- This projects uses a simple load-balancing problem to implement the solution using Swift Concurrency, GCD and OperationQueues. The user interface is implemented with SwiftUI.
- There are several types of requests that can be processed by different services.
- A LoadBalancer protocol and its concrete implementations CurrentMinLoadBalancer and AsyncCurrentLoadBalancerProxy receive the requests and distribute them among the services.
- GCD and OperationQueue based solutions can share the same load balancers. The async implementation needs to be separate because of the async requirements which can't be met by the synchronous counter parts.
- Cancellation is supported by all solutions: Swift Concurrency, GCD and OperationQueues.
- Global actors are used to synchronize access between services and the load balancer, so that decisions about which service to use are based on the latest data available.
In order to animate views in and out of the queue we need three sets of views:
- Dequeued Items
- Enqueued items (the queue itself)
- Items that have never been enqueued
The presenter class listens to updates from a load publisher. When a service's load changes, the presenter computes the new states of the items, which can be dequeued, enqueued, or none. These helps SwiftUI move and animate the views appropriately.
