Github user HeartSaVioR commented on a diff in the pull request:
https://github.com/apache/storm/pull/2628#discussion_r180614324
--- Diff: docs/metrics_v2.md ---
@@ -0,0 +1,149 @@
+---
+title: Metrics Reporting API v2
+layout: documentation
+documentation: true
+---
+Apache Storm version 1.2 introduced a new metrics system for reporting
+internal statistics (e.g. acked, failed, emitted, transferred, disruptor
queue metrics, etc.) as well as a
+new API for user defined metrics.
+
+The new metrics system is based on [Dropwizard
Metrics](http://metrics.dropwizard.io).
+
+
+## User Defined Metrics
+To allow users to define custom metrics, the following methods have been
added to the `TopologyContext`
+class, an instance of which is passed to spout's `open()` method and
bolt's `prepare()` method:
+
+ public Timer registerTimer(String name)
+
+ public Histogram registerHistogram(String name)
+
+ public Meter registerMeter(String name)
+
+ public Counter registerCounter(String name)
+
+ public Gauge registerGauge(String name, Gauge gauge)
+
+API documentation:
[Timer](http://metrics.dropwizard.io/4.0.0/apidocs/com/codahale/metrics/Timer.html),
+[Histogram](http://metrics.dropwizard.io/4.0.0/apidocs/com/codahale/metrics/Histogram.html),
+[Meter](http://metrics.dropwizard.io/4.0.0/apidocs/com/codahale/metrics/Meter.html),
+[Counter](http://metrics.dropwizard.io/4.0.0/apidocs/com/codahale/metrics/Counter.html),
+[Guage](http://metrics.dropwizard.io/4.0.0/apidocs/com/codahale/metrics/Gauge.html)
--- End diff --
nit: Guage -> Gauge. Missed spot while reviewing 1.x doc. Could you also
please raise a patch for 1.x version too?
---
