Fix exemplars (#4678)

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/instrumenter/Instrumenter.java

@@ -100,6 +100,7 @@ public class Instrumenter<REQUEST, RESPONSE> {
       attributesExtractors;
   private final List<? extends ContextCustomizer<? super REQUEST>> contextCustomizers;
   private final List<? extends RequestListener> requestListeners;
+  private final List<? extends RequestListener> requestMetricListeners;
   private final ErrorCauseExtractor errorCauseExtractor;
   @Nullable private final StartTimeExtractor<REQUEST> startTimeExtractor;
   @Nullable private final EndTimeExtractor<REQUEST, RESPONSE> endTimeExtractor;
@@ -117,6 +118,7 @@ public class Instrumenter<REQUEST, RESPONSE> {
     this.attributesExtractors = new ArrayList<>(builder.attributesExtractors);
     this.contextCustomizers = new ArrayList<>(builder.contextCustomizers);
     this.requestListeners = new ArrayList<>(builder.requestListeners);
+    this.requestMetricListeners = new ArrayList<>(builder.requestMetricListeners);
     this.errorCauseExtractor = builder.errorCauseExtractor;
     this.startTimeExtractor = builder.startTimeExtractor;
     this.endTimeExtractor = builder.endTimeExtractor;
@@ -192,6 +194,15 @@ public class Instrumenter<REQUEST, RESPONSE> {
     Span span = spanBuilder.startSpan();
     context = context.with(span);
 
+    // request metric listeners need to run after the span has been added to the context in order
+    // for them to generate exemplars
+    if (!requestMetricListeners.isEmpty()) {
+      long startNanos = getNanos(startTime);
+      for (RequestListener requestListener : requestMetricListeners) {
+        context = requestListener.start(context, attributes, startNanos);
+      }
+    }
+
     return spanSuppressionStrategy.storeInContext(context, spanKind, span);
   }
 
@@ -221,11 +232,14 @@ public class Instrumenter<REQUEST, RESPONSE> {
       endTime = endTimeExtractor.extract(request, response, error);
     }
 
-    if (!requestListeners.isEmpty()) {
+    if (!requestListeners.isEmpty() || !requestMetricListeners.isEmpty()) {
       long endNanos = getNanos(endTime);
       for (RequestListener requestListener : requestListeners) {
         requestListener.end(context, attributes, endNanos);
       }
+      for (RequestListener requestListener : requestMetricListeners) {
+        requestListener.end(context, attributes, endNanos);
+      }
     }
 
     StatusCode statusCode = spanStatusExtractor.extract(request, response, error);

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/instrumenter/InstrumenterBuilder.java

@@ -50,6 +50,7 @@ public final class InstrumenterBuilder<REQUEST, RESPONSE> {
       new ArrayList<>();
   final List<ContextCustomizer<? super REQUEST>> contextCustomizers = new ArrayList<>();
   final List<RequestListener> requestListeners = new ArrayList<>();
+  final List<RequestListener> requestMetricListeners = new ArrayList<>();
 
   SpanKindExtractor<? super REQUEST> spanKindExtractor = SpanKindExtractor.alwaysInternal();
   SpanStatusExtractor<? super REQUEST, ? super RESPONSE> spanStatusExtractor =
@@ -124,7 +125,7 @@ public final class InstrumenterBuilder<REQUEST, RESPONSE> {
   /** Adds a {@link RequestMetrics} whose metrics will be recorded for request start and stop. */
   @UnstableApi
   public InstrumenterBuilder<REQUEST, RESPONSE> addRequestMetrics(RequestMetrics factory) {
-    requestListeners.add(factory.create(meter));
+    requestMetricListeners.add(factory.create(meter));
     return this;
   }
 

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/instrumenter/http/HttpClientMetrics.java

@@ -76,7 +76,8 @@ public final class HttpClientMetrics implements RequestListener {
     }
     duration.record(
         (endNanos - state.startTimeNanos()) / NANOS_PER_MS,
-        applyClientDurationView(state.startAttributes(), endAttributes));
+        applyClientDurationView(state.startAttributes(), endAttributes),
+        context);
   }
 
   @AutoValue

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/instrumenter/http/HttpServerMetrics.java

@@ -71,7 +71,7 @@ public final class HttpServerMetrics implements RequestListener {
 
   @Override
   public Context start(Context context, Attributes startAttributes, long startNanos) {
-    activeRequests.add(1, applyActiveRequestsView(startAttributes));
+    activeRequests.add(1, applyActiveRequestsView(startAttributes), context);
 
     return context.with(
         HTTP_SERVER_REQUEST_METRICS_STATE,
@@ -89,7 +89,8 @@ public final class HttpServerMetrics implements RequestListener {
     activeRequests.add(-1, applyActiveRequestsView(state.startAttributes()));
     duration.record(
         (endNanos - state.startTimeNanos()) / NANOS_PER_MS,
-        applyServerDurationView(state.startAttributes(), endAttributes));
+        applyServerDurationView(state.startAttributes(), endAttributes),
+        context);
   }
 
   @AutoValue

instrumentation-api/src/test/java/io/opentelemetry/instrumentation/api/instrumenter/InstrumenterTest.java

@@ -10,6 +10,7 @@ import static io.opentelemetry.sdk.testing.assertj.OpenTelemetryAssertions.attri
 import static org.assertj.core.api.Assertions.entry;
 import static org.mockito.Mockito.when;
 
+import io.opentelemetry.api.common.Attributes;
 import io.opentelemetry.api.common.AttributesBuilder;
 import io.opentelemetry.api.trace.Span;
 import io.opentelemetry.api.trace.SpanContext;
@@ -39,6 +40,7 @@ import java.time.Instant;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.atomic.AtomicReference;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 import javax.annotation.Nullable;
@@ -410,6 +412,38 @@ class InstrumenterTest {
                             .hasParentSpanId("090a0b0c0d0e0f00")));
   }
 
+  @Test
+  void requestMetrics() {
+    AtomicReference<Context> startContext = new AtomicReference<>();
+    AtomicReference<Context> endContext = new AtomicReference<>();
+
+    RequestListener requestListener =
+        new RequestListener() {
+          @Override
+          public Context start(Context context, Attributes startAttributes, long startNanos) {
+            startContext.set(context);
+            return context;
+          }
+
+          @Override
+          public void end(Context context, Attributes endAttributes, long endNanos) {
+            endContext.set(context);
+          }
+        };
+
+    Instrumenter<Map<String, String>, Map<String, String>> instrumenter =
+        Instrumenter.<Map<String, String>, Map<String, String>>builder(
+                otelTesting.getOpenTelemetry(), "test", unused -> "span")
+            .addRequestMetrics(meter -> requestListener)
+            .newServerInstrumenter(new MapGetter());
+
+    Context context = instrumenter.start(Context.root(), REQUEST);
+    instrumenter.end(context, REQUEST, RESPONSE, null);
+
+    assertThat(Span.fromContext(startContext.get()).getSpanContext().isValid()).isTrue();
+    assertThat(Span.fromContext(endContext.get()).getSpanContext().isValid()).isTrue();
+  }
+
   @Test
   void shouldStartSpanWithGivenStartTime() {
     // given

instrumentation-api/src/test/java/io/opentelemetry/instrumentation/api/instrumenter/http/HttpClientMetricsTest.java

@@ -10,6 +10,10 @@ import static io.opentelemetry.sdk.testing.assertj.metrics.MetricAssertions.asse
 import static org.awaitility.Awaitility.await;
 
 import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.api.trace.Span;
+import io.opentelemetry.api.trace.SpanContext;
+import io.opentelemetry.api.trace.TraceFlags;
+import io.opentelemetry.api.trace.TraceState;
 import io.opentelemetry.context.Context;
 import io.opentelemetry.instrumentation.api.instrumenter.RequestListener;
 import io.opentelemetry.sdk.metrics.SdkMeterProvider;
@@ -47,7 +51,17 @@ class HttpClientMetricsTest {
             .put("http.status_code", 200)
             .build();
 
-    Context context1 = listener.start(Context.current(), requestAttributes, nanos(100));
+    Context parent =
+        Context.root()
+            .with(
+                Span.wrap(
+                    SpanContext.create(
+                        "ff01020304050600ff0a0b0c0d0e0f00",
+                        "090a0b0c0d0e0f00",
+                        TraceFlags.getSampled(),
+                        TraceState.getDefault())));
+
+    Context context1 = listener.start(parent, requestAttributes, nanos(100));
 
     // TODO(anuraaga): Remove await from this file after 1.8.0 hopefully fixes
     // https://github.com/open-telemetry/opentelemetry-java/issues/3725
@@ -58,7 +72,7 @@ class HttpClientMetricsTest {
               assertThat(metrics).isEmpty();
             });
 
-    Context context2 = listener.start(Context.current(), requestAttributes, nanos(150));
+    Context context2 = listener.start(Context.root(), requestAttributes, nanos(150));
 
     await()
         .untilAsserted(
@@ -82,7 +96,7 @@ class HttpClientMetricsTest {
                               .hasDoubleHistogram()
                               .points()
                               .satisfiesExactly(
-                                  point ->
+                                  point -> {
                                     assertThat(point)
                                         .hasSum(150 /* millis */)
                                         .attributes()
@@ -90,7 +104,12 @@ class HttpClientMetricsTest {
                                             attributeEntry("http.url", "https://localhost:1234/"),
                                             attributeEntry("http.method", "GET"),
                                             attributeEntry("http.flavor", "2.0"),
-                                              attributeEntry("http.status_code", 200))));
+                                            attributeEntry("http.status_code", 200));
+                                    assertThat(point).exemplars().hasSize(1);
+                                    assertThat(point.getExemplars().get(0))
+                                        .hasTraceId("ff01020304050600ff0a0b0c0d0e0f00")
+                                        .hasSpanId("090a0b0c0d0e0f00");
+                                  }));
             });
 
     listener.end(context2, responseAttributes, nanos(300));

instrumentation-api/src/test/java/io/opentelemetry/instrumentation/api/instrumenter/http/HttpServerMetricsTest.java

@@ -10,6 +10,10 @@ import static io.opentelemetry.sdk.testing.assertj.metrics.MetricAssertions.asse
 import static org.awaitility.Awaitility.await;
 
 import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.api.trace.Span;
+import io.opentelemetry.api.trace.SpanContext;
+import io.opentelemetry.api.trace.TraceFlags;
+import io.opentelemetry.api.trace.TraceState;
 import io.opentelemetry.context.Context;
 import io.opentelemetry.instrumentation.api.instrumenter.RequestListener;
 import io.opentelemetry.sdk.metrics.SdkMeterProvider;
@@ -23,7 +27,7 @@ class HttpServerMetricsTest {
 
   @Test
   void collectsMetrics() {
-    InMemoryMetricReader metricReader = new InMemoryMetricReader();
+    InMemoryMetricReader metricReader = InMemoryMetricReader.create();
     SdkMeterProvider meterProvider =
         SdkMeterProvider.builder().registerMetricReader(metricReader).build();
 
@@ -46,7 +50,17 @@ class HttpServerMetricsTest {
             .put("http.status_code", 200)
             .build();
 
-    Context context1 = listener.start(Context.current(), requestAttributes, nanos(100));
+    Context parent =
+        Context.root()
+            .with(
+                Span.wrap(
+                    SpanContext.create(
+                        "ff01020304050600ff0a0b0c0d0e0f00",
+                        "090a0b0c0d0e0f00",
+                        TraceFlags.getSampled(),
+                        TraceState.getDefault())));
+
+    Context context1 = listener.start(parent, requestAttributes, nanos(100));
 
     // TODO(anuraaga): Remove await from this file after 1.8.0 hopefully fixes
     // https://github.com/open-telemetry/opentelemetry-java/issues/3725
@@ -66,17 +80,22 @@ class HttpServerMetricsTest {
                               .hasLongSum()
                               .points()
                               .satisfiesExactly(
-                                  point ->
+                                  point -> {
                                     assertThat(point)
                                         .hasValue(1)
                                         .attributes()
                                         .containsOnly(
                                             attributeEntry("http.host", "host"),
                                             attributeEntry("http.method", "GET"),
-                                              attributeEntry("http.scheme", "https"))));
+                                            attributeEntry("http.scheme", "https"));
+                                    assertThat(point).exemplars().hasSize(1);
+                                    assertThat(point.getExemplars().get(0))
+                                        .hasTraceId("ff01020304050600ff0a0b0c0d0e0f00")
+                                        .hasSpanId("090a0b0c0d0e0f00");
+                                  }));
             });
 
-    Context context2 = listener.start(Context.current(), requestAttributes, nanos(150));
+    Context context2 = listener.start(Context.root(), requestAttributes, nanos(150));
 
     await()
         .untilAsserted(
@@ -116,7 +135,7 @@ class HttpServerMetricsTest {
                               .hasDoubleHistogram()
                               .points()
                               .satisfiesExactly(
-                                  point ->
+                                  point -> {
                                     assertThat(point)
                                         .hasSum(150 /* millis */)
                                         .attributes()
@@ -126,7 +145,12 @@ class HttpServerMetricsTest {
                                             attributeEntry("http.target", "/"),
                                             attributeEntry("http.method", "GET"),
                                             attributeEntry("http.status_code", 200),
-                                              attributeEntry("http.flavor", "2.0"))));
+                                            attributeEntry("http.flavor", "2.0"));
+                                    assertThat(point).exemplars().hasSize(1);
+                                    assertThat(point.getExemplars().get(0))
+                                        .hasTraceId("ff01020304050600ff0a0b0c0d0e0f00")
+                                        .hasSpanId("090a0b0c0d0e0f00");
+                                  }));
             });
 
     listener.end(context2, responseAttributes, nanos(300));