[AGENT++] Index allocation for multi-index shared table fails

[Frank Fock]

Hi Isaac,
You can find examples of the region registration in the subagent examples that come with AgentX++
The observed memory footprint depends on the index allocation mode you have chosen. Some modes require the master to remember allocated indexes until next reboot. Other modes do not. See the AgentX standard for details.
Best regards 
Frank

> Am 23.05.2018 um 08:19 schrieb Isaac Nickaein <nickaein.i at gmail.com>:
> 
> Hi Frank,
> 
> Thank you for the guidance on AgentX architecture. That's explains why the
> subagent always got only the first sub-index.
> 
> 1. It seems the region registration can be done with
> SubAgentXMib::register_region. Is there any example/reference code on
> region registration to demonstrate it?
> 
> 2. To unregister a region, It seems that register_region should be called
> with the same argument except with mode=FALSE. Is this correct?
> 
> 3. The documentation mentions that the last argument, *reference*, is a
> pointer to the AgentXSharedTable "which initiates the registration". What
> should be done in the table instance (e.g. overriding a method, calling
> register_entry, etc) to manage registration?
> 
> 
> By the way, I have managed to get the multi-index working by the following
> *HACK* in which uses a
> single OID index type instead of two INT types for AgentXSharedTable:
> 
> const index_info my_index_info[] = {
>       {sNMP_SYNTAX_OID, FALSE, 2, 2}
> };
> 
> const Oidx my_index_oids[1] = {
>       "1.3.6.1.4.1.38523.1.2.1537.1.1.1.1.1.1"
> };
> 
> However, there seems to be a memory leak in master. I start and stop the
> subagent multiple times. Each time the subagent will register the same
> table and same indices and then calls *remove_row* on all rows and *clear*
> for my AgentXSharedTable upon exit, but the memory footprint of master
> agent increases without any decline.
> 
> 4. Is there anything else that should be done to free up this memory in
> master agent?
> 
> Nevertheless, the region registration seems a promising approach and
> probably with less complications. I try to see how things work with it.
> 
> 
> Cheers,
> Isaac
> 
>> On Thu, May 17, 2018 at 11:07 AM Frank Fock <fock at agentpp.com> wrote:
>> 
>> Hi Isaac,
> 
>> The problem is the AgentX standard. It defines that only the first
> sub-index is relevant for the index allocation.
>> That is, of course, below common expectations. My recommendation is to do
> only region registration and to leave index allocation unused. It provides
> not much benefit for multi-variable indexed tables.
> 
>> Hope this helps anyway.
> 
>> Best regards,
>> Frank
> 
> 
>>> On 16. May 2018, at 15:44, Isaac Nickaein <nickaein.i at gmail.com> wrote:
>>> 
>>> Hi,
>>> 
>>> The shared table with multi-index is defined as below:
>>> 
>>> char* oid_table_root = "1.3.6.1.4.1.38523.1.2.1537.1.1.1.1.1";
>>> 
>>> index_info my_index_info[2] = {
>>>    {sNMP_SYNTAX_INT, FALSE, 1, 1},
>>>    {sNMP_SYNTAX_INT, FALSE, 1, 1}
>>> };
>>> 
>>> const Oidx my_index_oids[2] = {
>>>    "1.3.6.1.4.1.38523.1.2.1537.1.1.1.1.1.1",
>>>    "1.3.6.1.4.1.38523.1.2.1537.1.1.1.1.1.2",
>>> };
>>> 
>>> MyTableStatus::MyTableStatus(Agentpp::SubAgentXMib* mib_root)
>>> : AgentXSharedTable(
>>>    oid_table_root,
>>>    my_index_info, 2,
>>>    my_index_oids,
>>>    mib_root,
>>>    OctetStr()
>>> )
>>> {
>>>    // Code to add columns
>>> }
>>> 
>>> 
>>> I have tried different ways of allocating a multi-index for this table,
> but
>>> all of them fail with error 259 (AGENTX_INDEX_ALREADY_ALLOCATED):
>>> 
>>> 
>>> void MyTableStatus::my_init_table_rows()
>>> {
>>>    for(int dev_id = 0; dev_id < 10 ; dev_id++)
>>>    {
>>>        for(int tuner_id = 0; tuner_id < 4; tuner_id++)
>>>        {
>>>            // Index1 value: dev_id+1
>>>            // Index2 value: tuner_id+1
>>> 
>>>            // Method 1
>>>            // std::string index_oid_str = std::to_string(dev_id + 1) +
> "."
>>> + std::to_string(tuner_id + 1);
>>>            // Oid index_val_oid(index_oid_str.c_str());
>>> 
>>>            // Method 2
>>>            // Oid index_val_oid;
>>>            // index_val_oid += Oid(std::to_string(dev_id + 1).c_str());
>>>            // index_val_oid += Oid(std::to_string(tuner_id +
> 1).c_str());
>>> 
>>>            // Method 3
>>>            unsigned long* oid_values = new unsigned long[2];
>>>            oid_values[0] = dev_id + 1;
>>>            oid_values[1] = tuner_id + 1;
>>>            Oid index_val_oid(oid_values, 2);
>>> 
>>>            // Request new index
>>>            Oidx index_val(index_val_oid);
>>>            this->allocate_index(index_val);
>>>        }
>>>    }
>>> }
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