Qt with QAMQP / RabbitMQ - c++

Question

I’m using this connector to RabbitMQ:
https://github.com/fuCtor/QAMQP
I need performance and multi-thread in my application. Please, can I use multi-thread with this connector?
I tried:
void Test::newMessage(QAMQP::Queue * q) {
while (q->hasMessage()) {
QAMQP::MessagePtr message = q->getMessage();
MyEvent *me = new MyEvent();
me->message = message;
poolThreadPosicao->start(me);
}
}
class MyEvent : public QRunnable {
public:
QAMQP::MessagePtr message;
void run() {
s.queue->ack(this->message);
}
};
In some messages the RabbitMQ say: “Unacked 10 messages”. The 10 messages is my qos in broker message. What I need solve this? How to do?

Answer 1

First of all I recommend that you switch to https://github.com/mbroadst/qamqp, as it is the replacement for the original project (which is no longer in active development). The updated code contains many performance and memory enhancements, as well as more complete support for RabbitMQ. Having said that, currently both versions of the project are aimed at having one connection per thread. This means that any of the Channels that you create (an Exchange, or a Queue), will be parented to the connection (Client) which created it and therefore are bound to the creating thread.
One way to handle the problem you are facing would be to inherit from QRunnable and QObject, emitting the message when you have completed your task (NOTE: this is untested, I'm just giving the basic structure):
using namespace QAMQP;
class MessageJob : public QRunnable, public QObject
{
Q_OBJECT
public:
MessageJob(const Message &message)
: m_message(message)
{
}
virtual void run() {
// process the message
// when you are done, emit the finished signal
Q_EMIT finished(m_message);
}
Q_SIGNALS:
void finished(const Message &message);
private:
Message m_message;
};
class Test : public QObject
{
Q_OBJECT
public:
Test(QObject *parent = 0)
: QObject(parent)
{
// setup and connect client
// create queue and start consuming
}
private Q_SLOTS:
void messageReceived(const Message &message)
{
MessageJob *job = new MessageJob; // no parent, this will be autodeleted
connect(job, SIGNAL(finished(Message)), this, SLOT(jobFinished(Message)), Qt::QueuedConnection);
// NOTE: Qt::QueuedConnection is very important as it allows the signal to
// cross threads
QThreadPool::globalInstance()->start(job);
}
void jobFinished(const Message &message) {
m_queue->ack(message);
}
private:
Client m_client;
Queue *m_queue;
};