Allow request retry with custom HTTP codes (like 429 - Too Many Requests) and implement delay retry

[tciuro]

Q	A
BC Break	no
Version	0.9.15

Support Question

When a service returns HTTP 429 Too Many Requests, I was expecting RealHTTP to trigger the retry mechanism. Alas, this is not what I see. I get an HTTP 429 error right away without any retries. Shouldn't this scenario be handled by RealHTTP? 🤔

[malcommac]

Hi @tciuro,
In fact the current implementation of the HTTPDefaultValidator does not implement a way to retry based on HTTP status code. However is pretty simple to implement it and I think it could be useful.
So I've added it to the main repository and I'll push a new release.

Currently HTTPDefaultValidator exposes a new property:

• retriableHTTPStatusCodes: it defines a list of HTTPStatusCode which can trigger a retry of the call; it's a dictionaryw where the value is a TimeInterval (0 means retry immediately, a positive value like 2 means 2 seconds after retry).

Default implementation set .tooManyRequests's http status code with 3 seconds interval.
You can however set it as you need by modifying the client's HTTPDefaultValidator or provide your own subclass.

This is an example which works with the default shared HTTPClient but you can use it with your own instance.

let myValidator = HTTPDefaultValidator()
myValidator.retriableHTTPStatusCodes = [.tooManyRequests: 5] // wait 5 seconds for HTTP 429
HTTPClient.shared.validators = [myValidator]
        
request.maxRetries = 2 // you must set a retry > 1 in order to get it works
request.onRawResponse { response in
  // do something
}
request.run()

It will be part of the 0.9.16 version.