Struct RingBuffer

pub struct RingBuffer { /* private fields */ }

An interface for using BPF ringbuffer maps.

Implementations

impl RingBuffer

pub fn with_capacity(min_capacity: u32) -> Result<Self>

Creates a new ring buffer with the given number of pages. The capacity of a BPF ring buffer has to be a power of 2 pages. The min value given is rounded up to this capacity; get_capacity will return the actual allocated capacity of the ring buffer.

Arguments

• min_capacity - The minimum capacity of the ringbuffer.

Example

use bpf_api::collections::RingBuffer;

for capacity in [ 1, 4095, 4096, 8191, 8192, 16535, 16536, 40000 ] {
    let ringbuffer = RingBuffer::with_capacity(capacity).expect("Failed to create ringbuffer");
    assert!(ringbuffer.get_capacity() >= capacity as usize);
}

let ringbuffer = RingBuffer::with_capacity(4096).expect("Failed to create ringbuffer");
assert_eq!(ringbuffer.get_capacity(), 4096);

pub fn get_capacity(&self) -> usize

Returns the capacity of the ring buffer.

pub fn len(&self) -> usize

Returns the amount of data available for reading.

Example

use bpf_api::collections::RingBuffer;

let ringbuffer = RingBuffer::with_capacity(4096).expect("Failed to create ringbuffer");
assert_eq!(ringbuffer.len(), 0);

pub fn is_empty(&self) -> bool

Returns whether the ring buffer is empty or not.

Example

use bpf_api::collections::RingBuffer;

let ringbuffer = RingBuffer::with_capacity(4096).expect("Failed to create ringbuffer");
assert!(ringbuffer.is_empty());

pub fn get_buf(&self) -> &[u8]

Returns a slice that represents the readable range.

Example

use bpf_api::collections::RingBuffer;

let ringbuffer = RingBuffer::with_capacity(4096).expect("Failed to create ringbuffer");
assert_eq!(ringbuffer.get_buf().len(), 0);

pub fn consume(&mut self, size: usize)

Advances the read position by the given size. If the size is more than the number of bytes available, the read position is advanced to the write position, clearing the buffer.

Example

use bpf_api::collections::RingBuffer;

let mut ringbuffer = RingBuffer::with_capacity(4096).expect("Failed to create ringbuffer");
ringbuffer.consume(100);

pub fn get_identifier(&self) -> u32

Retrieve the BPF identifier for this map. This is the underlying file descriptor that’s used in eBPF programs.

Example

use bpf_api::collections::RingBuffer;

let ringbuffer = RingBuffer::with_capacity(8).expect("Failed to create ringbuffer");
ringbuffer.get_identifier();