Enum SizeClass 

pub enum SizeClass {
    Mib512,
    Mib1024,
    Mib2048,
    Mib4096,
    Mib8192,
}

One of the five documented size classes.

Closed, so an off-table memory figure is not a value that exists — the Python client’s S2 runtime check (sizing.py:95 size_class_for) becomes S1 for every caller who has a SizeClass in hand. SizeClass::from_baseline_mib is the one boundary where a bare integer still has to be judged, which is where TRAP-10 lives.

The variants are named for their baseline because that is the number the caller writes into minimumMemoryInMiB; the peak is deliberately not in any name, since naming both would suggest a caller gets to pick them independently.

Variants

Mib512

Mib1024

Mib2048

Mib4096

Mib8192

Implementations

impl SizeClass

pub const DEFAULT: SizeClass = SizeClass::Mib2048

The platform’s own default, and ours.

Deliberately not the smallest class, and the reason is the CEILING: picking 512 gives the guest a hard 2 GiB total — provisioned from the start, fixed for the whole run, nothing resizes past it — and a real test suite breaches it. Guest swap is absent (SwapTotal: 0 kB), so there is no paging phase to absorb the mistake — pressure goes straight to the OOM killer. The default’s job is a ceiling that survives a real test suite, and 8 GiB does.

pub const ALL: [SizeClass; 5]

Every class, smallest first, in SIZE_CLASSES order.

pub fn from_baseline_mib(mib: u32) -> Result<SizeClass, Error>

The class minimumMemoryInMiB = mib selects (TRAP-10).

Rejects anything not in the table rather than snapping to a neighbour: an off-table request has two plausible readings that differ in both memory and rate, and we have measured neither. This is the boundary a figure from a CLI flag or a config file crosses.

pub fn from_request( cpus: Option<f64>, memory_mib: Option<u32>, ) -> Result<SizeClass, Error>

The smallest class whose baseline covers a resource request (BIND-14).

A harness is handed CPUs and memory as requests (Harbor’s cpus and memory_mb). The baseline is the covering figure because it is what is billed and always present; the peak above it is provisioned too, but choosing by peak would hand a 2-vCPU task the 0.5-vCPU class. None or zero on an axis is no requirement on it; with no requirement on either the answer is SizeClass::DEFAULT, not the smallest class, for the reason DEFAULT gives. A request no class covers is an invalid-argument refusal naming the largest class, and so is a CPU figure that is not a finite non-negative number.

pub fn row(self) -> &'static SizeRow

This class’s row of the documented table.

The one reader of SIZE_CLASSES for a known class, which is what keeps every accessor below reading data rather than deriving it.

pub fn baseline_mib(self) -> u32

The value to send as minimumMemoryInMiB. Billed per running second.

pub fn peak_mib(self) -> u32

What the guest reports as MemTotal: the provisioned ceiling, present from the start of the run.

Read from the table. Never baseline_mib() * 4 — see the module docs.

pub fn headroom_mib(self) -> u32

The static headroom above the baseline: peak minus baseline, both read from this class’s table row.

Fixed at provision time — the headroom is always present, never granted by a scaling event — and usage inside it is billed by consumption. Computed as a difference of two table values, never as baseline * 3: the 4x regularity is AWS’s, not ours, and a row that breaks it must be reported as written (TRAP-13, same discipline as SizeClass::peak_mib).

pub fn baseline_vcpu(self) -> f64

Billed per running second, alongside SizeClass::baseline_mib.

pub fn peak_vcpu(self) -> f64

The provisioned vCPU ceiling, present from the start. Read from the table.

pub fn baseline_gb(self) -> f64

The figure a GB-second rate multiplies. Always the baseline, never the peak (COST-5).

pub fn peak_gb(self) -> f64

The peak in GB, for a report that shows the caller what the guest will say.

Trait Implementations

impl Clone for SizeClass

fn clone(&self) -> SizeClass

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for SizeClass

impl Debug for SizeClass

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

Formats the value using the given formatter.

impl Display for SizeClass

One line naming both numbers, for an error message or a CLI.

Both numbers or neither: naming only the peak invites someone to budget for memory they will not be billed for, and naming only the baseline invites a memory-pressure test written against a ceiling four times lower than the one the guest enforces.

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

Formats the value using the given formatter.

impl Eq for SizeClass

impl Hash for SizeClass

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for SizeClass

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for SizeClass