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v2fly/common/retry/retry.go
2017-04-09 01:43:25 +02:00

65 lines
1.4 KiB
Go

package retry
//go:generate go run $GOPATH/src/v2ray.com/core/tools/generrorgen/main.go -pkg retry -path Retry
import (
"time"
)
var (
ErrRetryFailed = newError("Retry: 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.After(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
},
}
}