Class: Cabin::Metrics

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/cabin/metrics.rb,
lib/cabin/namespace.rb

Overview

What type of metrics do we want?

What metrics should come by default? Per-call/transaction/request metrics like:

- hit (count++ type metrics)
- latencies/timings

Per app or generally long-lifetime metrics like:

- "uptime"
- cpu usage
- memory usage
- count of active/in-flight actions/requests/calls/transactions
- peer metrics (number of cluster members, etc)

github.com/codahale/metrics/tree/master/metrics-core/src/main/java/com/yammer/metrics/core Reading what Coda Hale’s “Metrics” stuff has, here’s my summary:

gauges (callback to return a number)
counters (.inc and .dec methods)
meters (.mark to track each 'hit')
  Also exposes 1, 5, 15 minute moving averages
histograms: (.update(value) to record a new value)
  like meter, but takes values more than simply '1'
  as a result, exposes percentiles, median, etc.
timers
  combination of meter + histogram
  meter for invocations, histogram for duration

With the exception of gauges, all the other metrics are all active/pushed. Gauges take callbacks, so their values are pulled, not pushed. The active metrics can be represented as events since they the update occurs at the time of the change.

These active/push metrics can therefore be considered events.

All metrics (active/passive) can be queried for ‘current state’, too, making this suitable for serving to interested parties like monitoring and management tools.

Defined Under Namespace

Classes: Counter, Gauge, Meter, Timer

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Metrics

Returns a new instance of Metrics.



51
52
53
 
# File 'lib/cabin/metrics.rb', line 51

def initialize
  @metrics = {}
end

Instance Method Details

#counter(instance, name = nil) ⇒ Object 



63
64
65
 
# File 'lib/cabin/metrics.rb', line 63

def counter(instance, name=nil)
  return create(instance, name, Cabin::Metrics::Counter.new)
end

#each(&block) ⇒ Object

iterate over each metric. yields identifer, metric



83
84
85
86
 
# File 'lib/cabin/metrics.rb', line 83

def each(&block)
  # delegate to the @metrics hash until we need something fancier
  @metrics.each(&block)
end

#meter(instance, name = nil) ⇒ Object 



68
69
70
 
# File 'lib/cabin/metrics.rb', line 68

def meter(instance, name=nil)
  return create(instance, name, Cabin::Metrics::Meter.new)
end

#timer(instance, name = nil) ⇒ Object 



78
79
80
 
# File 'lib/cabin/metrics.rb', line 78

def timer(instance, name=nil)
  return create(instance, name, Cabin::Metrics::Timer.new)
end