Struct SharedState

pub struct SharedState(/* private fields */);

Implementations

impl SharedState

pub fn get<T: Send + Sync + 'static>( &self, key: &str, ) -> Option<Result<Arc<T>, Error>>

Returns None if no entry exists for key. Returns Some(Err) if an entry exists for key, but is not of type T. Returns Some(Ok(Arc)) if the existing entry is successfully downcasted to T.

pub fn try_insert<T: Send + Sync + 'static>( &self, key: &str, val: T, ) -> Result<Arc<T>, Arc<dyn Any + Send + Sync + 'static>>

Insert val at key if key is not yet occupied. If SharedState did not have an entry for key, returns Ok(Arc<the inserted val>). Otherwise, does not insert val and returns Err(Arc)

pub async fn get_or_insert_with<F, Fut, T>( &self, key: &str, inserter: F, ) -> Result<Arc<T>, Error>

where F: FnOnce() -> Fut, Fut: Future<Output = Result<T, Error>>, T: Send + Sync + 'static,

This takes two type parameters, F and T. The inserter F is used in case key is not yet associated with an existing state value to create the value associated with key. T is the type of state expected to be associated with key. After possibly inserting the state associated with key in the map, we dynamically cast keys state into type T. Errors can stem from inserter failures, or existing types in the map not matching T.

Trait Implementations

impl Default for SharedState

fn default() -> SharedState

Returns the “default value” for a type.