Struct ProjectionRuntime 

pub struct ProjectionRuntime<P: Projection> { /* private fields */ }

Live read-model runtime owning the DB connection, the broadcaster handle, the projection impl, and the per-key Mutex registry (D-13).

Implementations

impl<P: Projection> ProjectionRuntime<P>

pub fn new( db: DatabaseConnection, broadcaster: Arc<Broadcaster>, projection: P, ) -> Self

Construct a new runtime. Consumers typically wrap in Arc for sharing across tokio tasks (and register requires Arc<Self> to wire into the global dispatcher).

pub async fn read( &self, key: &ProjectionKey, ) -> Result<Option<P::State>, ProjectionError>

Read the persisted snapshot for key. Returns Ok(None) if no row exists. Does NOT take the per-key Mutex (D-33) — readers see either the pre- or post-upsert state, no torn reads.

pub async fn read_required( &self, key: &ProjectionKey, ) -> Result<P::State, ProjectionError>

Read with a hard error if the snapshot is absent (D-30). Wraps read; consumers wanting Result<State, _> use this instead of Result<Option<State>, _>.

pub async fn apply_event(&self, event: &P::Event) -> Result<(), ProjectionError>

Apply a single event. Implements the 7-step D-19 sequence inside a per-key tokio::sync::Mutex. Cross-key applies run in parallel; same-key applies serialize.

pub fn register(self: Arc<Self>)

Register a ProjectionListener<P> into the global event dispatcher (D-15). Killer-feature one-line wiring; every P::Event::dispatch().await now flows through this projection.

Not idempotent on Arc identity (D-36). Calling register twice on the same Arc<Self> registers TWO listeners; both fire on each dispatch (same semantic as Laravel’s Event::listen). Register once at app startup.

pub async fn rebuild<I>( &self, key: &ProjectionKey, events: I, ) -> Result<P::State, ProjectionError>

where I: IntoIterator<Item = P::Event>,

Discard the persisted snapshot for key, fold the supplied event sequence through P::State::default() via P::apply, persist the final state, broadcast ONE "rebuild" frame, and return the rebuilt state (D-17).

Acquires the same per-key Mutex as apply_event, so rebuild serializes against in-flight applies.

Not transactional (D-44). DELETE + folded INSERT under the per-key Mutex; if the process crashes mid-rebuild, the snapshot is gone but a subsequent apply_event re-initializes from Default.

Empty iterator wipes the snapshot row (D-43): returns P::State::default() with no insert and no broadcast.

The broadcast event name is "rebuild" (overrides P::broadcast_event_name); payload is the final state. Clients reset their local state on receipt of a "rebuild" frame (D-41).