bool wait_for_activity(int fd, short events, const timespec *timeout_ts);
// Wait until a wakeup.
void wait_for_wakeup(const timespec *timeout_ts) { wait_for_activity(-1, 0, timeout_ts); }
bool wait_for_activity(int fd, short events, const timespec *timeout_ts);
// Wait until a wakeup.
void wait_for_wakeup(const timespec *timeout_ts) { wait_for_activity(-1, 0, timeout_ts); }