[DISCUSSION] IEP-114: Custom Metrics

[Vladimir Steshin]

Hi, Igniters! I'd like to propose a new feature - Custom Metrics. This 
would allow a user to register his own measurement and monitoring values.
Short IEP description: 1. Custom metrics are convenient to gather 
different application metrics using the same client/platform/API. Or 
when the existing metrics have no values that user would like to get. 2. 
Custom metrics are just the New Metric System. We only expose the APIs.
3. Custom metrics can be registered, for example, with services, tasks, 
computations.
4. Names of user's own metrics are required to start with "custom.". 5. 
Custom metrics aren't stored.
IEP-114 [1] has more details. Please share your thoughts. Thanks!
[1] 
https://cwiki.apache.org/confluence/display/IGNITE/IEP-114+Custom+metrics