NAME¶
buf_ring,
buf_ring_alloc,
buf_ring_free,
buf_ring_enqueue,
buf_ring_dequeue_mc,
buf_ring_dequeue_sc,
buf_ring_count,
buf_ring_empty,
buf_ring_full,
buf_ring_peek, —
multi-producer, {single, multi}-consumer lock-less
ring buffer
SYNOPSIS¶
#include
<sys/param.h>
#include
<sys/buf_ring.h>
struct buf_ring *
buf_ring_alloc(
int
count,
struct
malloc_type *type,
int flags,
struct mtx
*sc_lock);
void
buf_ring_free(
struct
buf_ring *br,
struct malloc_type
*type);
int
buf_ring_enqueue(
struct
buf_ring *br,
void *buf);
void *
buf_ring_dequeue_mc(
struct
buf_ring *br);
void *
buf_ring_dequeue_sc(
struct
buf_ring *br);
int
buf_ring_count(
struct
buf_ring *br);
int
buf_ring_empty(
struct
buf_ring *br);
int
buf_ring_full(
struct
buf_ring *br);
void *
buf_ring_peek(
struct
buf_ring *br);
DESCRIPTION¶
The
buf_ring functions provide a lock-less
multi-producer and lock-less multi-consumer as well as single-consumer ring
buffer.
The
buf_ring_alloc() function is used to
allocate a buf_ring ring buffer with
count
slots using malloc_type
type and memory flags
flags. The single consumer interface is
protected by
sc_lock.
The
buf_ring_free() function is used to free
a buf_ring. The user is responsible for freeing any enqueued items.
The
buf_ring_enqueue() function is used to
enqueue a buffer to a buf_ring.
The
buf_ring_dequeue_mc() function is a
multi-consumer safe way of dequeueing elements from a buf_ring.
The
buf_ring_dequeue_sc() function is a
single-consumer interface to dequeue elements - requiring the user to
serialize accesses with a lock.
The
buf_ring_count() function returns the
number of elements in a buf_ring.
The
buf_ring_empty() function returns
TRUE if the buf_ring is empty,
FALSE otherwise.
The
buf_ring_full() function returns
TRUE if no more items can be enqueued,
FALSE otherwise.
The
buf_ring_peek() function returns a
pointer to the last element in the buf_ring if the buf_ring is not empty,
NULL otherwise.
RETURN VALUES¶
The
buf_ring_enqueue() function return
ENOBUFS if there are no available slots in
the buf_ring.
HISTORY¶
These functions were introduced in
FreeBSD 8.0.
