Struct Context 

pub struct Context<M: MetricsState = DfirMetrics> { /* private fields */ }

A lightweight context for inline codegen that avoids the overhead of the full scheduled graph (no tokio channels, no scheduler queues, no loop machinery).

Exposes methods that operator-generated code calls on both df (for prologues: request_task) and context (for iterators: current_tick, schedule_subgraph, etc.).

Metrics typestate

The M type parameter is a MetricsState typestate which statically records whether this context tracks runtime metrics:

• Context<DfirMetrics> (the default) is created via Context::new_with_metrics and holds a shared Rc<DfirMetrics> handle, accessible via Context::metrics.
• Context<()> is created via Context::new and holds no metrics state whatsoever. The metrics() accessor does not exist on it, so it is a compile error to try to read metrics from a context which never tracked them.

Implementations

impl Context<()>

pub fn new() -> Self

Create a new inline context with a fresh wake state and no metrics tracking.

The returned Context<()> statically contains no metrics state. Use Context::new_with_metrics to create a Context<DfirMetrics> which tracks metrics.

impl Context<DfirMetrics>

pub fn new_with_metrics(metrics: DfirMetrics) -> Self

Create a new inline context with a fresh wake state and the given (pre-populated) metrics.

pub fn metrics(&self) -> &Rc<DfirMetrics>

Returns a reference to the runtime metrics.

impl<M: MetricsState> Context<M>

pub fn request_task<Fut>(&mut self, future: Fut)

where Fut: Future<Output = ()> + Send + 'static,

Available on crate feature tokio only.

Buffers an async task to be spawned later by Dfir::spawn_tasks.

Tasks are deferred because write_prologue runs during graph construction, which may occur before a tokio runtime is entered. Buffered tasks are drained and spawned via [tokio::spawn] at the start of Dfir::run_tick. Tasks requested after that point remain buffered until the next call to Dfir::run_tick.

The future must be Send so that the Context remains Send and so the task can be spawned onto any tokio runtime.

pub fn current_tick(&self) -> TickInstant

Gets the current tick count.

pub fn schedule_subgraph(&self, is_external: bool)

Signals that external data has arrived and a new tick should be started.

pub fn waker(&self) -> Waker

Returns a waker that signals external data has arrived.

Trait Implementations

impl Default for Context<()>

fn default() -> Self

Returns the “default value” for a type.