Struct ShapeControl 

pub(crate) struct ShapeControl {
    profile: Mutex<Option<ShapeProfile>>,
    generation: AtomicU64,
    enabled: Arc<AtomicBool>,
}

This proxy’s shaping profile, and whether it paces.

One per proxy, watched by every session it accepts. The generation is what lets a session notice a change without comparing profiles: a session caches the generation its scheduler was built at, and a mismatch is the signal to look.

Fields

profile: Mutex<Option<ShapeProfile>>

The profile a live request installed, or None while the proxy’s own template is what every session shapes with.

generation: AtomicU64

Bumped, under the lock above, every time the profile is replaced.

enabled: Arc<AtomicBool>

Whether the schedulers built from this pace at all. Behind its own Arc because every scheduler holds a clone of it.

Implementations

impl ShapeControl

fn new() -> Self

A control with no profile of its own and pacing switched on, which is the state that leaves a proxy behaving exactly as its configuration says.

fn set(&self, profile: ShapeProfile)

Replace the profile and move the generation on.

pub(crate) fn generation(&self) -> u64

The current generation, without cloning a profile.

What a session checks per stream; the clone below is paid only when this has moved.

pub(crate) fn snapshot(&self) -> (u64, Option<ShapeProfile>)

The generation and the profile it names, read together.

Read under the lock the setter writes under, so the pair cannot straddle two calls to Self::set — a session that cached a generation from one profile and a profile from another would stop noticing the newer of the two.

pub(crate) fn switch(&self) -> Arc<AtomicBool>

The switch every scheduler built from this reads.

fn set_enabled(&self, on: bool)

Turn pacing on or off for every session at once.