circuitbreaker

type CircuitBreaker interface {
	// BoundRule returns the associated circuit breaking rule.
	BoundRule() Rule
	// BoundStat returns the associated statistic data structure.
	BoundStat() interface{}
	// TryPass acquires permission of an invocation only if it is available at the time of invocation.
	TryPass(ctx *base.EntryContext) bool
	// CurrentState returns current state of the circuit breaker.
	CurrentState() State
	// OnRequestComplete record a completed request with the given response time as well as error (if present),
	// and handle state transformation of the circuit breaker.
	OnRequestComplete(rtt uint64, err error)
}

type CircuitBreakerGenFunc func(r Rule, reuseStat interface{}) CircuitBreaker

type CircuitBreakerSlot struct {
}

type MetricStatSlot struct {
}

type Rule interface {
	base.SentinelRule
	// BreakerStrategy returns the strategy.
	BreakerStrategy() Strategy
	// IsApplicable checks whether the rule is valid and could be converted to a corresponding circuit breaker.
	IsApplicable() error
	// BreakerStatIntervalMs returns the statistic interval of circuit breaker (in milliseconds).
	BreakerStatIntervalMs() uint32
	// IsEqualsTo checks whether current rule is consistent with the given rule.
	IsEqualsTo(r Rule) bool
	// IsStatReusable checks whether current rule is "statistically" equal to the given rule.
	IsStatReusable(r Rule) bool
}

type RuleBase struct {
	// unique id
	Id string
	// resource name
	Resource string
	Strategy Strategy
	// RetryTimeoutMs represents recovery timeout (in seconds) before the circuit breaker opens.
	// During the open period, no requests are permitted until the timeout has elapsed.
	// After that, the circuit breaker will transform to half-open state for trying a few "trial" requests.
	RetryTimeoutMs uint32
	// MinRequestAmount represents the minimum number of requests (in an active statistic time span)
	// that can trigger circuit breaking.
	MinRequestAmount uint64
	// StatIntervalMs represents statistic time interval of the internal circuit breaker (in ms).
	StatIntervalMs uint32
}

type State int32

type StateChangeListener interface {
	// OnTransformToClosed is triggered when circuit breaker state transformed to Closed.
	OnTransformToClosed(prev State, rule Rule)

	// OnTransformToOpen is triggered when circuit breaker state transformed to Open.
	// The "snapshot" indicates the triggered value when the transformation occurs.
	OnTransformToOpen(prev State, rule Rule, snapshot interface{})

	// OnTransformToHalfOpen is triggered when circuit breaker state transformed to HalfOpen.
	OnTransformToHalfOpen(prev State, rule Rule)
}

type Strategy int8