Make HTTP decompression limit configurable

[gwynne]

• When using HTTP compression (gzip, deflate), the decompression limit was hardcoded at a ratio of 1:10 (set HTTP request decompression ratio limit #2192). It is now possible to specify a custom limit. The default remains unchanged.

[calebkleveter]

I feel like there should be a way to combine both the supportDecompression and decompressionLimit parameters, but I can't think of a good way to do it at this point.

[tanner0101]

Thanks!

[tanner0101]

@calebkleveter agreed. I can't think of a good way either though. If we find something we can deprecate these methods.

[tanner0101]

These changes are now available in 4.0.0-beta.4.1

[t089]

Instead of a Boolean you could use an enum

enum Decompression {
   .disabled
   .enabled(limit: NIOHTTPDecompression.DecompressionLimit)
}

[tanner0101]

@t089 that's a good idea. An enum-like struct could be even better so that we can add new "cases" in the future.

[gwynne]

@t089 Yeah, I was thinking of something like that, but I couldn't quite put it together in my head without breaking the existing API (which I try to avoid). The enum you suggested looks great, I think it makes sense to just use that instead of trying to stick to API consistency while still in beta (just look at how much Fluent changed in the last few days 😆).

[calebkleveter]

The best part is that now enum cases with associated values can have default values.

[tanner0101]

public struct HTTPDecompressionConfiguration {
   public static var disabled: Self {
        .init(isEnabled: false, limit: ...)
   }
   
   public static func enabled(limit: NIOHTTPDecompression.DecompressionLimit = .ratio(10)) -> Self {
       .init(isEnabled: true, limit: limit)
   }

   var isEnabled: Bool
   var limit: NIOHTTPDecompression.DecompressionLimit
}

That's how you could do it with a struct so we can add new cases going forward.

[t089]

Even more elegant would be to use a private enum inside the struct to model the different states. Eg

public struct HTTPDecompressionConfiguration {
   public static var disabled: Self {
        .init(decompression: .disabled)
   }
   
   public static func enabled(limit: NIOHTTPDecompression.DecompressionLimit = .ratio(10)) -> Self {
       .init(decompression: .enabled(limit: limit)
   }

    enum Decompression {
       .disabled
       .enabled(limit: NIOHTTPDecompression
   }

    var decompression: Decompression
}

[tanner0101]

I've implemented an improved API here: #2214.