Draft Specification for Time‐Based Rolling Window

• Support time-based rolling window

  • do not support count-based rolling window

• Add BucketPeriod to the struct Settings:

type Settings struct {
	Name          string
	MaxRequests   uint32
	Interval      time.Duration
        BucketPeriod  time.Duration
	Timeout       time.Duration
	ReadyToTrip   func(counts Counts) bool
	OnStateChange func(name string, from State, to State)
	IsSuccessful  func(err error) bool
}

• Keep compatibility with the current version

  • If BucketPeriod is zero or the same value as Interval (i.e. the number of buckets is 1), the behavior of CircuitBreaker does not change at all.
  • If Interval is zero (no matter what value BucketPeriod takes), CircuitBreaker doesn't clear the internal Counts during the closed state.

• Adjust the value of Interval to be an integer multiple of BucketPeriod:
  Internal = (Internal + BucketPeriod - 1) / BucketPeriod * BucketPeriod
numBuckets = Internal / BucketPeriod

• Each bucket has BucketCounts:

type BucketCounts struct {
	Requests             uint32
	TotalSuccesses       uint32
	TotalFailures        uint32
	ConsecutiveSuccesses uint32
	ConsecutiveFailures  uint32
}

• The existing struct Counts holds the totals of all the BucketCounts.
  • Sum up ConsecutiveSuccesses/ConsecutiveFailures only if its value is the same as Requests

type Counts struct {
	Requests             uint32
	TotalSuccesses       uint32
	TotalFailures        uint32
	ConsecutiveSuccesses uint32
	ConsecutiveFailures  uint32
}