Trait Source 

pub trait Source<OutP, const OUT: usize>
where
    OutP: Payload,
{
    type Error;

    // Required methods
    fn open(&mut self) -> Result<(), Self::Error>;
    fn try_produce(&mut self) -> Option<(usize, Message<OutP>)>;
    fn ingress_occupancy(&self) -> EdgeOccupancy;
    fn peek_ingress_creation_tick(&self, item_index: usize) -> Option<u64>;
    fn output_acceptance(&self) -> [PlacementAcceptance; OUT];
    fn capabilities(&self) -> NodeCapabilities;
    fn policy(&self) -> NodePolicy;
    fn ingress_policy(&self) -> EdgePolicy;

    // Provided method
    fn into_sourcenode(self, policy: NodePolicy) -> SourceNode<Self, OutP, OUT>
       where Self: Sized { ... }
}

Uniform contract for source implementations (0 inputs / ≥1 outputs).

Source types produce messages for downstream nodes and report ingress pressure (items/bytes before the source, e.g., device FIFO depth), allowing schedulers to decide when to poll the source.

Type Parameters

• OutP — Payload type for produced messages.
• OUT — Number of output ports on the source node.

Required Associated Types

type Error

Source-specific error type for open().

Required Methods

fn open(&mut self) -> Result<(), Self::Error>

Prepare the source for production (e.g., open device, init driver).

Called from Node::initialize. Must be idempotent or fail safely if called multiple times by a higher layer.

fn try_produce(&mut self) -> Option<(usize, Message<OutP>)>

Attempt to produce exactly one (port, message) pair.

Return None if there is nothing to produce right now.

Contract

• Must be non-blocking.
• The returned port must be < OUT.

fn ingress_occupancy(&self) -> EdgeOccupancy

Report ingress pressure (items/bytes before the source).

Implementations should be non-blocking and may read hardware counters, driver FIFOs, ring buffer lengths, or cached snapshots.

policy is provided so implementations can compute a consistent EdgeOccupancy.watermark using the same thresholds as real edges.

fn peek_ingress_creation_tick(&self, item_index: usize) -> Option<u64>

Return the creation tick of the index’th ingress item (0-based) without dequeuing it. Implementations must be non-blocking and non-destructive. Return None if metadata is unavailable or index is out-of-range.

fn output_acceptance(&self) -> [PlacementAcceptance; OUT]

Return output placement acceptances for zero-copy compatibility.

fn capabilities(&self) -> NodeCapabilities

Describe source capabilities (device streams, degrade tiers, etc.).

fn policy(&self) -> NodePolicy

Provide the node policy bundle (batching/budget/deadlines).

fn ingress_policy(&self) -> EdgePolicy

Provude the ingress edge policy for this source node.

Provided Methods

fn into_sourcenode(self, policy: NodePolicy) -> SourceNode<Self, OutP, OUT>

where Self: Sized,

Convenience: wrap this source in a SourceNode with the provided policy.

This is a zero-overhead helper so all Source implementations can be lifted into a node uniformly without each impl writing a custom helper.

Implementors

impl<Clock, const BACKLOG_CAP: usize> Source<Tensor<u32, TEST_TENSOR_ELEMENT_COUNT, 2>, 1> for TestCounterSourceTensor<Clock, BACKLOG_CAP>

where Clock: PlatformClock,

type Error = Infallible