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module Datadog
# \Sampler performs client-side trace sampling.
class Sampler
def sample(_span)
raise NotImplementedError, 'samplers have to implement the sample() method'
end
end
# \AllSampler samples all the traces.
class AllSampler < Sampler
def sample(span)
span.sampled = true
end
end
# \RateSampler is based on a sample rate.
class RateSampler < Sampler
KNUTH_FACTOR = 1111111111111111111
SAMPLE_RATE_METRIC_KEY = '_sample_rate'.freeze()
attr_reader :sample_rate
# Initialize a \RateSampler.
# This sampler keeps a random subset of the traces. Its main purpose is to
# reduce the instrumentation footprint.
#
# * +sample_rate+: the sample rate as a \Float between 0.0 and 1.0. 0.0
# means that no trace will be sampled; 1.0 means that all traces will be
# sampled.
def initialize(sample_rate = 1.0)
unless sample_rate > 0.0 && sample_rate <= 1.0
Datadog::Tracer.log.error('sample rate is not between 0 and 1, disabling the sampler')
sample_rate = 1.0
end
self.sample_rate = sample_rate
end
def sample_rate=(sample_rate)
@sample_rate = sample_rate
@sampling_id_threshold = sample_rate * Span::MAX_ID
end
def sample(span)
span.sampled = ((span.trace_id * KNUTH_FACTOR) % Datadog::Span::MAX_ID) <= @sampling_id_threshold
span.set_metric(SAMPLE_RATE_METRIC_KEY, @sample_rate)
end
end
end
Version data entries
14 entries across 14 versions & 2 rubygems