registry: Add retryable executor and use it in parser

registry/exec/exec.go

@@ -0,0 +1,118 @@
+package exec
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+	"time"
+)
+
+type RetryableExecutor[T any] interface {
+	ExecWithFallback(execFn func() (T, error), fallbackFn func() error) (T, error)
+}
+
+type retryableExecutor[T any] struct {
+	opts *Opts
+}
+
+func NewRetryableExecutor[T any](opts ...OptsFn) RetryableExecutor[T] {
+	execOpts := NewDefaultExecOpts()
+
+	for _, opt := range opts {
+		opt(execOpts)
+	}
+
+	return &retryableExecutor[T]{
+		execOpts,
+	}
+}
+
+func (r *retryableExecutor[T]) ExecWithFallback(execFn func() (T, error), fallbackFn func() error) (res T, err error) {
+	if execFn == nil {
+		return res, errors.New("no exec function provided")
+	}
+
+	if fallbackFn == nil {
+		return res, errors.New("no fallback function provided")
+	}
+
+	execErr := &Error{}
+
+	for i := uint(0); i < r.opts.maxCount; i++ {
+		res, err = execFn()
+
+		if err == nil {
+			return res, nil
+		}
+
+		execErr.AddErr(fmt.Errorf("exec function error: %w", err))
+
+		if err = fallbackFn(); err != nil && !r.opts.retryOnFallbackError {
+			execErr.AddErr(fmt.Errorf("fallback function error: %w", err))
+
+			return res, execErr
+		}
+
+		time.Sleep(r.opts.errTimeout)
+	}
+
+	return res, execErr
+}
+
+const (
+	defaultExecMaxCount         = 3
+	defaultErrTimeout           = 0 * time.Second
+	defaultRetryOnFallbackError = true
+)
+
+type Opts struct {
+	maxCount             uint
+	errTimeout           time.Duration
+	retryOnFallbackError bool
+}
+
+func NewDefaultExecOpts() *Opts {
+	return &Opts{
+		maxCount:             defaultExecMaxCount,
+		errTimeout:           defaultErrTimeout,
+		retryOnFallbackError: defaultRetryOnFallbackError,
+	}
+}
+
+type OptsFn func(opts *Opts)
+
+func WithMaxCount(maxCount uint) OptsFn {
+	return func(opts *Opts) {
+		opts.maxCount = maxCount
+	}
+}
+
+func WithErrTimeout(errTimeout time.Duration) OptsFn {
+	return func(opts *Opts) {
+		opts.errTimeout = errTimeout
+	}
+}
+
+func WithRetryOnFallBackError(retryOnFallbackError bool) OptsFn {
+	return func(opts *Opts) {
+		opts.retryOnFallbackError = retryOnFallbackError
+	}
+}
+
+type Error struct {
+	errs []error
+}
+
+func (e *Error) AddErr(err error) {
+	e.errs = append(e.errs, err)
+}
+
+func (e *Error) Error() string {
+	sb := strings.Builder{}
+
+	for i, err := range e.errs {
+		sb.WriteString(fmt.Sprintf("error %d: %s\n", i, err))
+	}
+
+	return sb.String()
+}