Struct SubscriptionMap

pub struct SubscriptionMap<K, V>(/* private fields */)
where
    K: Clone + Debug + Eq + Hash + Ord,
    V: Clone + Debug;

A concurrent and self cleaning map of observable values to easily communicate dynamically across tasks.

let map = SubscriptionMap::<usize, usize>::default();
let mut subscription = map.get_or_insert(1, 0).await;

task::spawn(async move {
    // somewhere else in your program
    let mut subscription = map.get_or_insert(1, 0).await;
    log::info!("received update throguh map: {}", subscription.next().await);
});

// wait for some event and publish the state
subscription.publish(1);
// just drop the ref as soon as you are done with it to trigger the cleanup
drop(subscription);

Implementations

impl<K, V> SubscriptionMap<K, V>

where K: Clone + Debug + Eq + Hash + Ord, V: Clone + Debug,

pub fn new() -> Self

Create an empty SubscriptionMap

pub async fn get_or_insert(&self, key: K, value: V) -> SubscriptionRef<K, V>

Either creates a ref to a existing subscription or initializes a new one.

impl<K, V> SubscriptionMap<K, V>

where K: Clone + Debug + Eq + Hash + Ord, V: Clone + Debug + Eq,

pub async fn publish_if_changed(&self, key: &K, value: V) -> Result<bool>

Check if the provided value differs from the observable and return the info if a publish was made.

let map = SubscriptionMap::<usize, usize>::default();
let mut subscription = map.get_or_insert(1, 0).await;

assert_eq!(subscription.latest(), 0);
map.publish_if_changed(&1, 1);
assert_eq!(subscription.next().await, 1);
map.publish_if_changed(&1, 1);

// this will never resolve since we did not publish an update!
subscription.next().await

pub async fn modify_and_publish<F, R>(&self, key: &K, modify: F) -> Result<()>

where F: FnOnce(&mut V) -> R,

Modify the value contained in the subscription through a mutable reference and notify others.

This is handy for expensive data structures such as vectors, trees or maps.

let map = SubscriptionMap::<usize, usize>::default();
let mut subscription = map.get_or_insert(1, 0).await;

assert_eq!(subscription.latest(), 0);
map.modify_and_publish(&1, |mut v| *v = 1);
assert_eq!(subscription.latest(), 1);

Trait Implementations

impl<K, V> Clone for SubscriptionMap<K, V>

where K: Clone + Debug + Eq + Hash + Ord + Clone, V: Clone + Debug + Clone,

fn clone(&self) -> SubscriptionMap<K, V>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<K, V> Debug for SubscriptionMap<K, V>

where K: Clone + Debug + Eq + Hash + Ord + Debug, V: Clone + Debug + Debug,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<K, V> Default for SubscriptionMap<K, V>

where K: Clone + Debug + Eq + Hash + Ord, V: Clone + Debug,

fn default() -> Self

Returns the “default value” for a type.