Written by: Kip Macy <kmacy@FreeBSD.org>
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.Dd January 30, 2012 .Dt BUF_RING 9 .Os .Sh NAME .Nm buf_ring , .Nm buf_ring_alloc , .Nm buf_ring_free , .Nm buf_ring_enqueue , .Nm buf_ring_enqueue_bytes , .Nm buf_ring_dequeue_mc , .Nm buf_ring_dequeue_sc , .Nm buf_ring_count , .Nm buf_ring_empty , .Nm buf_ring_full , .Nm buf_ring_peek , .Nd multi-producer, {single, multi}-consumer lock-less ring buffer .Sh SYNOPSIS n sys/param.h n sys/buf_ring.h .Ft struct buf_ring * .Fn buf_ring_alloc "int count" "struct malloc_type *type" "int flags" "struct mtx *sc_lock" .Ft void .Fn buf_ring_free "struct buf_ring *br" "struct malloc_type *type" .Ft int .Fn buf_ring_enqueue "struct buf_ring *br" "void *buf" .Ft int .Fn buf_ring_enqueue_bytes "struct buf_ring *br" "void *buf" "int bytes" .Ft void * .Fn buf_ring_dequeue_mc "struct buf_ring *br" .Ft void * .Fn buf_ring_dequeue_sc "struct buf_ring *br" .Ft int .Fn buf_ring_count "struct buf_ring *br" .Ft int .Fn buf_ring_empty "struct buf_ring *br" .Ft int .Fn buf_ring_full "struct buf_ring *br" .Ft void * .Fn buf_ring_peek "struct buf_ring *br" .Sh DESCRIPTION The .Nm functions provide a lock-less multi-producer and lock-less multi-consumer as well as single-consumer ring buffer.
p The .Fn buf_ring_alloc function is used to allocate a buf_ring ring buffer with .Fa count slots using malloc_type .Fa type and memory flags .Fa flags . The single consumer interface is protected by .Fa sc_lock .
p The .Fn buf_ring_free function is used to free a buf_ring. The user is responsible for freeing any enqueued items.
p The .Fn buf_ring_enqueue function is used to enqueue a buffer to a buf_ring.
p The .Fn buf_ring_enqueue_bytes function is used to enqueue a buffer to a buf_ring and increment the number of bytes enqueued by .Fa bytes .
p The .Fn buf_ring_dequeue_mc function is a multi-consumer safe way of dequeueing elements from a buf_ring.
p The .Fn buf_ring_dequeue_sc function is a single-consumer interface to dequeue elements - requiring the user to serialize accesses with a lock.
p The .Fn buf_ring_count function returns the number of elements in a buf_ring.
p The .Fn buf_ring_empty function returns .Dv TRUE if the buf_ring is empty, .Dv FALSE otherwise.
p The .Fn buf_ring_full function returns .Dv TRUE if no more items can be enqueued, .Dv FALSE otherwise.
p The .Fn buf_ring_peek function returns a pointer to the last element in the buf_ring if the buf_ring is not empty, .Dv NULL otherwise. .Sh RETURN VALUES The .Fn buf_ring_enqueue and .Fn buf_ring_enqueue_bytes functions return .Er ENOBUFS if there are no available slots in the buf_ring. .Sh HISTORY These functions were introduced in .Fx 8.0 .