Allow passing URLRequest as PathConfiguration source

[zoejessica]

This non-breaking change introduces another case to the PathConfiguration.Source enum, a .serverRequest(URLRequest) so that clients can customize how the configuration file is loaded from the network.

This was prompted by our use in HEY – we'd like to be able to set a different cache policy on the request so that locally cached files are ignored and we always retrieve the latest possible file from the server. But I can see this being a reasonable use case for other clients too, while default behaviour is still provided by the .server(URL) source type.

[joemasilotti]

Is it worth exploring a configuration setting on Path Configuration to replicate this caching behavior?

[zoejessica]

That's a good question!

For the use case I describe, we need control of the NSURLRequest.CachePolicy which is available to be customized either by the URLRequest, or by the URLSession itself. So we could definitely introduce some options to the PathConfiguration to customize this behaviour.

public struct PathConfigurationLoaderOptions {
    /// If present, the ``PathConfigurationLoader`` will initialize a new `URLSession` with
    /// this configuration to make its network request
    let urlSessionConfiguration: URLSessionConfiguration?
}

(Naming a configuration struct for a Configuration class is hard!)

PathConfiguration's init method becomes

public init(sources: [Source] = [], options: PathConfigurationLoaderOptions? = nil)

and the options flow down to the PathConfigurationLoader which uses the config to instantiate a custom URLSession if needed:

        let session = options?.urlSessionConfiguration.map { URLSession(configuration: $0) } ?? URLSession.shared
        session.dataTask(with: url) ...

Was this the kind of solution you had in mind? It does set up a nice structure for further customization down the road, if there's appetite for that, but it's also a bit more complex of course.

[olivaresf]

It does set up a nice structure for further customization down the road, if there's appetite for that, but it's also a bit more complex of course.

This structure would be a good idea to explore, but for our use case right now a minor update feels like the way to go.

[zoejessica]

@joemasilotti I'll leave this open until tomorrow in case you have feedback on the configuration option above.

[joemasilotti]

Nope! If we keep it simple like this it looks good to me. 👍

[joemasilotti]

I thought we were going with the request and not full on configuration? What sparked the last minute change?