> For the complete documentation index, see [llms.txt](https://book.bsdcn.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://book.bsdcn.org/man/man9/buf_ring.9.md).

# buf\_ring.9

`buf_ring` — 多生产者、{单, 多}消费者无锁环形缓冲区

## 名称

`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`

## 概要

```c
#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)
```

## 描述

buf\_ring 函数提供无锁多生产者和无锁多消费者以及单消费者环形缓冲区。

`buf_ring_alloc` 函数用于分配具有 `count` 个槽位的 buf\_ring 环形缓冲区，使用 malloc\_type `type` 和内存标志 `flags`。单消费者接口由 `sc_lock` 保护。

`buf_ring_free` 函数用于释放 buf\_ring。用户负责释放任何已入队的项。

`buf_ring_enqueue` 函数用于将缓冲区入队到 buf\_ring。

`buf_ring_dequeue_mc` 函数是从 buf\_ring 出队元素的多消费者安全方式。

`buf_ring_dequeue_sc` 函数是出队元素的单消费者接口，要求用户使用锁串行化访问。

`buf_ring_count` 函数返回 buf\_ring 中的元素数量。

`buf_ring_empty` 函数在 buf\_ring 为空时返回 `TRUE`，否则返回 `FALSE`。

`buf_ring_full` 函数在不能再入队更多项时返回 `TRUE`，否则返回 `FALSE`。

`buf_ring_peek` 函数在 buf\_ring 不为空时返回指向 buf\_ring 中最后一个元素的指针，否则返回 `NULL`。

## 返回值

`buf_ring_enqueue` 函数在 buf\_ring 中没有可用槽位时返回 `ENOBUFS`。

## 历史

这些函数引入于 FreeBSD 8.0。


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