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Contents
# frozen_string_literal: true
require_relative 'sampler'
require_relative '../utils'
module Datadog
module Tracing
module Sampling
# {Datadog::Tracing::Sampling::RateSampler} is based on a sample rate.
class RateSampler < Sampler
KNUTH_FACTOR = 1111111111111111111
# Initialize a {Datadog::Tracing::Sampling::RateSampler}.
# This sampler keeps a random subset of the traces. Its main purpose is to
# reduce the instrumentation footprint.
#
# @param sample_rate [Numeric] the sample rate between 0.0 and 1.0, inclusive.
# 0.0 means that no trace will be sampled; 1.0 means that all traces will be sampled.
def initialize(sample_rate = 1.0, decision: nil)
super()
unless sample_rate >= 0.0 && sample_rate <= 1.0
Datadog.logger.error('sample rate is not between 0 and 1, falling back to 1')
sample_rate = 1.0
end
self.sample_rate = sample_rate
@decision = decision
end
def sample_rate(*_)
@sample_rate
end
def sample_rate=(sample_rate)
@sample_rate = sample_rate
@sampling_id_threshold = sample_rate * Tracing::Utils::EXTERNAL_MAX_ID
end
def sample?(trace)
((trace.id * KNUTH_FACTOR) % Tracing::Utils::EXTERNAL_MAX_ID) <= @sampling_id_threshold
end
def sample!(trace)
sampled = sample?(trace)
return false unless sampled
trace.sample_rate = @sample_rate
trace.set_tag(Tracing::Metadata::Ext::Distributed::TAG_DECISION_MAKER, @decision) if @decision
true
end
end
end
end
end
Version data entries
6 entries across 6 versions & 1 rubygems