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kernel: k_queue: extend k_queue API to append unique element

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k_queue has k_queue_append API which does not check if the element's
address already exists. This creates a problem if the same element
address is appended to queue. This forms circular list showing
unintended behaviour for the application using queue. The proposed
API k_queue_find_and_append takes care of checking if element exists
already before appending. This API is complimentary to k_queue_remove
which checks if the queue element is present before removing.

Signed-off-by: Dhananjay Gundapu Jayakrishnan <dhananjay.jayakrishnan@proglove.de>
This commit is contained in:
Dhananjay Gundapu Jayakrishnan 2018-08-22 12:33:00 +02:00 • committed by Anas Nashif
commit 24bfa40964
1 changed files with 28 additions and 0 deletions
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28
include/kernel.h
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@ -1986,6 +1986,34 @@ static inline bool k_queue_remove(struct k_queue *queue, void *data)
return sys_sflist_find_and_remove(&queue->data_q, (sys_sfnode_t *)data);
}
/**
* @brief Append an element to a queue only if it's not present already.
*
* This routine appends data item to @a queue. The first 32 bits of the
* data item are reserved for the kernel's use. Appending elements to k_queue
* relies on sys_slist_is_node_in_list which is not a constant time operation.
*
* @note Can be called by ISRs
*
* @param queue Address of the queue.
* @param data Address of the data item.
*
* @return true if data item was added, false if not
*/
static inline bool k_queue_unique_append(struct k_queue *queue, void *data)
{
sys_sfnode_t *test;
SYS_SFLIST_FOR_EACH_NODE(&queue->data_q, test) {
if (test == (sys_sfnode_t *) data) {
return false;
}
}
k_queue_append(queue, data);
return true;
}
/**
* @brief Query a queue to see if it has data available.
*