How can I use this client with tarantool queues?

[AndreyAlifanov]

Hello!

I try to use this client with queues in tarantool (it's modified code from Simple.cpp). And can't do it in normal way.

int main()
{
	Connector<Buf_t, Net_t> client;
	Connection<Buf_t, Net_t> conn(client);
	int rc = client.connect(conn, {.address = address,
				       .service = std::to_string(port),
				       /*.user = ...,*/
				       /*.passwd = ...,*/
				       /* .transport = STREAM_SSL, */});
	if (rc != 0)
	{
		std::cerr << conn.getError().msg << std::endl;
		return -1;
	}

	rid_t f1 = conn.call("queue.create_tube", std::make_tuple("test", "fifo"));

	while (!conn.futureIsReady(f1))
	{
		if (client.wait(conn, f1, WAIT_TIMEOUT) != 0)
		{
			std::cerr << conn.getError().msg << std::endl;
			conn.reset();
		}
	}

	std::optional<Response<Buf_t>> response = conn.getResponse(f1);
	assert(response != std::nullopt);

	printResponse<Buf_t>(conn, *response); // this method from sample without modifications

	client.close(conn);

	return 0;
}

As result I get an error from conn.call:

RESPONSE ERROR: msg=unsupported Lua type 'function' line=/usr/src/tarantool/src/lua/utils.c file=/usr/src/tarantool/src/lua/utils.c errno=0 type=LuajitError code=32

But tube is created, in fact.

I guess, that I should use eval instead of call. But client doesn't contain this method.

So I have 2 questions:

1. How to use this client with Tarantool queues properly?
2. How to write wrappers for queue methods? Is it possible at all?

[AndreyAlifanov]

I wrote wrapper for eval. And now I can use it in a such way:

//	rid_t f1 = conn.eval("queue.create_tube('test2', 'fifo')");
	rid_t f1 = conn.eval("queue.tube.test2:drop()");

In my case it works. But I'm not sure if I've done it correctly.

template<class BUFFER>
size_t
RequestEncoder<BUFFER>::encodeEval(const std::string &expr)
{
	iterator_t<BUFFER> request_start = m_Buf.end();
	m_Buf.write('\xce');
	m_Buf.write(uint32_t{0});
	encodeHeader(Iproto::EVAL);
	tnt::mpp::encode(m_Buf, tnt::mpp::as_map(std::forward_as_tuple(
		MPP_AS_CONST(Iproto::EXPR), expr)));
	uint32_t request_size = (m_Buf.end() - request_start) - PREHEADER_SIZE;
	++request_start;
	request_start.set(__builtin_bswap32(request_size));
	return request_size + PREHEADER_SIZE;
}

template<class BUFFER, class NetProvider>
rid_t
Connection<BUFFER, NetProvider>::eval(const std::string &expr)
{
	impl->enc.encodeEval(expr);
	impl->connector.readyToSend(*this);
	return RequestEncoder<BUFFER>::getSync();
}

[Totktonada]

unsupported Lua type 'function'

It seems the same as tarantool/go-tarantool#94. I suggest to create a wrapper around queue.create_tube(), which will not return a function as part of the result.

local function queue_create_tube(...)
    queue.create_tube(...)
end

_G.queue_create_tube = queue_create_tube
box.schema.func.create('queue_create_tube', {if_not_exists = true})
box.schema.user.grant('username', 'execute', 'function', 'queue_create_tube', {
    if_not_exists = true
})

[AndreyAlifanov]

Thank you for solution. I'll try it.