Added MetricsTracker and -Factory to emit JFR events

pom.xml

@@ -22,7 +22,7 @@
       <sureFireForks11>false</sureFireForks11>
       <!--java11.sourceDirectory>${project.basedir}/src/main/java11</java11.sourceDirectory -->
       <!--java11.build.outputDirectory>${project.build.directory}/classes-java11</java11.build.outputDirectory -->
-      <artifact.classifier />
+      <artifact.classifier/>
 
       <!-- When releasing a new version, this property controls whether the staged artifacts will be automatically
            released in Nexus. If this is set to false (-DautoReleaseStagedArtifacts=false), artifacts will need to
@@ -304,10 +304,9 @@
             <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
-               <version>3.10.1</version>
+               <version>3.14.0</version>
                <configuration>
-                  <source>11</source>
-                  <target>11</target>
+                  <release>11</release>
                   <compilerArgs>-Xlint</compilerArgs>
                </configuration>
             </plugin>
@@ -577,7 +576,8 @@
                      com.zaxxer.hikari.metrics,
                      com.zaxxer.hikari.metrics.dropwizard,
                      com.zaxxer.hikari.metrics.micrometer,
-                     com.zaxxer.hikari.metrics.prometheus
+                     com.zaxxer.hikari.metrics.prometheus,
+                     com.zaxxer.hikari.metrics.jfr,
                   </Export-Package>
                   <Private-Package>com.zaxxer.hikari.*</Private-Package>
                   <Include-Resource>{maven-resources}</Include-Resource>
@@ -593,6 +593,7 @@
                      javax.sql.rowset,
                      javax.sql.rowset.serial,
                      javax.sql.rowset.spi,
+                     jdk.jfr,
                      com.codahale.metrics;resolution:=optional,
                      com.codahale.metrics.health;resolution:=optional,
                      io.dropwizard.metrics5;resolution:=optional,

src/main/java/com/zaxxer/hikari/metrics/jfr/JFREventMetricsTracker.java

@@ -0,0 +1,142 @@
+/*
+ * Copyright (C) 2025 Brett Wooldridge
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.zaxxer.hikari.metrics.jfr;
+
+import com.zaxxer.hikari.metrics.IMetricsTracker;
+import com.zaxxer.hikari.metrics.PoolStats;
+import com.zaxxer.hikari.metrics.jfr.events.*;
+import jdk.jfr.Event;
+import jdk.jfr.FlightRecorder;
+
+import java.util.*;
+
+public class JFREventMetricsTracker implements IMetricsTracker {
+
+   private final String poolName;
+   private final PoolStats poolStats;
+   private final Map<Class<? extends Event>, Runnable> periodicEvents = new HashMap<>();
+
+   JFREventMetricsTracker(final String poolName, final PoolStats poolStats) {
+      this.poolName = Objects.requireNonNull(poolName, "Missing pool name");
+      this.poolStats = Objects.requireNonNull(poolStats, "Missing pool stats");
+      this.periodicEvents.put(ConnectionsActive.class, () -> {
+         ConnectionsActive event = new ConnectionsActive();
+         if (event.isEnabled()) {
+            event.poolName = this.poolName;
+            event.activeConnections = this.poolStats.getActiveConnections();
+            event.commit();
+         }
+      });
+      this.periodicEvents.put(ConnectionsIdle.class, () -> {
+         ConnectionsIdle event = new ConnectionsIdle();
+         if (event.isEnabled()) {
+            event.poolName = this.poolName;
+            event.idleConnections = this.poolStats.getIdleConnections();
+            event.commit();
+         }
+      });
+      this.periodicEvents.put(ConnectionsMax.class, () -> {
+         ConnectionsMax event = new ConnectionsMax();
+         if (event.isEnabled()) {
+            event.poolName = this.poolName;
+            event.maxConnections = this.poolStats.getMaxConnections();
+            event.commit();
+         }
+      });
+      this.periodicEvents.put(ConnectionsMin.class, () -> {
+         ConnectionsMin event = new ConnectionsMin();
+         if (event.isEnabled()) {
+            event.poolName = this.poolName;
+            event.minConnections = this.poolStats.getMinConnections();
+            event.commit();
+         }
+      });
+      this.periodicEvents.put(ConnectionsTotal.class, () -> {
+         ConnectionsTotal event = new ConnectionsTotal();
+         if (event.isEnabled()) {
+            event.poolName = this.poolName;
+            event.totalConnections = this.poolStats.getTotalConnections();
+            event.commit();
+         }
+      });
+      this.periodicEvents.put(ThreadsPending.class, () -> {
+         ThreadsPending event = new ThreadsPending();
+         if (event.isEnabled()) {
+            event.poolName = this.poolName;
+            event.threadsPending = this.poolStats.getPendingThreads();
+            event.commit();
+         }
+      });
+      registerEventClasses(periodicEvents.keySet(), ConnectionAcquired.class, ConnectionCreated.class, ConnectionTimeout.class, ConnectionUsage.class);
+      addPeriodicEvents(periodicEvents);
+   }
+
+   @SafeVarargs
+   private static void registerEventClasses(Set<Class<? extends Event>> events, Class<? extends Event> ... additional) {
+      events.forEach(FlightRecorder::register);
+      Arrays.stream(additional).forEach(FlightRecorder::register);
+   }
+
+   private static void addPeriodicEvents(Map<Class<? extends Event>, Runnable> periodicEvents) {
+      periodicEvents.forEach(FlightRecorder::addPeriodicEvent);
+   }
+
+   @Override
+   public void recordConnectionCreatedMillis(long connectionCreatedMillis) {
+      ConnectionCreated event = new ConnectionCreated();
+      if (event.isEnabled()) {
+         event.poolName = this.poolName;
+         event.connectionCreatedMillis = connectionCreatedMillis;
+         event.commit();
+      }
+   }
+
+   @Override
+   public void recordConnectionAcquiredNanos(long elapsedAcquiredNanos) {
+      ConnectionAcquired event = new ConnectionAcquired();
+      if (event.isEnabled()) {
+         event.poolName = this.poolName;
+         event.elapsedAcquiredNanos = elapsedAcquiredNanos;
+         event.commit();
+      }
+   }
+
+   @Override
+   public void recordConnectionUsageMillis(long elapsedBorrowedMillis) {
+      ConnectionUsage event = new ConnectionUsage();
+      if (event.isEnabled()) {
+         event.poolName = this.poolName;
+         event.elapsedBorrowedMillis = elapsedBorrowedMillis;
+         event.commit();
+      }
+   }
+
+   @Override
+   public void recordConnectionTimeout() {
+      ConnectionTimeout event = new ConnectionTimeout();
+      if (event.isEnabled()) {
+         event.poolName = this.poolName;
+         event.commit();
+      }
+   }
+
+   @Override
+   public void close() {
+      this.periodicEvents.values().forEach(FlightRecorder::removePeriodicEvent);
+   }
+
+}

src/main/java/com/zaxxer/hikari/metrics/jfr/JFREventMetricsTrackerFactory.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2025 Brett Wooldridge
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.zaxxer.hikari.metrics.jfr;
+
+import com.zaxxer.hikari.metrics.IMetricsTracker;
+import com.zaxxer.hikari.metrics.MetricsTrackerFactory;
+import com.zaxxer.hikari.metrics.PoolStats;
+
+public class JFREventMetricsTrackerFactory implements MetricsTrackerFactory {
+
+   @Override
+   public IMetricsTracker create(String poolName, PoolStats poolStats) {
+      return new JFREventMetricsTracker(poolName, poolStats);
+   }
+
+}

src/main/java/com/zaxxer/hikari/metrics/jfr/events/ConnectionAcquired.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2025 Brett Wooldridge
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.zaxxer.hikari.metrics.jfr.events;
+
+import jdk.jfr.*;
+
+@StackTrace(false)
+@Category({"HikariCP"})
+public class ConnectionAcquired extends Event {
+
+   @Label("Pool name")
+   @Name("pool")
+   public String poolName;
+
+   @Label("Connection acquisition time")
+   @Name("hikaricp_connection_acquisition_time")
+   @Timespan(Timespan.NANOSECONDS)
+   public long elapsedAcquiredNanos;
+
+}

src/main/java/com/zaxxer/hikari/metrics/jfr/events/ConnectionCreated.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2025 Brett Wooldridge
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.zaxxer.hikari.metrics.jfr.events;
+
+import jdk.jfr.*;
+
+@StackTrace(false)
+@Category({"HikariCP"})
+public class ConnectionCreated extends Event {
+
+   @Label("Pool name")
+   @Name("pool")
+   public String poolName;
+
+   @Label("Connection creation time")
+   @Name("hikaricp_connection_creation_time")
+   @Timespan(Timespan.MILLISECONDS)
+   public long connectionCreatedMillis;
+
+}

src/main/java/com/zaxxer/hikari/metrics/jfr/events/ConnectionTimeout.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2025 Brett Wooldridge
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.zaxxer.hikari.metrics.jfr.events;
+
+import jdk.jfr.*;
+
+@StackTrace(false)
+@Category({"HikariCP"})
+public class ConnectionTimeout extends Event {
+
+   @Label("Pool name")
+   @Name("pool")
+   public String poolName;
+
+}

src/main/java/com/zaxxer/hikari/metrics/jfr/events/ConnectionUsage.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2025 Brett Wooldridge
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.zaxxer.hikari.metrics.jfr.events;
+
+import jdk.jfr.*;
+
+@StackTrace(false)
+@Category({"HikariCP"})
+public class ConnectionUsage extends Event {
+
+   @Label("Pool name")
+   @Name("pool")
+   public String poolName;
+
+   @Label("Connection usage time")
+   @Name("hikaricp_connection_usage_time")
+   @Timespan(Timespan.MILLISECONDS)
+   public long elapsedBorrowedMillis;
+
+}

src/main/java/com/zaxxer/hikari/metrics/jfr/events/ConnectionsActive.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2025 Brett Wooldridge
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.zaxxer.hikari.metrics.jfr.events;
+
+import jdk.jfr.*;
+
+@StackTrace(false)
+@Period("1 s")
+@Category({"HikariCP"})
+public class ConnectionsActive extends Event {
+
+   @Label("Pool name")
+   @Name("pool")
+   public String poolName;
+
+   @Label("Connections active")
+   @Name("hikaricp_connections_active")
+   public int activeConnections;
+
+}