[SNMP4J] Statistics about number of retries and snmp request times

[Frank Fock]

Hi Michal,

The latest SNMP4J 2.4.2 snapshot version contains an implementation that 
provides
the statistics you were interested in by using the CounterSupport mechanism.
Please try it out. Comments/suggestions are welcome :-)

Best regards,
Frank

Am 23.01.2016 um 11:06 schrieb Frank Fock:
> Hi Michal,
> This is a very good idea. I missed it yet, because I  only thought about the standard SNMP
> message counters, which do not include retries and response times.
> I will add that for the next release (soon to come because of two other bug reports).
>
> Best regards,
> Frank
>
>
>
>> On 22 Jan 2016, at 10:05, Michał Steiner <mist at mist.pl> wrote:
>>
>> Hi,
>>
>> I'm looking for  a way to gather detailed statistics about SNMP
>> communication (number of retries and exact times).
>> SNMP4j supports  re-sending request if response didn't come within timeout
>> limit which is very useful feature but it can mask some issues existing in
>> the network. For example when there is a lot of retries because we are
>> loosing some pockets, it will not be obviously visible. To find out how
>> many retries was required you need to measure time between send request and
>> getting response then depending on your TimeOutModel you need make some
>> calculations.
>>
>> This approach is not very useful because:
>> - calculations may not be accurate  because we measure time of whole
>> message handling not sending single PDU
>> - you will need to modify all places in your code where you calling SNMP4j
>> send method. It could be many of them.
>>
>> Much better would be have possibility to get such info from Snmp class. For
>> example you could add request  listener to the Snmp, and  in
>> PendingRequest#responseReceived() method notify it about received
>> response, something like this:
>>
>> public void responseReceived() {
>>
>> requestListener.onResponseReceived(
>> target.getAddress(), //ip address
>> pdu.getType(),  //get get-next etc
>> pdu.size(),  //how many oids
>> (System.nanoTime() - startedInNano) /
>> SnmpConstants.MILLISECOND_TO_NANOSECOND ,  //how many ms was from creation
>> of thiss PendingRequest till getting response
>> target.getRetries() - retryCount);//how many retries
>>
>> this.responseReceived = true;
>> ...
>>
>>   public interface RequestListener{
>>     void onResponseReceived(Address address,int type, int size, long
>> durationInMs, int retries);
>>   }
>>
>>
>>
>> Passing this request listener would be optional. It would be useful to have
>> also info about request without response and cancelled.
>>
>> Do you think it is good approach ?
>>
>> Maybe you have other ideas how to gather such data?
>>
>> Best Regards
>> Michal
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