ck_ring_enqueue_spmc_size(3)
enqueue pointer into bounded FIFO and return size of buffer
LIBRARY
Concurrency Kit (libck, -lck)
SYNOPSIS
In ck_ring.h
Ft bool
Fn ck_ring_enqueue_spmc_size ck_ring_t *ring ck_ring_buffer_t *buffer void *entry unsigned int *length
DESCRIPTION
The
Fn ck_ring_enqueue_spmc 3
function enqueues the pointer
Fa entry
into the bounded buffer pointed to by
Fa ring
in FIFO fashion.
The buffer pointed to by
Fa buffer
must be unique to
Fa 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
Fa entry .
This function is safe to call without locking for UINT_MAX
concurrent invocations of
Fn ck_ring_dequeue_spmc 3
or
Fn ck_ring_trydequeue_spmc 3 .
This function provides wait-free progress
guarantees for one active invocation.
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
enqueue(void)
{
void *entry = some_object;
unsigned int length;
/* Attempt to enqueue pointer to some_object into buffer. */
if (ck_ring_enqueue_spmc_size(&ring, &buffer, &entry, &length) == false) {
/*
* The buffer was full and the enqueue operation
* has failed.
*/
return;
}
/*
* If entry was the 101st or greater pointer in the buffer,
* do something.
*/
if (length > 100) {
do_something;
}
return;
}
RETURN VALUES
The function returns true if the value of
Fa entry
was successfully enqueued into
Fa ring .
The function will return false if the value of
Fa entry
could not be enqueued which only occurs if
Fa ring
was full. The number of entries in the buffer
with respect to the point in time that
Fa entry
is enqueued is stored in the integer pointed to by
Fa length .