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Add an error sampler for Log probes #10638

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8 changes: 7 additions & 1 deletion dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/probe/LogProbe.java
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Original file line number Diff line number Diff line change
Expand Up @@ -325,6 +325,7 @@ public String toString() {
protected transient Map<DDTraceId, AtomicInteger> budget =
Collections.synchronizedMap(new WeakIdentityHashMap<>());
protected transient Sampler sampler;
protected transient Sampler errorSampler;

// no-arg constructor is required by Moshi to avoid creating instance with unsafe and by-passing
// constructors, including field initializers.
Expand Down Expand Up @@ -461,6 +462,7 @@ public void initSamplers() {
? ProbeRateLimiter.DEFAULT_SNAPSHOT_RATE
: ProbeRateLimiter.DEFAULT_LOG_RATE);
sampler = ProbeRateLimiter.createSampler(rate);
errorSampler = ProbeRateLimiter.createSampler(1.0); // errors are always sampled at 1/s rate
}

public List<CaptureExpression> getCaptureExpressions() {
Expand Down Expand Up @@ -565,9 +567,13 @@ private void sample(LogStatus logStatus, MethodLocation methodLocation) {
if (!MethodLocation.isSame(methodLocation, evaluateAt)) {
return;
}
// if condition has error and no capture Snapshot, the error is reported using errorSampler
// at 1/s rate instead of the log template one
Sampler localSampler =
logStatus.hasConditionErrors && !isCaptureSnapshot() ? errorSampler : sampler;
boolean sampled =
!logStatus.getDebugSessionStatus().isDisabled()
&& ProbeRateLimiter.tryProbe(sampler, isCaptureSnapshot());
&& ProbeRateLimiter.tryProbe(localSampler, isCaptureSnapshot());
logStatus.setSampled(sampled);
if (!sampled) {
DebuggerAgent.getSink()
Expand Down
62 changes: 60 additions & 2 deletions ...a-agent/agent-debugger/src/test/java/com/datadog/debugger/agent/CapturedSnapshotTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -73,6 +73,7 @@
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.function.DoubleConsumer;
import java.util.stream.Collectors;
import org.jetbrains.kotlin.com.intellij.util.lang.JavaVersion;
import org.joor.Reflect;
Expand Down Expand Up @@ -1296,6 +1297,35 @@ public void nullCondition() throws IOException, URISyntaxException {
assertEquals("Cannot dereference field: fld", snapshot.getMessage());
}

@Test
public void nullConditionTemplateOnly() throws IOException, URISyntaxException {
final String CLASS_NAME = "CapturedSnapshot08";
LogProbe logProbes =
createProbeBuilder(PROBE_ID, CLASS_NAME, "doit", "int (java.lang.String)")
.when(
new ProbeCondition(
DSL.when(
DSL.eq(
DSL.getMember(
DSL.getMember(DSL.getMember(DSL.ref("nullTyped"), "fld"), "fld"),
"msg"),
DSL.value("hello"))),
"nullTyped.fld.fld.msg == 'hello'"))
.captureSnapshot(false)
.template("plain log", Collections.emptyList())
.build();
TestSnapshotListener listener = installProbes(logProbes);
Class<?> testClass = compileAndLoadClass(CLASS_NAME);
int result = Reflect.onClass(testClass).call("main", "1").get();
assertEquals(3, result);
Snapshot snapshot = assertOneSnapshot(listener);
assertEquals("Cannot dereference field: fld", snapshot.getMessage());
List<EvaluationError> evaluationErrors = snapshot.getEvaluationErrors();
assertEquals(1, evaluationErrors.size());
assertEquals("nullTyped.fld.fld", evaluationErrors.get(0).getExpr());
assertEquals("Cannot dereference field: fld", evaluationErrors.get(0).getMessage());
}

@Test
public void shortCircuitingCondition() throws IOException, URISyntaxException {
final String CLASS_NAME = "CapturedSnapshot08";
Expand Down Expand Up @@ -2676,19 +2706,47 @@ public void ensureCallingSamplingLineProbeCondition() throws IOException, URISyn
doSamplingTest(this::lineProbeCondition, 1, 1);
}

@Test
public void ensureCallingSamplingLogTemplateOnlyConditionError()
throws IOException, URISyntaxException {
doSamplingTest(this::nullConditionTemplateOnly, ProbeRateLimiter::setGlobalLogRate, 1, 0, 1);
}

private void doSamplingTest(TestMethod testRun, int expectedGlobalCount, int expectedProbeCount)
throws IOException, URISyntaxException {
doSamplingTest(
testRun,
ProbeRateLimiter::setGlobalSnapshotRate,
expectedGlobalCount,
expectedProbeCount,
0);
}

private void doSamplingTest(
TestMethod testRun,
DoubleConsumer globalRateSetter,
int expectedGlobalCount,
int expectedProbeCount,
int expectedErrorCount)
throws IOException, URISyntaxException {
MockSampler probeSampler = new MockSampler();
MockSampler errorSampler = new MockSampler();
MockSampler globalSampler = new MockSampler();
ProbeRateLimiter.setSamplerSupplier(rate -> rate < 101 ? probeSampler : globalSampler);
ProbeRateLimiter.setGlobalSnapshotRate(1000);
ProbeRateLimiter.setSamplerSupplier(
rate -> {
if (rate < 2) return errorSampler;
if (rate < 101) return probeSampler;
return globalSampler;
});
globalRateSetter.accept(1000);
try {
testRun.run();
} finally {
ProbeRateLimiter.setSamplerSupplier(null);
}
assertEquals(expectedGlobalCount, globalSampler.getCallCount());
assertEquals(expectedProbeCount, probeSampler.getCallCount());
assertEquals(expectedErrorCount, errorSampler.getCallCount());
}

@Test
Expand Down