Merge #2593 into 2.0.0-M4

reactor-netty5-http/src/main/java/reactor/netty5/http/client/HttpClient.java

@@ -61,6 +61,8 @@
 import reactor.netty5.tcp.SslProvider;
 import reactor.netty5.transport.ClientTransport;
 import reactor.netty5.transport.ProxyProvider;
+import reactor.util.Logger;
+import reactor.util.Loggers;
 import reactor.util.annotation.Nullable;
 
 /**
@@ -1036,6 +1038,9 @@ public final HttpClient mapConnect(
 	 * For example instead of using the actual uri {@code "/users/1"} as uri tag value, templated uri
 	 * {@code "/users/{id}"} can be used.
 	 * <p><strong>Note:</strong>
+	 * It is strongly recommended to provide template-like form for the URIs. Without a conversion to a template-like form,
+	 * each distinct URI leads to the creation of a distinct tag, which takes a lot of memory for the metrics.
+	 * <p><strong>Note:</strong>
 	 * It is strongly recommended applications to configure an upper limit for the number of the URI tags.
 	 * For example:
 	 * <pre class="code">
@@ -1058,6 +1063,12 @@ public final HttpClient metrics(boolean enable, Function<String, String> uriTagV
 						"To enable metrics, you must add the dependencies to `io.micrometer:micrometer-core`" +
 								" and `io.micrometer:micrometer-tracing` to the class path first");
 			}
+			if (uriTagValue == Function.<String>identity()) {
+				log.debug("Metrics are enabled with [uriTagValue=Function#identity]. " +
+						"It is strongly recommended to provide template-like form for the URIs. " +
+						"Without a conversion to a template-like form, each distinct URI leads " +
+						"to the creation of a distinct tag, which takes a lot of memory for the metrics.");
+			}
 			HttpClient dup = duplicate();
 			dup.configuration().metricsRecorder(() -> configuration().defaultMetricsRecorder());
 			dup.configuration().uriTagValue = uriTagValue;
@@ -1389,6 +1400,8 @@ static String reactorNettyVersion() {
 		               .orElse("dev");
 	}
 
+	static final Logger log = Loggers.getLogger(HttpClient.class);
+
 	static final String HTTP_SCHEME = "http";
 
 	static final String HTTPS_SCHEME = "https";

reactor-netty5-http/src/main/java/reactor/netty5/http/server/HttpServer.java

@@ -431,6 +431,9 @@ public final HttpServer maxKeepAliveRequests(int maxKeepAliveRequests) {
 	 * For example instead of using the actual uri {@code "/users/1"} as uri tag value, templated uri
 	 * {@code "/users/{id}"} can be used.
 	 * <p><strong>Note:</strong>
+	 * It is strongly recommended to provide template-like form for the URIs. Without a conversion to a template-like form,
+	 * each distinct URI leads to the creation of a distinct tag, which takes a lot of memory for the metrics.
+	 * <p><strong>Note:</strong>
 	 * It is strongly recommended applications to configure an upper limit for the number of the URI tags.
 	 * For example:
 	 * <pre class="code">
@@ -453,6 +456,12 @@ public final HttpServer metrics(boolean enable, Function<String, String> uriTagV
 						"To enable metrics, you must add the dependencies to `io.micrometer:micrometer-core`" +
 								" and `io.micrometer:micrometer-tracing` to the class path first");
 			}
+			if (uriTagValue == Function.<String>identity()) {
+				log.debug("Metrics are enabled with [uriTagValue=Function#identity]. " +
+						"It is strongly recommended to provide template-like form for the URIs. " +
+						"Without a conversion to a template-like form, each distinct URI leads " +
+						"to the creation of a distinct tag, which takes a lot of memory for the metrics.");
+			}
 			HttpServer dup = duplicate();
 			dup.configuration().metricsRecorder(() -> configuration().defaultMetricsRecorder());
 			dup.configuration().uriTagValue = uriTagValue;