[rabbitmq-discuss] rabbitmq-c amqp_table_t (high availability configuration params)

[Arun Chandrasekaran]

Hi all,

Has anyone used rabbitmq-c with high availability configuration?

I am stuck with a memory corruption when using rabbitmq-c with high 
availability configuration in my own code (the crash is not in 
librabbitmq). For HA, since the nodes names have to be taken from a config 
file, I have implemented the following way of getting the key value params.


   std::map<std::string, std::vector<std::string> >ha_map;
   // Load the map here. Typical values:
   // x-ha-policy - nodes; x-ha-policy-params - rabbit at centos,rabbit at centos

   amqp_table_t table;
   std::vector<amqp_field_value_t_ *> array_ptrs;

   memset(&table, 0, sizeof(table));
   table.num_entries = ha_map.size();
   if (table.num_entries)
       table.entries = (amqp_table_entry_t *) calloc(1, 
sizeof(amqp_table_entry_t) * table.num_entries);
   int i = 0;

   std::map<std::string, std::vector<std::string> >::const_iterator it;
   for (it = ha_map.begin(); it != ha_map.end(); it++, i++) {
      table.entries[i].key.len = (*it).first.size();
      table.entries[i].key.bytes = (void *) (*it).first.c_str();

      if ((*it).second.size() == 1) {
         table.entries[i].value.kind = AMQP_FIELD_KIND_UTF8;
         table.entries[i].value.value.bytes.len = (*it).second[0].size();
         table.entries[i].value.value.bytes.bytes = (void *) 
(*it).second[0].c_str();

      } else if ((*it).second.size() > 1) {
         table.entries[i].value.kind = AMQP_FIELD_KIND_ARRAY;
         table.entries[i].value.value.array.num_entries = 
(*it).second.size();
         amqp_field_value_t *f = (amqp_field_value_t_ *) 
malloc(sizeof(amqp_field_value_t_) * (*it).second.size());
         array_ptrs.push_back(f);
         table.entries[i].value.value.array.entries = f;
         LogInfo(("Before pointer: %p", 
table.entries[i].value.value.array.entries));
         for (size_t j = 0; j < (*it).second.size(); j++) {
            table.entries[i].value.value.array.entries[j].kind = 
AMQP_FIELD_KIND_UTF8;
            table.entries[i].value.value.array.entries[j].value.bytes.len = 
(*it).second[j].size();
            table.entries[i].value.value.array.entries[j].value.bytes.bytes 
= (void *) (*it).second[j].c_str();
         }
         LogInfo(("Before1 pointer: %p", 
table.entries[i].value.value.array.entries));
      }
   }

   amqp_queue_declare_ok_t *r =
      amqp_queue_declare(m_conn, m_channel, 
amqp_cstring_bytes(m_queue.c_str()), 0, 1, 0, 0, table);

   for (size_t i = 0; i < array_ptrs.size(); i++) {
      free(array_ptrs[i]);
   }
   free(table.entries);

This works perfectly fine. But the crash happens when I replace

   for (size_t i = 0; i < array_ptrs.size(); i++) {
      free(array_ptrs[i]);
   }

with
   for (int k = 0; k < table.num_entries; k++) {
       LogInfo(("After pointer: %p", 
table.entries[i].value.value.array.entries));
*       free(table.entries[k].value.value.array.entries);*
   }

The "After pointer:" is never the same as "Before pointer:". What wrong am 
I doing here?

Thanks,
Arun

PS: I'm using the following diagnostic log library: 
https://github.com/visionofarun/CPPLogger
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