Enum Message 

pub enum Message<T> {
    Start,
    Pause(LockId),
    Resume(LockId),
    Pull(PullDemand),
    Dirty,
    Data(T),
    Resolved,
    Invalidate,
    Complete,
    Error(GraphError),
    Teardown,
}

One protocol message. A Vec<Message<T>> (Wave) is one wave (D8) and may mix tiers. The closed set is 11 kinds (D9 + D269 + the Start handshake); adding a kind is a constitutional change (/spec-amend).

Debug is hand-written to print only the kind tag (not the payload), so Message<AnyValue> — whose payload Rc<dyn Any> is not Debug — stays assertable: tests compare wave shapes like ["DIRTY", "DATA"].

Variants

Start

Subscribe handshake (substrate-internal, not a user ctx.up kind).

Pause(LockId)

Acquire a pause lock (control, up-allowed).

Resume(LockId)

Release a pause lock (control, up-allowed).

Pull(PullDemand)

Demand one pull delivery from the matching pullId holder (control/demand, up-allowed). RESUME is pause-lock release only (D269).

Dirty

Dirty notification — phase 1 of the two-phase wave (notification, up-allowed).

Data(T)

A real value (value tier, down-only). Absence-of-DATA is the SENTINEL (None per D16), represented at the node’s per-dep cache, not as a message.

Resolved

Settle with no value change (value tier, down-only).

Invalidate

Invalidate-request — cache-drop, fire onInvalidate, cascade (settle, up-allowed: a depless source honors it at the terminus per D38/R-up-at-source).

Complete

Terminal success (down-only).

Error(GraphError)

Terminal failure carrying the untyped error (down-only, D31).

Teardown

Teardown (up-allowed; a depless source drops it per D38).

Implementations

impl<T> Message<T>

pub fn tier(&self) -> Tier

The tier of this message per the D34 const table.

pub fn is_up_allowed(&self) -> bool

Whether this kind may travel upstream via ctx.up (R-ctx-up).

Control/demand-tier only: DIRTY / PAUSE / RESUME / PULL / INVALIDATE / TEARDOWN. DATA / RESOLVED / COMPLETE / ERROR are down-only. START is a substrate handshake, not a user ctx.up kind.

Trait Implementations

impl<T> Debug for Message<T>

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

Formats the value using the given formatter.