import "github.com/andy2046/gopie/pkg/breaker"
Package breaker implements Circuit Breaker pattern.
var (
// ErrTooManyRequests is returned when the state is half open
// and the requests count is more the maxRequests.
ErrTooManyRequests = errors.New("too many requests, requests count is more the maxRequests in half open state")
// ErrOpenState is returned when the state is open.
ErrOpenState = errors.New("circuit breaker is open")
)var DefaultSettings = Settings{
Name: "CircuitBreaker",
MaxRequests: 1,
Interval: 0,
Timeout: 60 * time.Second,
ShouldTrip: func(counts Counts) bool {
return counts.ConsecutiveFailures > 5
},
OnStateChange: nil,
}DefaultSettings is the default CircuitBreaker Settings.
type CircuitBreaker struct {
// contains filtered or unexported fields
}CircuitBreaker prevent an application repeatedly trying to execute an operation that is likely to fail.
func New(options ...Option) *CircuitBreakerNew returns a new CircuitBreaker with options applied.
func (cb *CircuitBreaker) Execute(request func() (interface{}, error)) (interface{}, error)Execute runs the given request if the CircuitBreaker accepts it. Execute returns an error instantly if the CircuitBreaker rejects the request. Otherwise, Execute returns the result of the request. If a panic occurs in the request, the CircuitBreaker handles it as an error and causes the same panic again.
func (cb *CircuitBreaker) Name() stringName returns the name of the CircuitBreaker.
func (cb *CircuitBreaker) State() StateState returns the current state of the CircuitBreaker.
type Counts struct {
Requests uint64
TotalSuccesses uint64
TotalFailures uint64
ConsecutiveSuccesses uint64
ConsecutiveFailures uint64
}Counts holds the numbers of requests and their successes/failures. CircuitBreaker clears the internal Counts either on the change of the state or at the closed-state intervals. Counts ignores the results of the requests sent before clearing.
type Option = func(*Settings) errorOption applies settings to CircuitBreaker Settings.
type Settings struct {
// Name is the name of the CircuitBreaker.
Name string
// MaxRequests is the maximum number of requests allowed to pass through
// when the CircuitBreaker is half-open.
// If MaxRequests is 0, the CircuitBreaker allows only 1 request.
MaxRequests uint64
// Interval is the cyclic period of the closed state
// for the CircuitBreaker to clear the internal Counts.
// If Interval is 0, the CircuitBreaker doesn't clear internal Counts during the closed state.
Interval time.Duration
// Timeout is the period of the open state,
// after which the state of the CircuitBreaker becomes half-open.
// If Timeout is 0, the timeout for the CircuitBreaker is 60 seconds.
Timeout time.Duration
// ShouldTrip is called with a copy of Counts whenever a request fails in the closed state.
// If ShouldTrip returns true, the CircuitBreaker will be placed into the open state.
// If ShouldTrip is nil, default ShouldTrip is used.
// Default ShouldTrip returns true when the number of consecutive failures is more than 5.
ShouldTrip func(counts Counts) bool
// OnStateChange is called whenever the state of the CircuitBreaker changes.
OnStateChange func(name string, from, to State)
}Settings represents settings for CircuitBreaker.
type State intState is the type representing a state of CircuitBreaker.
const (
// StateClosed represents Closed State.
StateClosed State = iota
// StateHalfOpen represents HalfOpen State.
StateHalfOpen
// StateOpen represents Open State.
StateOpen
)func (s State) String() stringString implements stringer interface.
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