wait

static VALUE
rb_condvar_wait(int argc, VALUE *argv, VALUE self)
{
    struct rb_condvar *cv = condvar_ptr(self);
    VALUE mutex, timeout;
    struct sleep_call args;
    struct sync_waiter w;

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

    args.mutex   = mutex;
    args.timeout = timeout;
    w.th = GET_THREAD();
    list_add_tail(&cv->waitq, &w.node);
    rb_ensure(do_sleep, (VALUE)&args, delete_from_waitq, (VALUE)&w);

    return self;
}