A way to add to the default retry policy of a client

[copumpkin]

Describe the Feature

Sometimes I logically want to add a retry condition to a certain client, without changing the rest of its default retry policy, especially if it already uses a custom one like DynamoDB.

Is your Feature Request related to a problem?

I don't seem to have a way to get at this DynamoDbRetryPolicy class, for example, because it's marked as an internal API. Furthermore, I need to look at the SDK source code to even see which retry policy I should be aiming to modify or copy.

Proposed Solution

Not sure, maybe provide some sort of builder method that gives me access to the default value I'd be overriding?

Describe alternatives you've considered

Reflection to get at the internal class, but then it can break from commits like this.

Additional Context

N/A

[copumpkin]

The old SDK had PredefinedRetryPolicies (and similar Predefined classes) to facilitate stuff like this.

[cenedhryn]

Can you give a code example of a typical usecase? Using 1) the (internal) DynamoDbRetryPolicy class 2) an imaginary builder method. It'd help to pinpoint what you want to achieve.

[copumpkin]

I've gotten rid of my code that reflectively jumped into the internal DynamoDbRetryPolicy class, but from a high level I wanted to also retry on TransactionConflictException in addition to all the standard DDB retry behavior.

[copumpkin]

As for the imaginary builder method, I'm not really sure what it would be. I could imagine exposing defaults in the builder classes themselves (not sure this happens today, vs. null/empty getting replaced further down), then having a builder method like .modifyX that takes a function from whatever X's type is to that same type, allowing me to consume the old one and replace it with a new one.

[zoewangg]

The reason we decided to put service specific retry policy within service modules is to keep service specific logic out of core. I agree with you that predefined retry policies for each service can be difficult to extend now.

We might be able to exposing it in the builder class. Marking this as feature request.