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.