pokey909/ringbuf

Atomic ring buffer (MPSC)

Atomic ring buffer

Atomic multi-producer single-consumer ring buffer with passive tail update and contiguous range operations. This implementation is written in C11 and distributed under the 2-clause BSD license.

API

• ringbuf_t *ringbuf_create(size_t length)

  • Construct a new ring buffer of a given length.

• void ringbuf_destroy(ringbuf_t *rbuf)

  • Destroy the ring buffer object.

• int ringbuf_register(ringbuf_t *rbuf)

  • Register the current thread as a producer. Each producer must register.

• ssize_t ringbuf_acquire(ringbuf_t *rbuf, size_t len)

  • Request a space of a given length in the ring buffer. Returns the offset at which the space is available or -1 on failure. Once the data is ready (typically, when writing to the ring buffer is complete), the ringbuf_produce function must be called to indicate that.

• void ringbuf_produce(ringbuf_t *rbuf)

  • Indicate the acquired range in the buffer is produced and is ready to be consumed.

• size_t ringbuf_consume(ringbuf_t *rbuf, size_t *offset)

  • Get a contiguous range which is ready to be consumed. Returns zero if there is no data available for consumption. Once the data is consumed (typically, when reading from the ring buffer is complete), the ringbuf_release function must be called to indicate that.

• void ringbuf_release(ringbuf_t *rbuf, size_t nbytes)

  • Indicate that the consumed range can now be released and may now be reused by the producers.

Example

Producers:

if (ringbuf_register(r) == -1)
	err(EXIT_FAILURE, "ringbuf_register")

...

if ((off = ringbuf_acquire(r, len)) != -1) {
	memcpy(&buf[off], payload, len);
	ringbuf_produce(r);
}

Consumer:

if ((len = ringbuf_consume(r, &off)) != 0) {
	process(&buf[off], len);
	ringbuf_release(r, len);
}