Struct Shared 

pub(crate) struct Shared {
    pub(crate) inner: Arc<Inner>,
    pub(crate) thread: Mutex<Option<JoinHandle<()>>>,
}

Per-AudioCapture shared handle: the lock-free Inner state plus the lifecycle-locked join handle for the capture thread.

Fields

inner: Arc<Inner>

thread: Mutex<Option<JoinHandle<()>>>

Lifecycle lock: serializes take/join/reassign of the capture thread’s handle.