Construct LettuceObservationContext with parent observation

After this commit, LettuceObservationContext.setParentObservation() is called right after Context rather than Observation created, then Context.getParentObservation() could be used in ObservationPredicate to determine whether Observation should be created.

Fixes #2591
Original pull request: #2592

Author: quaff

src/main/java/org/springframework/data/redis/connection/lettuce/observability/MicrometerTracingAdapter.java

@@ -44,6 +44,7 @@
  * arguments will be captured in traces including these that may contain sensitive details.
  *
  * @author Mark Paluch
+ * @author Yanming Zhou
  * @since 3.0
  */
 public class MicrometerTracingAdapter implements Tracing {
@@ -121,29 +122,28 @@ public MicrometerTracer(ObservationRegistry observationRegistry) {
 
 		@Override
 		public Tracer.Span nextSpan() {
-			return this.postProcessSpan(createObservation());
+			return this.postProcessSpan(createObservation(null));
 		}
 
 		@Override
 		public Tracer.Span nextSpan(TraceContext traceContext) {
-
-			if (traceContext instanceof MicrometerTraceContext micrometerTraceContext) {
-
-				return micrometerTraceContext.observation == null ? nextSpan()
-						: postProcessSpan(createObservation().parentObservation(micrometerTraceContext.observation()));
-			}
-
-			return nextSpan();
+			return postProcessSpan(createObservation(traceContext));
 		}
 
-		private Observation createObservation() {
+		private Observation createObservation(@Nullable TraceContext traceContext) {
 			return RedisObservation.REDIS_COMMAND_OBSERVATION.observation(observationRegistry,
-					() -> new LettuceObservationContext(serviceName));
+					() -> {
+						LettuceObservationContext context = new LettuceObservationContext(serviceName);
+						if (traceContext instanceof MicrometerTraceContext micrometerTraceContext) {
+							context.setParentObservation(micrometerTraceContext.observation);
+						}
+						return context;
+					});
 		}
 
 		private Tracer.Span postProcessSpan(Observation observation) {
 
-			return observation != null && !observation.isNoop()
+			return !observation.isNoop()
 					? new MicrometerSpan(observation.observationConvention(observationConvention))
 					: NoOpSpan.INSTANCE;
 		}
@@ -292,6 +292,7 @@ public void finish() {
 	record MicrometerTraceContextProvider(ObservationRegistry registry) implements TraceContextProvider {
 
 		@Override
+		@Nullable
 		public TraceContext getTraceContext() {
 
 			Observation observation = registry.getCurrentObservation();

src/test/java/org/springframework/data/redis/connection/lettuce/observability/SynchronousIntegrationTests.java

@@ -35,6 +35,7 @@
  * Collection of tests that log metrics and tracing using the synchronous API.
  *
  * @author Mark Paluch
+ * @author Yanming Zhou
  */
 @ExtendWith(SpringExtension.class)
 @ContextConfiguration(classes = TestConfig.class)
@@ -77,6 +78,9 @@ public SampleTestRunnerConsumer yourCode() {
 						.containsEntry("net.sock.peer.port", "" + SettingsUtils.getPort());
 				assertThat(finishedSpan.getTags()).containsKeys("db.operation");
 			}
+
+			assertThat(TestConfig.PARENT_OBSERVATION_NAMES_COLLECTED_IN_PREDICATE).isNotEmpty();
+			TestConfig.PARENT_OBSERVATION_NAMES_COLLECTED_IN_PREDICATE.clear();
 		};
 	}
 

src/test/java/org/springframework/data/redis/connection/lettuce/observability/TestConfig.java

@@ -22,6 +22,8 @@
 import io.micrometer.observation.ObservationRegistry;
 
 import java.time.Duration;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.concurrent.TimeUnit;
 
 import org.springframework.context.annotation.Bean;
@@ -33,15 +35,23 @@
 
 /**
  * @author Mark Paluch
+ * @author Yanming Zhou
  */
 @Configuration
 class TestConfig {
 
 	static final MeterRegistry METER_REGISTRY = new SimpleMeterRegistry();
 	static final ObservationRegistry OBSERVATION_REGISTRY = ObservationRegistry.create();
+	static final List<String> PARENT_OBSERVATION_NAMES_COLLECTED_IN_PREDICATE = new ArrayList<>();
 
 	static {
 		OBSERVATION_REGISTRY.observationConfig().observationHandler(new DefaultMeterObservationHandler(METER_REGISTRY));
+		OBSERVATION_REGISTRY.observationConfig().observationPredicate((name, context) -> {
+			if (context.getParentObservation() != null) {
+				PARENT_OBSERVATION_NAMES_COLLECTED_IN_PREDICATE.add(context.getParentObservation().getContextView().getName());
+			}
+			return true;
+		});
 	}
 
 	@Bean(destroyMethod = "timer")