first version

internal/tinvest/retry.go

@@ -0,0 +1,64 @@
+package tinvest
+
+import (
+	"context"
+	"time"
+
+	backofflib "github.com/cenkalti/backoff/v4"
+)
+
+func withRetry(ctx context.Context, attempts int, interval time.Duration, fn func() error) error {
+	if attempts <= 0 {
+		attempts = 1
+	}
+	if interval < 0 {
+		interval = 0
+	}
+	policy := backofflib.NewExponentialBackOff()
+	policy.InitialInterval = interval
+	policy.MaxInterval = interval * 8
+	policy.Multiplier = 2
+	policy.MaxElapsedTime = 0
+	policy.Reset()
+	var lastErr error
+	for attempt := 0; attempt < attempts; attempt++ {
+		if err := ctx.Err(); err != nil {
+			return err
+		}
+		if err := fn(); err != nil {
+			lastErr = err
+		} else {
+			return nil
+		}
+		if attempt == attempts-1 || interval <= 0 {
+			continue
+		}
+		timer := time.NewTimer(policy.NextBackOff())
+		select {
+		case <-timer.C:
+		case <-ctx.Done():
+			if !timer.Stop() {
+				select {
+				case <-timer.C:
+				default:
+				}
+			}
+			return ctx.Err()
+		}
+	}
+	return lastErr
+}
+
+func retryValue[T any](ctx context.Context, attempts int, interval time.Duration, fn func() (T, error)) (T, error) {
+	var out T
+	err := withRetry(ctx, attempts, interval, func() error {
+		var err error
+		out, err = fn()
+		return err
+	})
+	if err != nil {
+		var zero T
+		return zero, err
+	}
+	return out, nil
+}