BUF_RING(9)            FreeBSD Kernel Developer's Manual           BUF_RING(9)

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.

FreeBSD 13.1-RELEASE-p6       September 27, 2012       FreeBSD 13.1-RELEASE-p6