feat(metrics): add HTTP server and client active network connection gauge metrics

Author: i-m-addycoder

extensions/micrometer/runtime/src/main/java/io/quarkus/micrometer/runtime/binder/vertx/NetworkMetrics.java

@@ -1,7 +1,10 @@
 package io.quarkus.micrometer.runtime.binder.vertx;
 
+import java.util.concurrent.atomic.LongAdder;
+
 import io.micrometer.core.instrument.Counter;
 import io.micrometer.core.instrument.DistributionSummary;
+import io.micrometer.core.instrument.Gauge;
 import io.micrometer.core.instrument.LongTaskTimer;
 import io.micrometer.core.instrument.Meter;
 import io.micrometer.core.instrument.MeterRegistry;
@@ -16,14 +19,17 @@ public class NetworkMetrics implements TCPMetrics<LongTaskTimer.Sample> {
     final DistributionSummary received;
     final DistributionSummary sent;
     final Meter.MeterProvider<Counter> exceptionCounter;
+    final Gauge activeConnections;
 
     final Tags tags;
     private final LongTaskTimer connDuration;
+    private final LongAdder connCount;
 
     public NetworkMetrics(MeterRegistry registry, Tags tags, String prefix, String receivedDesc, String sentDesc,
-            String connDurationDesc) {
+            String connDurationDesc, String connCountDesc) {
         this.registry = registry;
         this.tags = tags == null ? Tags.empty() : tags;
+        connCount = new LongAdder();
         received = DistributionSummary.builder(prefix + ".bytes.read")
                 .description(receivedDesc)
                 .tags(this.tags)
@@ -38,6 +44,10 @@ public NetworkMetrics(MeterRegistry registry, Tags tags, String prefix, String r
                 .register(registry);
         exceptionCounter = Counter.builder(prefix + ".errors")
                 .withRegistry(registry);
+        activeConnections = Gauge.builder(prefix + ".active.connections", connCount, LongAdder::longValue)
+                .description(connCountDesc)
+                .tags(this.tags)
+                .register(registry);
     }
 
     /**
@@ -53,6 +63,7 @@ public NetworkMetrics(MeterRegistry registry, Tags tags, String prefix, String r
      */
     @Override
     public LongTaskTimer.Sample connected(SocketAddress remoteAddress, String remoteName) {
+        connCount.increment();
         return connDuration.start();
     }
 
@@ -65,6 +76,7 @@ public LongTaskTimer.Sample connected(SocketAddress remoteAddress, String remote
      */
     @Override
     public void disconnected(LongTaskTimer.Sample sample, SocketAddress remoteAddress) {
+        connCount.decrement();
         if (sample == null) {
             return;
         }

extensions/micrometer/runtime/src/main/java/io/quarkus/micrometer/runtime/binder/vertx/VertxTcpClientMetrics.java

@@ -9,7 +9,8 @@ public class VertxTcpClientMetrics extends NetworkMetrics {
         super(registry, tags, prefix,
                 "Number of bytes received by the client",
                 "Number of bytes sent by the client",
-                "The duration of the connections");
+                "The duration of the connections",
+                "Number of connections to the remote host currently opened");
     }
 
 }

extensions/micrometer/runtime/src/main/java/io/quarkus/micrometer/runtime/binder/vertx/VertxTcpServerMetrics.java

@@ -9,7 +9,8 @@ public class VertxTcpServerMetrics extends NetworkMetrics {
         super(registry, tags, prefix,
                 "Number of bytes received by the server",
                 "Number of bytes sent by the server",
-                "The duration of the connections");
+                "The duration of the connections",
+                "Number of opened connections to the HTTP Server");
     }
 
 }