[rabbitmq-discuss] Why is the "select" always getting timed out in consumer?

Fri Dec 13 16:33:40 GMT 2013

If you REALLY need to know the number of messages in a queue: the
queue.declare method returns a queue.declare-ok which includes a
message-count field - which will tell you the number of messages in a
queue. Keep in mind this involves a round-trip to the broker and is worse
for efficiency than polling with basic.get, if all you want to do is grab a
message when it becomes available.  If you'd like to do just that use
basic.consume.

-Alan

On Fri, Dec 13, 2013 at 8:08 AM, kingsmasher1 <raj.kumar.sanpui at gmail.com>wrote:

> Thanks a lot for the reply Alan.
> Seems like i made some basic mistake, my bindQueue happened inside the
> consume method, and i was planning to call consume only after the "select(
> )" validation, so that might be the reason as you suggested that the
> messages are dropped.
>
> In betwn. here is the functions we use, it's from an already-existing old
> code, which does not have "message in queue or not" validation, which i am
> trying to add.
>
> #define EXCHANGE "topicex"
> #define QUEUETYPE "topic"
> #define ROUTINGKEY "pname"
> #define QUEUENAME "MyprefetchQ"
>
>
> void createPrefetchQueue(void)  {
>         amqConnection *conn =  util.getAMQConnection ();
>         int rc = conn->declareExchange(EXCHANGE, QUEUETYPE, 1);
>         if (rc != 0) {
>                 ErrLog("%s() - declare exchange %s %s failed\n",
> __FUNCTION__, EXCHANGE, QUEUETYPE);
>                 util.returnAMQConnection(conn);
>                 pthread_exit(0) ;
>         }
>         // Create my prefetch queue
>         rc = conn->createQueue(QUEUENAME, 0, 1, 1, 0);
>
>         if (rc != 0) {
>          ErrLog("%s() - create MyprefetchQ %s failed\n", __FUNCTION__,
> QUEUENAME);
>          util.returnAMQConnection(conn);
>                         pthread_exit(0) ;
>     }
> }
>
> int amqConnection::createQueue(std::string queue, int passive, int durable,
> int exclusive, int autoDelete){
>         Debug("%s - Create queue %s \n", __FUNCTION__, queue.c_str());
> /*
>  amqp_queue_declare(amqp_connection_state_t state, amqp_channel_t channel,
> amqp_bytes_t queue, amqp_boolean_t passive, amqp_boolean_t durable,
> amqp_boolean_t exclusive, amqp_boolean_t auto_delete, amqp_table_t
> arguments)
> */
>         int channel=1;
>         amqp_queue_declare(conn, channel,
> amqp_cstring_bytes(queue.c_str()), 0
>                         , 0, 0, 1,  amqp_empty_table);
>           amqp_rpc_reply_t res = amqp_get_rpc_reply(conn);
>           return check_amqp_error(res, "create queue");
>
> }
>
> Binding:
> int amqConnection::bindQueue(const char* queue, const char* exchange, const
> char* bindingkey) {
>         Debug("%s() - %s %s\n", __FUNCTION__, queue, exchange, bindingkey);
>         amqp_queue_bind(conn, 1,
>                         amqp_cstring_bytes(queue),
>                         amqp_cstring_bytes(exchange),
>                         amqp_cstring_bytes(bindingkey),
>                         amqp_empty_table);
>
>         amqp_rpc_reply_t res = amqp_get_rpc_reply(conn);
>         return check_amqp_error(res, "bind queue");
> }
>
>
> std::string amqConnection::consume(amqp_bytes_t queuename, std::string
> exchange, std::string routingkey) {
>         Debug("%s q %s ex %s rk %s- \n", __FUNCTION__,
> (char*)queuename.bytes,
> exchange.c_str(), routingkey.c_str());
>
>         if (exchange.length() > 0) bindQueue(queuename, exchange.c_str(),
> routingkey.c_str());
>
> <snip>
> }
>
>
>
> --
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