Refactor: move retry into single package.

1 files changed, 47 insertions, 0 deletions

diff --git a/common/retry/retry.go b/common/retry/retry.go
new file mode 100644
index 0000000..43e7d69
--- /dev/null
+++ b/common/retry/retry.go
@@ -0,0 +1,47 @@
+package retry
+
+import (
+	"context"
+	"github.com/keuin/slbr/logging"
+	"time"
+)
+
+// AutoRetry retries the supplier automatically, with given time limit and interval.
+// If maximum retry time limit is reached and the supplier still fails,
+// the last error will be returned.
+// If logger is not nil, retry information will be printed to it.
+func AutoRetry[T any](
+	ctx context.Context,
+	supplier func() (T, error),
+	maxRetryTimes int,
+	retryInterval time.Duration,
+	logger *logging.Logger) (T, error) {
+	var err error
+	var ret T
+	for i := 0; i < maxRetryTimes+1; i++ {
+		ret, err = supplier()
+		if err != nil {
+			if logger != nil {
+				logger.Info("Try %v/%v (sleep %v): %v",
+					i, maxRetryTimes, retryInterval, err)
+			}
+			timer := time.NewTimer(retryInterval)
+			select {
+			case <-timer.C:
+				// time to have the next try
+				continue
+			case <-ctx.Done():
+				// context is cancelled
+				var zero T
+				return zero, ctx.Err()
+			}
+		}
+		// success
+		return ret, nil
+	}
+	if logger != nil {
+		logger.Error("Max retry times reached, but it still fails. Last error: %v", err)
+	}
+	var zero T
+	return zero, err
+}