class Cabin::Metrics
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 a time-observing interface on top of histogram.
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.
Public Class Methods
Get us a new metrics container.
# File lib/cabin/metrics.rb, line 53 def initialize @metrics_lock = Mutex.new @metrics = {} end
Public Instance Methods
Create a new Counter
metric 'instance' is usually an object owning this metric, but it can be a string. 'name' is the name of the metric.
# File lib/cabin/metrics.rb, line 89 def counter(instance, name=nil) return create(instance, name, Cabin::Metrics::Counter.new) end
iterate over each metric. yields identifer, metric
# File lib/cabin/metrics.rb, line 118 def each(&block) # delegate to the @metrics hash until we need something fancier @metrics_lock.synchronize do @metrics.each(&block) end end
Create a new Histogram
metric 'instance' is usually an object owning this metric, but it can be a string. 'name' is the name of the metric.
# File lib/cabin/metrics.rb, line 105 def histogram(instance, name=nil) return create(instance, name, Cabin::Metrics::Histogram.new) end
Create a new Meter
metric 'instance' is usually an object owning this metric, but it can be a string. 'name' is the name of the metric.
# File lib/cabin/metrics.rb, line 97 def meter(instance, name=nil) return create(instance, name, Cabin::Metrics::Meter.new) end
Create a new Timer
metric 'instance' is usually an object owning this metric, but it can be a string. 'name' is the name of the metric.
# File lib/cabin/metrics.rb, line 113 def timer(instance, name=nil) return create(instance, name, Cabin::Metrics::Timer.new) end
Private Instance Methods
# File lib/cabin/metrics.rb, line 59 def create(instance, name, metric_object) if !instance.is_a?(String) instance = "#{instance.class.name}<#{instance.object_id}>" end if name.nil? # If no name is given, use the class name of the metric. # For example, if we invoke Metrics#timer("foo"), the metric # name will be "foo/timer" metric_name = "#{instance}/#{metric_object.class.name.split("::").last.downcase}" else # Otherwise, use "instance/name" as the name. metric_name = "#{instance}/#{name}" end metric_object.channel = @channel metric_object.instance = metric_name if @channel @channel.debug("Created metric", :instance => instance, :type => metric_object.class) end return @metrics_lock.synchronize do @metrics[metric_name] = metric_object end end