`MusicDataRequest.tokenProvider` is not concurrency-safe

Number:rdar://FB13373750 Date Originated:2023-11-14
Status:Open Resolved:
Product:MusicKit Product Version:iOS 17.2 Seed 1 (21C5029g)
Classification:Incorrect/Unexpected Behavior Reproducible:Always
I have attached a sample project that tries to use `MusicDataRequest.tokenProvider` to request a token. It results in a compiler warning.

Here is the relevant code:
private func requestDeveloperToken() async throws -> String {
  return try await MusicDataRequest.tokenProvider.developerToken(options: [])

After setting the “Strict Concurrency Checking” Xcode build setting to “Complete”, the compiler produces the following warning:
> Reference to static property 'tokenProvider' is not concurrency-safe because it involves shared mutable state

Indeed, MusicKit defines `tokenProvider` as a mutable static property. Perhaps it should be made immutable?



While you’re free to request the developer token as you are doing in this snippet of code, we also believe very few clients should have a valid reason to do so.

Indeed, all relevant MusicKit requests that need to use a developer token already take care of that automatically under the hood, including MusicCatalogResourceRequest, MusicCatalogSearchRequest, MusicPersonalRecommendationsRequest, etc. Even the general purpose data request, MusicDataRequest, does that automatically.

We would love to hear from you why you feel like you should request the developer token as you’re doing, to make sure it’s something you even need to do.

By darren.mo at Dec. 5, 2023, 8:33 p.m. (reply...)


Thanks for the response. I have already found that MusicDataRequest automatically adds the token to the URL request, so I no longer need to access the tokenProvider property.

I think there could be some changes that might make this clearer:

  1. Update the MusicDataRequest documentation comment to note that it automatically adds the appropriate tokens to the URL request.
  2. Consider removing the tokenProvider property or updating its documentation comment to explain its intended use case.
By darren.mo at Jan. 4, 2024, 1:32 a.m. (reply...)

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