// close to free up resources. Once close is called, init
// must be called before another use.
type wakeableSleep struct {
	timer *timer

	// lock protects access to wakeup, but not send/recv on it.
	lock   mutex
	wakeup chan struct{}
}

// newWakeableSleep initializes a new wakeableSleep and returns it.
func newWakeableSleep() *wakeableSleep {
	s := new(wakeableSleep)

	EvGoBlockSend       event.Type = 22 // goroutine blocks on chan send [timestamp, stack]
	EvGoBlockRecv       event.Type = 23 // goroutine blocks on chan recv [timestamp, stack]
	EvGoBlockSelect     event.Type = 24 // goroutine blocks on select [timestamp, stack]
	EvGoBlockSync       event.Type = 25 // goroutine blocks on Mutex/RWMutex [timestamp, stack]