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Add more tests.
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@songy23
songy23 committed May 23, 2019
1 parent 7c5b7dc commit d3d027e
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207 changes: 207 additions & 0 deletions sdk/src/test/java/io/opentelemetry/sdk/trace/samplers/ProbabilitySamplerTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,22 @@

import static com.google.common.truth.Truth.assertThat;

import io.opentelemetry.trace.AttributeValue;
import io.opentelemetry.trace.Event;
import io.opentelemetry.trace.Link;
import io.opentelemetry.trace.Sampler;
import io.opentelemetry.trace.Span;
import io.opentelemetry.trace.SpanContext;
import io.opentelemetry.trace.SpanId;
import io.opentelemetry.trace.Status;
import io.opentelemetry.trace.TraceId;
import io.opentelemetry.trace.TraceOptions;
import io.opentelemetry.trace.Tracestate;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.UUID;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ExpectedException;
Expand All @@ -28,6 +44,65 @@
@RunWith(JUnit4.class)
public class ProbabilitySamplerTest {

private static final String SPAN_NAME = "MySpanName";
private static final int NUM_SAMPLE_TRIES = 1000;
private final TraceId traceId = generateRandomTraceId();
private final SpanId parentSpanId = generateRandomSpanId();
private final Tracestate tracestate = Tracestate.builder().build();
private final SpanContext sampledSpanContext =
SpanContext.create(
traceId, parentSpanId, TraceOptions.builder().setIsSampled(true).build(), tracestate);
private final SpanContext notSampledSpanContext =
SpanContext.create(traceId, parentSpanId, TraceOptions.DEFAULT, tracestate);
private final Span sampledSpan =
new Span() {
@Override
public void setAttribute(String key, String value) {}

@Override
public void setAttribute(String key, long value) {}

@Override
public void setAttribute(String key, double value) {}

@Override
public void setAttribute(String key, boolean value) {}

@Override
public void setAttribute(String key, AttributeValue value) {}

@Override
public void addEvent(String name) {}

@Override
public void addEvent(String name, Map<String, AttributeValue> attributes) {}

@Override
public void addEvent(Event event) {}

@Override
public void addLink(Link link) {}

@Override
public void setStatus(Status status) {}

@Override
public void updateName(String name) {}

@Override
public void end() {}

@Override
public SpanContext getContext() {
return sampledSpanContext;
}

@Override
public boolean isRecordingEvents() {
return true;
}
};

@Rule public final ExpectedException thrown = ExpectedException.none();

@Test
Expand All @@ -52,4 +127,136 @@ public void probabilitySampler_getDescription() {
public void probabilitySampler_ToString() {
assertThat(ProbabilitySampler.create(0.5).toString()).contains("0.5");
}

// Applies the given sampler to NUM_SAMPLE_TRIES random traceId/spanId pairs.
private static void assertSamplerSamplesWithProbability(
Sampler sampler, SpanContext parent, List<Span> parentLinks, double probability) {
int count = 0; // Count of spans with sampling enabled
for (int i = 0; i < NUM_SAMPLE_TRIES; i++) {
if (sampler.shouldSample(
parent, false, generateRandomTraceId(), generateRandomSpanId(), SPAN_NAME, parentLinks)) {
count++;
}
}
double proportionSampled = (double) count / NUM_SAMPLE_TRIES;
// Allow for a large amount of slop (+/- 10%) in number of sampled traces, to avoid flakiness.
assertThat(proportionSampled < probability + 0.1 && proportionSampled > probability - 0.1)
.isTrue();
}

@Test
public void probabilitySampler_DifferentProbabilities_NotSampledParent() {
final Sampler fiftyPercentSample = ProbabilitySampler.create(0.5);
assertSamplerSamplesWithProbability(
fiftyPercentSample, notSampledSpanContext, Collections.<Span>emptyList(), 0.5);
final Sampler twentyPercentSample = ProbabilitySampler.create(0.2);
assertSamplerSamplesWithProbability(
twentyPercentSample, notSampledSpanContext, Collections.<Span>emptyList(), 0.2);
final Sampler twoThirdsSample = ProbabilitySampler.create(2.0 / 3.0);
assertSamplerSamplesWithProbability(
twoThirdsSample, notSampledSpanContext, Collections.<Span>emptyList(), 2.0 / 3.0);
}

@Test
public void probabilitySampler_DifferentProbabilities_SampledParent() {
final Sampler fiftyPercentSample = ProbabilitySampler.create(0.5);
assertSamplerSamplesWithProbability(
fiftyPercentSample, sampledSpanContext, Collections.<Span>emptyList(), 1.0);
final Sampler twentyPercentSample = ProbabilitySampler.create(0.2);
assertSamplerSamplesWithProbability(
twentyPercentSample, sampledSpanContext, Collections.<Span>emptyList(), 1.0);
final Sampler twoThirdsSample = ProbabilitySampler.create(2.0 / 3.0);
assertSamplerSamplesWithProbability(
twoThirdsSample, sampledSpanContext, Collections.<Span>emptyList(), 1.0);
}

@Test
public void probabilitySampler_DifferentProbabilities_SampledParentLink() {
final Sampler fiftyPercentSample = ProbabilitySampler.create(0.5);
assertSamplerSamplesWithProbability(
fiftyPercentSample, notSampledSpanContext, Arrays.asList(sampledSpan), 1.0);
final Sampler twentyPercentSample = ProbabilitySampler.create(0.2);
assertSamplerSamplesWithProbability(
twentyPercentSample, notSampledSpanContext, Arrays.asList(sampledSpan), 1.0);
final Sampler twoThirdsSample = ProbabilitySampler.create(2.0 / 3.0);
assertSamplerSamplesWithProbability(
twoThirdsSample, notSampledSpanContext, Arrays.asList(sampledSpan), 1.0);
}

@Test
public void probabilitySampler_SampleBasedOnTraceId() {
final Sampler defaultProbability = ProbabilitySampler.create(0.0001);
// This traceId will not be sampled by the ProbabilitySampler because the first 8 bytes as long
// is not less than probability * Long.MAX_VALUE;
TraceId notSampledtraceId =
TraceId.fromBytes(
new byte[] {
(byte) 0x8F,
(byte) 0xFF,
(byte) 0xFF,
(byte) 0xFF,
(byte) 0xFF,
(byte) 0xFF,
(byte) 0xFF,
(byte) 0xFF,
0,
0,
0,
0,
0,
0,
0,
0
},
0);
assertThat(
defaultProbability.shouldSample(
null,
false,
notSampledtraceId,
generateRandomSpanId(),
SPAN_NAME,
Collections.<Span>emptyList()))
.isFalse();
// This traceId will be sampled by the ProbabilitySampler because the first 8 bytes as long
// is less than probability * Long.MAX_VALUE;
TraceId sampledtraceId =
TraceId.fromBytes(
new byte[] {
(byte) 0x00,
(byte) 0x00,
(byte) 0xFF,
(byte) 0xFF,
(byte) 0xFF,
(byte) 0xFF,
(byte) 0xFF,
(byte) 0xFF,
0,
0,
0,
0,
0,
0,
0,
0
},
0);
assertThat(
defaultProbability.shouldSample(
null,
false,
sampledtraceId,
generateRandomSpanId(),
SPAN_NAME,
Collections.<Span>emptyList()))
.isTrue();
}

private static TraceId generateRandomTraceId() {
return TraceId.fromLowerBase16(UUID.randomUUID().toString().replace("-", ""), 0);
}

private static SpanId generateRandomSpanId() {
return SpanId.fromLowerBase16(UUID.randomUUID().toString().replace("-", ""), 0);
}
}

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