Struct DeliveryRing 

pub(crate) struct DeliveryRing {
    pub(crate) q: Mutex<Option<VecDeque<(Vec<u8>, u64)>>>,
    pub(crate) cv: Condvar,
    pub(crate) dropped: AtomicU64,
    pub(crate) capacity: usize,
}

Bounded, drop-oldest hand-off from the capture thread to the Python delivery thread, so a slow or GIL-blocked callback can never stall the PulseAudio pump.

The capture thread pushes encoded (frame, pts) pairs; the delivery thread blocks in pop. Stale audio is worthless, so overflow past capacity (a few frames of slack) discards the OLDEST frame and bumps dropped. close empties the queue to None and wakes the consumer so it exits.

Fields

q: Mutex<Option<VecDeque<(Vec<u8>, u64)>>>

cv: Condvar

dropped: AtomicU64

capacity: usize

Implementations

impl DeliveryRing

pub(crate) fn new(capacity: usize) -> Self

Create an open ring pre-sized to capacity frames.

pub(crate) fn push(&self, data: Vec<u8>, pts: u64)

Enqueue one encoded frame, dropping the oldest (and bumping dropped) if the ring is at capacity, then wake the consumer. A no-op once closed.

pub(crate) fn pop(&self) -> Option<(Vec<u8>, u64)>

Block until a frame is available and return it, or return None once the ring is closed and drained — the delivery thread’s loop condition.

pub(crate) fn close(&self)

Close the ring: drop any queued frames and wake every waiter so pop returns None. Called during capture teardown to join the delivery thread.