holoscan::LockFreeQueue

template <typename T>
class LockFreeQueue

Lock-free queue implementation using MoodyCamel’s ConcurrentQueue.

This is a high-performance lock-free MPMC (Multiple Producer Multiple Consumer) queue that uses per-producer sub-queues for optimal concurrency.

Thread Safety:

• Fully thread-safe for concurrent enqueue and dequeue operations
• No locks or blocking operations (wait-free for producers, lock-free for consumers)
• Safe to call from multiple threads simultaneously

Ordering Guarantees:

• Maintains FIFO order per-producer (items from the same thread stay ordered)
• Does NOT guarantee global FIFO order across multiple producers
• Items from different threads may be interleaved in any order

Performance Characteristics:

• Excellent throughput with minimal contention
• size_approx() returns an estimate that may be stale immediately after return

#include <holoscan/data_logger_queue.hpp>

Template parameters

Inherits from: holoscan::DataLoggerQueue< T > (public)

Constructors

LockFreeQueue

holoscan::LockFreeQueue<T>::LockFreeQueue(
    size_t capacity
)

Construct a lock-free queue with the specified capacity.

Parameters

Methods

try_enqueue

bool holoscan::LockFreeQueue<T>::try_enqueue(
    T &&item
) override

Attempt to enqueue an item (thread-safe).

Returns: true if successfully enqueued, false if queue is full

Parameters

try_dequeue

bool holoscan::LockFreeQueue<T>::try_dequeue(
    T &item
) override

Attempt to dequeue an item (thread-safe).

Returns: true if an item was dequeued, false if queue is empty

Parameters

size_approx

size_t holoscan::LockFreeQueue<T>::size_approx() const override

Get size of the queue (thread-safe).

Note: The accuracy of this value depends on the implementation:

• LockFreeQueue: Returns an approximation that may be stale by the time it’s returned
• OrderedQueue: Returns the exact size at the moment the mutex was acquired

Returns: Number of items in the queue (approximation or exact, depending on implementation)

Member variables