backoff

Documentation

Index

• Constants
• Variables
• func ErrRetryableAfter(err error) (retryAfter time.Duration)
• func Retry(ctx context.Context, operation Operation, policy RetryPolicy, ...) error
• type Clock
• type ConcurrentRetrier
  • func NewConcurrentRetrier(retryPolicy RetryPolicy) *ConcurrentRetrier
  • func (c *ConcurrentRetrier) Failed()
  • func (c *ConcurrentRetrier) Succeeded()
  • func (c *ConcurrentRetrier) Throttle()
• type ExponentialRetryPolicy
  • func NewExponentialRetryPolicy(initialInterval time.Duration) *ExponentialRetryPolicy
  • func (p *ExponentialRetryPolicy) ComputeNextDelay(elapsedTime time.Duration, numAttempts int) time.Duration
  • func (p *ExponentialRetryPolicy) SetBackoffCoefficient(backoffCoefficient float64)
  • func (p *ExponentialRetryPolicy) SetExpirationInterval(expirationInterval time.Duration)
  • func (p *ExponentialRetryPolicy) SetInitialInterval(initialInterval time.Duration)
  • func (p *ExponentialRetryPolicy) SetMaximumAttempts(maximumAttempts int)
  • func (p *ExponentialRetryPolicy) SetMaximumInterval(maximumInterval time.Duration)
• type IsRetryable
• type Operation
• type Retrier
  • func NewRetrier(policy RetryPolicy, clock Clock) Retrier
• type RetryPolicy

Constants

const (
	// NoInterval represents Maximim interval
	NoInterval = 0

	// DefaultBackoffCoefficient is default backOffCoefficient for retryPolicy
	DefaultBackoffCoefficient = 2.0
)

Variables

var SystemClock = systemClock{}

SystemClock implements Clock interface that uses time.Now().

Functions

func ErrRetryableAfter

func ErrRetryableAfter(err error) (retryAfter time.Duration)

ErrRetryableAfter returns a minimum delay until the next attempt.

for most errors this will be 0, and normal backoff logic will determine the full retry period, but e.g. service busy errors (or any case where the server knows a "time until it is not useful to retry") are safe to assume that a literally immediate retry is *not* going to be useful.

note that this is only a minimum, however. longer delays are assumed to be equally valid.

func Retry

func Retry(ctx context.Context, operation Operation, policy RetryPolicy, isRetriable IsRetryable) error

Retry function can be used to wrap any call with retry logic using the passed in policy

Types

type Clock

type Clock interface {
	Now() time.Time
}

Clock used by ExponentialRetryPolicy implementation to get the current time. Mainly used for unit testing

type ConcurrentRetrier

type ConcurrentRetrier struct {
	sync.Mutex
	// contains filtered or unexported fields
}

ConcurrentRetrier is used for client-side throttling. It determines whether to throttle outgoing traffic in case downstream backend server rejects requests due to out-of-quota or server busy errors.

func NewConcurrentRetrier

func NewConcurrentRetrier(retryPolicy RetryPolicy) *ConcurrentRetrier

NewConcurrentRetrier returns an instance of concurrent backoff retrier.

func (*ConcurrentRetrier) Failed

func (c *ConcurrentRetrier) Failed()

Failed marks client request failed because backend is busy.

func (*ConcurrentRetrier) Succeeded

func (c *ConcurrentRetrier) Succeeded()

Succeeded marks client request succeeded.

func (*ConcurrentRetrier) Throttle

func (c *ConcurrentRetrier) Throttle()

Throttle Sleep if there were failures since the last success call.

type ExponentialRetryPolicy

type ExponentialRetryPolicy struct {
	// contains filtered or unexported fields
}

ExponentialRetryPolicy provides the implementation for retry policy using a coefficient to compute the next delay. Formula used to compute the next delay is: initialInterval * math.Pow(backoffCoefficient, currentAttempt)

func NewExponentialRetryPolicy

func NewExponentialRetryPolicy(initialInterval time.Duration) *ExponentialRetryPolicy

NewExponentialRetryPolicy returns an instance of ExponentialRetryPolicy using the provided initialInterval

func (*ExponentialRetryPolicy) ComputeNextDelay

func (p *ExponentialRetryPolicy) ComputeNextDelay(elapsedTime time.Duration, numAttempts int) time.Duration

ComputeNextDelay returns the next delay interval. This is used by Retrier to delay calling the operation again

func (*ExponentialRetryPolicy) SetBackoffCoefficient

func (p *ExponentialRetryPolicy) SetBackoffCoefficient(backoffCoefficient float64)

SetBackoffCoefficient sets the coefficient used by ExponentialRetryPolicy to compute next delay for each retry All retries are computed using the following formula: initialInterval * math.Pow(backoffCoefficient, currentAttempt)

func (*ExponentialRetryPolicy) SetExpirationInterval

func (p *ExponentialRetryPolicy) SetExpirationInterval(expirationInterval time.Duration)

SetExpirationInterval sets the absolute expiration interval for all retries

func (*ExponentialRetryPolicy) SetInitialInterval

func (p *ExponentialRetryPolicy) SetInitialInterval(initialInterval time.Duration)

SetInitialInterval sets the initial interval used by ExponentialRetryPolicy for the very first retry All later retries are computed using the following formula: initialInterval * math.Pow(backoffCoefficient, currentAttempt)

func (*ExponentialRetryPolicy) SetMaximumAttempts

func (p *ExponentialRetryPolicy) SetMaximumAttempts(maximumAttempts int)

SetMaximumAttempts sets the maximum number of retry attempts

func (*ExponentialRetryPolicy) SetMaximumInterval

func (p *ExponentialRetryPolicy) SetMaximumInterval(maximumInterval time.Duration)

SetMaximumInterval sets the maximum interval for each retry

type IsRetryable

type IsRetryable func(error) bool

IsRetryable handler can be used to exclude certain errors during retry

type Operation

type Operation func() error

Operation to retry

type Retrier

type Retrier interface {
	NextBackOff() time.Duration
	Reset()
}

Retrier manages the state of retry operation

func NewRetrier

func NewRetrier(policy RetryPolicy, clock Clock) Retrier

NewRetrier is used for creating a new instance of Retrier

type RetryPolicy

type RetryPolicy interface {
	ComputeNextDelay(elapsedTime time.Duration, numAttempts int) time.Duration
}

RetryPolicy is the API which needs to be implemented by various retry policy implementations