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# Copyright (c) 2018 Sqreen. All Rights Reserved.
# Please refer to our terms for more information: https://www.sqreen.io/terms.html
require 'sqreen/metrics/base'
module Sqreen
module Metric
# Takes numbers as samples and bins them (effectively, rounds them).
class Binning < Base
# upper bound of i-th bin is factor * base^(i-1)
def initialize(base, factor)
super()
@base = base
@factor = factor
log_base = Math.log(base)
log_factor = Math.log(factor)
@inv_log_base = 1 / log_base
@add_parcel = - log_factor / log_base
new_sample(Time.now.utc)
end
def update(_at, _key, x)
h = @sample[OBSERVATION_KEY]
bin = bin_no(x)
h[bin] += 1
end
def next_sample(time)
return nil if @sample[OBSERVATION_KEY].empty?
super(time)
end
protected
# these two are called by next_sample
def finalize_sample(time)
@sample[FINISH_KEY] = time
h = @sample[OBSERVATION_KEY]
@sample[OBSERVATION_KEY] = { 'u' => @factor, 'b' => @base, 'v' => h }
end
def new_sample(time)
@sample = {
OBSERVATION_KEY => Hash.new { |hash, key| hash[key] = 0 },
START_KEY => time,
}
end
private
def bin_no(x)
res = 2 + (@inv_log_base * Math.log(x) + @add_parcel).floor
res < 1 ? 1 : res
end
end
# overrides the constructor
class ParameterizedBinning < Binning
def initialize
raise 'Not configured' unless self.class.base && self.class.factor
super(self.class.base, self.class.factor)
end
class << self
attr_reader :base, :factor
def parameters(opts)
@base = opts[:base]
@factor = opts[:factor]
end
end
end
end
end
Version data entries
18 entries across 18 versions & 2 rubygems