorOwn::new`]: struct.ActorOwn.html#method.new
/// [`ActorOwn`]: struct.ActorOwn.html
/// [`Actor`]: struct.Actor.html
/// [`Cx::fail_str`]: struct.Cx.html#method.fail_str
/// [`Cx::fail_string`]: struct.Cx.html#method.fail_string
/// [`Cx::fail`]: struct.Cx.html#method.fail
/// [`Cx::stop`]: struct.Cx.html#method.stop
/// [`Fwd`]: struct.Fwd.html
/// [`Ret`]: struct.Ret.html
/// [`StopCause`]: enum.StopCause.html
/// [`fail!`]: macro.fail.html
/// [`kill!`]: macro.kill.html
pub struct Actor<A: 'static> {
rc: ActorRc<A>,
}
#[derive(Eq, PartialEq, Copy, Clone)]
pub(crate) enum State {
// In 'prep' state, all it does is accumulate calls made to the
// actor ready to be executed when it enters 'ready'
Prep = 0,
// In 'ready' state, actor has stored state `A` and is working,
// receiving calls
Ready = 1,
// In 'zombie' state, contents have been dropped, and the only the
// empty ActorBox remains allocated waiting for references to go
// away.
Zombie = 2,
}
pub(crate) struct Prep {
pub(crate) queue: FnOnceQueue<Stakker>,
}
impl<A> Actor<A> {
/// Check whether the actor is a zombie. Note that this call is
/// less useful than it appears, since the actor may become a
/// zombie between the time you make this call and whatever
/// asynchronous operation follows. It is better to make a call
/// with a [`ret_to!`] callback which will send back a `None` if
/// the actor has died or if the actor drops the [`Ret`] for any
/// other reason.
///
/// [`Ret`]: struct.Ret.html
/// [`ret_to!`]: macro.ret_to.html
pub fn is_zombie(&self) -> bool {
self.rc.is_zombie()
}
// Initialise actor, taking it from **Prep** to **Ready**. Panics
// if called twice on the same actor. Runs the queue of calls
// waiting for this actor to be initialised. Has no effect if the
// actor is already a **Zombie**.
fn to_ready(&self, s: &mut Stakker, val: A) {
self.rc.to_ready(s, val);
}
// Terminate actor, moving to **Zombie** state and dropping
// contained value if any. The actor can never return from the
// **Zombie** state. The `died` value is sent to the
// [`StopCause`] handler set up when the actor was created.
fn terminate(&self, s: &mut Stakker, died: StopCause) {
if let Some(notify) = self.rc.to_zombie(s) {
self.log_termination(s, &died);
notify.ret(died);
}
}
fn log_termination(&self, core: &mut Core, died: &StopCause) {
if cfg!(feature = "logger") {
match died {
StopCause::Stopped => core.log_span_close(self.id(), format_args!(""), |_| {}),
StopCause::Failed(ref e) => {
core.log_span_close(self.id(), format_args!("{}", e), |out| {
out.kv_null(Some("failed"))
})
}
StopCause::Killed(ref e) => {
core.log_span_close(self.id(), format_args!("{}", e), |out| {
out.kv_null(Some("killed"))
})
}
StopCause::Dropped => core.log_span_close(self.id(), format_args!(""), |out| {
out.kv_null(Some("dropped"))
}),
StopCause::Lost => core
.log_span_close(self.id(), format_args!(""), |out| out.kv_null(Some("lost"))),
};
}
}
/// Apply a closure to the actor if it is in the **Prep** state,
/// otherwise do nothing. This is used to implement deferred prep
/// calls.
#[inline]
pub fn apply_prep(&self, s: &mut Stakker, f: impl FnOnce(&mut Cx<'_, A>) -> Option<A>) {
if self.rc.is_prep() {
let mut cx = Cx::new(&mut s.core, self);
let val = f(&mut cx);
if let Some(die) = cx.die {
self.terminate(s, die);
} else if let Some(val) = val {
self.to_ready(s, val);
}
}
}
/// Apply a closure to the actor when it reaches the **Ready**
/// state. If the actor is already in the **Ready** state, the
/// closure is executed immediately. If the actor is in the
/// **Prep** state, then it queues the operation instead of
/// executing it. This is used to implement deferred ready calls.
#[inline]
pub fn apply(&self, s: &mut Stakker, f: impl FnOnce(&mut A, &mut Cx<'_, A>) + 'static) {
if let Some(val) = self.rc.borrow_ready(&mut s.actor_owner) {
let mut cx = Cx::new(&mut s.core, self);
f(val, &mut cx);
if let Some(die) = cx.die {
self.terminate(s, die);
}
} else if let Some(prep) = self.rc.borrow_prep(&mut s.actor_owner) {
let actor = self.clone();
prep.queue.push(move |s| actor.apply(s, f));
}
}
/// Query an actor from outside the runtime. This is a
/// synchronous call intended for use when interfacing to external
/// code. Executes the closure on the actor immediately if the
/// actor has a `Self` value (i.e. is in the **Ready** state), and
/// returns the result. Otherwise returns `None`.
#[inline]
pub fn query<R>(
&self,
s: &mut Stakker,
f: impl FnOnce(&mut A, &mut Cx<'_, A>) -> R,
) -> Option<R> {
if let Some(val) = self.rc.borrow_ready(&mut s.actor_owner) {
let mut cx = Cx::new(&mut s.core, self);
let rv = f(val, &mut cx);
if let Some(die) = cx.die {
self.terminate(s, die);
}
Some(rv)
} else {
None
}
}
/// Get the logging-ID of this actor. If the **logger** feature
/// isn't enabled, returns 0.
#[inline]
pub fn id(&self) -> LogID {
self.rc.id()
}
/// This may be used to submit items to the [`Deferrer`] main
/// queue from a drop handler, without needing a [`Core`]
/// reference.
///
/// [`Core`]: struct.Core.html
/// [`Deferrer`]: struct.Deferrer.html
#[inline]
pub fn defer(&self, f: impl FnOnce(&mut Stakker) + 'static) {
self.rc.access_deferrer().defer(f);
}
/// Used in macros to get a [`Deferrer`] reference
///
/// [`Deferrer`]: struct.Deferrer.html
#[inline]
pub fn access_deferrer(&self) -> &Deferrer {
self.rc.access_deferrer()
}
/// Used in macros to get an [`Actor`] reference
///
/// [`Actor`]: struct.Actor.html
#[inline]
pub fn access_actor(&self) -> &Self {
self
}
/// Used in macros to get the actor's logging-ID. If the
/// **logger** feature isn't enabled, returns 0.
#[inline]
pub fn access_log_id(&self) -> LogID {
self.rc.id()
}
}
impl<A> Clone for Actor<A> {
fn clone(&self) -> Self {
Self {
rc: self.rc.clone(),
}
}
}
/// Indicates reason for actor termination
///
/// In case of failure, this is not intended to provide a full
/// backtrace of actor failures leading up to this failure. It only
/// provides information on the immediate failure that occurred, to
/// allow the actor receiving this indication to make a decision on
/// what to do next.
///
/// To trace back exactly what happened, enable the **logger** feature
/// and record the `Open` and `Close` events.
pub enum StopCause {
/// Actor terminated using [`Cx::stop`]
///
/// [`Cx::stop`]: struct.Cx.html#method.stop
Stopped,
/// Actor failed using [`Cx::fail`]
///
/// [`Cx::fail`]: struct.Cx.html#method.fail
Failed(Box<dyn Error>),
/// Actor was killed through [`ActorOwn::kill`]
///
/// [`ActorOwn::kill`]: struct.ActorOwn.html#method.kill
Killed(Box<dyn Error>),
/// Last owning reference to the actor was dropped
Dropped,
/// Lost the connection to a remote actor's host. (This will be
/// used when remote actors are implemented.)
Lost,
}
impl StopCause {
/// Test whether this the actor died with an associated error,
/// i.e. `Failed` or `Killed`.
pub fn has_error(&self) -> bool {
matches!(self, StopCause::Failed(_) | StopCause::Killed(_))
}
}
impl std::fmt::Display for StopCause {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
Self::Stopped => write!(f, "Actor stopped"),
Self::Failed(e) => write!(f, "Actor failed: {}", e),
Self::Killed(e) => write!(f, "Actor was killed: {}", e),
Self::Dropped => write!(f, "Actor was dropped"),
Self::Lost => write!(f, "Lost connection to actor"),
}
}
}
impl std::fmt::Debug for StopCause {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "{}", self)
}
}
/// 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`].
///
/// [`Core`]: struct.Core.html
/// [`Cx::this`]: struct.Cx.html#method.this
/// [`fail!`]: macro.fail.html
/// [`stop!`]: macro.stop.html
pub struct Cx<'a, A: 'static> {
pub(crate) core: &'a mut Core,
pub(crate) this: &'a Actor<A>,
pub(crate) die: Option<StopCause>,
}
impl<'a, A> Cx<'a, A> {
#[inline]
pub(super) fn new(core: &'a mut Core, this: &'a Actor<A>) -> Self {
Self {
this,
core,
die: None,
}
}
/// Borrow the current actor reference temporarily. If you need a
/// longer-lived reference to the actor, then use
/// `cx.this().clone()`.
#[inline]
pub fn this(&self) -> &Actor<A> {
self.this
}
/// Get the logging-ID of the current actor. If the **logger** feature
/// isn't enabled, returns 0.
#[inline]
pub fn id(&self) -> LogID {
self.this.id()
}
/// 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. See also the [`stop!`] macro.
///
/// [`StopCause`]: enum.StopCause.html
/// [`stop!`]: macro.stop.html
#[inline]
pub fn stop(&mut self) {
if self.die.is_none() {
self.die = Some(StopCause::Stopped);
}
}
/// 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. See also the [`fail!`] macro.
///
/// [`StopCause`]: enum.StopCause.html
/// [`fail!`]: macro.fail.html
#[inline]
pub fn fail(&mut self, e: impl Error + 'static) {
if self.die.is_none() {
self.die = Some(StopCause::Failed(Box::new(e)));
}
}
/// 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. See also the [`fail!`] macro.
///
/// [`StopCause`]: enum.StopCause.html
/// [`fail!`]: macro.fail.html
#[inline]
pub fn fail_str(&mut self, e: &'static str) {
if self.die.is_none() {
self.die = Some(StopCause::Failed(Box::new(StrError(e))));
}
}
/// 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. See also the [`fail!`] macro.
///
/// [`StopCause`]: enum.StopCause.html
/// [`fail!`]: macro.fail.html
#[inline]
pub fn fail_string(&mut self, e: impl Into<String>) {
if self.die.is_none() {
self.die = Some(StopCause::Failed(Box::new(StringError(e.into()))));
}
}
/// Used in macros to get an [`Actor`] reference
///
/// [`Actor`]: struct.Actor.html
#[inline]
pub fn access_actor(&self) -> &Actor<A> {
self.this
}
/// Used in macros to get the actor's logging-ID. If the
/// **logger** feature isn't enabled, returns 0.
#[inline]
pub fn access_log_id(&self) -> LogID {
self.this.id()
}
}
impl<'a, A> Deref for Cx<'a, A> {
type Target = Core;
fn deref(&self) -> &Core {
self.core
}
}
impl<'a, A> DerefMut for Cx<'a, A> {
fn deref_mut(&mut self) -> &mut Core {
self.core
}
}
/// A miscellaneous error with a string description
#[derive(Debug)]
pub(crate) struct StrError(&'static str);
impl Error for StrError {}
impl fmt::Display for StrError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}", self.0)
}
}
/// A miscellaneous error with a string description
#[derive(Debug)]
pub(crate) struct StringError(pub String);
impl Error for StringError {}
impl fmt::Display for StringError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}", self.0)
}
}
/// A set of owning actor references
///
/// This type may be convenient when an actor will have many children
/// of the same type and the parent doesn't need to differentiate
/// between them, nor access them with a key. This type keeps track of
/// them and automatically takes care of removing each child actor
/// from the set when it terminates. It also allows iterating through
/// them in case the parent needs to make a call to all child actors.
///
/// The [`actor_in_slab!`] macro provides a wrapper around this to
/// make its use more readable.
///
/// However for more complicated cases, you might want to do all this
/// in your own code instead of using this type. For example for the
/// case where you already have a key that you want to associate with
/// the child actor, and you want to use that key to get hold of the
/// actor reference, in that case you need a `HashMap`, not a slab.
///
/// Note that this doesn't expose the `usize` slab key. This is
/// intentional. Cases where the slab key would be useful are better
/// handled in user code, i.e. they would probably need a `HashMap`,
/// and in that case the [`ActorOwn`] would be better kept in that
/// `HashMap` instead of in this slab.
///
/// [`ActorOwn`]: struct.ActorOwn.html
/// [`actor_in_slab!`]: macro.actor_in_slab.html
pub struct ActorOwnSlab<T: 'static> {
slab: Slab<ActorOwn<T>>,
}
impl<T: 'static> ActorOwnSlab<T> {
/// Create a new [`ActorOwnSlab`]
///
/// [`ActorOwnSlab`]: struct.ActorOwnSlab.html
pub fn new() -> Self {
Self::default()
}
/// Create an actor whose [`ActorOwn`] is stored in the slab, with
/// a termination notification handler which automatically removes
/// it from this slab when it fails or terminates. `get_slab`
/// would typically be `|this| this.children`, assuming `children`
/// is what the [`ActorOwnSlab`] is called in the actor's state.
/// The `notify` handler is called as normal with the
/// [`StopCause`].
///
/// This call does the same as [`actor_new!`], i.e. it creates the
/// actor but does not initialise it. It returns an [`Actor`]
/// reference which can be used to initialise the actor.
///
/// [`ActorOwnSlab`]: struct.ActorOwnSlab.html
/// [`ActorOwn`]: struct.ActorOwn.html
/// [`Actor`]: struct.Actor.html
/// [`StopCause`]: enum.StopCause.html
/// [`actor_new!`]: macro.actor_new.html
#[inline]
pub fn add<P>(
&mut self,
core: &mut Core,
parent: Actor<P>,
get_slab: impl for<'a> FnOnce(&'a mut P) -> &'a mut Self + 'static,
notify: Ret<StopCause>,
) -> Actor<T> {
let vacant = self.slab.vacant_entry();
let key = vacant.key();
let parid = parent.id();
let actorown = ActorOwn::new(
core,
ret_some_do!(move |cause| {
let parent2 = parent.clone();
parent.defer(move |s| {
parent2.apply(s, move |this, _| {
get_slab(this).slab.remove(key);
});
});
ret!([notify], cause);
}),
parid,
);
let actor = actorown.clone();
vacant.insert(actorown);
actor
}
/// Returns the number of actors held in the slab
#[inline]
pub fn len(&self) -> usize {
self.slab.len()
}
/// Returns `true` if there are no values left in the slab
#[inline]
pub fn is_empty(&self) -> bool {
self.slab.is_empty()
}
}
impl<T> Default for ActorOwnSlab<T> {
fn default() -> Self {
Self { slab: Slab::new() }
}
}
impl<'a, T> IntoIterator for &'a ActorOwnSlab<T> {
type Item = &'a ActorOwn<T>;
type IntoIter = ActorOwnSlabIter<'a, T>;
fn into_iter(self) -> ActorOwnSlabIter<'a, T> {
ActorOwnSlabIter(self.slab.iter())
}
}
/// Iterator over actors in an [`ActorOwnSlab`]
///
/// [`ActorOwnSlab`]: struct.ActorOwnSlab.html
pub struct ActorOwnSlabIter<'a, T: 'static>(slab::Iter<'a, ActorOwn<T>>);
impl<'a, T> Iterator for ActorOwnSlabIter<'a, T> {
type Item = &'a ActorOwn<T>;
fn next(&mut self) -> Option<Self::Item> {
self.0.next().map(|item| item.1)
}
}