Class: NewRelic::Agent::AdaptiveSampler

Inherits:
Object
  • Object
show all
Defined in:
lib/new_relic/agent/adaptive_sampler.rb

Instance Method Summary collapse

Constructor Details

#initialize(target_samples = 10, period_duration = 60) ⇒ AdaptiveSampler

Returns a new instance of AdaptiveSampler.



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# File 'lib/new_relic/agent/adaptive_sampler.rb', line 8

def initialize(target_samples = 10, period_duration = 60)
  @target = target_samples
  @seen = 0
  @seen_last = 0
  @sampled_count = 0
  @period_duration = period_duration
  @first_period = true
  @period_start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
  @lock = Mutex.new
  register_config_callbacks
end

Instance Method Details

#exponential_backoff ⇒ Object 



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# File 'lib/new_relic/agent/adaptive_sampler.rb', line 42

def exponential_backoff
  @target**(@target.to_f / @sampled_count) - @target**0.5
end

#sampled? ⇒ Boolean

Called at the beginning of each transaction, increments seen and returns a boolean indicating if we should mark the transaction as sampled. This uses the adaptive sampling algorithm.

Returns:

  • (Boolean) 


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# File 'lib/new_relic/agent/adaptive_sampler.rb', line 23

def sampled?
  @lock.synchronize do
    reset_if_period_expired!
    sampled = if @first_period
      @sampled_count < 10
    elsif @sampled_count < @target
      rand(@seen_last) < @target
    else
      # you've met the target and need to exponentially back off
      rand(@seen) < exponential_backoff
    end

    @sampled_count += 1 if sampled
    @seen += 1

    sampled
  end
end

#stats ⇒ Object 



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# File 'lib/new_relic/agent/adaptive_sampler.rb', line 46

def stats
  @lock.synchronize do
    {
      target: @target,
      seen: @seen,
      seen_last: @seen_last,
      sampled_count: @sampled_count
    }
  end
end