Package retrier

func ConstantBackoff ¶

func ConstantBackoff(n int, amount time.Duration) []time.Duration

ConstantBackoff generates a simple back-off strategy of retrying 'n' times, and waiting 'amount' time after each one.

func ExponentialBackoff ¶

func ExponentialBackoff(n int, initialAmount time.Duration) []time.Duration

ExponentialBackoff generates a simple back-off strategy of retrying 'n' times, and doubling the amount of time waited after each one.

type Action ¶

Action is the type returned by a Classifier to indicate how the Retrier should proceed.

type Action int

const (
    Succeed Action = iota // Succeed indicates the Retrier should treat this value as a success.
    Fail                  // Fail indicates the Retrier should treat this value as a hard failure and not retry.
    Retry                 // Retry indicates the Retrier should treat this value as a soft failure and retry.
)

type BlacklistClassifier ¶

BlacklistClassifier classifies errors based on a blacklist. If the error is nil, it returns Succeed; if the error is in the blacklist, it returns Fail; otherwise, it returns Retry.

type BlacklistClassifier []error

func (BlacklistClassifier) Classify ¶

func (list BlacklistClassifier) Classify(err error) Action

Classify implements the Classifier interface.

type Classifier ¶

Classifier is the interface implemented by anything that can classify Errors for a Retrier.

type Classifier interface {
    Classify(error) Action
}

type DefaultClassifier ¶

DefaultClassifier classifies errors in the simplest way possible. If the error is nil, it returns Succeed, otherwise it returns Retry.

type DefaultClassifier struct{}

func (DefaultClassifier) Classify ¶

func (c DefaultClassifier) Classify(err error) Action

Classify implements the Classifier interface.

type Retrier ¶

Retrier implements the "retriable" resiliency pattern, abstracting out the process of retrying a failed action a certain number of times with an optional back-off between each retry.

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

r := New(ConstantBackoff(3, 100*time.Millisecond), nil)

err := r.Run(func() error {
    // do some work
    return nil
})

if err != nil {
    // handle the case where the work failed three times
}

func New ¶

func New(backoff []time.Duration, class Classifier) *Retrier

New constructs a Retrier with the given backoff pattern and classifier. The length of the backoff pattern indicates how many times an action will be retried, and the value at each index indicates the amount of time waited before each subsequent retry. The classifier is used to determine which errors should be retried and which should cause the retrier to fail fast. The DefaultClassifier is used if nil is passed.

func (*Retrier) Run ¶

func (r *Retrier) Run(work func() error) error

Run executes the given work function, then classifies its return value based on the classifier used to construct the Retrier. If the result is Succeed or Fail, the return value of the work function is returned to the caller. If the result is Retry, then Run sleeps according to the its backoff policy before retrying. If the total number of retries is exceeded then the return value of the work function is returned to the caller regardless.

func (*Retrier) SetJitter ¶

func (r *Retrier) SetJitter(jit float64)

SetJitter sets the amount of jitter on each back-off to a factor between 0.0 and 1.0 (values outside this range are silently ignored). When a retry occurs, the back-off is adjusted by a random amount up to this value.

type WhitelistClassifier ¶

WhitelistClassifier classifies errors based on a whitelist. If the error is nil, it returns Succeed; if the error is in the whitelist, it returns Retry; otherwise, it returns Fail.

type WhitelistClassifier []error

func (WhitelistClassifier) Classify ¶

func (list WhitelistClassifier) Classify(err error) Action

Classify implements the Classifier interface.