wait

static VALUE
rb_condvar_wait(int argc, VALUE *argv, VALUE self)
{
    VALUE waiters = GET_CONDVAR_WAITERS(self);
    VALUE mutex, timeout;
    struct sleep_call args;

    rb_scan_args(argc, argv, "11", &mutex, &timeout);

    args.mutex   = mutex;
    args.timeout = timeout;
    rb_ary_push(waiters, rb_thread_current());
    rb_ensure(do_sleep, (VALUE)&args, delete_current_thread, waiters);

    return self;
}