Struct PacingOffsets 

pub struct PacingOffsets { /* private fields */ }

The pacing predicate’s operands, as displacements: where the Heap hangs off a RuntimeContext, and where its two pacing words sit inside it.

Not a constructor argument, anywhere

Self::new takes nothing and reads all three off Heap’s own Heap::BYTES_SINCE_COLLECT_OFFSET and Heap::COLLECT_THRESHOLD_OFFSET, so a site that described a table to probe — or a block to claim — without carrying the pacing predicate’s operands has no spelling. That is the one thing InlineInternSite exists to withhold, and skipping the predicate is the one thing ADR-040’s Safepoint exists to make unwritable.

One value, because the compare has one authority

Heap::collection_is_due is the one statement of the predicate and generated code is the one reader that cannot call it: it loads these two words and compares them. The direction (>=, so that a zero threshold is always due) and the operand order are therefore transcribed from a rule the compiler cannot check, and every transcription is a fresh chance to write it backwards. Both InlineInternSite and InlineClaimSite carry this value rather than three fields each, so the backend’s emit_pacing_test — the one place the transcription lives — cannot pair one site’s since with another’s threshold.

Implementations

impl PacingOffsets

pub const fn heap_offset(self) -> usize

Where the Heap pointer sits in a RuntimeContext. The first load of the sequence, and the base the two pacing loads are relative to.

pub const fn bytes_since_collect_offset(self) -> usize

Where Heap::bytes_since_collect sits within a Heap.

The predicate’s left operand — and, for the claim sequence, the word it loads a second time and stores back, once, at the end: the pacing charge, which is not the predicate.

pub const fn collect_threshold_offset(self) -> usize

Where Heap::collect_threshold sits within a Heap.

Generated code loads this word and the one above and takes the branch since >= threshold to its cold path. That is Heap::collection_is_due transcribed, and that function’s doc is where the obligation is written down.

Trait Implementations

impl Clone for PacingOffsets

fn clone(&self) -> PacingOffsets

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for PacingOffsets

impl Debug for PacingOffsets

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

Formats the value using the given formatter.

impl Eq for PacingOffsets

impl PartialEq for PacingOffsets

fn eq(&self, other: &PacingOffsets) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for PacingOffsets