Struct watch_handler::WatchHandler

pub struct WatchHandler<T, ST> { /* private fields */ }

Handler for hanging gets. The common way to use this is to implement the Sender trait for the FIDL responder that the handler is used for. There should be one instance of HangingGetHandler per interface per connection, as the handler needs to keep track of state per connection.

Implementations

impl<T, ST> WatchHandler<T, ST>

where T: Clone + PartialEq + 'static, ST: Sender<T> + 'static,

pub fn create(initial_value: Option<T>) -> Self

Creates a new instance of WatchHandler. If |initial_value| is provided, it will return immediately on first watch. Otherwise, the first watch returns when the value is set for the first time. Uses default change function which just checks for any change.

impl<T, ST> WatchHandler<T, ST>

where T: Clone + 'static, ST: Sender<T> + 'static,

pub fn create_with_change_fn( change_function: Box<dyn Fn(&T, &T) -> bool + Send + Sync + 'static>, initial_value: Option<T> ) -> Self

Creates a new instance of WatchHandler. If |initial_value| is provided, it will return immediately on first watch. Otherwise, the first watch returns when the value is set for the first time.

pub fn watch(&mut self, responder: ST) -> Result<(), WatchError<ST>>

Park a new hanging get in the handler. If a hanging get is already parked, returns the new responder.

pub fn set_change_function( &mut self, change_function: Box<dyn Fn(&T, &T) -> bool + Send + Sync + 'static> )

Sets a new change function. The hanging get will only return when the change function evaluates to true when comparing the last value sent to the client and the current value. Takes effect immediately; if change function evaluates to true then the pending responder will be called.

pub fn set_value(&mut self, new_value: T)

Called to update the current value of the handler, sending changes using the watcher if needed.