Struct PerCpuHashMap 

pub struct PerCpuHashMap<T, K: Pod, V: Pod> { /* private fields */ }

Similar to HashMap but each CPU holds a separate value for a given key. Typically used to minimize lock contention in eBPF programs.

This type can be used with eBPF maps of type BPF_MAP_TYPE_PERCPU_HASH and BPF_MAP_TYPE_LRU_PERCPU_HASH.

Minimum kernel version

The minimum kernel version required to use this feature is 4.6.

Examples

use aya::maps::PerCpuHashMap;

const CPU_IDS: u8 = 1;
const WAKEUPS: u8 = 2;

let mut hm = PerCpuHashMap::<_, u8, u32>::try_from(bpf.map_mut("PER_CPU_STORAGE").unwrap())?;
let cpu_ids = unsafe { hm.get(&CPU_IDS, 0)? };
let wakeups = unsafe { hm.get(&WAKEUPS, 0)? };
for (cpu_id, wakeups) in cpu_ids.iter().zip(wakeups.iter()) {
    println!("cpu {} woke up {} times", cpu_id, wakeups);
}

Implementations

impl<T: Borrow<MapData>, K: Pod, V: Pod> PerCpuHashMap<T, K, V>

pub fn get(&self, key: &K, flags: u64) -> Result<PerCpuValues<V>, MapError>

Returns a slice of values - one for each CPU - associated with the key.

pub fn iter(&self) -> MapIter<'_, K, PerCpuValues<V>, Self>

An iterator visiting all key-value pairs in arbitrary order. The iterator item type is Result<(K, PerCpuValues<V>), MapError>.

pub fn keys(&self) -> MapKeys<'_, K>

An iterator visiting all keys in arbitrary order. The iterator element type is Result<K, MapError>.

impl<T: BorrowMut<MapData>, K: Pod, V: Pod> PerCpuHashMap<T, K, V>

pub fn insert( &mut self, key: impl Borrow<K>, values: PerCpuValues<V>, flags: u64, ) -> Result<(), MapError>

Inserts a slice of values - one for each CPU - for the given key.

Examples

use aya::maps::{PerCpuHashMap, PerCpuValues};
use aya::util::nr_cpus;

const RETRIES: u8 = 1;

let nr_cpus = nr_cpus().map_err(|(_, error)| error)?;
let mut hm = PerCpuHashMap::<_, u8, u32>::try_from(bpf.map_mut("PER_CPU_STORAGE").unwrap())?;
hm.insert(
    RETRIES,
    PerCpuValues::try_from(vec![3u32; nr_cpus])?,
    0,
)?;

pub fn remove(&mut self, key: &K) -> Result<(), MapError>

Removes a key from the map.

impl<T: Borrow<MapData>, K: Pod, V: Pod> PerCpuHashMap<T, K, V>

pub fn pin<P: AsRef<Path>>(self, path: P) -> Result<(), PinError>

Pins the map to a BPF filesystem.

When a map is pinned it will remain loaded until the corresponding file is deleted. All parent directories in the given path must already exist.

impl<K: Pod, V: Pod> PerCpuHashMap<MapData, K, V>

pub fn create(max_entries: u32, flags: u32) -> Result<Self, MapError>

Creates a standalone map with the given max_entries capacity and flags.

Trait Implementations

impl<'a, T: Borrow<MapData>, K: Pod, V: Pod> IntoIterator for &'a PerCpuHashMap<T, K, V>

type Item = Result<(K, PerCpuValues<V>), MapError>

The type of the elements being iterated over.

type IntoIter = MapIter<'a, K, PerCpuValues<V>, PerCpuHashMap<T, K, V>>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<T: Borrow<MapData>, K: Pod, V: Pod> IterableMap<K, PerCpuValues<V>> for PerCpuHashMap<T, K, V>

fn map(&self) -> &MapData

Get a generic map handle

fn get(&self, key: &K) -> Result<PerCpuValues<V>, MapError>

Get the value for the provided key

impl<'a, K: Pod, V: Pod> TryFrom<&'a Map> for PerCpuHashMap<&'a MapData, K, V>

type Error = MapError

The type returned in the event of a conversion error.

fn try_from(map: &'a Map) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a, K: Pod, V: Pod> TryFrom<&'a mut Map> for PerCpuHashMap<&'a mut MapData, K, V>

type Error = MapError

The type returned in the event of a conversion error.

fn try_from(map: &'a mut Map) -> Result<Self, Self::Error>

Performs the conversion.

impl<K: Pod, V: Pod> TryFrom<Map> for PerCpuHashMap<MapData, K, V>

type Error = MapError

The type returned in the event of a conversion error.

fn try_from(map: Map) -> Result<Self, Self::Error>

Performs the conversion.