Auto-configure binding of Micrometer's JettyServerThreadPoolMetrics

Closes gh-14591

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/web/jetty/JettyServerThreadPoolMetricsBinder.java

@@ -0,0 +1,78 @@
+/*
+ * Copyright 2012-2018 the original author or authors.
+ *
+ * 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 org.springframework.boot.actuate.metrics.web.jetty;
+
+import java.util.Collections;
+
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.Tag;
+import io.micrometer.core.instrument.binder.jetty.JettyServerThreadPoolMetrics;
+import org.eclipse.jetty.util.thread.ThreadPool;
+
+import org.springframework.boot.context.event.ApplicationStartedEvent;
+import org.springframework.boot.web.context.WebServerApplicationContext;
+import org.springframework.boot.web.embedded.jetty.JettyWebServer;
+import org.springframework.boot.web.server.WebServer;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.ApplicationListener;
+
+/**
+ * Binds {@link JettyServerThreadPoolMetrics} in response to the
+ * {@link ApplicationStartedEvent}.
+ *
+ * @author Andy Wilkinson
+ * @since 2.1.0
+ */
+public class JettyServerThreadPoolMetricsBinder
+		implements ApplicationListener<ApplicationStartedEvent> {
+
+	private final MeterRegistry meterRegistry;
+
+	private final Iterable<Tag> tags;
+
+	public JettyServerThreadPoolMetricsBinder(MeterRegistry meterRegistry) {
+		this(meterRegistry, Collections.emptyList());
+	}
+
+	public JettyServerThreadPoolMetricsBinder(MeterRegistry meterRegistry,
+			Iterable<Tag> tags) {
+		this.meterRegistry = meterRegistry;
+		this.tags = tags;
+	}
+
+	@Override
+	public void onApplicationEvent(ApplicationStartedEvent event) {
+		ApplicationContext applicationContext = event.getApplicationContext();
+		ThreadPool threadPool = findThreadPool(applicationContext);
+		if (threadPool != null) {
+			new JettyServerThreadPoolMetrics(threadPool, this.tags)
+					.bindTo(this.meterRegistry);
+		}
+	}
+
+	private ThreadPool findThreadPool(ApplicationContext applicationContext) {
+		if (applicationContext instanceof WebServerApplicationContext) {
+			WebServer webServer = ((WebServerApplicationContext) applicationContext)
+					.getWebServer();
+			if (webServer instanceof JettyWebServer) {
+				return ((JettyWebServer) webServer).getServer().getThreadPool();
+			}
+		}
+		return null;
+	}
+
+}

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/web/jetty/package-info.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2012-2017 the original author or authors.
+ *
+ * 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.
+ */
+
+/**
+ * Actuator support for Jetty metrics.
+ */
+package org.springframework.boot.actuate.metrics.web.jetty;