Struct MetaService

pub struct MetaService<S: ?Sized = dyn MetaSource> {
    initial_fetch_waiter: Waiter,
    meta_update_notify: Notify,
    source: S,
}

Service for managing the caching of meta fields.

Fields

initial_fetch_waiter: Waiter

meta_update_notify: Notify

source: S

Implementations

impl<S: MetaSource + ?Sized> MetaService<S>

pub fn new(source: S) -> Arc<MetaService>

where S: Sized,

pub async fn get_field<V: DeserializeOwned + 'static>( &self, db: &Database, field: &str, ) -> Option<MetaValue<V>>

Get the value for the meta field.

This may wait for significant time on first run.

async fn get_field_from_db<V: DeserializeOwned + 'static>( &self, db: &Database, field: &str, ) -> Option<MetaValue<V>>

async fn current_revision( &self, dbtx: &mut DatabaseTransaction<'_>, ) -> Option<u64>

pub async fn wait_initialization(&self)

Wait until Meta Service is initialized, after this get_field will not block.

pub fn subscribe_to_updates(&self) -> impl Stream<Item = ()> + '_

NOTE: this subscription never ends even after update task is shutdown. You should consume this stream in a spawn_cancellable.

pub fn subscribe_to_field<'a, V: DeserializeOwned + 'static>( &'a self, db: &'a Database, name: &'a str, ) -> impl Stream<Item = Option<MetaValue<V>>> + 'a

NOTE: this subscription never ends even after update task is shutdown. You should consume this stream in a spawn_cancellable.

Stream will yield the first element immediately without blocking. The first element will be initial value of the field.

This may yield an outdated initial value if you didn’t call Self::wait_initialization.

pub(crate) async fn update_continuously(&self, client: &Client) -> !

Update all source in background.

Caller should run this method in a task.

async fn save_meta_values(&self, client: &Client, meta_values: &MetaValues)