package retry //go:generate go run github.com/v2fly/v2ray-core/v4/common/errors/errorgen import ( "time" ) var ( ErrRetryFailed = newError("all retry attempts failed") ) // Strategy is a way to retry on a specific function. type Strategy interface { // On performs a retry on a specific function, until it doesn't return any error. On(func() error) error } type retryer struct { totalAttempt int nextDelay func() uint32 } // On implements Strategy.On. func (r *retryer) On(method func() error) error { attempt := 0 accumulatedError := make([]error, 0, r.totalAttempt) for attempt < r.totalAttempt { err := method() if err == nil { return nil } numErrors := len(accumulatedError) if numErrors == 0 || err.Error() != accumulatedError[numErrors-1].Error() { accumulatedError = append(accumulatedError, err) } delay := r.nextDelay() time.Sleep(time.Duration(delay) * time.Millisecond) attempt++ } return newError(accumulatedError).Base(ErrRetryFailed) } // Timed returns a retry strategy with fixed interval. func Timed(attempts int, delay uint32) Strategy { return &retryer{ totalAttempt: attempts, nextDelay: func() uint32 { return delay }, } } func ExponentialBackoff(attempts int, delay uint32) Strategy { nextDelay := uint32(0) return &retryer{ totalAttempt: attempts, nextDelay: func() uint32 { r := nextDelay nextDelay += delay return r }, } }