99 lines
2.9 KiB
Ruby
99 lines
2.9 KiB
Ruby
# frozen_string_literal: true
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RSpec.shared_examples 'metrics sampler' do |env_prefix|
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context 'when sampling interval is passed explicitly' do
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subject(:sampler) { described_class.new(interval: 42, logger: double) }
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specify { expect(sampler.interval).to eq(42) }
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end
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context 'when sampling interval is passed through the environment' do
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subject(:sampler) { described_class.new(logger: double) }
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before do
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stub_env("#{env_prefix}_INTERVAL_SECONDS", '42')
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end
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specify { expect(sampler.interval).to eq(42) }
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end
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context 'when no sampling interval is passed anywhere' do
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subject(:sampler) { described_class.new(logger: double) }
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it 'uses the hardcoded default' do
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expect(sampler.interval).to eq(described_class::DEFAULT_SAMPLING_INTERVAL_SECONDS)
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end
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end
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describe '#start' do
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include WaitHelpers
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subject(:sampler) { described_class.new(interval: 0.1) }
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it 'calls the sample method on the sampler thread' do
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sampling_threads = []
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expect(sampler).to receive(:sample).at_least(:once) { sampling_threads << Thread.current }
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sampler.start
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wait_for('sampler has sampled', max_wait_time: 3) { sampling_threads.any? }
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expect(sampling_threads.first.name).to eq(sampler.thread_name)
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sampler.stop
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end
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context 'with warmup set to true' do
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subject(:sampler) { described_class.new(interval: 0.1, warmup: true) }
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it 'calls the sample method first on the caller thread' do
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sampling_threads = []
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current_thread = Thread.current
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# Instead of sampling, we're keeping track of which thread the sampling happened on.
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# We want the first sample to be on the spec thread, which would mean a blocking sample
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# before the actual sampler thread starts.
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expect(sampler).to receive(:sample).at_least(:once) { sampling_threads << Thread.current }
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sampler.start
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wait_for('sampler has sampled', max_wait_time: 3) { sampling_threads.size == 2 }
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expect(sampling_threads.first).to be(current_thread)
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expect(sampling_threads.last.name).to eq(sampler.thread_name)
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sampler.stop
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end
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end
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end
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describe '#safe_sample' do
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let(:logger) { Logger.new(File::NULL) }
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subject(:sampler) { described_class.new(logger: logger) }
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it 'calls #sample once' do
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expect(sampler).to receive(:sample)
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sampler.safe_sample
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end
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context 'when sampling fails with error' do
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before do
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expect(sampler).to receive(:sample).and_raise "something failed"
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end
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it 'recovers from errors' do
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expect { sampler.safe_sample }.not_to raise_error
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end
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context 'with logger' do
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let(:logger) { double('logger') }
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it 'logs errors' do
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expect(logger).to receive(:warn).with(an_instance_of(String))
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expect { sampler.safe_sample }.not_to raise_error
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end
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end
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end
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end
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end
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