Struct WatchBpfMap 

pub struct WatchBpfMap { /* private fields */ }

Host-side, observer-effect-free read of a NAMED scheduler BPF-map field, surfaced as an assertable run-level metric.

The free-running host monitor resolves the field once (lazily, after the scheduler attaches and its maps appear) via BTF, then reads it each monitor tick WITHOUT freezing the guest — turning “the scheduler computed X” into an assertable metric. Read via crate::vmm::result::VmResult::run_metric under the key <scheduler-obj>_<label> (scalar, scalar-counter, or per-CPU-counter) or <scheduler-obj>_<label>_{avg,max} (per-CPU gauge), e.g. scx_lavd_avg_lat_cri, scx_lavd_lat_headroom_avg. <scheduler-obj> is libbpf’s object name for the active scheduler, which can differ from its source / ops name (e.g. scx-ktstr’s object is bpf_bpf). Each target’s label must be unique within a test: duplicate labels resolve to one metric key and are rejected at VM build time.

Construct with WatchBpfMap::new, which const-asserts the field formats at compile time. Direct struct-literal construction is rejected (fields are crate-private) so every constructed value passes the gate.

Implementations

impl WatchBpfMap

pub const fn new( map_name_suffix: &'static str, field: &'static str, agg: BpfMapAgg, label: &'static str, ) -> Self

Const constructor for use in static/const context.

map_name_suffix matches a loaded BPF map by ends_with (kernel map names truncate to 15 bytes). Unlike BpfMapWrite::new it does NOT require a leading .: a watched map may be a section map (.bss) OR a named map (cpu_ctx_stor). field is a dot-path into the map’s value type (sys_stat.avg_lat_cri, or a bare lat_headroom). label is the metric-key leaf appended to the scheduler-obj prefix.

Panics

Panics at compile time when any of map_name_suffix / field / label is empty or carries whitespace, a path separator (/, \), or a non-printable / control / high-bit byte. Additionally field may not have a leading/trailing . or a doubled .. (an empty path segment the resolver could never match), and label may not contain . at all (it is a single metric-key leaf, not a path).

pub const fn map_name_suffix(&self) -> &'static str

The validated map-name suffix to match (via ends_with) against loaded BPF maps (e.g. ".bss", "cpu_ctx_stor").

pub const fn field(&self) -> &'static str

The dot-path into the map’s value type (e.g. "sys_stat.avg_lat_cri" or "lat_headroom").

pub const fn agg(&self) -> BpfMapAgg

How the per-tick reads aggregate into run-level metric key(s).

pub const fn label(&self) -> &'static str

The metric-key leaf appended to the scheduler-obj prefix.

Trait Implementations

impl Clone for WatchBpfMap

fn clone(&self) -> WatchBpfMap

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for WatchBpfMap

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

Formats the value using the given formatter.

impl Hash for WatchBpfMap

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

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 WatchBpfMap

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for WatchBpfMap

impl Eq for WatchBpfMap

impl StructuralPartialEq for WatchBpfMap