Struct PlayQueue 

pub(crate) struct PlayQueue {
    pub(crate) buf: Mutex<VecDeque<u8>>,
    pub(crate) max_bytes: AtomicUsize,
    pub(crate) frame_bytes: AtomicUsize,
}

Bounded, drop-oldest byte queue for the mic-PCM handoff into the virtual “input” sink — the whole of the playback path’s buffering in a single bound.

push runs on the Python side with the GIL released; drain_upto runs on the playback thread. Overflow discards the OLDEST bytes, keeping the newest window (mic audio is drift-tolerant and stale samples are worthless).

Fields

buf: Mutex<VecDeque<u8>>

max_bytes: AtomicUsize

Bounds (re)published by start(); atomics so a restart can reconfigure the Arc-shared queue in place without swapping it. frame_bytes >= 1 (set at new()).

frame_bytes: AtomicUsize

Implementations

impl PlayQueue

pub(crate) fn new() -> Self

pub(crate) fn configure(&self, max_bytes: usize, frame_bytes: usize)

Apply this run’s byte bound and frame alignment, and drop any stale audio left from a prior run. frame_bytes is floored to 1; the bound is floored to a whole-frame multiple (min one frame) so overflow drops can never split a sample frame.

pub(crate) fn clear(&self)

Drop everything queued, keeping the bounds. Used when a run starts and whenever the playback session is reopened, since audio buffered across an outage is stale.

pub(crate) fn push(&self, data: &[u8])

Append client PCM, dropping the OLDEST whole frames once the queue passes the byte bound so the newest audio is always retained. Drops stay frame-aligned: trimming mid-frame would phase-shift every later drain into interleaved garbage.

pub(crate) fn drain_upto(&self, n: usize, out: &mut Vec<u8>)

Drain up to n bytes into out, clamped to what is queued and floored to a whole frame, since a PA write must be a multiple of the sample-spec frame size.