fix(gax): manage OpenTelemetry scope in OpenTelemetryTracingTracer

Manage the lifecycle of the OpenTelemetry Scope in OpenTelemetryTracingTracer so that log records emitted during attempt lifecycle can access the active span context. Also order ApiTracerFactory before LoggingTracerFactory in CompositeTracerFactory to ensure span scope remains active during error logging.

Fixes: b/499388983

Author: jinseopkim0

sdk-platform-java/gax-java/gax/src/main/java/com/google/api/gax/rpc/ClientContext.java

@@ -300,7 +300,7 @@ static ApiTracerFactory getApiTracerFactory(
     if (LoggingUtils.isLoggingEnabled()) {
       apiTracerFactory =
           new CompositeTracerFactory(
-              ImmutableList.of(new LoggingTracerFactory(), apiTracerFactory));
+              ImmutableList.of(apiTracerFactory, new LoggingTracerFactory()));
     }
 
     if (apiTracerFactory.needsContext()) {

sdk-platform-java/gax-java/gax/src/main/java/com/google/api/gax/tracing/OpenTelemetryTracingTracer.java

@@ -53,6 +53,7 @@ class OpenTelemetryTracingTracer implements ApiTracer {
   private final String attemptSpanName;
   private final ApiTracerContext apiTracerContext;
   private @Nullable Span attemptSpan;
+  private io.opentelemetry.context.@Nullable Scope scope;
 
   @Override
   public void injectTraceContext(java.util.Map<String, String> carrier) {
@@ -146,6 +147,7 @@ public void attemptStarted(Object request, int attemptNumber) {
     spanBuilder.setAllAttributes(ObservabilityUtils.toOtelAttributes(currentAttemptAttributes));
 
     this.attemptSpan = spanBuilder.startSpan();
+    this.scope = attemptSpan.makeCurrent();
   }
 
   @Override
@@ -234,6 +236,10 @@ private void recordErrorAndEndAttempt(@Nullable Throwable error) {
   }
 
   private void endAttempt() {
+    if (scope != null) {
+      scope.close();
+      scope = null;
+    }
     if (attemptSpan == null) {
       return;
     }

sdk-platform-java/gax-java/gax/src/test/java/com/google/api/gax/tracing/OpenTelemetryTracingTracerTest.java

@@ -33,6 +33,7 @@
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.lenient;
 import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
@@ -49,6 +50,7 @@
 import io.opentelemetry.api.trace.SpanBuilder;
 import io.opentelemetry.api.trace.SpanKind;
 import io.opentelemetry.api.trace.Tracer;
+import io.opentelemetry.context.Scope;
 import java.net.ConnectException;
 import java.net.SocketTimeoutException;
 import java.util.Map;
@@ -64,6 +66,7 @@ class OpenTelemetryTracingTracerTest {
   @Mock private Tracer tracer;
   @Mock private SpanBuilder spanBuilder;
   @Mock private Span span;
+  @Mock private Scope scope;
   private OpenTelemetryTracingTracer openTelemetryTracingTracer;
   private static final String ATTEMPT_SPAN_NAME = "Service/Method/attempt";
 
@@ -73,6 +76,7 @@ void setUp() {
     when(spanBuilder.setSpanKind(any(SpanKind.class))).thenReturn(spanBuilder);
     when(spanBuilder.setAllAttributes(any(Attributes.class))).thenReturn(spanBuilder);
     when(spanBuilder.startSpan()).thenReturn(span);
+    lenient().when(span.makeCurrent()).thenReturn(scope);
     openTelemetryTracingTracer =
         new OpenTelemetryTracingTracer(tracer, ApiTracerContext.empty(), ATTEMPT_SPAN_NAME);
   }
@@ -680,4 +684,46 @@ void testInjectTraceContext_addsHeaders() {
     assertThat(carrier.get("traceparent")).contains("00000000000000000000000000000001");
     assertThat(carrier.get("traceparent")).contains("0000000000000002");
   }
+
+  @Test
+  void testAttemptStarted_makesSpanCurrent() {
+    openTelemetryTracingTracer.attemptStarted(new Object(), 1);
+    verify(span).makeCurrent();
+  }
+
+  @Test
+  void testAttemptEnded_closesScope_succeeded() {
+    openTelemetryTracingTracer.attemptStarted(new Object(), 1);
+    openTelemetryTracingTracer.attemptSucceeded();
+    verify(scope).close();
+  }
+
+  @Test
+  void testAttemptEnded_closesScope_failedRetriesExhausted() {
+    openTelemetryTracingTracer.attemptStarted(new Object(), 1);
+    openTelemetryTracingTracer.attemptFailedRetriesExhausted(new RuntimeException());
+    verify(scope).close();
+  }
+
+  @Test
+  void testAttemptEnded_closesScope_failedDuration() {
+    openTelemetryTracingTracer.attemptStarted(new Object(), 1);
+    openTelemetryTracingTracer.attemptFailedDuration(
+        new RuntimeException(), java.time.Duration.ofMillis(100));
+    verify(scope).close();
+  }
+
+  @Test
+  void testAttemptEnded_closesScope_permanentFailure() {
+    openTelemetryTracingTracer.attemptStarted(new Object(), 1);
+    openTelemetryTracingTracer.attemptPermanentFailure(new RuntimeException());
+    verify(scope).close();
+  }
+
+  @Test
+  void testAttemptEnded_closesScope_cancelled() {
+    openTelemetryTracingTracer.attemptStarted(new Object(), 1);
+    openTelemetryTracingTracer.attemptCancelled();
+    verify(scope).close();
+  }
 }