void (*fd_event)(Unit *u, int fd, uint32_t events, Watch *w);
void (*sigchld_event)(Unit *u, pid_t pid, int code, int status);
void (*timer_event)(Unit *u, uint64_t n_elapsed, Watch *w);
void (*fd_event)(Unit *u, int fd, uint32_t events, Watch *w);
void (*sigchld_event)(Unit *u, pid_t pid, int code, int status);
void (*timer_event)(Unit *u, uint64_t n_elapsed, Watch *w);