Method drain_into

nodedb-bridge/src/buffer.rs:271–294

Drain up to `max` items into the provided vector. Returns the count drained. More efficient than calling `try_pop` in a loop because it batches the atomic tail load.

(&mut self, buf: &mut Vec<T>, max: usize)

    /// More efficient than calling `try_pop` in a loop because it batches the
    /// atomic tail load.
    pub fn drain_into(&mut self, buf: &mut Vec<T>, max: usize) -> usize {
        let head = self.shared.head.value.load(Ordering::Relaxed);
        self.cached_tail = self.shared.tail.value.load(Ordering::Acquire);

        let available = self.cached_tail.wrapping_sub(head) as usize;
        let count = available.min(max);

        for i in 0..count {
            let idx = ((head.wrapping_add(i as u64)) as usize) & self.shared.mask;
            // SAFETY: same as try_pop — we've verified these slots are occupied.
            let value = unsafe { (*self.shared.slots[idx].get()).take() };
            buf.push(value.expect("BUG: slot was None during drain"));
        }

        if count > 0 {
            self.shared
                .head
                .value
                .store(head.wrapping_add(count as u64), Ordering::Release);
            self.shared.metrics.record_pops(count as u64);
        }

        count
    }

    /// Returns the number of items currently in the queue.
    pub fn len(&self) -> usize {