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Author SHA1 Message Date
smarm-agent 0cf6b80396 gen_statem: GenStatem* type prefix + cleanup
- rename StatemRef/StatemCallError/StatemSendError -> GenStatem*
- move the inline unit test out of src; consolidate the Switch coverage
  onto a single macro-driven harness in tests/gen_statem.rs
- drop the redundant hand-written Switch test machine and the two
  untracked rejected-direction probes (succ_enums, typed_edges)
- rename examples statem_{fused,macro}.rs -> gen_statem_{fused,macro}.rs
- strip RFC/chunk/spike provenance and fix the mislabeled "throwaway"
  example header and dead cross-references
2026-06-20 10:48:33 +00:00
smarm-agent 3e316066c3 gen_server: prefix public types with Gen (GenServerRef, GenServerCtx, GenServerName, GenServerBuilder, NamedGenServerBuilder) 2026-06-20 10:48:33 +00:00
13 changed files with 275 additions and 386 deletions
@@ -1,11 +1,9 @@
//! SPIKE (throwaway) — RFC 017 "fused" approach. //! The hand-written **expansion target** of the `gen_statem!` macro: the same
//! machine as `examples/gen_statem_macro.rs`, written out in full so the
//! primitives can be judged standing on their own. The macro generates exactly
//! this shape; nothing here needs the macro to be correct or safe.
//! //!
//! This is the hand-written *expansion target* of the eventual `statem!` macro, //! The design:
//! written out in full so the primitives can be judged standing on their own.
//! A macro would generate exactly this from a `transitions { … }` block; nothing
//! here needs the macro to be correct or safe.
//!
//! The design, as settled over the prior iterations:
//! //!
//! * States and events are real enums. An invalid state is unrepresentable; //! * States and events are real enums. An invalid state is unrepresentable;
//! there are no bitflags, no `u32` superpositions, no unsafe unions. //! there are no bitflags, no `u32` superpositions, no unsafe unions.
@@ -27,18 +25,18 @@
//! wired in is dead code — and dead_code is denied below, making an orphan //! wired in is dead code — and dead_code is denied below, making an orphan
//! handler a compile error. //! handler a compile error.
//! //!
//! * Drops onto the committed `Machine` / `Resolution` / `Cx` primitives with //! * Drops onto the `Machine` / `Resolution` / `Cx` primitives with no change
//! no change to `src/statem.rs`. //! to `src/gen_statem.rs`.
//! //!
//! Default build is clean and runs. A BREAK-CASE MENU at the bottom documents //! Default build is clean and runs. A BREAK-CASE MENU at the bottom documents
//! how to make each of the four guarantees fire. //! how to make each of the four guarantees fire.
//! //!
//! Run: `cargo run --example statem_fused` //! Run: `cargo run --example gen_statem_fused`
#![deny(dead_code, unreachable_patterns)] #![deny(dead_code, unreachable_patterns)]
use smarm::run; use smarm::run;
use smarm::gen_statem::{spawn, Cx, Machine, Reply, Resolution, StatemRef}; use smarm::gen_statem::{spawn, Cx, Machine, Reply, Resolution, GenStatemRef};
// === user types ============================================================ // === user types ============================================================
@@ -114,7 +112,7 @@ struct DoorSm {
} }
impl DoorSm { impl DoorSm {
fn start(init: Door) -> StatemRef<DoorSm> { fn start(init: Door) -> GenStatemRef<DoorSm> {
spawn(DoorSm { spawn(DoorSm {
state: init, state: init,
data: Data { enters: 0, pushes: 0 }, data: Data { enters: 0, pushes: 0 },
@@ -184,7 +182,7 @@ impl Machine for DoorSm {
self.state = s; // sole writer of the state cell self.state = s; // sole writer of the state cell
self.enter(cx); self.enter(cx);
} }
Resolution::Postpone => unreachable!("postpone lands in chunk 3"), Resolution::Postpone => unreachable!("postpone is not generated yet"),
Resolution::Unhandled => cx.on_unhandled(), Resolution::Unhandled => cx.on_unhandled(),
} }
} }
@@ -1,18 +1,18 @@
//! RFC 017 — the **same** machine as `examples/statem_fused.rs`, written through //! The **same** machine as `examples/gen_statem_fused.rs`, written through the
//! the `gen_statem!` macro. Diff this file against that one to see exactly what //! `gen_statem!` macro. Diff this file against that one to see exactly what the
//! the macro buys: every `// ===` section there that was boilerplate (the `Ev` //! macro buys: every `// ===` section there that was boilerplate (the `Ev`
//! enum, the `DoorSm` struct, `start`, the whole `Machine` impl, the `enter` //! enum, the `DoorSm` struct, `start`, the whole `Machine` impl, the `enter`
//! dispatch, the stay/transition apply-tail) collapses into the invocation //! dispatch, the stay/transition apply-tail) collapses into the invocation
//! below. What stays hand-written is what carries meaning: the four types, the //! below. What stays hand-written is what carries meaning: the four types, the
//! per-state successor enum, and the handler fns. //! per-state successor enum, and the handler fns.
//! //!
//! The point of the exercise is that the macro is *pure sugar*: the four //! The point of the exercise is that the macro is *pure sugar*: the four
//! compile-time guarantees the fused spike demonstrates are properties of the //! compile-time guarantees the hand-written form demonstrates are properties of
//! emitted code, not of the macro, so they survive expansion unchanged. The //! the emitted code, not of the macro, so they survive expansion unchanged. The
//! BREAK-CASE MENU at the bottom is the same four cases, re-expressed against //! BREAK-CASE MENU at the bottom is the same four cases, re-expressed against
//! the macro surface — flip any one on and the compiler fires identically. //! the macro surface — flip any one on and the compiler fires identically.
//! //!
//! Run: `cargo run --example statem_macro` //! Run: `cargo run --example gen_statem_macro`
#![deny(dead_code)] // guarantee #3 (orphan handlers); the macro denies the #![deny(dead_code)] // guarantee #3 (orphan handlers); the macro denies the
// dispatch's own unreachable_patterns internally. // dispatch's own unreachable_patterns internally.
@@ -21,7 +21,7 @@ use smarm::gen_statem;
use smarm::run; use smarm::run;
use smarm::gen_statem::Reply; use smarm::gen_statem::Reply;
// === user types (identical to statem_fused.rs) ============================= // === user types (identical to gen_statem_fused.rs) =========================
#[derive(Clone, Copy, PartialEq, Eq, Debug)] #[derive(Clone, Copy, PartialEq, Eq, Debug)]
enum Door { enum Door {
@@ -91,7 +91,7 @@ gen_statem! {
// You name the bindings the bodies use; the macro can't lend you its own // You name the bindings the bodies use; the macro can't lend you its own
// `self`/`cx` across macro hygiene. `data` = &mut Data, `prev` = current // `self`/`cx` across macro hygiene. `data` = &mut Data, `prev` = current
// state tag, `cx` = context handle (unused in chunk 1). // state tag, `cx` = context handle (unused here).
context(data, prev, cx); context(data, prev, cx);
enter { enter {
@@ -145,7 +145,7 @@ fn main() {
// =========================================================================== // ===========================================================================
// BREAK-CASE MENU — the four guarantees, through the macro. Each fires exactly // BREAK-CASE MENU — the four guarantees, through the macro. Each fires exactly
// as it does in the hand-written statem_fused.rs. // as it does in the hand-written gen_statem_fused.rs.
// //
// 1. ORPHAN HANDLER (dead_code -> error): // 1. ORPHAN HANDLER (dead_code -> error):
// add `fn on_slam(_d: &mut Data) {}` and don't reference it. // add `fn on_slam(_d: &mut Data) {}` and don't reference it.
@@ -157,8 +157,8 @@ fn main() {
// NOTE: this example is a separate crate from `smarm`, so rustc's // NOTE: this example is a separate crate from `smarm`, so rustc's
// in_external_macro rule SILENCES this lint here even though the macro // in_external_macro rule SILENCES this lint here even though the macro
// denies it — the duplicate compiles. The guarantee is real only for // denies it — the duplicate compiles. The guarantee is real only for
// machines defined inside the smarm crate (see the unit test in // machines defined inside the `smarm` crate itself. This is the documented
// src/statem.rs). This is the documented macro_rules! limitation. // macro_rules! limitation.
// //
// 3. MISSING PAIR (non-exhaustive match, E0004): // 3. MISSING PAIR (non-exhaustive match, E0004):
// delete the `cast Cast::Push | Cast::Pull | Cast::Lock => unhandled,` // delete the `cast Cast::Push | Cast::Pull | Cast::Lock => unhandled,`
+7 -7
View File
@@ -2,11 +2,11 @@
//! //!
//! A gen_server is multi-message (call / cast over one inbox), so it is named //! A gen_server is multi-message (call / cast over one inbox), so it is named
//! by the *server* type rather than by a single message type. Registering it //! by the *server* type rather than by a single message type. Registering it
//! under a [`ServerName`] lets clients `call` and `cast` by name, resolving on //! under a [`GenServerName`] lets clients `call` and `cast` by name, resolving on
//! every use — so the address keeps working across a supervised restart, with //! every use — so the address keeps working across a supervised restart, with
//! no stale [`ServerRef`] to refresh. //! no stale [`GenServerRef`] to refresh.
use smarm::{call, cast, run, whereis_server, GenServer, ServerBuilder, ServerName, ServerRef}; use smarm::{call, cast, run, whereis_server, GenServer, GenServerBuilder, GenServerName, GenServerRef};
/// A counter server: synchronous `Get`, asynchronous `Inc` / `Add`. /// A counter server: synchronous `Get`, asynchronous `Inc` / `Add`.
struct Counter { struct Counter {
@@ -41,13 +41,13 @@ impl GenServer for Counter {
/// A durable name typed by the server, so by-name `call` / `cast` check against /// A durable name typed by the server, so by-name `call` / `cast` check against
/// `Counter`'s `Call` / `Cast` / `Reply`. /// `Counter`'s `Call` / `Cast` / `Reply`.
const COUNTER: ServerName<Counter> = ServerName::new("counter"); const COUNTER: GenServerName<Counter> = GenServerName::new("counter");
fn main() { fn main() {
run(|| { run(|| {
// Start the server and bind its name in one step. A named start is // Start the server and bind its name in one step. A named start is
// fallible: the name may already be held by another live server. // fallible: the name may already be held by another live server.
ServerBuilder::new(Counter { n: 0 }) GenServerBuilder::new(Counter { n: 0 })
.named(COUNTER) .named(COUNTER)
.start() .start()
.unwrap(); .unwrap();
@@ -60,8 +60,8 @@ fn main() {
assert_eq!(call(COUNTER, Query::Get).unwrap(), 42); assert_eq!(call(COUNTER, Query::Get).unwrap(), 42);
// When you want a handle to hold or pass on rather than resolve per // When you want a handle to hold or pass on rather than resolve per
// call, recover a typed `ServerRef` from the name. // call, recover a typed `GenServerRef` from the name.
let svc: Option<ServerRef<Counter>> = whereis_server(COUNTER); let svc: Option<GenServerRef<Counter>> = whereis_server(COUNTER);
if let Some(svc) = svc { if let Some(svc) = svc {
let _ = svc.call(Query::Get); let _ = svc.call(Query::Get);
} }
+71 -71
View File
@@ -2,9 +2,9 @@
//! //!
//! A thin request-reply layer on top of [`channel`](crate::channel()), modelled //! A thin request-reply layer on top of [`channel`](crate::channel()), modelled
//! on Erlang's `gen_server`. A *server* is an actor owning a state value that //! on Erlang's `gen_server`. A *server* is an actor owning a state value that
//! implements [`GenServer`]; clients hold a clonable [`ServerRef`] and issue //! implements [`GenServer`]; clients hold a clonable [`GenServerRef`] and issue
//! [`call`](ServerRef::call) (synchronous, returns a reply) or //! [`call`](GenServerRef::call) (synchronous, returns a reply) or
//! [`cast`](ServerRef::cast) (fire-and-forget). //! [`cast`](GenServerRef::cast) (fire-and-forget).
//! //!
//! ## One inbox, many arms //! ## One inbox, many arms
//! //!
@@ -15,7 +15,7 @@
//! //!
//! Out-of-band messages ride *separate* channels composed at the wait via //! Out-of-band messages ride *separate* channels composed at the wait via
//! [`select`](channel::select): info channels handed over at start //! [`select`](channel::select): info channels handed over at start
//! ([`ServerBuilder::with_info`]) are dispatched to //! ([`GenServerBuilder::with_info`]) are dispatched to
//! [`handle_info`](GenServer::handle_info). Arm priority is //! [`handle_info`](GenServer::handle_info). Arm priority is
//! **infos before inbox**, in declaration order — a hot inbox cannot starve //! **infos before inbox**, in declaration order — a hot inbox cannot starve
//! an out-of-band message; conversely a hot info channel CAN starve the //! an out-of-band message; conversely a hot info channel CAN starve the
@@ -45,19 +45,19 @@
//! //!
//! ## Time (timers and idle) //! ## Time (timers and idle)
//! //!
//! A server arms timers through a [`TimerHandle`] cloned from the [`ServerCtx`] //! A server arms timers through a [`TimerHandle`] cloned from the [`GenServerCtx`]
//! in `init` and stored on the state — the same shape as [`Watcher`] for //! in `init` and stored on the state — the same shape as [`Watcher`] for
//! monitors. [`arm_after`](TimerHandle::arm_after) is a one-shot, //! monitors. [`arm_after`](TimerHandle::arm_after) is a one-shot,
//! [`tick_every`](TimerHandle::tick_every) a periodic; both fire into //! [`tick_every`](TimerHandle::tick_every) a periodic; both fire into
//! [`handle_timer`](GenServer::handle_timer) at *system priority* (above infos //! [`handle_timer`](GenServer::handle_timer) at *system priority* (above infos
//! and the inbox, by arm position), and [`cancel`](TimerHandle::cancel) carries //! and the inbox, by arm position), and [`cancel`](TimerHandle::cancel) carries
//! the substrate's race signal. Separately, [`ServerCtx::idle_after`] sets a //! the substrate's race signal. Separately, [`GenServerCtx::idle_after`] sets a
//! receive-timeout window: quiet for the whole window fires //! receive-timeout window: quiet for the whole window fires
//! [`handle_idle`](GenServer::handle_idle). //! [`handle_idle`](GenServer::handle_idle).
//! //!
//! Two unrelated things share the word *timeout*: the server-side **idle / //! Two unrelated things share the word *timeout*: the server-side **idle /
//! receive timeout** above, and the client-side **call deadline** //! receive timeout** above, and the client-side **call deadline**
//! ([`ServerRef::call_timeout`]) — how long a caller waits for a reply. They sit //! ([`GenServerRef::call_timeout`]) — how long a caller waits for a reply. They sit
//! on different axes and never interact (RFC 015 §7). //! on different axes and never interact (RFC 015 §7).
//! //!
//! ## Not here (yet) //! ## Not here (yet)
@@ -85,15 +85,15 @@ use std::time::{Duration, Instant};
/// [`terminate`](Self::terminate) are optional lifecycle hooks with no-op /// [`terminate`](Self::terminate) are optional lifecycle hooks with no-op
/// defaults. /// defaults.
pub trait GenServer: Send + 'static { pub trait GenServer: Send + 'static {
/// Synchronous request type (carried by [`ServerRef::call`]). /// Synchronous request type (carried by [`GenServerRef::call`]).
type Call: Send + 'static; type Call: Send + 'static;
/// Reply type returned for a `Call`. /// Reply type returned for a `Call`.
type Reply: Send + 'static; type Reply: Send + 'static;
/// Asynchronous request type (carried by [`ServerRef::cast`]). /// Asynchronous request type (carried by [`GenServerRef::cast`]).
type Cast: Send + 'static; type Cast: Send + 'static;
/// Out-of-band message type, delivered to [`handle_info`](Self::handle_info) /// Out-of-band message type, delivered to [`handle_info`](Self::handle_info)
/// from the info channels registered at start /// from the info channels registered at start
/// ([`ServerBuilder::with_info`]). Servers with several out-of-band /// ([`GenServerBuilder::with_info`]). Servers with several out-of-band
/// sources enum them up into one `Info`. Use `()` if unused. /// sources enum them up into one `Info`. Use `()` if unused.
type Info: Send + 'static; type Info: Send + 'static;
/// The server's own scheduled-timer payload, delivered to /// The server's own scheduled-timer payload, delivered to
@@ -107,10 +107,10 @@ pub trait GenServer: Send + 'static {
type Timer: Send + 'static; type Timer: Send + 'static;
/// Runs once inside the server actor before any message is handled. The /// Runs once inside the server actor before any message is handled. The
/// [`ServerCtx`] is the loop's one runtime hook: clone its [`Watcher`] /// [`GenServerCtx`] is the loop's one runtime hook: clone its [`Watcher`]
/// into the state here to be able to [`watch`](Watcher::watch) monitors /// into the state here to be able to [`watch`](Watcher::watch) monitors
/// from any later handler. /// from any later handler.
fn init(&mut self, _ctx: &ServerCtx<Self>) fn init(&mut self, _ctx: &GenServerCtx<Self>)
where where
Self: Sized, Self: Sized,
{ {
@@ -138,7 +138,7 @@ pub trait GenServer: Send + 'static {
fn handle_timer(&mut self, _msg: Self::Timer) {} fn handle_timer(&mut self, _msg: Self::Timer) {}
/// Handle a receive/idle timeout: fired when the loop has waited a full /// Handle a receive/idle timeout: fired when the loop has waited a full
/// idle window (set once via [`ServerCtx::idle_after`]) with no message of /// idle window (set once via [`GenServerCtx::idle_after`]) with no message of
/// any kind dispatched. The window resets on every dispatched message and /// any kind dispatched. The window resets on every dispatched message and
/// re-arms after this fires (a steady idle detector); a server wanting /// re-arms after this fires (a steady idle detector); a server wanting
/// one-shot idle-shutdown simply requests its own stop here. Default: no-op /// one-shot idle-shutdown simply requests its own stop here. Default: no-op
@@ -157,27 +157,27 @@ enum Envelope<G: GenServer> {
} }
/// A clonable handle to a running server. Cloning yields another sender to the /// A clonable handle to a running server. Cloning yields another sender to the
/// same inbox; the server lives until the last `ServerRef` is dropped, at which /// same inbox; the server lives until the last `GenServerRef` is dropped, at which
/// point its inbox closes and the loop exits normally. /// point its inbox closes and the loop exits normally.
pub struct ServerRef<G: GenServer> { pub struct GenServerRef<G: GenServer> {
tx: Sender<Envelope<G>>, tx: Sender<Envelope<G>>,
pid: Pid, pid: Pid,
} }
impl<G: GenServer> Clone for ServerRef<G> { impl<G: GenServer> Clone for GenServerRef<G> {
fn clone(&self) -> Self { fn clone(&self) -> Self {
ServerRef { tx: self.tx.clone(), pid: self.pid } GenServerRef { tx: self.tx.clone(), pid: self.pid }
} }
} }
/// Returned by [`ServerRef::call`] when the server is no longer reachable. /// Returned by [`GenServerRef::call`] when the server is no longer reachable.
#[derive(Debug, PartialEq, Eq, Clone, Copy)] #[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub enum CallError { pub enum CallError {
/// The server was already gone, or died before replying. /// The server was already gone, or died before replying.
ServerDown, ServerDown,
} }
/// Returned by [`ServerRef::call_timeout`]. /// Returned by [`GenServerRef::call_timeout`].
#[derive(Debug, PartialEq, Eq, Clone, Copy)] #[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub enum CallTimeoutError { pub enum CallTimeoutError {
/// The server was already gone, or died before replying. /// The server was already gone, or died before replying.
@@ -190,14 +190,14 @@ pub enum CallTimeoutError {
Timeout, Timeout,
} }
/// Returned by [`ServerRef::cast`] when the server is no longer reachable. /// Returned by [`GenServerRef::cast`] when the server is no longer reachable.
#[derive(Debug, PartialEq, Eq, Clone, Copy)] #[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub enum CastError { pub enum CastError {
/// The server inbox was closed (the server is gone). /// The server inbox was closed (the server is gone).
ServerDown, ServerDown,
} }
impl<G: GenServer> ServerRef<G> { impl<G: GenServer> GenServerRef<G> {
/// The server actor's pid — usable with `monitor`, `request_stop`, `link`. /// The server actor's pid — usable with `monitor`, `request_stop`, `link`.
pub fn pid(&self) -> Pid { pub fn pid(&self) -> Pid {
self.pid self.pid
@@ -219,7 +219,7 @@ impl<G: GenServer> ServerRef<G> {
/// ///
/// This `timeout` is a **client-side call deadline** — how long *this caller* /// This `timeout` is a **client-side call deadline** — how long *this caller*
/// waits for a reply — and is wholly separate from the server-side idle / /// waits for a reply — and is wholly separate from the server-side idle /
/// receive timeout ([`ServerCtx::idle_after`] → /// receive timeout ([`GenServerCtx::idle_after`] →
/// [`GenServer::handle_idle`]), which measures quiet on the *server's* inbox. /// [`GenServer::handle_idle`]), which measures quiet on the *server's* inbox.
/// Same word ("timeout"), two different axes (RFC 015 §7); neither touches /// Same word ("timeout"), two different axes (RFC 015 §7); neither touches
/// the other. /// the other.
@@ -264,8 +264,8 @@ impl<G: GenServer> ServerRef<G> {
/// stop unwind). Returns immediately if the server was already gone. /// stop unwind). Returns immediately if the server was already gone.
/// ///
/// This is the explicit teardown for a server pinned alive by a registered /// This is the explicit teardown for a server pinned alive by a registered
/// [`ServerName`] (whose stored sender means dropping every external /// [`GenServerName`] (whose stored sender means dropping every external
/// [`ServerRef`] no longer closes the inbox). Best-effort like all /// [`GenServerRef`] no longer closes the inbox). Best-effort like all
/// cooperative cancellation: a server wedged in a tight loop with no /// cooperative cancellation: a server wedged in a tight loop with no
/// observation point cannot be stopped. Panics if called outside /// observation point cannot be stopped. Panics if called outside
/// `Runtime::run()`. /// `Runtime::run()`.
@@ -302,17 +302,17 @@ enum Sys<G: GenServer> {
/// loop's two clonable intake handles — the [`Watcher`] (monitors) and the /// loop's two clonable intake handles — the [`Watcher`] (monitors) and the
/// [`TimerHandle`] (timers) — plus the one-shot idle-window setter. Opaque, so /// [`TimerHandle`] (timers) — plus the one-shot idle-window setter. Opaque, so
/// fields can grow without breaking. /// fields can grow without breaking.
pub struct ServerCtx<G: GenServer> { pub struct GenServerCtx<G: GenServer> {
sys_tx: Sender<Sys<G>>, sys_tx: Sender<Sys<G>>,
reg: Arc<Mutex<TimerReg<G>>>, reg: Arc<Mutex<TimerReg<G>>>,
/// The idle/receive-timeout window, set once via [`idle_after`](Self::idle_after) /// The idle/receive-timeout window, set once via [`idle_after`](Self::idle_after)
/// during `init` and read by the loop after `init` returns. Interior-mutable /// during `init` and read by the loop after `init` returns. Interior-mutable
/// because `init` holds only `&ctx`; not `Send`, but `ServerCtx` is only ever /// because `init` holds only `&ctx`; not `Send`, but `GenServerCtx` is only ever
/// borrowed on the actor's own stack during `init`, never sent. /// borrowed on the actor's own stack during `init`, never sent.
idle: Cell<Option<Duration>>, idle: Cell<Option<Duration>>,
} }
impl<G: GenServer> ServerCtx<G> { impl<G: GenServer> GenServerCtx<G> {
/// A clonable handle to the loop's monitor intake. Store it in the state /// A clonable handle to the loop's monitor intake. Store it in the state
/// during `init` to watch monitors from later handlers. /// during `init` to watch monitors from later handlers.
pub fn watcher(&self) -> Watcher<G> { pub fn watcher(&self) -> Watcher<G> {
@@ -341,7 +341,7 @@ impl<G: GenServer> ServerCtx<G> {
/// detector); a server wanting one-shot idle-shutdown requests its own stop /// detector); a server wanting one-shot idle-shutdown requests its own stop
/// in `handle_idle`. /// in `handle_idle`.
/// ///
/// Distinct from [`ServerRef::call_timeout`], which is a *client-side* call /// Distinct from [`GenServerRef::call_timeout`], which is a *client-side* call
/// deadline — same word, different axis (§7). /// deadline — same word, different axis (§7).
pub fn idle_after(&self, after: Duration) { pub fn idle_after(&self, after: Duration) {
self.idle.set(Some(after)); self.idle.set(Some(after));
@@ -414,7 +414,7 @@ impl<G: GenServer> TimerReg<G> {
} }
/// Arms, cancels, and (chunk 4) periodically ticks server timers, the time-side /// Arms, cancels, and (chunk 4) periodically ticks server timers, the time-side
/// twin of [`Watcher`] (RFC 015 §4.3). Handed out by [`ServerCtx::timer`] in /// twin of [`Watcher`] (RFC 015 §4.3). Handed out by [`GenServerCtx::timer`] in
/// `init` and stored on the state; later handlers arm timers without any change /// `init` and stored on the state; later handlers arm timers without any change
/// to their signatures. Clonable; the arm stays open while any clone (or an /// to their signatures. Clonable; the arm stays open while any clone (or an
/// in-flight fire) lives. /// in-flight fire) lives.
@@ -527,20 +527,20 @@ impl<G: GenServer> Watcher<G> {
/// [`start`]: info channels, a supervisor. Consumed by [`start`](Self::start). /// [`start`]: info channels, a supervisor. Consumed by [`start`](Self::start).
/// ///
/// ```ignore /// ```ignore
/// let server = ServerBuilder::new(state) /// let server = GenServerBuilder::new(state)
/// .with_info(events_rx) /// .with_info(events_rx)
/// .under(supervisor_pid) /// .under(supervisor_pid)
/// .start(); /// .start();
/// ``` /// ```
pub struct ServerBuilder<G: GenServer> { pub struct GenServerBuilder<G: GenServer> {
state: G, state: G,
infos: Vec<Receiver<G::Info>>, infos: Vec<Receiver<G::Info>>,
supervisor: Option<Pid>, supervisor: Option<Pid>,
} }
impl<G: GenServer> ServerBuilder<G> { impl<G: GenServer> GenServerBuilder<G> {
pub fn new(state: G) -> Self { pub fn new(state: G) -> Self {
ServerBuilder { state, infos: Vec::new(), supervisor: None } GenServerBuilder { state, infos: Vec::new(), supervisor: None }
} }
/// Add an out-of-band channel; messages arriving on it are dispatched to /// Add an out-of-band channel; messages arriving on it are dispatched to
@@ -558,33 +558,33 @@ impl<G: GenServer> ServerBuilder<G> {
self self
} }
/// Spawn the server actor and hand back its [`ServerRef`]. The server's /// Spawn the server actor and hand back its [`GenServerRef`]. The server's
/// lifetime is governed by its refs, not by joining, so the backing join /// lifetime is governed by its refs, not by joining, so the backing join
/// handle is dropped. /// handle is dropped.
pub fn start(self) -> ServerRef<G> { pub fn start(self) -> GenServerRef<G> {
self.spawn_server() self.spawn_server()
} }
/// Bind the server to a durable [`ServerName`] as it starts. Switches to the /// Bind the server to a durable [`GenServerName`] as it starts. Switches to the
/// fallible [`NamedServerBuilder::start`] (the name may already be held by a /// fallible [`NamedGenServerBuilder::start`] (the name may already be held by a
/// live server). Consumes the builder, carrying its `with_info` / `under` /// live server). Consumes the builder, carrying its `with_info` / `under`
/// configuration through. /// configuration through.
pub fn named(self, name: ServerName<G>) -> NamedServerBuilder<G> { pub fn named(self, name: GenServerName<G>) -> NamedGenServerBuilder<G> {
NamedServerBuilder { builder: self, name: name.as_str() } NamedGenServerBuilder { builder: self, name: name.as_str() }
} }
/// The shared spawn body behind [`start`](Self::start) and /// The shared spawn body behind [`start`](Self::start) and
/// [`NamedServerBuilder::start`]: make the inbox, spawn the loop, return the /// [`NamedGenServerBuilder::start`]: make the inbox, spawn the loop, return the
/// ref. (The named path additionally publishes the inbox sender under the /// ref. (The named path additionally publishes the inbox sender under the
/// name before returning.) /// name before returning.)
fn spawn_server(self) -> ServerRef<G> { fn spawn_server(self) -> GenServerRef<G> {
let (tx, rx) = channel::<Envelope<G>>(); let (tx, rx) = channel::<Envelope<G>>();
let ServerBuilder { state, infos, supervisor } = self; let GenServerBuilder { state, infos, supervisor } = self;
let handle = match supervisor { let handle = match supervisor {
Some(sup) => spawn_under(sup, move || server_loop::<G>(rx, state, infos)), Some(sup) => spawn_under(sup, move || server_loop::<G>(rx, state, infos)),
None => spawn(move || server_loop::<G>(rx, state, infos)), None => spawn(move || server_loop::<G>(rx, state, infos)),
}; };
ServerRef { tx, pid: handle.pid() } GenServerRef { tx, pid: handle.pid() }
} }
} }
@@ -594,19 +594,19 @@ impl<G: GenServer> ServerBuilder<G> {
/// `G`'s `Call` / `Cast` / `Reply`. Declared as a constant and shared freely: /// `G`'s `Call` / `Cast` / `Reply`. Declared as a constant and shared freely:
/// ///
/// ```ignore /// ```ignore
/// const COUNTER: ServerName<Counter> = ServerName::new("counter"); /// const COUNTER: GenServerName<Counter> = GenServerName::new("counter");
/// ``` /// ```
/// ///
/// Under the hood the server's inbox is published into the registry as a /// Under the hood the server's inbox is published into the registry as a
/// `Sender<Envelope<G>>` keyed by its message `TypeId` — the same channel store /// `Sender<Envelope<G>>` keyed by its message `TypeId` — the same channel store
/// every other name uses — so naming needs no separate directory. `Envelope` /// every other name uses — so naming needs no separate directory. `Envelope`
/// stays private: only `ServerName<G>` opens that door. /// stays private: only `GenServerName<G>` opens that door.
pub struct ServerName<G> { pub struct GenServerName<G> {
name: &'static str, name: &'static str,
_marker: PhantomData<fn() -> G>, _marker: PhantomData<fn() -> G>,
} }
impl<G> ServerName<G> { impl<G> GenServerName<G> {
/// Bind a static string as a server name. `const`, so names live as /// Bind a static string as a server name. `const`, so names live as
/// associated constants at call sites. /// associated constants at call sites.
#[inline] #[inline]
@@ -621,30 +621,30 @@ impl<G> ServerName<G> {
} }
} }
impl<G> Copy for ServerName<G> {} impl<G> Copy for GenServerName<G> {}
impl<G> Clone for ServerName<G> { impl<G> Clone for GenServerName<G> {
fn clone(&self) -> Self { fn clone(&self) -> Self {
*self *self
} }
} }
/// A [`ServerBuilder`] that will bind a [`ServerName`] as it starts. Reached via /// A [`GenServerBuilder`] that will bind a [`GenServerName`] as it starts. Reached via
/// [`ServerBuilder::named`]; its [`start`](Self::start) is fallible because the /// [`GenServerBuilder::named`]; its [`start`](Self::start) is fallible because the
/// name may already be held by a live server. `with_info` / `under` stay /// name may already be held by a live server. `with_info` / `under` stay
/// available so configuration can come before or after `named`. /// available so configuration can come before or after `named`.
pub struct NamedServerBuilder<G: GenServer> { pub struct NamedGenServerBuilder<G: GenServer> {
builder: ServerBuilder<G>, builder: GenServerBuilder<G>,
name: &'static str, name: &'static str,
} }
impl<G: GenServer> NamedServerBuilder<G> { impl<G: GenServer> NamedGenServerBuilder<G> {
/// Add an out-of-band info channel (see [`ServerBuilder::with_info`]). /// Add an out-of-band info channel (see [`GenServerBuilder::with_info`]).
pub fn with_info(mut self, rx: Receiver<G::Info>) -> Self { pub fn with_info(mut self, rx: Receiver<G::Info>) -> Self {
self.builder = self.builder.with_info(rx); self.builder = self.builder.with_info(rx);
self self
} }
/// Spawn under an explicit supervisor (see [`ServerBuilder::under`]). /// Spawn under an explicit supervisor (see [`GenServerBuilder::under`]).
pub fn under(mut self, supervisor: Pid) -> Self { pub fn under(mut self, supervisor: Pid) -> Self {
self.builder = self.builder.under(supervisor); self.builder = self.builder.under(supervisor);
self self
@@ -659,8 +659,8 @@ impl<G: GenServer> NamedServerBuilder<G> {
/// `start()` returns — no race with the server body. On a name clash the /// `start()` returns — no race with the server body. On a name clash the
/// just-spawned server is wound down (its only ref is dropped, closing the /// just-spawned server is wound down (its only ref is dropped, closing the
/// inbox), so a failed bind leaks no actor. /// inbox), so a failed bind leaks no actor.
pub fn start(self) -> Result<ServerRef<G>, RegisterError> { pub fn start(self) -> Result<GenServerRef<G>, RegisterError> {
let NamedServerBuilder { builder, name } = self; let NamedGenServerBuilder { builder, name } = self;
let server = builder.spawn_server(); let server = builder.spawn_server();
match register_with::<Envelope<G>>(server.pid, name, server.tx.clone()) { match register_with::<Envelope<G>>(server.pid, name, server.tx.clone()) {
Ok(()) => Ok(server), Ok(()) => Ok(server),
@@ -672,13 +672,13 @@ impl<G: GenServer> NamedServerBuilder<G> {
} }
} }
/// Resolve a [`ServerName`] to a [`ServerRef`] when you want a handle to hold or /// Resolve a [`GenServerName`] to a [`GenServerRef`] when you want a handle to hold or
/// pass on rather than resolve per call. Rebuilds the ref from the registry's /// pass on rather than resolve per call. Rebuilds the ref from the registry's
/// stored inbox sender; `None` if no live server holds the name. /// stored inbox sender; `None` if no live server holds the name.
/// ///
/// Panics if called outside `Runtime::run()`. /// Panics if called outside `Runtime::run()`.
pub fn whereis_server<G: GenServer>(name: ServerName<G>) -> Option<ServerRef<G>> { pub fn whereis_server<G: GenServer>(name: GenServerName<G>) -> Option<GenServerRef<G>> {
resolve_named_sender::<Envelope<G>>(name.as_str()).map(|(pid, tx)| ServerRef { tx, pid }) resolve_named_sender::<Envelope<G>>(name.as_str()).map(|(pid, tx)| GenServerRef { tx, pid })
} }
/// Synchronous request-reply to the server currently registered under `name`, /// Synchronous request-reply to the server currently registered under `name`,
@@ -687,7 +687,7 @@ pub fn whereis_server<G: GenServer>(name: ServerName<G>) -> Option<ServerRef<G>>
/// server holds the name, or if it dies before replying. /// server holds the name, or if it dies before replying.
/// ///
/// Panics if called outside `Runtime::run()`. /// Panics if called outside `Runtime::run()`.
pub fn call<G: GenServer>(name: ServerName<G>, request: G::Call) -> Result<G::Reply, CallError> { pub fn call<G: GenServer>(name: GenServerName<G>, request: G::Call) -> Result<G::Reply, CallError> {
match whereis_server(name) { match whereis_server(name) {
Some(server) => server.call(request), Some(server) => server.call(request),
None => Err(CallError::ServerDown), None => Err(CallError::ServerDown),
@@ -698,7 +698,7 @@ pub fn call<G: GenServer>(name: ServerName<G>, request: G::Call) -> Result<G::Re
/// [`CastError::ServerDown`] if no live server holds the name. /// [`CastError::ServerDown`] if no live server holds the name.
/// ///
/// Panics if called outside `Runtime::run()`. /// Panics if called outside `Runtime::run()`.
pub fn cast<G: GenServer>(name: ServerName<G>, request: G::Cast) -> Result<(), CastError> { pub fn cast<G: GenServer>(name: GenServerName<G>, request: G::Cast) -> Result<(), CastError> {
match whereis_server(name) { match whereis_server(name) {
Some(server) => server.cast(request), Some(server) => server.cast(request),
None => Err(CastError::ServerDown), None => Err(CastError::ServerDown),
@@ -706,25 +706,25 @@ pub fn cast<G: GenServer>(name: ServerName<G>, request: G::Cast) -> Result<(), C
} }
/// Terminate the server registered under `name` and block until it is down (see /// Terminate the server registered under `name` and block until it is down (see
/// [`ServerRef::shutdown`]). A no-op if no live server holds the name. /// [`GenServerRef::shutdown`]). A no-op if no live server holds the name.
/// ///
/// Panics if called outside `Runtime::run()`. /// Panics if called outside `Runtime::run()`.
pub fn shutdown<G: GenServer>(name: ServerName<G>) { pub fn shutdown<G: GenServer>(name: GenServerName<G>) {
if let Some(server) = whereis_server(name) { if let Some(server) = whereis_server(name) {
server.shutdown(); server.shutdown();
} }
} }
/// Spawn `state` as a server under the current actor (via [`spawn`]). Returns a /// Spawn `state` as a server under the current actor (via [`spawn`]). Returns a
/// [`ServerRef`]. Shorthand for `ServerBuilder::new(state).start()`. /// [`GenServerRef`]. Shorthand for `GenServerBuilder::new(state).start()`.
pub fn start<G: GenServer>(state: G) -> ServerRef<G> { pub fn start<G: GenServer>(state: G) -> GenServerRef<G> {
ServerBuilder::new(state).start() GenServerBuilder::new(state).start()
} }
/// Like [`start`], but spawns the server under an explicit supervisor pid (via /// Like [`start`], but spawns the server under an explicit supervisor pid (via
/// [`spawn_under`]) so it slots into the supervision tree. /// [`spawn_under`]) so it slots into the supervision tree.
pub fn start_under<G: GenServer>(supervisor: Pid, state: G) -> ServerRef<G> { pub fn start_under<G: GenServer>(supervisor: Pid, state: G) -> GenServerRef<G> {
ServerBuilder::new(state).under(supervisor).start() GenServerBuilder::new(state).under(supervisor).start()
} }
fn server_loop<G: GenServer>( fn server_loop<G: GenServer>(
@@ -788,7 +788,7 @@ fn server_loop<G: GenServer>(
// Bind the ctx so the idle window set during init can be read back, then // Bind the ctx so the idle window set during init can be read back, then
// drop it — that drops the loop's own Sys sender, so a state that cloned no // drop it — that drops the loop's own Sys sender, so a state that cloned no
// Watcher/TimerHandle lets the arm auto-close (the unused-ctx behaviour). // Watcher/TimerHandle lets the arm auto-close (the unused-ctx behaviour).
let ctx = ServerCtx { sys_tx, reg: reg.clone(), idle: Cell::new(None) }; let ctx = GenServerCtx { sys_tx, reg: reg.clone(), idle: Cell::new(None) };
guard.0.init(&ctx); guard.0.init(&ctx);
let idle = ctx.idle.get(); let idle = ctx.idle.get();
drop(ctx); drop(ctx);
+45 -120
View File
@@ -1,50 +1,45 @@
//! gen_statem — generic finite state machine behaviour (RFC 017). //! gen_statem — generic finite state machine behaviour.
//! //!
//! The sibling of [`gen_server`](crate::gen_server): where a `gen_server` //! The sibling of [`gen_server`](crate::gen_server): where a `gen_server`
//! carries one undifferentiated blob of state and a single `handle` that //! carries one undifferentiated blob of state and a single `handle` that
//! re-derives "what mode am I in" on every message, a `gen_statem` makes the //! re-derives "what mode am I in" on every message, a `gen_statem` makes the
//! state an explicit **tag**, routes event handling by it, and (in later //! state an explicit **tag** and routes event handling by it.
//! chunks) adds the machinery state machines need — state-entry callbacks, a
//! timeout taxonomy, and event postponement.
//! //!
//! ## What this layer is //! ## What this layer is
//! //!
//! This module is the **runtime support** a state machine runs on, *not* the //! This module is the **runtime support** a state machine runs on. A machine is
//! authoring surface. A machine is any type implementing [`Machine`]: it owns //! any type implementing [`Machine`]: it owns its state tag and data, and its
//! its state tag and data, and its [`handle`](Machine::handle) reduces a //! [`handle`](Machine::handle) reduces a `(state, event)` pair to a
//! `(state, event)` pair to a [`Resolution`]. The loop here drives it — spawn, //! [`Resolution`]. The loop here drives it — spawn,
//! [`on_start`](Machine::on_start), then one [`handle`](Machine::handle) per //! [`on_start`](Machine::on_start), then one [`handle`](Machine::handle) per
//! inbox event — mirroring `gen_server`'s spawn/teardown idioms. //! inbox event — mirroring `gen_server`'s spawn/teardown idioms.
//! //!
//! The RFC's `statem!` macro (deferred) would *generate* a `Machine` impl from //! The [`gen_statem!`](crate::gen_statem) macro is the authoring surface: it
//! a declarative `transitions { … }` graph plus per-state handler blocks, and //! *generates* a `Machine` impl from per-state handler blocks. Edge-validity is
//! add the expansion-time edge-lint. Until then a machine is hand-written //! not a separate check — it falls out of the generated total `match (state,
//! against these primitives; see `examples/statem_switch.rs` for the shape the //! event)` under denied lints (a forgotten or duplicated pair is a compile
//! macro would target. //! error), so no proc-macro is needed. See `examples/gen_statem_macro.rs` for
//! the macro form and `examples/gen_statem_fused.rs` for the hand-written shape
//! it expands to.
//! //!
//! ## The unified event //! ## The unified event
//! //!
//! A machine's [`Ev`](Machine::Ev) is the single payload its inbox carries. //! A machine's [`Ev`](Machine::Ev) is the single payload its inbox carries. By
//! By convention (and in the macro's desugaring) it folds the user's `cast` //! convention (and in the macro's desugaring) it folds the user's `cast` and
//! and `call` enums together with the runtime's own internal events: //! `call` enums together:
//! //!
//! ```ignore //! ```ignore
//! enum Ev { Cast(MyCast), Call(MyCall) /* later: StateTimeout, Timeout(name) */ } //! enum Ev { Cast(MyCast), Call(MyCall) }
//! ``` //! ```
//! //!
//! [`StatemRef::send`] pushes any event (a cast is just a `send`); //! [`GenStatemRef::send`] pushes any event (a cast is just a `send`);
//! [`StatemRef::call`] builds a one-shot [`Reply`] channel, hands it to a //! [`GenStatemRef::call`] builds a one-shot [`Reply`] channel, hands it to a
//! `call` variant, and parks until the machine answers — exactly the //! `call` variant, and parks until the machine answers — exactly the
//! `gen_server` call round-trip, but with the reply handle riding *inside* the //! `gen_server` call round-trip, but with the reply handle riding *inside* the
//! user's own event so a handler can answer (or, later, postpone) it. //! user's own event so a handler can answer it.
//! //!
//! ## Chunk status (RFC 017 §Sequencing) //! [`Resolution::Postpone`] and the timeout arming on [`Cx`] are part of the
//! //! type surface but are not yet wired up.
//! This is **chunk 1**: macro-free dispatch against real time — spawn,
//! `on_start`, stay/transition, and the `enter` callback (a method on the
//! machine, run on entry to a state). [`Resolution::Postpone`] and the timeout
//! arming on [`Cx`] are part of the type surface but are not yet acted on; they
//! land in chunks 23.
use crate::channel::{channel, Receiver, Sender}; use crate::channel::{channel, Receiver, Sender};
use crate::pid::Pid; use crate::pid::Pid;
@@ -85,7 +80,7 @@ pub trait Machine: Send + 'static {
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
/// The outcome of handling one event, before the loop/handler acts on it: /// The outcome of handling one event, before the loop/handler acts on it:
/// dispatch reduces to `(state, event) -> Resolution<State>` (RFC §Semantics). /// dispatch reduces to `(state, event) -> Resolution<State>`.
/// ///
/// [`From<S>`](From) is why a bare state tag works as an arm tail and why /// [`From<S>`](From) is why a bare state tag works as an arm tail and why
/// "stay" needs no keyword — `Tag.into()` is `To(Tag)`, and the handler treats /// "stay" needs no keyword — `Tag.into()` is `To(Tag)`, and the handler treats
@@ -95,7 +90,7 @@ pub enum Resolution<S> {
/// run `enter`); a **stay** when `s == current` (no `enter`). /// run `enter`); a **stay** when `s == current` (no `enter`).
To(S), To(S),
/// Defer the current event onto the postpone queue, to be replayed after /// Defer the current event onto the postpone queue, to be replayed after
/// the next real transition. Produced by `cx.postpone()` (chunk 3); present /// the next real transition. Produced by `cx.postpone()`; present
/// here for forward-compatibility but not yet generated. /// here for forward-compatibility but not yet generated.
Postpone, Postpone,
/// No arm matched `(state, event)`: log-and-drop via /// No arm matched `(state, event)`: log-and-drop via
@@ -116,11 +111,11 @@ impl<S> From<S> for Resolution<S> {
/// The context handle injected into [`Machine::on_start`] and /// The context handle injected into [`Machine::on_start`] and
/// [`Machine::handle`]. Non-state outcomes (postpone, timeout arming) live here /// [`Machine::handle`]. Non-state outcomes (postpone, timeout arming) live here
/// as method calls rather than keywords (RFC §"Non-state outcomes live on cx"). /// as method calls rather than keywords.
/// ///
/// In chunk 1 it carries only the [`on_unhandled`](Self::on_unhandled) hook; /// For now it carries only the [`on_unhandled`](Self::on_unhandled) hook;
/// `cx.state_timeout(d)` / `cx.timeout(name, d)` (chunk 2) and `cx.postpone()` /// `cx.state_timeout(d)` / `cx.timeout(name, d)` and `cx.postpone()` will attach
/// (chunk 3) attach here as those chunks land. It lives only on the actor's own /// here when implemented. It lives only on the actor's own
/// stack and is never sent. /// stack and is never sent.
pub struct Cx<Ev> { pub struct Cx<Ev> {
_ev: PhantomData<fn() -> Ev>, _ev: PhantomData<fn() -> Ev>,
@@ -132,7 +127,7 @@ impl<Ev> Cx<Ev> {
} }
/// The default for an event no arm matched: **log-and-drop**. Overridable /// The default for an event no arm matched: **log-and-drop**. Overridable
/// hook wiring is a follow-on (RFC Open Q5); for now an unmatched event is /// hook wiring is a follow-on; for now an unmatched event is
/// silently dropped, as `gen_server` does with unexpected messages. /// silently dropped, as `gen_server` does with unexpected messages.
pub fn on_unhandled(&mut self) {} pub fn on_unhandled(&mut self) {}
} }
@@ -143,14 +138,14 @@ impl<Ev> Cx<Ev> {
/// The reply side of a synchronous `call`, carried *inside* the machine's own /// The reply side of a synchronous `call`, carried *inside* the machine's own
/// `call` event variant (`GetCount(Reply<u32>)`). Move-only: answering consumes /// `call` event variant (`GetCount(Reply<u32>)`). Move-only: answering consumes
/// it, so a handler replies at most once. Built by [`StatemRef::call`]; the /// it, so a handler replies at most once. Built by [`GenStatemRef::call`]; the
/// caller parks on the matching receiver until `reply` is invoked (or the /// caller parks on the matching receiver until `reply` is invoked (or the
/// machine dies, closing the channel). /// machine dies, closing the channel).
/// ///
/// Carrying the handle in the event — rather than the loop owning a reply slot /// Carrying the handle in the event — rather than the loop owning a reply slot
/// — is what lets a later chunk **postpone a call**: the whole event, reply /// — is what lets a later chunk **postpone a call**: the whole event, reply
/// handle included, moves onto the postpone queue and is answered by a later /// handle included, moves onto the postpone queue and is answered by a later
/// state (RFC §Postpone). /// state.
pub struct Reply<T> { pub struct Reply<T> {
tx: Sender<T>, tx: Sender<T>,
} }
@@ -168,14 +163,14 @@ impl<T> Reply<T> {
// Client handle // Client handle
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
/// Returned by [`StatemRef::call`] when the machine is unreachable. /// Returned by [`GenStatemRef::call`] when the machine is unreachable.
#[derive(Debug, PartialEq, Eq, Clone, Copy)] #[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub enum CallError { pub enum CallError {
/// The machine was already gone, or died before replying. /// The machine was already gone, or died before replying.
Down, Down,
} }
/// Returned by [`StatemRef::send`] when the machine's inbox is closed. /// Returned by [`GenStatemRef::send`] when the machine's inbox is closed.
#[derive(Debug, PartialEq, Eq, Clone, Copy)] #[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub enum SendError { pub enum SendError {
/// The machine is gone (its inbox is closed). /// The machine is gone (its inbox is closed).
@@ -183,20 +178,20 @@ pub enum SendError {
} }
/// A clonable handle to a running machine. Cloning yields another sender to the /// A clonable handle to a running machine. Cloning yields another sender to the
/// same inbox; the machine lives until the last `StatemRef` is dropped, at which /// same inbox; the machine lives until the last `GenStatemRef` is dropped, at which
/// point its inbox closes and the loop exits. /// point its inbox closes and the loop exits.
pub struct StatemRef<M: Machine> { pub struct GenStatemRef<M: Machine> {
tx: Sender<M::Ev>, tx: Sender<M::Ev>,
pid: Pid, pid: Pid,
} }
impl<M: Machine> Clone for StatemRef<M> { impl<M: Machine> Clone for GenStatemRef<M> {
fn clone(&self) -> Self { fn clone(&self) -> Self {
StatemRef { tx: self.tx.clone(), pid: self.pid } GenStatemRef { tx: self.tx.clone(), pid: self.pid }
} }
} }
impl<M: Machine> StatemRef<M> { impl<M: Machine> GenStatemRef<M> {
/// The machine actor's pid — usable with `monitor`, `request_stop`, `link`. /// The machine actor's pid — usable with `monitor`, `request_stop`, `link`.
pub fn pid(&self) -> Pid { pub fn pid(&self) -> Pid {
self.pid self.pid
@@ -235,15 +230,15 @@ impl<M: Machine> StatemRef<M> {
// Spawn + loop // Spawn + loop
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
/// Spawn `machine` as an actor and hand back its [`StatemRef`]. Shape mirrors /// Spawn `machine` as an actor and hand back its [`GenStatemRef`]. Shape mirrors
/// `gen_server::start`: make the inbox, spawn the loop, return the ref; the /// `gen_server::start`: make the inbox, spawn the loop, return the ref; the
/// backing join handle is dropped (lifetime is governed by refs, not joining). /// backing join handle is dropped (lifetime is governed by refs, not joining).
/// ///
/// Panics if called outside `Runtime::run()`. /// Panics if called outside `Runtime::run()`.
pub fn spawn<M: Machine>(machine: M) -> StatemRef<M> { pub fn spawn<M: Machine>(machine: M) -> GenStatemRef<M> {
let (tx, rx) = channel::<M::Ev>(); let (tx, rx) = channel::<M::Ev>();
let handle = spawn_actor(move || statem_loop(rx, machine)); let handle = spawn_actor(move || statem_loop(rx, machine));
StatemRef { tx, pid: handle.pid() } GenStatemRef { tx, pid: handle.pid() }
} }
/// The machine actor body: `on_start`, then one `handle` per inbox event until /// The machine actor body: `on_start`, then one `handle` per inbox event until
@@ -266,7 +261,7 @@ fn statem_loop<M: Machine>(rx: Receiver<M::Ev>, mut machine: M) {
} }
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
// gen_statem! — the authoring macro (RFC 017 §Surface, fused variant) // gen_statem! — the authoring macro (fused total-match variant)
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
/// Assemble a complete [`Machine`] from hand-written types, a glanceable /// Assemble a complete [`Machine`] from hand-written types, a glanceable
@@ -393,7 +388,7 @@ fn statem_loop<M: Machine>(rx: Receiver<M::Ev>, mut machine: M) {
/// # What it emits /// # What it emits
/// ///
/// `enum $Ev { Cast($Cast), Call($Call) }`, `struct $Sm { state, data }`, /// `enum $Ev { Cast($Cast), Call($Call) }`, `struct $Sm { state, data }`,
/// `$Sm::start(init, data) -> StatemRef<$Sm>`, the `Machine` impl (`on_start` /// `$Sm::start(init, data) -> GenStatemRef<$Sm>`, the `Machine` impl (`on_start`
/// running the initial `enter`; `handle` = the dispatch match + the /// running the initial `enter`; `handle` = the dispatch match + the
/// stay/transition/unhandled apply-tail, the cell's sole writer), and the /// stay/transition/unhandled apply-tail, the cell's sole writer), and the
/// `enter` dispatch. Chunk 1: real time, no timers, no postpone. /// `enter` dispatch. Chunk 1: real time, no timers, no postpone.
@@ -426,7 +421,7 @@ macro_rules! gen_statem {
} }
impl $sm { impl $sm {
fn start(init: $State, data: $Data) -> $crate::gen_statem::StatemRef<$sm> { fn start(init: $State, data: $Data) -> $crate::gen_statem::GenStatemRef<$sm> {
$crate::gen_statem::spawn($sm { state: init, data }) $crate::gen_statem::spawn($sm { state: init, data })
} }
@@ -466,7 +461,7 @@ macro_rules! gen_statem {
self.enter(s, $cx); self.enter(s, $cx);
} }
$crate::gen_statem::Resolution::Postpone => { $crate::gen_statem::Resolution::Postpone => {
unreachable!("postpone is unreachable until chunk 3") unreachable!("postpone is not generated yet")
} }
$crate::gen_statem::Resolution::Unhandled => $cx.on_unhandled(), $crate::gen_statem::Resolution::Unhandled => $cx.on_unhandled(),
} }
@@ -527,73 +522,3 @@ macro_rules! gen_statem {
$crate::gen_statem!(@arms ($Ev) ($ss, $se) [ $($arms)* ] $($more)*) $crate::gen_statem!(@arms ($Ev) ($ss, $se) [ $($arms)* ] $($more)*)
}; };
} }
#[cfg(test)]
mod gen_statem_tests {
use crate::gen_statem::Reply;
#[derive(Clone, Copy, PartialEq, Eq, Debug)]
enum Switch {
Off,
On,
}
struct Counts {
flips: u32,
enters: u32,
}
enum Cast {
Flip,
Nudge,
}
enum Call {
GetFlips(Reply<u32>),
GetEnters(Reply<u32>),
}
fn on_flip(data: &mut Counts) {
data.flips += 1;
}
crate::gen_statem! {
machine: SwitchSm { state: Switch, data: Counts };
event: Ev { cast: Cast, call: Call };
context(data, prev, cx);
enter {
_ => data.enters += 1,
}
on Switch::Off => {
cast Cast::Flip => { on_flip(data); Switch::On },
cast Cast::Nudge => unhandled,
}
on Switch::On => {
cast Cast::Flip => { on_flip(data); Switch::Off },
cast Cast::Nudge => prev, // explicit stay
}
on _ => {
call Call::GetFlips(r) => { r.reply(data.flips); prev },
call Call::GetEnters(r) => { r.reply(data.enters); prev },
}
}
// NOTE (guarantee #2): because this machine lives in the SAME crate as
// `gen_statem!`, adding a duplicate row here — e.g. a second
// `cast Cast::Nudge => unhandled,` under `on Switch::Off` — is a hard
// `unreachable pattern` error. (From a downstream crate it is silently
// suppressed by rustc's in_external_macro rule; see the macro docs.)
#[test]
fn macro_machine_drives_and_counts() {
crate::run(|| {
let sm = SwitchSm::start(Switch::Off, Counts { flips: 0, enters: 0 });
sm.send(Ev::Cast(Cast::Flip)).unwrap(); // Off -> On (flip=1, enter)
sm.send(Ev::Cast(Cast::Nudge)).unwrap(); // On: stay (no enter)
sm.send(Ev::Cast(Cast::Flip)).unwrap(); // On -> Off (flip=2, enter)
let flips = sm.call(|r| Ev::Call(Call::GetFlips(r))).unwrap();
let enters = sm.call(|r| Ev::Call(Call::GetEnters(r))).unwrap();
assert_eq!(flips, 2);
assert_eq!(enters, 3); // Off(start) + On + Off
});
}
}
+3 -3
View File
@@ -56,11 +56,11 @@ pub use channel::{
}; };
pub use gen_server::{ pub use gen_server::{
call, cast, shutdown, whereis_server, CallError, CallTimeoutError, CastError, GenServer, call, cast, shutdown, whereis_server, CallError, CallTimeoutError, CastError, GenServer,
NamedServerBuilder, ServerBuilder, ServerCtx, ServerName, ServerRef, TimerHandle, Watcher, NamedGenServerBuilder, GenServerBuilder, GenServerCtx, GenServerName, GenServerRef, TimerHandle, Watcher,
}; };
pub use gen_statem::{ pub use gen_statem::{
CallError as StatemCallError, Cx, Machine, Reply, Resolution, SendError as StatemSendError, CallError as GenStatemCallError, Cx, Machine, Reply, Resolution, SendError as GenStatemSendError,
StatemRef, GenStatemRef,
}; };
pub use introspect::{ pub use introspect::{
actor_info, snapshot, tree, tree_from, ActorInfo, ActorState, RuntimeSnapshot, RuntimeTree, actor_info, snapshot, tree, tree_from, ActorInfo, ActorState, RuntimeSnapshot, RuntimeTree,
+5 -5
View File
@@ -29,7 +29,7 @@
//! channel by value; that is intended, it is exactly what a remote observer //! channel by value; that is intended, it is exactly what a remote observer
//! (RFC 011) will serialize across a node boundary. //! (RFC 011) will serialize across a node boundary.
use crate::gen_server::{GenServer, ServerBuilder, ServerRef}; use crate::gen_server::{GenServer, GenServerBuilder, GenServerRef};
use crate::introspect::{actor_info, snapshot, tree}; use crate::introspect::{actor_info, snapshot, tree};
use crate::introspect::{ActorInfo, RuntimeSnapshot, RuntimeTree}; use crate::introspect::{ActorInfo, RuntimeSnapshot, RuntimeTree};
use crate::pid::Pid; use crate::pid::Pid;
@@ -89,8 +89,8 @@ impl GenServer for Observer {
} }
} }
/// Spawn the observer under the current actor and hand back its [`ServerRef`]. /// Spawn the observer under the current actor and hand back its [`GenServerRef`].
/// Shorthand for `ServerBuilder::new(Observer).start()`; use the builder /// Shorthand for `GenServerBuilder::new(Observer).start()`; use the builder
/// directly (e.g. `.under(sup)`) to slot it into a supervision tree. /// directly (e.g. `.under(sup)`) to slot it into a supervision tree.
/// ///
/// ``` /// ```
@@ -109,6 +109,6 @@ impl GenServer for Observer {
/// assert!(snap.actors.iter().any(|a| a.pid == obs.pid())); /// assert!(snap.actors.iter().any(|a| a.pid == obs.pid()));
/// }); /// });
/// ``` /// ```
pub fn start() -> ServerRef<Observer> { pub fn start() -> GenServerRef<Observer> {
ServerBuilder::new(Observer).start() GenServerBuilder::new(Observer).start()
} }
+2 -2
View File
@@ -53,7 +53,7 @@ impl std::fmt::Display for RawPid {
} }
/// Phantom actor type for a pid that has no single message type: raw `spawn` /// Phantom actor type for a pid that has no single message type: raw `spawn`
/// actors, gen_servers (intrinsically multi-message, addressed via `ServerRef`), /// actors, gen_servers (intrinsically multi-message, addressed via `GenServerRef`),
/// and every identity-only context. Deliberately **not** [`Addressable`], so a /// and every identity-only context. Deliberately **not** [`Addressable`], so a
/// typed `send` to a `Pid<Erased>` does not compile; the runtime-checked /// typed `send` to a `Pid<Erased>` does not compile; the runtime-checked
/// `send_dyn` escape hatch (RFC 014 §4.6) is the sanctioned bare-pid path. /// `send_dyn` escape hatch (RFC 014 §4.6) is the sanctioned bare-pid path.
@@ -166,7 +166,7 @@ impl<A> std::fmt::Display for Pid<A> {
/// An actor type with a single associated message type, so a [`Pid<Self>`] is a /// An actor type with a single associated message type, so a [`Pid<Self>`] is a
/// typed address. The raw channel layer has no such trait (actors are closures /// typed address. The raw channel layer has no such trait (actors are closures
/// over channels) and `GenServer` is intrinsically multi-message (addressed via /// over channels) and `GenServer` is intrinsically multi-message (addressed via
/// its own `ServerRef`); this is the minimal hook that lets the single-message /// its own `GenServerRef`); this is the minimal hook that lets the single-message
/// actors carry their message type in their pid. (RFC 014 §4.2.) /// actors carry their message type in their pid. (RFC 014 §4.2.)
pub trait Addressable: 'static { pub trait Addressable: 'static {
/// The message this actor receives. A `Pid<Self>` delivers `Self::Msg`. /// The message this actor receives. A `Pid<Self>` delivers `Self::Msg`.
+1 -1
View File
@@ -425,7 +425,7 @@ pub fn lookup_as<A: Addressable>(name: &str) -> Option<Pid<A>> {
/// lock (clone-under-lock, then release). The crate-internal building block for /// lock (clone-under-lock, then release). The crate-internal building block for
/// `gen_server`'s by-name addressing: a named server publishes its inbox as a /// `gen_server`'s by-name addressing: a named server publishes its inbox as a
/// `Sender<Envelope<G>>` (via [`register_with`]), and `whereis_server` / `call` /// `Sender<Envelope<G>>` (via [`register_with`]), and `whereis_server` / `call`
/// / `cast` recover that exact typed sender here to rebuild a `ServerRef<G>`. /// / `cast` recover that exact typed sender here to rebuild a `GenServerRef<G>`.
/// `None` if unbound, dead (pruned on the way out), or holding no `M` channel. /// `None` if unbound, dead (pruned on the way out), or holding no `M` channel.
pub(crate) fn resolve_named_sender<M: Send + 'static>(name: &str) -> Option<(Pid, Sender<M>)> { pub(crate) fn resolve_named_sender<M: Send + 'static>(name: &str) -> Option<(Pid, Sender<M>)> {
with_runtime(|inner| { with_runtime(|inner| {
+1 -1
View File
@@ -206,7 +206,7 @@ pub fn spawn_under<A>(supervisor: Pid<A>, f: impl FnOnce() + Send + 'static) ->
/// [`send_to`](crate::send_to) always resolves, never racing the body's first /// [`send_to`](crate::send_to) always resolves, never racing the body's first
/// instruction. The actor is detached — its lifetime is governed by its own /// instruction. The actor is detached — its lifetime is governed by its own
/// logic (an explicit stop message, or returning), like /// logic (an explicit stop message, or returning), like
/// [`ServerBuilder::start`](crate::ServerBuilder::start) — so the backing join /// [`GenServerBuilder::start`](crate::GenServerBuilder::start) — so the backing join
/// handle is dropped. Spawns under the current actor (via [`spawn`]). /// handle is dropped. Spawns under the current actor (via [`spawn`]).
/// ///
/// Panics if called outside `Runtime::run()`. /// Panics if called outside `Runtime::run()`.
+10 -10
View File
@@ -1,7 +1,7 @@
//! gen_server tests: call round-trip, cast, lifecycle callbacks, and the two //! gen_server tests: call round-trip, cast, lifecycle callbacks, and the two
//! server-down detection paths (reply-channel close vs. inbox-send failure). //! server-down detection paths (reply-channel close vs. inbox-send failure).
use smarm::gen_server::{start, CallError, GenServer, ServerBuilder}; use smarm::gen_server::{start, CallError, GenServer, GenServerBuilder};
use smarm::run; use smarm::run;
use std::sync::{Arc, Mutex}; use std::sync::{Arc, Mutex};
@@ -73,7 +73,7 @@ impl GenServer for Lifecycle {
type Info = (); type Info = ();
type Timer = (); type Timer = ();
fn init(&mut self, _ctx: &smarm::gen_server::ServerCtx<Self>) { fn init(&mut self, _ctx: &smarm::gen_server::GenServerCtx<Self>) {
self.log.lock().unwrap().push("init"); self.log.lock().unwrap().push("init");
} }
@@ -275,7 +275,7 @@ fn info_is_dispatched() {
let got2 = got.clone(); let got2 = got.clone();
run(move || { run(move || {
let (info_tx, info_rx) = smarm::channel::<&'static str>(); let (info_tx, info_rx) = smarm::channel::<&'static str>();
let server = ServerBuilder::new(Logger { log: Vec::new() }) let server = GenServerBuilder::new(Logger { log: Vec::new() })
.with_info(info_rx) .with_info(info_rx)
.start(); .start();
info_tx.send("info").unwrap(); info_tx.send("info").unwrap();
@@ -293,7 +293,7 @@ fn info_outranks_inbox() {
let got2 = got.clone(); let got2 = got.clone();
run(move || { run(move || {
let (info_tx, info_rx) = smarm::channel::<&'static str>(); let (info_tx, info_rx) = smarm::channel::<&'static str>();
let server = ServerBuilder::new(Logger { log: Vec::new() }) let server = GenServerBuilder::new(Logger { log: Vec::new() })
.with_info(info_rx) .with_info(info_rx)
.start(); .start();
// The server actor hasn't run yet: both messages are queued before // The server actor hasn't run yet: both messages are queued before
@@ -314,7 +314,7 @@ fn info_arms_keep_declaration_priority() {
run(move || { run(move || {
let (hi_tx, hi_rx) = smarm::channel::<&'static str>(); let (hi_tx, hi_rx) = smarm::channel::<&'static str>();
let (lo_tx, lo_rx) = smarm::channel::<&'static str>(); let (lo_tx, lo_rx) = smarm::channel::<&'static str>();
let server = ServerBuilder::new(Logger { log: Vec::new() }) let server = GenServerBuilder::new(Logger { log: Vec::new() })
.with_info(hi_rx) .with_info(hi_rx)
.with_info(lo_rx) .with_info(lo_rx)
.start(); .start();
@@ -335,7 +335,7 @@ fn closed_info_arm_is_dropped_silently() {
let got2 = got.clone(); let got2 = got.clone();
run(move || { run(move || {
let (info_tx, info_rx) = smarm::channel::<&'static str>(); let (info_tx, info_rx) = smarm::channel::<&'static str>();
let server = ServerBuilder::new(Logger { log: Vec::new() }) let server = GenServerBuilder::new(Logger { log: Vec::new() })
.with_info(info_rx) .with_info(info_rx)
.start(); .start();
drop(info_tx); // closed before the server's first select drop(info_tx); // closed before the server's first select
@@ -371,7 +371,7 @@ impl GenServer for Pool {
type Info = (); type Info = ();
type Timer = (); type Timer = ();
fn init(&mut self, ctx: &smarm::gen_server::ServerCtx<Self>) { fn init(&mut self, ctx: &smarm::gen_server::GenServerCtx<Self>) {
self.watcher = Some(ctx.watcher()); self.watcher = Some(ctx.watcher());
} }
@@ -448,7 +448,7 @@ fn unused_ctx_closes_control_arm_silently() {
// RFC 015 — gen_server timers. A server that arms one-shot timers from a cast // RFC 015 — gen_server timers. A server that arms one-shot timers from a cast
// and records each fire's payload, plus the cancel race signal. // and records each fire's payload, plus the cancel race signal.
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
use smarm::gen_server::{ServerCtx, TimerHandle}; use smarm::gen_server::{GenServerCtx, TimerHandle};
use smarm::TimerId; use smarm::TimerId;
enum TkCast { enum TkCast {
@@ -471,7 +471,7 @@ impl GenServer for Timed {
type Info = (); type Info = ();
type Timer = u32; type Timer = u32;
fn init(&mut self, ctx: &ServerCtx<Self>) { fn init(&mut self, ctx: &GenServerCtx<Self>) {
self.timer = Some(ctx.timer()); self.timer = Some(ctx.timer());
} }
@@ -597,7 +597,7 @@ impl GenServer for Idler {
type Info = (); type Info = ();
type Timer = (); type Timer = ();
fn init(&mut self, ctx: &ServerCtx<Self>) { fn init(&mut self, ctx: &GenServerCtx<Self>) {
ctx.idle_after(self.window); ctx.idle_after(self.window);
} }
fn handle_call(&mut self, _: ()) -> u32 { fn handle_call(&mut self, _: ()) -> u32 {
+108
View File
@@ -0,0 +1,108 @@
//! gen_statem behaviour tests, driven through the `gen_statem!` macro: cast/call
//! round-trip, `enter` firing on start and on every real transition (but not on
//! a stay), and the machine-down path when a handler panics.
use smarm::gen_statem;
use smarm::gen_statem::{CallError, Reply};
use smarm::run;
use std::sync::{Arc, Mutex};
// A two-state machine: Flip toggles, calls read counters, Boom panics.
#[derive(Clone, Copy, PartialEq, Eq, Debug)]
enum Switch {
Off,
On,
}
struct Counts {
flips: u32,
enters: u32,
}
enum Cast {
Flip,
}
enum Call {
GetFlips(Reply<u32>),
GetEnters(Reply<u32>),
Boom(Reply<u32>),
}
gen_statem! {
machine: Sm { state: Switch, data: Counts };
event: Ev { cast: Cast, call: Call };
context(data, prev, cx);
enter {
_ => data.enters += 1,
}
on Switch::Off => {
cast Cast::Flip => { data.flips += 1; Switch::On },
}
on Switch::On => {
cast Cast::Flip => Switch::Off,
}
// State-independent queries: reply, then stay via `prev`. Boom panics
// (`boom()` is typed as a state tag so the arm stays well-formed).
on _ => {
call Call::GetFlips(r) => { r.reply(data.flips); prev },
call Call::GetEnters(r) => { r.reply(data.enters); prev },
call Call::Boom(_r) => boom(),
}
}
fn boom() -> Switch {
panic!("boom")
}
// Casts are applied in order and a later call observes the accumulated data.
#[test]
fn cast_then_call_roundtrip() {
let got = Arc::new(Mutex::new(0u32));
let got2 = got.clone();
run(move || {
let sw = Sm::start(Switch::Off, Counts { flips: 0, enters: 0 });
sw.send(Ev::Cast(Cast::Flip)).unwrap(); // Off -> On (flips = 1)
sw.send(Ev::Cast(Cast::Flip)).unwrap(); // On -> Off (no flip count)
let flips = sw.call(|r| Ev::Call(Call::GetFlips(r))).unwrap();
*got2.lock().unwrap() = flips;
});
assert_eq!(*got.lock().unwrap(), 1, "turned On once across the two flips");
}
// `enter` fires once on start and once per *real* transition; a stay (a call
// that returns the current tag) does not re-enter.
#[test]
fn enter_on_start_and_each_transition_but_not_stay() {
let got = Arc::new(Mutex::new((0u32, 0u32, 0u32)));
let got2 = got.clone();
run(move || {
let sw = Sm::start(Switch::Off, Counts { flips: 0, enters: 0 }); // enter -> 1
let after_start = sw.call(|r| Ev::Call(Call::GetEnters(r))).unwrap();
// Two stays (the reads) must not bump enters.
let _ = sw.call(|r| Ev::Call(Call::GetFlips(r))).unwrap();
let still = sw.call(|r| Ev::Call(Call::GetEnters(r))).unwrap();
sw.send(Ev::Cast(Cast::Flip)).unwrap(); // Off -> On -> enter -> 2
let after_flip = sw.call(|r| Ev::Call(Call::GetEnters(r))).unwrap();
*got2.lock().unwrap() = (after_start, still, after_flip);
});
assert_eq!(*got.lock().unwrap(), (1, 1, 2));
}
// A handler that panics tears the loop down; the in-flight call's reply channel
// closes as the stack unwinds, so the parked caller wakes with Down (mirrors
// gen_server's panicking-handler path).
#[test]
fn call_to_panicking_handler_is_down() {
let got = Arc::new(Mutex::new(None::<Result<u32, CallError>>));
let got2 = got.clone();
run(move || {
let sw = Sm::start(Switch::Off, Counts { flips: 0, enters: 0 });
let r = sw.call(|rep| Ev::Call(Call::Boom(rep)));
*got2.lock().unwrap() = Some(r);
});
assert_eq!(*got.lock().unwrap(), Some(Err(CallError::Down)));
}
-142
View File
@@ -1,142 +0,0 @@
//! gen_statem (RFC 017) chunk-1 tests: call/cast round-trip against a
//! hand-written machine, `enter` firing on start and on every real transition
//! (but not on a stay), and the machine-down path when a handler panics.
//!
//! These drive the `smarm::gen_statem` primitives directly, the same way a
//! `statem!`-generated machine eventually will.
use smarm::run;
use smarm::gen_statem::{self, CallError, Cx, Machine, Reply, Resolution, StatemRef};
use std::sync::{Arc, Mutex};
// ---------------------------------------------------------------------------
// A hand-written two-state machine: Flip toggles, calls read, Boom panics.
// ---------------------------------------------------------------------------
#[derive(Clone, Copy, PartialEq, Eq, Debug)]
enum Switch {
Off,
On,
}
struct Counts {
flips: u32,
enters: u32,
}
enum Cast {
Flip,
}
enum Call {
GetFlips(Reply<u32>),
GetEnters(Reply<u32>),
Boom(Reply<u32>),
}
enum Ev {
Cast(Cast),
Call(Call),
}
struct Sm {
state: Switch,
data: Counts,
}
impl Sm {
fn start(init: Switch) -> StatemRef<Sm> {
gen_statem::spawn(Sm { state: init, data: Counts { flips: 0, enters: 0 } })
}
fn enter(&mut self, _s: Switch, _cx: &mut Cx<Ev>) {
self.data.enters += 1;
}
}
impl Machine for Sm {
type Ev = Ev;
fn on_start(&mut self, cx: &mut Cx<Ev>) {
let s = self.state;
self.enter(s, cx);
}
fn handle(&mut self, ev: Ev, cx: &mut Cx<Ev>) {
let prev = self.state;
let next: Resolution<Switch> = match (self.state, ev) {
(Switch::Off, Ev::Cast(Cast::Flip)) => {
self.data.flips += 1;
Switch::On.into()
}
(Switch::On, Ev::Cast(Cast::Flip)) => Switch::Off.into(),
(s, Ev::Call(Call::GetFlips(r))) => {
r.reply(self.data.flips);
s.into() // stay
}
(s, Ev::Call(Call::GetEnters(r))) => {
r.reply(self.data.enters);
s.into() // stay
}
(_, Ev::Call(Call::Boom(_r))) => panic!("boom"),
};
match next {
Resolution::To(s) if s == prev => {}
Resolution::To(s) => {
self.state = s;
self.enter(s, cx);
}
Resolution::Postpone => {}
Resolution::Unhandled => cx.on_unhandled(),
}
}
}
// Casts are applied in order and a later call observes the accumulated data.
#[test]
fn cast_then_call_roundtrip() {
let got = Arc::new(Mutex::new(0u32));
let got2 = got.clone();
run(move || {
let sw = Sm::start(Switch::Off);
sw.send(Ev::Cast(Cast::Flip)).unwrap(); // Off -> On
sw.send(Ev::Cast(Cast::Flip)).unwrap(); // On -> Off
let flips = sw.call(|r| Ev::Call(Call::GetFlips(r))).unwrap();
*got2.lock().unwrap() = flips;
});
assert_eq!(*got.lock().unwrap(), 1, "turned On once across the two flips");
}
// `enter` fires once on start and once per *real* transition; a stay (a call
// that returns the current tag) does not re-enter.
#[test]
fn enter_on_start_and_each_transition_but_not_stay() {
let got = Arc::new(Mutex::new((0u32, 0u32, 0u32)));
let got2 = got.clone();
run(move || {
let sw = Sm::start(Switch::Off); // on_start enter -> enters = 1
let after_start = sw.call(|r| Ev::Call(Call::GetEnters(r))).unwrap();
// Two stays (the reads above + below) must not bump enters.
let _ = sw.call(|r| Ev::Call(Call::GetFlips(r))).unwrap();
let still = sw.call(|r| Ev::Call(Call::GetEnters(r))).unwrap();
sw.send(Ev::Cast(Cast::Flip)).unwrap(); // Off -> On -> enter -> enters = 2
let after_flip = sw.call(|r| Ev::Call(Call::GetEnters(r))).unwrap();
*got2.lock().unwrap() = (after_start, still, after_flip);
});
assert_eq!(*got.lock().unwrap(), (1, 1, 2));
}
// A handler that panics tears the loop down; the in-flight call's reply channel
// closes as the stack unwinds, so the parked caller wakes with Down (mirrors
// gen_server's panicking-handler path).
#[test]
fn call_to_panicking_handler_is_down() {
let got = Arc::new(Mutex::new(None::<Result<u32, CallError>>));
let got2 = got.clone();
run(move || {
let sw = Sm::start(Switch::Off);
let r = sw.call(|rep| Ev::Call(Call::Boom(rep)));
*got2.lock().unwrap() = Some(r);
});
assert_eq!(*got.lock().unwrap(), Some(Err(CallError::Down)));
}