cma_lib_queue_try_requeue

Inserts an element at the front of an atomic queue.

Syntax

status = cma_lib_queue_try_requeue (queue, element)

Argument Data Type Access

status Boolean cma_t_boolean write queue opaque cma_lib_t_queue read element opaque cma_t_address read

C Binding

cma_t_boolean
cma_lib_queue_requeue (
cma_lib_t_queue *queue,
cma_lib_t_address element);

Arguments

status: Boolean value that specifies whether the element was requeued.
queue: Handle of the queue to which the element is inserted.
element: Address of the queue element inserted.

Description

This routine inserts an element at the front of a queue. If the queue is full, the calling thread does not wait until an element is removed from the queue. Instead, the routine returns with the status cma_c_false. If the queue is not full, the element is added to the front of the queue and the routine returns with the status cma_c_true.

Call cma_lib_queue_requeue if you want to insert an element into a queue but cause the calling thread to block if the queue is full.

This routine allows you to replace an element that was erroneously removed from a queue. For example, a queue might hold information of various types. In that case a thread can remove the oldest (first) element of the queue, check its type, and requeue the element if it is not the desired type (rather than enqueuing it, which would place the element at the end of the queue).

Exceptions

cma_e_existence
cma_e_use_error