func lookup()

in Sources/ServiceDiscovery/ServiceDiscovery.swift [46:70]

• 4 lines of code
• 1 McCabe index (conditional complexity)

    func lookup(_ service: Service, deadline: DispatchTime?, callback: @escaping (Result<[Instance], Error>) -> Void)

    /// Subscribes to receive a service's instances whenever they change.
    ///
    /// The service's current list of instances will be sent to `nextResultHandler` when this method is first called. Subsequently,
    /// `nextResultHandler` will only be invoked when the `service`'s instances change.
    ///
    /// ### Threading
    ///
    /// `nextResultHandler` and `completionHandler` may be invoked on arbitrary threads, as determined by implementation.
    ///
    /// - Parameters:
    ///   - service: The service to subscribe to
    ///   - nextResultHandler: The closure to receive update result
    ///   - completionHandler: The closure to invoke when the subscription completes (e.g., when the `ServiceDiscovery` instance exits, etc.),
    ///                 including cancellation requested through `CancellationToken`.
    ///
    /// -  Returns: A `CancellationToken` instance that can be used to cancel the subscription in the future.
    func subscribe(to service: Service, onNext nextResultHandler: @escaping (Result<[Instance], Error>) -> Void, onComplete completionHandler: @escaping (CompletionReason) -> Void) -> CancellationToken
}

// MARK: - Subscription

/// Enables cancellation of service discovery subscription.
public class CancellationToken {