| .. _queues: |
| |
| Queues |
| ###### |
| |
| A Queue in Zephyr is a kernel object that implements a traditional queue, allowing |
| threads and ISRs to add and remove data items of any size. The queue is similar |
| to a FIFO and serves as the underlying implementation for both :ref:`k_fifo |
| <fifos_v2>` and :ref:`k_lifo <lifos_v2>`. For more information on usage see |
| :ref:`k_fifo <fifos_v2>`. |
| |
| Cancelling a Wait |
| ***************** |
| |
| A thread that is blocked waiting to retrieve an item from a queue can be released |
| without an item by calling :c:func:`k_queue_cancel_wait` from another thread or |
| an ISR. The first thread pending on the queue returns from its |
| :c:func:`k_queue_get` call with a ``NULL`` value, exactly as if its timeout had |
| expired. If the queue is instead being waited on through :c:func:`k_poll`, that |
| call returns ``-EINTR`` with the poll event in the cancelled state. |
| |
| This mechanism is also available to the queue-based primitives through |
| :c:macro:`k_fifo_cancel_wait` and :c:macro:`k_lifo_cancel_wait`. |
| |
| Configuration Options |
| ********************* |
| |
| Related configuration options: |
| |
| * None |
| |
| API Reference |
| ************* |
| |
| .. doxygengroup:: queue_apis |
