Expose request id at the ServerHttpRequest level

Hiding it (at AbstractServerHttpRequest) complicates matters since
requests are often mutated and decorated, plus it's also possible to
implement the interface directly (we've one, albeit corner case).

Issue: SPR-16966

spring-web/src/main/java/org/springframework/http/server/reactive/AbstractServerHttpRequest.java

@@ -64,7 +64,7 @@ public abstract class AbstractServerHttpRequest implements ServerHttpRequest {
 	private SslInfo sslInfo;
 
 	@Nullable
-	private String connectionId;
+	private String id;
 
 	@Nullable
 	private String logPrefix;
@@ -83,6 +83,26 @@ public abstract class AbstractServerHttpRequest implements ServerHttpRequest {
 	}
 
 
+	public String getId() {
+		if (this.id == null) {
+			this.id = initId();
+			if (this.id == null) {
+				this.id = ObjectUtils.getIdentityHexString(this);
+			}
+		}
+		return this.id;
+	}
+
+	/**
+	 * Obtain the request id to use, or {@code null} in which case the Object
+	 * identity of this request instance is used.
+	 * @since 5.1
+	 */
+	@Nullable
+	protected String initId() {
+		return null;
+	}
+
 	@Override
 	public URI getURI() {
 		return this.uri;
@@ -186,37 +206,13 @@ public abstract class AbstractServerHttpRequest implements ServerHttpRequest {
 	 */
 	public abstract <T> T getNativeRequest();
 
-	/**
-	 * Return an id representing the underlying connection, if available, or
-	 * otherwise the identify of the request object.
-	 * @since 5.1
-	 */
-	public String getConnectionId() {
-		if (this.connectionId == null) {
-			this.connectionId = initConnectionId();
-			if (this.connectionId == null) {
-				this.connectionId = ObjectUtils.getIdentityHexString(this);
-			}
-		}
-		return this.connectionId;
-	}
-
-	/**
-	 * Obtain the connection id, if available.
-	 * @since 5.1
-	 */
-	@Nullable
-	protected String initConnectionId() {
-		return null;
-	}
-
 	/**
 	 * For internal use in logging at the HTTP adapter layer.
 	 * @since 5.1
 	 */
 	String getLogPrefix() {
 		if (this.logPrefix == null) {
-			this.logPrefix = "[" + getConnectionId() + "] ";
+			this.logPrefix = "[" + getId() + "] ";
 		}
 		return this.logPrefix;
 	}

spring-web/src/main/java/org/springframework/http/server/reactive/DefaultServerHttpRequestBuilder.java

@@ -32,7 +32,6 @@ import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
-import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
 
 /**
@@ -192,8 +191,6 @@ class DefaultServerHttpRequestBuilder implements ServerHttpRequest.Builder {
 
 		private final ServerHttpRequest originalRequest;
 
-		private final String requestId;
-
 
 		public MutatedServerHttpRequest(URI uri, @Nullable String contextPath,
 				HttpHeaders headers, String methodValue, MultiValueMap<String, HttpCookie> cookies,
@@ -206,9 +203,6 @@ class DefaultServerHttpRequestBuilder implements ServerHttpRequest.Builder {
 			this.sslInfo = sslInfo != null ? sslInfo : originalRequest.getSslInfo();
 			this.body = body;
 			this.originalRequest = originalRequest;
-			this.requestId = originalRequest instanceof AbstractServerHttpRequest ?
-					((AbstractServerHttpRequest) originalRequest).getConnectionId() :
-					ObjectUtils.getIdentityHexString(originalRequest);
 		}
 
 		@Override
@@ -245,8 +239,8 @@ class DefaultServerHttpRequestBuilder implements ServerHttpRequest.Builder {
 		}
 
 		@Override
-		public String getConnectionId() {
+		public String getId() {
-			return this.requestId;
+			return this.originalRequest.getId();
 		}
 	}
 

spring-web/src/main/java/org/springframework/http/server/reactive/ReactorServerHttpRequest.java

@@ -176,7 +176,7 @@ class ReactorServerHttpRequest extends AbstractServerHttpRequest {
 
 	@Override
 	@Nullable
-	protected String initConnectionId() {
+	protected String initId() {
 		return this.request instanceof Connection ?
 				((Connection) this.request).channel().id().asShortText() : null;
 	}

spring-web/src/main/java/org/springframework/http/server/reactive/ServerHttpRequest.java

@@ -38,6 +38,14 @@ import org.springframework.util.MultiValueMap;
  */
 public interface ServerHttpRequest extends HttpRequest, ReactiveHttpInputMessage {
 
+	/**
+	 * Return an id that represents the underlying connection, if available, or
+	 * the request, for the purpose of correlating log messages.
+	 * @since 5.1
+	 * @see org.springframework.web.server.ServerWebExchange#getLogPrefix()
+	 */
+	String getId();
+
 	/**
 	 * Returns a structured representation of the request path including the
 	 * context path + path within application portions, path segments with

spring-web/src/main/java/org/springframework/http/server/reactive/ServerHttpRequestDecorator.java

@@ -55,6 +55,11 @@ public class ServerHttpRequestDecorator implements ServerHttpRequest {
 
 	// ServerHttpRequest delegation methods...
 
+	@Override
+	public String getId() {
+		return getDelegate().getId();
+	}
+
 	@Override
 	@Nullable
 	public HttpMethod getMethod() {

spring-web/src/main/java/org/springframework/http/server/reactive/UndertowServerHttpRequest.java

@@ -129,7 +129,7 @@ class UndertowServerHttpRequest extends AbstractServerHttpRequest {
 	}
 
 	@Override
-	protected String initConnectionId() {
+	protected String initId() {
 		return ObjectUtils.getIdentityHexString(this.exchange.getConnection());
 	}
 

spring-web/src/main/java/org/springframework/web/server/adapter/HttpWebHandlerAdapter.java

@@ -29,13 +29,11 @@ import org.springframework.core.NestedExceptionUtils;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.codec.LoggingCodecSupport;
 import org.springframework.http.codec.ServerCodecConfigurer;
-import org.springframework.http.server.reactive.AbstractServerHttpRequest;
 import org.springframework.http.server.reactive.HttpHandler;
 import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.http.server.reactive.ServerHttpResponse;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
-import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
 import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.WebHandler;
@@ -216,7 +214,7 @@ public class HttpWebHandlerAdapter extends WebHandlerDecorator implements HttpHa
 	public Mono<Void> handle(ServerHttpRequest request, ServerHttpResponse response) {
 
 		ServerWebExchange exchange = createExchange(request, response);
-		exchange.getAttributes().put(ServerWebExchange.LOG_ID_ATTRIBUTE, initLogId(request));
+		exchange.getAttributes().put(ServerWebExchange.LOG_ID_ATTRIBUTE, request.getId());
 		logExchange(exchange);
 
 		return getDelegate().handle(exchange)
@@ -230,11 +228,6 @@ public class HttpWebHandlerAdapter extends WebHandlerDecorator implements HttpHa
 				getCodecConfigurer(), getLocaleContextResolver(), this.applicationContext);
 	}
 
-	private String initLogId(ServerHttpRequest request) {
-		return request instanceof AbstractServerHttpRequest ?
-				((AbstractServerHttpRequest) request).getConnectionId() : ObjectUtils.getIdentityHexString(request);
-	}
-
 	private void logExchange(ServerWebExchange exchange) {
 		if (logger.isDebugEnabled()) {
 			String logPrefix = exchange.getLogPrefix();

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/DefaultServerRequestBuilder.java

@@ -178,7 +178,7 @@ class DefaultServerRequestBuilder implements ServerRequest.Builder {
 
 	@Override
 	public ServerRequest build() {
-		ServerHttpRequest serverHttpRequest = new BuiltServerHttpRequest(
+		ServerHttpRequest serverHttpRequest = new BuiltServerHttpRequest(this.exchange.getRequest().getId(),
 				this.methodName, this.uri, this.headers, this.cookies, this.body);
 		ServerWebExchange exchange = new DelegatingServerWebExchange(
 				serverHttpRequest, this.exchange, this.messageReaders);
@@ -190,6 +190,8 @@ class DefaultServerRequestBuilder implements ServerRequest.Builder {
 
 		private static final Pattern QUERY_PATTERN = Pattern.compile("([^&=]+)(=?)([^&]+)?");
 
+		private final String id;
+
 		private final String method;
 
 		private final URI uri;
@@ -204,9 +206,10 @@ class DefaultServerRequestBuilder implements ServerRequest.Builder {
 
 		private final Flux<DataBuffer> body;
 
-		public BuiltServerHttpRequest(String method, URI uri, HttpHeaders headers,
+		public BuiltServerHttpRequest(String id, String method, URI uri, HttpHeaders headers,
 				MultiValueMap<String, HttpCookie> cookies, Flux<DataBuffer> body) {
 
+			this.id = id;
 			this.method = method;
 			this.uri = uri;
 			this.path = RequestPath.parse(uri, null);
@@ -241,6 +244,11 @@ class DefaultServerRequestBuilder implements ServerRequest.Builder {
 			return queryParams;
 		}
 
+		@Override
+		public String getId() {
+			return this.id;
+		}
+
 		@Override
 		public String getMethodValue() {
 			return this.method;