聊聊springboot的TomcatMetricsBinder

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本文主要研究一下springboot的TomcatMetricsBinder

TomcatMetricsAutoConfiguration

org/springframework/boot/actuate/autoconfigure/metrics/web/tomcat/TomcatMetricsAutoConfiguration.java

@Configuration(proxyBeanMethods = false)
@ConditionalOnWebApplication
@ConditionalOnClass({ TomcatMetrics.class, Manager.class })
@AutoConfigureAfter(CompositeMeterRegistryAutoConfiguration.class)
public class TomcatMetricsAutoConfiguration {@Bean@ConditionalOnBean(MeterRegistry.class)@ConditionalOnMissingBean({ TomcatMetrics.class, TomcatMetricsBinder.class })public TomcatMetricsBinder tomcatMetricsBinder(MeterRegistry meterRegistry) {return new TomcatMetricsBinder(meterRegistry);}}

TomcatMetricsAutoConfiguration在CompositeMeterRegistryAutoConfiguration之后自动配置，它会创建TomcatMetricsBinder

TomcatMetricsBinder

org/springframework/boot/actuate/metrics/web/tomcat/TomcatMetricsBinder.java

public class TomcatMetricsBinder implements ApplicationListener<ApplicationStartedEvent>, DisposableBean {private final MeterRegistry meterRegistry;private final Iterable<Tag> tags;private volatile TomcatMetrics tomcatMetrics;public TomcatMetricsBinder(MeterRegistry meterRegistry) {this(meterRegistry, Collections.emptyList());}public TomcatMetricsBinder(MeterRegistry meterRegistry, Iterable<Tag> tags) {this.meterRegistry = meterRegistry;this.tags = tags;}@Overridepublic void onApplicationEvent(ApplicationStartedEvent event) {ApplicationContext applicationContext = event.getApplicationContext();Manager manager = findManager(applicationContext);this.tomcatMetrics = new TomcatMetrics(manager, this.tags);this.tomcatMetrics.bindTo(this.meterRegistry);}private Manager findManager(ApplicationContext applicationContext) {if (applicationContext instanceof WebServerApplicationContext) {WebServer webServer = ((WebServerApplicationContext) applicationContext).getWebServer();if (webServer instanceof TomcatWebServer) {Context context = findContext((TomcatWebServer) webServer);return context.getManager();}}return null;}private Context findContext(TomcatWebServer tomcatWebServer) {for (Container container : tomcatWebServer.getTomcat().getHost().findChildren()) {if (container instanceof Context) {return (Context) container;}}return null;}@Overridepublic void destroy() {if (this.tomcatMetrics != null) {this.tomcatMetrics.close();}}}

TomcatMetricsBinder实现了ApplicationListener监听ApplicationStartedEvent，同时也实现了DisposableBean接口；其onApplicationEvent方法会获取applicationContext再获取tomcat的Manager，最后创建tomcatMetrics，然后执行bindTo方法；其close方法主要是执行tomcatMetrics的close方法

TomcatMetrics

io/micrometer/core/instrument/binder/tomcat/TomcatMetrics.java

@NonNullApi
@NonNullFields
public class TomcatMetrics implements MeterBinder {private static final String JMX_DOMAIN_EMBEDDED = "Tomcat";private static final String JMX_DOMAIN_STANDALONE = "Catalina";private static final String OBJECT_NAME_SERVER_SUFFIX = ":type=Server";private static final String OBJECT_NAME_SERVER_EMBEDDED = JMX_DOMAIN_EMBEDDED + OBJECT_NAME_SERVER_SUFFIX;private static final String OBJECT_NAME_SERVER_STANDALONE = JMX_DOMAIN_STANDALONE + OBJECT_NAME_SERVER_SUFFIX;@Nullableprivate final Manager manager;private final MBeanServer mBeanServer;private final Iterable<Tag> tags;private volatile String jmxDomain;@Overridepublic void bindTo(MeterRegistry registry) {registerGlobalRequestMetrics(registry);registerServletMetrics(registry);registerCacheMetrics(registry);registerThreadPoolMetrics(registry);registerSessionMetrics(registry);}//......
}            

TomcatMetrics实现了MeterBinder接口，其bindTo方法主要是执行了registerGlobalRequestMetrics、registerServletMetrics、registerCacheMetrics、registerThreadPoolMetrics、registerSessionMetrics

registerGlobalRequestMetrics

    private void registerGlobalRequestMetrics(MeterRegistry registry) {registerMetricsEventually("type", "GlobalRequestProcessor", (name, allTags) -> {FunctionCounter.builder("tomcat.global.sent", mBeanServer,s -> safeDouble(() -> s.getAttribute(name, "bytesSent"))).tags(allTags).baseUnit(BaseUnits.BYTES).register(registry);FunctionCounter.builder("tomcat.global.received", mBeanServer,s -> safeDouble(() -> s.getAttribute(name, "bytesReceived"))).tags(allTags).baseUnit(BaseUnits.BYTES).register(registry);FunctionCounter.builder("tomcat.global.error", mBeanServer,s -> safeDouble(() -> s.getAttribute(name, "errorCount"))).tags(allTags).register(registry);FunctionTimer.builder("tomcat.global.request", mBeanServer,s -> safeLong(() -> s.getAttribute(name, "requestCount")),s -> safeDouble(() -> s.getAttribute(name, "processingTime")), TimeUnit.MILLISECONDS).tags(allTags).register(registry);TimeGauge.builder("tomcat.global.request.max", mBeanServer, TimeUnit.MILLISECONDS,s -> safeDouble(() -> s.getAttribute(name, "maxTime"))).tags(allTags).register(registry);});}    

registerGlobalRequestMetrics主要是注册了请求相关的指标

registerServletMetrics

    private void registerServletMetrics(MeterRegistry registry) {registerMetricsEventually("j2eeType", "Servlet", (name, allTags) -> {FunctionCounter.builder("tomcat.servlet.error", mBeanServer,s -> safeDouble(() -> s.getAttribute(name, "errorCount"))).tags(allTags).register(registry);FunctionTimer.builder("tomcat.servlet.request", mBeanServer,s -> safeLong(() -> s.getAttribute(name, "requestCount")),s -> safeDouble(() -> s.getAttribute(name, "processingTime")), TimeUnit.MILLISECONDS).tags(allTags).register(registry);TimeGauge.builder("tomcat.servlet.request.max", mBeanServer, TimeUnit.MILLISECONDS,s -> safeDouble(() -> s.getAttribute(name, "maxTime"))).tags(allTags).register(registry);});}

registerServletMetrics主要是注册了servlet相关的errorCount、requestCount及maxTime

registerCacheMetrics

    private void registerCacheMetrics(MeterRegistry registry) {registerMetricsEventually("type", "StringCache", (name, allTags) -> {FunctionCounter.builder("tomcat.cache.access", mBeanServer,s -> safeDouble(() -> s.getAttribute(name, "accessCount"))).tags(allTags).register(registry);FunctionCounter.builder("tomcat.cache.hit", mBeanServer,s -> safeDouble(() -> s.getAttribute(name, "hitCount"))).tags(allTags).register(registry);});}

registerCacheMetrics主要是注册了tomcat内部cache的accessCount、hitCount

registerThreadPoolMetrics

    private void registerThreadPoolMetrics(MeterRegistry registry) {registerMetricsEventually("type", "ThreadPool", (name, allTags) -> {Gauge.builder("tomcat.threads.config.max", mBeanServer,s -> safeDouble(() -> s.getAttribute(name, "maxThreads"))).tags(allTags).baseUnit(BaseUnits.THREADS).register(registry);Gauge.builder("tomcat.threads.busy", mBeanServer,s -> safeDouble(() -> s.getAttribute(name, "currentThreadsBusy"))).tags(allTags).baseUnit(BaseUnits.THREADS).register(registry);Gauge.builder("tomcat.threads.current", mBeanServer,s -> safeDouble(() -> s.getAttribute(name, "currentThreadCount"))).tags(allTags).baseUnit(BaseUnits.THREADS).register(registry);});}

registerThreadPoolMetrics主要是注册了tomcat线程池的相关指标

registerSessionMetrics

    private void registerSessionMetrics(MeterRegistry registry) {if (manager == null) {// If the binder is created but unable to find the session manager don't register those metricsreturn;}Gauge.builder("tomcat.sessions.active.max", manager, Manager::getMaxActive).tags(tags).baseUnit("sessions").register(registry);Gauge.builder("tomcat.sessions.active.current", manager, Manager::getActiveSessions).tags(tags).baseUnit("sessions").register(registry);FunctionCounter.builder("tomcat.sessions.created", manager, Manager::getSessionCounter).tags(tags).baseUnit("sessions").register(registry);FunctionCounter.builder("tomcat.sessions.expired", manager, Manager::getExpiredSessions).tags(tags).baseUnit("sessions").register(registry);FunctionCounter.builder("tomcat.sessions.rejected", manager, Manager::getRejectedSessions).tags(tags).baseUnit("sessions").register(registry);TimeGauge.builder("tomcat.sessions.alive.max", manager, TimeUnit.SECONDS, Manager::getSessionMaxAliveTime).tags(tags).register(registry);}

registerSessionMetrics主要是注册了tomcat的session相关指标

小结

springboot的TomcatMetricsBinder主要是接收ApplicationStartedEvent然后创建TomcatMetrics执行bindTo进行注册，TomcatMetrics主要注册了globalRequest、servlet、cache、threadPool、session相关的指标。