caller

type Caller interface {
	Do() (resp interface{}, err error)
}

type Config struct {
	// Key represents keyName of this session
	// and mandatory if using Cache / Singleflight
	// else optional.
	Key string

	// Timeout define the amount of time
	// for WorkFn to finish the task.
	Timeout time.Duration

	// WorkFn is function that will be run.
	WorkFn func() (interface{}, error)

	// Cache store data in memory
	// in a way depending on their method.
	Cache cache.Cache

	// Singleflight make duplicate caller
	// flight in one execution.
	Singleflight singleflight.Singleflight

	// Breaker do go/no-go call to WorkFn
	// under certain threshold.
	Breaker breaker.Breaker

	// SuccessFn runs if WorkFn got success.
	SuccessFn func()

	// FailFn runs if WorkFn got fail.
	FailFn func()

	// TimeoutFn runs if WorkFn got timeout.
	TimeoutFn func()

	// BreakerFn runs if IsErrBerakerOpen=true.
	BreakerFn func()
}