Struct ChannelData 

pub struct ChannelData { /* private fields */ }

MPSC-style synchronous channel storage.

ADR-006 §2.7.20 / Q21 amendment (Wave 15 W15-channel-rebuild, 2026-05-10). Channel is a concurrency primitive; unlike the HashMap/HashSet siblings (insertion-ordered immutable-on-clone keys-buffer with Arc::make_mut clone-on-write), Channel needs interior mutability so that two Arc<ChannelData> shares of the same channel observe each other’s send / recv mutations (the producer and consumer endpoints share the same buffer). The inner state therefore lives behind a Mutex<ChannelInner>; the outer Arc is purely a refcount carrier.

Sync same-thread path only at landing. Cross-task / cross- thread blocking recv() (the canonical async-channel use case) requires integration with the §2.7.4 task-scheduler boundary (shape-vm/src/executor/task_scheduler.rs), which is itself a phase-2c surface; per the W15 playbook the async paths SURFACE cleanly. The sync path (same-thread send then recv) lands here end-to-end.

Element typing. The buffer stores KindedSlot payloads directly so heterogeneous-element queues are first-class (a channel can carry ints, strings, or typed objects without a per-element-kind specialisation). Each slot owns one strong- count share for heap-bearing kinds; the KindedSlot::Drop dispatch retires shares cleanly when the channel itself drops. This is the same shape concurrency_methods.rs (Mutex/Atomic/ Lazy) will use when those primitives rebuild — Channel is the first concurrency primitive to land kinded.

Closed flag. closed: bool records whether the producer side has signalled end-of-stream. After close() further send() calls return a closed-channel error; recv() continues to drain queued elements and only errors once the queue is empty (canonical drain-on-close semantics).

Implementations

impl ChannelData

pub fn new() -> Self

Build an empty open channel.

pub fn len(&self) -> usize

Number of pending elements. Useful for diagnostics; not part of the user-facing method surface.

pub fn is_empty(&self) -> bool

Whether the queue currently holds zero pending elements.

pub fn is_closed(&self) -> bool

Whether close() has been called.

pub fn send(&self, slot: KindedSlot) -> Result<(), ()>

Append slot to the queue.

Returns Ok(()) on success, Err(()) if the channel is already closed (callers surface this as a runtime error from the send method body).

pub fn try_recv(&self) -> Option<KindedSlot>

Pop the front element non-blocking.

Returns Some(slot) if an element was available, None otherwise. Per ADR §2.7.20 the same-thread sync path is the supported surface; blocking recv() (await-style) requires the §2.7.4 task-scheduler boundary and is SURFACE’d at the method body.

pub fn close(&self)

Mark the channel closed. Idempotent — calling close on an already-closed channel is a no-op.

Trait Implementations

impl Debug for ChannelData

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

Formats the value using the given formatter.

impl Default for ChannelData

fn default() -> Self

Returns the “default value” for a type.