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.Dd April 20, 2013
.Dt CK_RING_ENQUEUE_SPMC_SIZE 3
.Sh NAME
.Nm ck_ring_enqueue_spmc_size
.Nd enqueue pointer into bounded FIFO and return size of buffer
.Sh LIBRARY
Concurrency Kit (libck, \-lck)
.Sh 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"
.Sh 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.
.Sh EXAMPLE
.Bd -literal -offset indent
#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;
}
.Ed
.Sh 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 .
.Sh SEE ALSO
.Xr ck_ring_init 3 ,
.Xr ck_ring_dequeue_spmc 3 ,
.Xr ck_ring_trydequeue_spmc 3 ,
.Xr ck_ring_enqueue_spmc 3 ,
.Xr ck_ring_dequeue_spsc 3 ,
.Xr ck_ring_enqueue_spsc 3 ,
.Xr ck_ring_enqueue_spsc_size 3 ,
.Xr ck_ring_capacity 3 ,
.Xr ck_ring_size 3
.Pp
Additional information available at http://concurrencykit.org/
