Reorganize server observability packages

Prior to this commit, the server observability support would create a
cycle in Java packages.

This commit refactors the current arrangement to solve this by:

* "flattening" the reactive HTTP instrumentation; this removes the
  dependency to the `ServerWebExchange` and `PathPattern` types
* moving the `observation` package under
  `org.springframework.http.server` and
  `org.springframework.http.server.reactive`

See gh-29477

Author: bclozel

gradle.properties

@@ -1,4 +1,4 @@
-version=6.0.0-SNAPSHOT
+version=6.0.0-RC4
 
 org.gradle.caching=true
 org.gradle.jvmargs=-Xmx2048m

spring-web/src/main/java/org/springframework/http/observation/DefaultServerRequestObservationConvention.java renamed to spring-web/src/main/java/org/springframework/http/server/observation/DefaultServerRequestObservationConvention.java

@@ -14,15 +14,15 @@
  * limitations under the License.
  */
 
-package org.springframework.http.observation;
+package org.springframework.http.server.observation;
 
 import io.micrometer.common.KeyValue;
 import io.micrometer.common.KeyValues;
 
 import org.springframework.http.HttpStatus;
 import org.springframework.http.HttpStatusCode;
-import org.springframework.http.observation.ServerHttpObservationDocumentation.HighCardinalityKeyNames;
-import org.springframework.http.observation.ServerHttpObservationDocumentation.LowCardinalityKeyNames;
+import org.springframework.http.server.observation.ServerHttpObservationDocumentation.HighCardinalityKeyNames;
+import org.springframework.http.server.observation.ServerHttpObservationDocumentation.LowCardinalityKeyNames;
 import org.springframework.util.StringUtils;
 
 /**

spring-web/src/main/java/org/springframework/http/observation/ServerHttpObservationDocumentation.java renamed to spring-web/src/main/java/org/springframework/http/server/observation/ServerHttpObservationDocumentation.java

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package org.springframework.http.observation;
+package org.springframework.http.server.observation;
 
 import io.micrometer.common.KeyValue;
 import io.micrometer.common.docs.KeyName;
@@ -33,9 +33,9 @@
 public enum ServerHttpObservationDocumentation implements ObservationDocumentation {
 
 	/**
-	 * HTTP exchanges observations for Servlet-based servers.
+	 * HTTP request observations for Servlet-based servers.
 	 */
-	HTTP_SERVLET_SERVER_EXCHANGES {
+	HTTP_SERVLET_SERVER_REQUESTS {
 		@Override
 		public Class<? extends ObservationConvention<? extends Observation.Context>> getDefaultConvention() {
 			return DefaultServerRequestObservationConvention.class;

spring-web/src/main/java/org/springframework/http/observation/ServerRequestObservationContext.java renamed to spring-web/src/main/java/org/springframework/http/server/observation/ServerRequestObservationContext.java

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package org.springframework.http.observation;
+package org.springframework.http.server.observation;
 
 import io.micrometer.observation.transport.RequestReplyReceiverContext;
 import jakarta.servlet.http.HttpServletRequest;
@@ -23,10 +23,10 @@
 import org.springframework.lang.Nullable;
 
 /**
- * Context that holds information for metadata collection during observations
- * for {@link ServerHttpObservationDocumentation#HTTP_SERVLET_SERVER_EXCHANGES Servlet HTTP exchanges}.
+ * Context that holds information for metadata collection regarding
+ * {@link ServerHttpObservationDocumentation#HTTP_SERVLET_SERVER_REQUESTS Servlet HTTP requests} observations.
  * <p>This context also extends {@link RequestReplyReceiverContext} for propagating
- * tracing information with the HTTP server exchange.
+ * tracing information during HTTP request processing.
  *
  * @author Brian Clozel
  * @since 6.0

spring-web/src/main/java/org/springframework/http/observation/ServerRequestObservationConvention.java renamed to spring-web/src/main/java/org/springframework/http/server/observation/ServerRequestObservationConvention.java

@@ -14,13 +14,13 @@
  * limitations under the License.
  */
 
-package org.springframework.http.observation;
+package org.springframework.http.server.observation;
 
 import io.micrometer.observation.Observation;
 import io.micrometer.observation.ObservationConvention;
 
 /**
- * Interface for an {@link ObservationConvention} for {@link ServerHttpObservationDocumentation#HTTP_SERVLET_SERVER_EXCHANGES Servlet HTTP exchanges}.
+ * Interface for an {@link ObservationConvention} for {@link ServerHttpObservationDocumentation#HTTP_SERVLET_SERVER_REQUESTS Servlet HTTP requests}.
  *
  * @author Brian Clozel
  * @since 6.0

spring-web/src/main/java/org/springframework/http/observation/package-info.java renamed to spring-web/src/main/java/org/springframework/http/server/observation/package-info.java

@@ -1,9 +1,9 @@
 /**
- * Instrumentation for {@link io.micrometer.observation.Observation observing} HTTP applications.
+ * Instrumentation for {@link io.micrometer.observation.Observation observing} HTTP server applications.
  */
 @NonNullApi
 @NonNullFields
-package org.springframework.http.observation;
+package org.springframework.http.server.observation;
 
 import org.springframework.lang.NonNullApi;
 import org.springframework.lang.NonNullFields;

spring-web/src/main/java/org/springframework/http/observation/reactive/DefaultServerRequestObservationConvention.java renamed to spring-web/src/main/java/org/springframework/http/server/reactive/observation/DefaultServerRequestObservationConvention.java

@@ -14,17 +14,16 @@
  * limitations under the License.
  */
 
-package org.springframework.http.observation.reactive;
+package org.springframework.http.server.reactive.observation;
 
 import io.micrometer.common.KeyValue;
 import io.micrometer.common.KeyValues;
 
 import org.springframework.http.HttpStatus;
 import org.springframework.http.HttpStatusCode;
-import org.springframework.http.observation.reactive.ServerHttpObservationDocumentation.HighCardinalityKeyNames;
-import org.springframework.http.observation.reactive.ServerHttpObservationDocumentation.LowCardinalityKeyNames;
+import org.springframework.http.server.reactive.observation.ServerHttpObservationDocumentation.HighCardinalityKeyNames;
+import org.springframework.http.server.reactive.observation.ServerHttpObservationDocumentation.LowCardinalityKeyNames;
 import org.springframework.util.StringUtils;
-import org.springframework.web.util.pattern.PathPattern;
 
 /**
  * Default {@link ServerRequestObservationConvention}.
@@ -117,12 +116,12 @@ protected KeyValue status(ServerRequestObservationContext context) {
 
 	protected KeyValue uri(ServerRequestObservationContext context) {
 		if (context.getCarrier() != null) {
-			PathPattern pattern = context.getPathPattern();
+			String pattern = context.getPathPattern();
 			if (pattern != null) {
-				if (pattern.toString().isEmpty()) {
+				if (pattern.isEmpty()) {
 					return URI_ROOT;
 				}
-				return KeyValue.of(LowCardinalityKeyNames.URI, pattern.toString());
+				return KeyValue.of(LowCardinalityKeyNames.URI, pattern);
 			}
 			if (context.getResponse() != null && context.getResponse().getStatusCode() != null) {
 				HttpStatus status = HttpStatus.resolve(context.getResponse().getStatusCode().value());

spring-web/src/main/java/org/springframework/http/observation/reactive/ServerHttpObservationDocumentation.java renamed to spring-web/src/main/java/org/springframework/http/server/reactive/observation/ServerHttpObservationDocumentation.java

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package org.springframework.http.observation.reactive;
+package org.springframework.http.server.reactive.observation;
 
 import io.micrometer.common.KeyValue;
 import io.micrometer.common.docs.KeyName;
@@ -33,9 +33,9 @@
 public enum ServerHttpObservationDocumentation implements ObservationDocumentation {
 
 	/**
-	 * HTTP exchanges observations for reactive servers.
+	 * HTTP request observations for reactive servers.
 	 */
-	HTTP_REACTIVE_SERVER_EXCHANGES {
+	HTTP_REACTIVE_SERVER_REQUESTS {
 		@Override
 		public Class<? extends ObservationConvention<? extends Observation.Context>> getDefaultConvention() {
 			return DefaultServerRequestObservationConvention.class;

spring-web/src/main/java/org/springframework/http/observation/reactive/ServerRequestObservationContext.java renamed to spring-web/src/main/java/org/springframework/http/server/reactive/observation/ServerRequestObservationContext.java

@@ -14,46 +14,47 @@
  * limitations under the License.
  */
 
-package org.springframework.http.observation.reactive;
+package org.springframework.http.server.reactive.observation;
+
+import java.util.Collections;
+import java.util.Map;
 
 import io.micrometer.observation.transport.RequestReplyReceiverContext;
 
 import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.http.server.reactive.ServerHttpResponse;
 import org.springframework.lang.Nullable;
-import org.springframework.web.server.ServerWebExchange;
-import org.springframework.web.util.pattern.PathPattern;
 
 /**
- * Context that holds information for metadata collection during observations
- * for {@link ServerHttpObservationDocumentation#HTTP_REACTIVE_SERVER_EXCHANGES reactive HTTP exchanges}.
+ * Context that holds information for metadata collection regarding
+ * {@link ServerHttpObservationDocumentation#HTTP_REACTIVE_SERVER_REQUESTS reactive HTTP requests} observations.
  * <p>This context also extends {@link RequestReplyReceiverContext} for propagating
- * tracing information with the HTTP server exchange.
+ * tracing information during HTTP request processing.
  *
  * @author Brian Clozel
  * @since 6.0
  */
 public class ServerRequestObservationContext extends RequestReplyReceiverContext<ServerHttpRequest, ServerHttpResponse> {
 
-	private final ServerWebExchange serverWebExchange;
+	private final Map<String, Object> attributes;
 
 	@Nullable
-	private PathPattern pathPattern;
+	private String pathPattern;
 
 	private boolean connectionAborted;
 
-	public ServerRequestObservationContext(ServerWebExchange exchange) {
-		super((request, key) -> request.getHeaders().getFirst(key));
-		this.serverWebExchange = exchange;
-		setCarrier(exchange.getRequest());
-		setResponse(exchange.getResponse());
+	public ServerRequestObservationContext(ServerHttpRequest request, ServerHttpResponse response, Map<String, Object> attributes) {
+		super((req, key) -> req.getHeaders().getFirst(key));
+		setCarrier(request);
+		setResponse(response);
+		this.attributes = Collections.unmodifiableMap(attributes);
 	}
 
 	/**
-	 * Return the current {@link ServerWebExchange HTTP exchange}.
+	 * Return an immutable map of the current request attributes.
 	 */
-	public ServerWebExchange getServerWebExchange() {
-		return this.serverWebExchange;
+	public Map<String, Object> getAttributes() {
+		return this.attributes;
 	}
 
 	/**
@@ -63,7 +64,7 @@ public ServerWebExchange getServerWebExchange() {
 	 * @return the path pattern, or {@code null} if none found
 	 */
 	@Nullable
-	public PathPattern getPathPattern() {
+	public String getPathPattern() {
 		return this.pathPattern;
 	}
 
@@ -72,7 +73,7 @@ public PathPattern getPathPattern() {
 	 * <p>Path patterns must have a low cardinality for the entire application.
 	 * @param pathPattern the path pattern, for example {@code "/projects/{name}"}.
 	 */
-	public void setPathPattern(@Nullable PathPattern pathPattern) {
+	public void setPathPattern(@Nullable String pathPattern) {
 		this.pathPattern = pathPattern;
 	}
 

spring-web/src/main/java/org/springframework/http/observation/reactive/ServerRequestObservationConvention.java renamed to spring-web/src/main/java/org/springframework/http/server/reactive/observation/ServerRequestObservationConvention.java

@@ -14,13 +14,13 @@
  * limitations under the License.
  */
 
-package org.springframework.http.observation.reactive;
+package org.springframework.http.server.reactive.observation;
 
 import io.micrometer.observation.Observation;
 import io.micrometer.observation.ObservationConvention;
 
 /**
- * Interface for an {@link ObservationConvention} for {@link ServerHttpObservationDocumentation#HTTP_REACTIVE_SERVER_EXCHANGES reactive HTTP exchanges}.
+ * Interface for an {@link ObservationConvention} for {@link ServerHttpObservationDocumentation#HTTP_REACTIVE_SERVER_REQUESTS reactive HTTP requests}.
  *
  * @author Brian Clozel
  * @since 6.0