Ambiguities in Challenge 20: Circuit Breaker

[asarkar]

type Config struct {
    MaxRequests      uint32        // Max requests allowed in half-open state
    Interval         time.Duration // Statistical window for closed state
    Timeout          time.Duration // Time to wait before half-open
    ReadyToTrip      func(Metrics) bool // Function to determine when to trip
    OnStateChange    func(name string, from State, to State) // State change callback
}

While implementing the Circuit Breaker challenge, I found some unclear aspects in the Config struct.
For reference, I compared the design to the Azure Circuit Breaker pattern to clarify expected behavior.

Issues

• MaxRequests - Should be renamed to HalfOpenMaxRequests. If cb.halfOpenRequests is equal to this value, say n, the state changes to closed. The error ErrTooManyRequests doesn't make sense here; in the half-open state, even if one request fails, the CB moves to the open state. If n number of requests all succeed, the CB transitions to closed state. At no time, the CB will receive more than n requests in the half-open state.

• Interval – The comment "Statistical window for closed state" is unclear. It seems to represent the time window used to measure failures in the closed state. Suggest renaming the field and/or updating the comment.

• Timeout – The period the breaker stays open before moving to half-open. Clear enough.

• ReadyToTrip – Allowing the client to decide when to trip may lead to abuse (e.g., always returning false). This logic should ideally be internal.