Fix npe on ConflatingMetricsAggregator when the resource is null (#9909)

Author: amarziali

dd-trace-core/src/main/java/datadog/trace/common/metrics/ConflatingMetricsAggregator.java

@@ -277,7 +277,8 @@ public boolean publish(List<? extends CoreSpan<?>> trace) {
       for (CoreSpan<?> span : trace) {
         boolean isTopLevel = span.isTopLevel();
         if (shouldComputeMetric(span)) {
-          if (ignoredResources.contains(span.getResourceName().toString())) {
+          final CharSequence resourceName = span.getResourceName();
+          if (resourceName != null && ignoredResources.contains(resourceName.toString())) {
             // skip publishing all children
             forceKeep = false;
             break;

dd-trace-core/src/test/groovy/datadog/trace/common/metrics/ConflatingMetricAggregatorTest.groovy

@@ -1,22 +1,21 @@
 package datadog.trace.common.metrics
 
+import static datadog.trace.bootstrap.instrumentation.api.Tags.SPAN_KIND
+import static java.util.concurrent.TimeUnit.MILLISECONDS
+import static java.util.concurrent.TimeUnit.SECONDS
+
 import datadog.communication.ddagent.DDAgentFeaturesDiscovery
 import datadog.trace.api.WellKnownTags
 import datadog.trace.bootstrap.instrumentation.api.UTF8BytesString
 import datadog.trace.core.CoreSpan
 import datadog.trace.core.monitor.HealthMetrics
 import datadog.trace.test.util.DDSpecification
-import spock.lang.Shared
-
 import java.util.concurrent.CompletableFuture
 import java.util.concurrent.CountDownLatch
 import java.util.concurrent.TimeUnit
 import java.util.concurrent.TimeoutException
 import java.util.function.Supplier
-
-import static datadog.trace.bootstrap.instrumentation.api.Tags.SPAN_KIND
-import static java.util.concurrent.TimeUnit.MILLISECONDS
-import static java.util.concurrent.TimeUnit.SECONDS
+import spock.lang.Shared
 
 class ConflatingMetricAggregatorTest extends DDSpecification {
 
@@ -96,6 +95,48 @@ class ConflatingMetricAggregatorTest extends DDSpecification {
     aggregator.close()
   }
 
+  def "should be resilient to null resource names"() {
+    setup:
+    MetricWriter writer = Mock(MetricWriter)
+    Sink sink = Stub(Sink)
+    DDAgentFeaturesDiscovery features = Mock(DDAgentFeaturesDiscovery)
+    features.supportsMetrics() >> true
+    features.peerTags() >> []
+    ConflatingMetricsAggregator aggregator = new ConflatingMetricsAggregator(empty,
+      features, HealthMetrics.NO_OP, sink, writer, 10, queueSize, reportingInterval, SECONDS)
+    aggregator.start()
+
+    when:
+    CountDownLatch latch = new CountDownLatch(1)
+    aggregator.publish([
+      new SimpleSpan("service", "operation", null, "type", false, true, false, 0, 100, HTTP_OK)
+      .setTag(SPAN_KIND, "baz")
+    ])
+    aggregator.report()
+    def latchTriggered = latch.await(2, SECONDS)
+
+    then:
+    latchTriggered
+    1 * writer.startBucket(1, _, _)
+    1 * writer.add(new MetricKey(
+      null,
+      "service",
+      "operation",
+      "type",
+      HTTP_OK,
+      false,
+      false,
+      "baz",
+      []
+      ), _) >> { MetricKey key, AggregateMetric value ->
+        value.getHitCount() == 1 && value.getTopLevelCount() == 1 && value.getDuration() == 100
+      }
+    1 * writer.finishBucket() >> { latch.countDown() }
+
+    cleanup:
+    aggregator.close()
+  }
+
   def "unmeasured top level spans have metrics computed"() {
     setup:
     MetricWriter writer = Mock(MetricWriter)