NAME¶
ck_ring_dequeue_spsc
—
dequeue pointer from bounded FIFO
LIBRARY¶
Concurrency Kit (libck, -lck)
SYNOPSIS¶
#include
<ck_ring.h>
bool
ck_ring_dequeue_spsc
(
ck_ring_t
*ring,
ck_ring_buffer_t
*buffer,
void
*result);
DESCRIPTION¶
The
ck_ring_dequeue_spsc
(
3)
function dequeues a pointer from the bounded buffer pointed to by
ring in FIFO fashion. The pointer is stored
in the pointer pointed to by
result. The
buffer pointed to by
buffer must be unique to
ring and point to an array of
ck_ring_buffer_t of sufficient length (according to the power-of-2 elements in
the buffer). The decoupling of the ring from the buffer serves to address
use-cases involving multiple address spaces and DMA, among others. If you are
on non-POSIX platforms or wish for strict compliance with C, then it is
recommended to pass a pointer of type void ** for
result. This function is safe to call without
locking for one concurrent invocation of
ck_ring_dequeue_spsc
(
3)
and up to one concurrent
ck_ring_enqueue_spsc
(
3)
invocation. This function provides wait-free progress guarantees.
EXAMPLE¶
#include <ck_ring.h>
/* This ring was previously initialized with ck_ring_init. */
ck_ring_t ring;
/* The ring was initialized for 1023 elements. */
ck_ring_buffer_t buffer[1024];
void
dequeue(void)
{
void *result;
/* Dequeue from ring until it is empty. */
while (ck_ring_dequeue_spsc(&ring, &buffer, &result) == true) {
/*
* Results contains the oldest pointer in ring
* since the dequeue operation returned true.
*/
operation(result);
}
/* An empty ring was encountered, leave. */
return;
}
RETURN VALUES¶
The function returns true if the buffer was non-empty. The result of the dequeue
operation is stored in the value pointed to by
result. The function will return false if the
buffer was empty and the value in
result will
be undefined.
SEE ALSO¶
ck_ring_init(3),
ck_ring_trydequeue_spmc(3),
ck_ring_enqueue_spmc(3),
ck_ring_enqueue_spmc_size(3),
ck_ring_dequeue_spmc(3),
ck_ring_enqueue_spsc(3),
ck_ring_enqueue_spsc_size(3),
ck_ring_capacity(3),
ck_ring_size(3)
Additional information available at
http://concurrencykit.org/