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, buf_ring_drops – 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, 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);
uint64_t
buf_ring_drops(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 lock. Supported lock types are mutex(9), rwlock(9), and rmlock(9).
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.
The buf_ring_drops() functions returns how many times the buf_ring_enqueue() was not able to queue an element due to no available slots.
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.