[FEATURE REQ] RetryPolicy / RetryOptions - configurable exponent & random boundaries and/or custom retry mode (user provided CalculateExponentialDelay)

Library name

Azure.Core

Please describe the feature.

Consider the existing method for calculating exponential backoff delay: https://github.com/Azure/azure-sdk-for-net/blob/4d8a0979d83ffd6f52e97b3eeeab28858f50ccba/sdk/core/Azure.Core/src/Pipeline/RetryPolicy.cs#L331

As you can see, the following are hard-coded:

1. Exponent 1 << basically means Math.Pow(2, attempt - 1) (so it’s set to 2)
2. Lower random boundary (0.8)
3. Upper random boundary (1.2)

The exponent especially can be critical to the resulting delay time series, but since exposing all the above seems very simple (basically add 3 properties to RetryOptions), might as well add them too.

In addition, a RetryMode.Custom could be added which allows setting a custom-provided CalculateExponentialDelay. I suppose if we have this kind of extensibility then parametrizing the above properties won’t be strictly needed, but IMHO it would be nice to have all the same (e.g. the Azure.Core team might improve the method yet retain the constants used, for example guard better against overflow).

[JoshLove-msft]

Updated sample in https://github.com/Azure/azure-sdk-for-net/pull/35654

[JoshLove-msft]

Ah my bad - you were referring to the exponent factor not the jitter factor. For that, you would need to define your own custom strategy as well.