[Hawkular-dev] [Metrics] Pluggable aggregation functions: next steps

[Jay Shaughnessy]

Sure, sorry to have missed the point.  This is interesting though, it 
may pave the way for being to alert on values generated by a plugin 
specifically for the purpose of that alert use case.

On 7/22/2015 5:02 AM, Thomas Segismont wrote:
> Thanks for the pointers, we'll have a look.
>
> Le 21/07/2015 23:27, Jay Shaughnessy a écrit :
>> Right, you may find what you need is already in place, or you may find
>> that you can spend time on higher-level functions.  In particular, see:
>>
>> MetricsService:
>> <T> Observable<T> findGaugeData(String tenantId, MetricId id, Long
>> start, Long end,Func1<Observable<DataPoint<Double>>, Observable<T>>...
>> funcs);
>>
>> Aggregate:
>> predefined functions.
>>
>> Here is an example snippen from
>> org.hawkular.alerts.external.metrics.Manager to gather multiple
>> aggregates in one call and determine the range:
>>
>>                       case range: {
>>                           Iterator<Double> iterator =
>> metrics.findGaugeData(tenantId, metricId, start, end,
>>                                   Aggregate.Min, Aggregate.Max)
>> .toBlocking().toIterable().iterator();
>>                           Double min = iterator.next();
>>                           Double max = iterator.next();
>>                           value = max - min;
>>                           break;
>>                       }
>>
>>
>> -Jay
>>
>> On 7/21/2015 10:43 AM, John Sanda wrote:
>>> Keep the following in mind. Since the core metrics API is now built on
>>> RxJava, function params and return types should probably be
>>> rx.Observable. Some of the work described below may already be covered
>>> by the work Jay did for HWKMETRICS-144 which involved adding
>>> min/max/avg functions. To be honest, I think functions like
>>> min/max/avg are poor candidates for some of the changes being
>>> discussed because they are so simple. Here is our avg function,
>>>
>>> Func1<Observable<DataPoint<Double>>, Observable<Double>> Average =
>>> data ->
>>> MathObservable.averageDouble(data.map(DataPoint::getValue));
>>>
>>> For other, more involved functions, I think we should look first at
>>> the core operators in Rx.Observable and then maybe consider custom
>>> operators[1].
>>>
>>> [1]
>>> https://github.com/ReactiveX/RxJava/wiki/Implementing-Your-Own-Operators
>>>
>>>> On Jul 21, 2015, at 5:43 AM, Thomas Segismont <tsegismo at redhat.com
>>>> <mailto:tsegismo at redhat.com>> wrote:
>>>>
>>>> Hi,
>>>>
>>>> I have looked at Aakarsh's repo:
>>>> https://github.com/Akki5/hawkular_plugin/
>>>>
>>>> It's a good start with an interface describing a doubles to double
>>>> function, a classloader for implementation loading and a set of initial
>>>> implementations.
>>>>
>>>> In order to integrate this work into Metrics, I think we should follow
>>>> the following steps:
>>>>
>>>> =====
>>>> #1 Change the contract
>>>>
>>>> Doubles to double works great for avg/min/max/... functions on gauge
>>>> metrics. But we need to consider other metric types.
>>>>
>>>> Also, the interface should not only accept data point values, but whole
>>>> data points. Because some functions need the timestamp to compute the
>>>> result. % of up availability is a good example.
>>>>
>>>> And functions may return different types: Double, Long, AvailabilityType.
>>>>
>>>> #2 Update configuration options to let the user set a plugins directory
>>>>
>>>> Metrics doc needs will have to be updated.
>>>>
>>>> #3 Create a function repository for each metric type
>>>>
>>>> We can build on JDK's service loader + Aakarsh's classloader
>>>> implementation.
>>>>
>>>> #4 Add builtin aggregate functions
>>>>
>>>> Extract existing Metrics code (min, max, avg, % of up avail, downtime
>>>> duration) into builtin functions.
>>>>
>>>> #5 Document the process of implementing a pluggable function
>>>>
>>>> We need to think about function naming as well. Should we use a prefix
>>>> to identify a builtin function?
>>>> =====
>>>>
>>>> I will start another thread to discuss REST and Core API data query
>>>> changes.
>>>>
>>>> Thoughts?
>>>>
>>>> Thanks,
>>>> Thomas
>>>> _______________________________________________
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>>>> https://lists.jboss.org/mailman/listinfo/hawkular-dev
>>>
>>>
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>>
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