Enum WaitStrategy 

pub enum WaitStrategy {
    BusySpin,
    YieldSpin,
    BackoffSpin,
    Adaptive {
        spin_iters: u32,
        yield_iters: u32,
    },
    MonitorWaitFallback,
}

Strategy for blocking recv().

All variants are no_std compatible — no OS thread primitives required.

Strategy	Latency	CPU usage	Best for
BusySpin	Lowest (~0 ns wakeup)	100% core	Dedicated, pinned cores
YieldSpin	Low (~30 ns on x86)	High	Shared cores, SMT
BackoffSpin	Medium (exponential)	Decreasing	Background consumers
Adaptive	Auto-scaling	Varies	General purpose
MonitorWaitFallback	Near-zero (~30 ns on Intel)	Near-zero	Intel Alder Lake+

Variants

BusySpin

Pure busy-spin with no PAUSE instruction. Minimum wakeup latency but consumes 100% of one CPU core. Use on dedicated, pinned cores.

YieldSpin

Spin with core::hint::spin_loop() (PAUSE on x86, YIELD on ARM) between iterations. Yields the CPU pipeline to the SMT sibling and reduces power consumption vs BusySpin.

BackoffSpin

Exponential backoff spin. Starts with bare spins, then escalates to PAUSE-based spins with increasing delays. Good for consumers that may be idle for extended periods without burning a full core.

Adaptive

Three-phase escalation: bare spin for spin_iters iterations, then PAUSE-spin for yield_iters, then repeated PAUSE bursts.

Fields

spin_iters: u32

Number of bare-spin iterations before escalating to PAUSE.

yield_iters: u32

Number of PAUSE iterations before entering deep backoff.

MonitorWaitFallback

TPAUSE on Intel (Tremont+, Alder Lake+) or WFE on ARM.

On x86_64 with WAITPKG support: TPAUSE puts the core into an optimized C0.1 state for a bounded interval, giving near-zero power consumption with ~30 ns wakeup latency. It monitors no address, which is what makes it safe to offer — a variant taking an address to watch cannot be constructed safely.

Falls back to YieldSpin on x86 CPUs without WAITPKG support. On aarch64: uses SEVL+WFE (identical to YieldSpin). On x86_64 with WAITPKG: TPAUSE (timed wait in C0.1 state) for low-power waiting. On aarch64: SEVL+WFE. On other x86: PAUSE.

Trait Implementations

impl Clone for WaitStrategy

fn clone(&self) -> WaitStrategy

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for WaitStrategy

impl Debug for WaitStrategy

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

Formats the value using the given formatter.

impl Default for WaitStrategy

fn default() -> Self

Returns the “default value” for a type.

impl Eq for WaitStrategy

impl PartialEq for WaitStrategy

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for WaitStrategy