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require 'metriks/counter'
require 'metriks/timer'
require 'metriks/utilization_timer'
require 'metriks/meter'
require 'metriks/gauge'
module Metriks
# Public: A collection of metrics
class Registry
# Public: The default registry for the process.
#
# Returns the default Registry for the process.
def self.default
@default ||= new
end
# Public: Initializes a new Registry.
def initialize
@mutex = Mutex.new
@metrics = {}
end
# Public: Clear all of the metrics in the Registry. This ensures all
# metrics that have been added are stopped.
#
# Returns nothing.
def clear
@mutex.synchronize do
@metrics.each do |key, metric|
metric.stop if metric.respond_to?(:stop)
end
@metrics = {}
end
end
# Public: Clear all of the metrics in the Registry. This has the same
# effect as calling #clear.
#
# Returns nothing.
def stop
clear
end
# Public: Iterate over all of the counters.
#
# Examples
#
# registry.each do |name, metric|
# puts name
# end
#
# Returns nothing.
def each(&block)
metrics = @mutex.synchronize do
@metrics.dup
end
metrics.each(&block)
end
# Public: Fetch or create a new counter metric. Counters are one of the
# simplest metrics whose only operations are increment and decrement.
#
# name - The String name of the metric to define or fetch
#
# Examples
#
# registry.counter('method.calls')
#
# Returns the Metriks::Counter identified by the name.
def counter(name)
add_or_get(name, Metriks::Counter)
end
# Public: Fetch or create a new gauge metric.
#
# name - The String name of the metric to define or fetch
#
# Examples
#
# registry.gauge('disk_space.used') { 1 }
#
# Returns the Metriks::Gauge identified by the name.
def gauge(name, callable = nil, &block)
add_or_get(name, Metriks::Gauge) do
Metriks::Gauge.new(callable, &block)
end
end
# Public: Fetch or create a new meter metric. Meters are a counter that
# tracks throughput along with the count.
#
# name - The String name of the metric to define or fetch
#
# Examples
#
# registry.meter('resque.calls')
#
# Returns the Metriks::Meter identified by the name.
def meter(name)
add_or_get(name, Metriks::Meter)
end
# Public: Fetch or create a new timer metric. Timers provide the means to
# time the execution of a method including statistics on the number of
# invocations, average length of time, throughput.
#
# name - The String name of the metric to define or fetch
#
# Examples
#
# registry.timer('resque.worker')
#
# Returns the Metriks::Timer identified by the name.
def timer(name)
add_or_get(name, Metriks::Timer)
end
# Public: Fetch or create a new utilization timer metric.
#
# Utilization timers are a specialized version of a timer that calculate
# the percentage of wall-clock time (between 0 and 1) that was spent in
# the method. This metric is most valuable in a single-threaded
# environment where a processes is waiting on an external resource like a
# message queue or HTTP server.
#
# name - The String name of the metric to define or fetch
#
# Examples
#
# registry.utilization_timer('rack.utilization')
#
# Returns the Metriks::UtilizationTimer identified by the name.
def utilization_timer(name)
add_or_get(name, Metriks::UtilizationTimer)
end
# Public: Fetch or create a new histogram metric. Histograms record values
# and expose statistics about the distribution of the data like median and
# 95th percentile.
#
# name - The String name of the metric to define or fetch
#
# Examples
#
# registry.histogram('backlog.wait')
#
# Returns the Metriks::Histogram identified by the name.
def histogram(name)
add_or_get(name, Metriks::Histogram) do
Metriks::Histogram.new_exponentially_decaying
end
end
# Public: Fetch an existing metric.
#
# name - The String name of the metric to fetch
#
# Examples
#
# registry.get('rack.utilization')
#
# Returns the metric or nil.
def get(name)
@mutex.synchronize do
@metrics[name]
end
end
# Public: Add a new metric.
#
# name - The String name of the metric to add
# metric - The metric instance to add
#
# Examples
#
# registry.add('method.calls', Metriks::Counter.new)
#
# Returns nothing.
# Raises RuntimeError if the metric name is already defined
def add(name, metric)
@mutex.synchronize do
if @metrics[name]
raise "Metric '#{name}' already defined"
else
@metrics[name] = metric
end
end
end
protected
def add_or_get(name, klass, &create_metric)
@mutex.synchronize do
if metric = @metrics[name]
if !metric.is_a?(klass)
raise "Metric already defined as '#{metric.class}'"
else
return metric
end
else
@metrics[name] = create_metric ? create_metric.call : klass.new
end
end
end
end
end
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