add retry package

internal/retry/config.go

@@ -0,0 +1,76 @@
+package retry
+
+import (
+	"context"
+	"reflect"
+	"time"
+
+	"github.com/cenkalti/backoff/v4"
+)
+
+type config struct {
+	maxInterval time.Duration
+	watches     []watch
+
+	backoff.BackOff
+}
+
+// watch is a helper struct to watch multiple channels
+type watch struct {
+	name string
+	ch   reflect.Value
+	fn   func(context.Context) error
+	this bool
+}
+
+// Option configures the retry handler
+type Option func(*config)
+
+// WithWatch adds a watch to the retry handler
+// that will be triggered when a value is received on the channel
+// and the function will be called, also within a retry handler
+func WithWatch[T any](name string, ch <-chan T, fn func(context.Context) error) Option {
+	return func(cfg *config) {
+		cfg.watches = append(cfg.watches, watch{name: name, ch: reflect.ValueOf(ch), fn: fn, this: false})
+	}
+}
+
+// WithMaxInterval sets the upper bound for the retry handler
+func WithMaxInterval(d time.Duration) Option {
+	return func(cfg *config) {
+		cfg.maxInterval = d
+	}
+}
+
+func newConfig(opts ...Option) ([]watch, backoff.BackOff) {
+	cfg := new(config)
+	for _, opt := range []Option{
+		WithMaxInterval(time.Minute * 5),
+	} {
+		opt(cfg)
+	}
+
+	for _, opt := range opts {
+		opt(cfg)
+	}
+
+	for i, w := range cfg.watches {
+		cfg.watches[i].fn = withRetry(cfg, w)
+	}
+
+	bo := backoff.NewExponentialBackOff()
+	bo.MaxInterval = cfg.maxInterval
+	bo.MaxElapsedTime = 0
+
+	return cfg.watches, bo
+}
+
+func withRetry(cfg *config, w watch) func(context.Context) error {
+	if w.fn == nil {
+		return func(_ context.Context) error { return nil }
+	}
+
+	return func(ctx context.Context) error {
+		return Retry(ctx, w.name, w.fn, WithMaxInterval(cfg.maxInterval))
+	}
+}