v1.0.0

common/retry/retry.go

@@ -0,0 +1,64 @@
+package retry // import "github.com/xtls/xray-core/v1/common/retry"
+
+//go:generate go run github.com/xtls/xray-core/v1/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
+		},
+	}
+}