Struct BoundedQueue 

pub struct BoundedQueue<T> {
    pub total_enqueued: AtomicU64,
    pub total_dequeued: AtomicU64,
    pub total_dropped: AtomicU64,
    /* private fields */
}

Thread-safe bounded FIFO queue with condvar-based blocking and backpressure.

The internal state is stored behind a Mutex<VecDeque<(T, Instant)>>. Two Condvars (not_empty and not_full) allow producers and consumers to park efficiently instead of busy-waiting.

Fields

total_enqueued: AtomicU64

Cumulative items enqueued without being dropped.

total_dequeued: AtomicU64

Cumulative items dequeued.

total_dropped: AtomicU64

Cumulative items rejected due to a full queue.

Implementations

impl<T: Send> BoundedQueue<T>

pub fn new(capacity: usize) -> Self

Create a new bounded queue with the given maximum capacity.

pub fn try_push(&self, item: T) -> bool

Attempt to push item without blocking.

Returns true on success, false if the queue is already at capacity (backpressure: the caller should propagate a 503 to the client).

pub fn push_timeout(&self, item: T, timeout: Duration) -> bool

Push item, blocking up to timeout for a free slot.

Returns true if the item was enqueued before the timeout elapsed, false otherwise.

pub fn pop(&self) -> Option<T>

Remove and return the oldest item without blocking.

Returns None if the queue is empty.

pub fn pop_timeout(&self, timeout: Duration) -> Option<T>

Remove and return the oldest item, blocking up to timeout for one to become available.

Returns None on timeout.

pub fn len(&self) -> usize

Current number of items in the queue.

pub fn is_empty(&self) -> bool

true if the queue contains no items.

pub fn is_full(&self) -> bool

true if the queue is at capacity.

pub fn capacity(&self) -> usize

Maximum number of items the queue can hold.

pub fn utilization(&self) -> f32

Current fill level as a fraction in [0.0, 1.0].

pub fn stats(&self) -> QueueStats

Take a snapshot of queue statistics.

pub fn drain(&self) -> Vec<T>

Drain all items from the queue and return them in FIFO order.