Class: VCAP::RollingMetric

Inherits:
Object
  • Object
show all
Defined in:
lib/vcap/rolling_metric.rb

Direct Known Subclasses

ThreadSafeRollingMetric

Instance Method Summary collapse

Constructor Details

#initialize(duration, num_buckets = 60) ⇒ RollingMetric

Returns a new instance of RollingMetric.



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# File 'lib/vcap/rolling_metric.rb', line 7

def initialize(duration, num_buckets = 60)
  @duration = duration
  num_buckets = [@duration, num_buckets].min
  @bucket_duration = (@duration / num_buckets).to_i
  @eviction_duration = @bucket_duration * 2
  @buckets = []
  num_buckets.times do
    @buckets << {:timestamp => 0, :value => 0, :samples => 0}
  end
end

Instance Method Details

#<<(value) ⇒ Object 



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# File 'lib/vcap/rolling_metric.rb', line 18

def <<(value)
  timestamp = Time.now.to_i
  bucket = @buckets[(timestamp / @bucket_duration) % @buckets.length]
  if timestamp - bucket[:timestamp] > @eviction_duration
    bucket[:timestamp] = timestamp
    bucket[:value] = value
    bucket[:samples] = 1
  else
    bucket[:value] += value
    bucket[:samples] += 1
  end
end

#to_json ⇒ Object 



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# File 'lib/vcap/rolling_metric.rb', line 51

def to_json
  Yajl::Encoder.encode(value)
end

#value ⇒ Object 



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# File 'lib/vcap/rolling_metric.rb', line 31

def value
  timestamp = Time.now.to_i
  min_timestamp = timestamp - @duration

  value = 0
  samples = 0

  @buckets.each do |bucket|
    if bucket[:timestamp] > min_timestamp
      value += bucket[:value]
      samples += bucket[:samples]
    end
  end

  {
    :value => value,
    :samples => samples
  }
end