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.

Debian                                         September 27, 2012                                    BUF_RING(9)