Java tutorial
/** * Copyright 2017 Pivotal Software, Inc. * * 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.metrics.instrument.web; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.metrics.annotation.Timed; import org.springframework.metrics.instrument.MeterRegistry; import org.springframework.metrics.instrument.Tag; import org.springframework.metrics.instrument.Timer; import org.springframework.metrics.instrument.internal.TimedUtils; import org.springframework.metrics.instrument.stats.WindowSketchQuantiles; import org.springframework.web.context.request.RequestContextHolder; import org.springframework.web.method.HandlerMethod; import org.springframework.web.servlet.handler.HandlerInterceptorAdapter; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.lang.reflect.Method; import java.util.Collections; import java.util.Map; import java.util.Set; import java.util.concurrent.ConcurrentHashMap; import java.util.concurrent.TimeUnit; import java.util.stream.IntStream; import java.util.stream.Stream; import static java.util.stream.Collectors.toSet; import static org.springframework.web.context.request.RequestAttributes.SCOPE_REQUEST; /** * Intercepts incoming HTTP requests and records metrics about execution time and results. * * @author Jon Schneider */ public class MetricsHandlerInterceptor extends HandlerInterceptorAdapter { private static final Log logger = LogFactory.getLog(MetricsHandlerInterceptor.class); private static final String TIMING_REQUEST_ATTRIBUTE = "requestStartTime"; private final MeterRegistry registry; private final WebmvcTagConfigurer tagConfigurer; private final String metricName; private final Map<Timed, Long> longTaskTimerIds = new ConcurrentHashMap<>(); public MetricsHandlerInterceptor(MeterRegistry registry, WebmvcTagConfigurer tagConfigurer, String metricName) { this.registry = registry; this.tagConfigurer = tagConfigurer; this.metricName = metricName; } @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { longTaskTimed(handler).forEach(t -> { if (t.value().isEmpty()) { logger.warn("Unable to perform metrics timing on " + ((HandlerMethod) handler).getShortLogMessage() + ": @Timed annotation must have a value used to name the metric"); return; } longTaskTimerIds.put(t, registry.longTaskTimer(t.value(), tagConfigurer.httpLongRequestTags(request, handler)).start()); }); RequestContextHolder.getRequestAttributes().setAttribute(TIMING_REQUEST_ATTRIBUTE, System.nanoTime(), SCOPE_REQUEST); return super.preHandle(request, response, handler); } @Override public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { RequestContextHolder.getRequestAttributes().setAttribute("exception", ex, SCOPE_REQUEST); Long startTime = (Long) RequestContextHolder.getRequestAttributes().getAttribute(TIMING_REQUEST_ATTRIBUTE, SCOPE_REQUEST); if (startTime != null) recordMetric(request, response, handler, startTime); super.afterCompletion(request, response, handler, ex); } private void recordMetric(HttpServletRequest request, HttpServletResponse response, Object handler, Long startTime) { long endTime = System.nanoTime(); // complete any LongTaskTimer tasks running for this method longTaskTimed(handler).forEach(t -> { if (!t.value().isEmpty()) { registry.longTaskTimer(t.value(), tagConfigurer.httpLongRequestTags(request, handler)) .stop(longTaskTimerIds.remove(t)); } }); // record Timer values timed(handler).forEach(t -> { String name = metricName; if (!t.value().isEmpty()) { name = t.value(); } Timer.Builder timerBuilder = registry.timerBuilder(name) .tags(tagConfigurer.httpRequestTags(request, response)); String[] extraTags = t.extraTags(); if (extraTags.length > 0) { if (extraTags.length % 2 != 0) { if (logger.isErrorEnabled()) { Method method = ((HandlerMethod) handler).getMethod(); String target = method.getDeclaringClass().getName() + "." + method.getName(); logger.error("@Timed extraTags array on method " + target + " size must be even, it is a set of key=value pairs"); } } else { timerBuilder = timerBuilder.tags(IntStream.range(0, extraTags.length / 2) .mapToObj(i -> Tag.of(extraTags[i], extraTags[i + 1]))); } } if (t.quantiles().length > 0) { timerBuilder = timerBuilder .quantiles(WindowSketchQuantiles.build().quantile(t.quantiles()).create()); } timerBuilder.create().record(endTime - startTime, TimeUnit.NANOSECONDS); }); } private Set<Timed> longTaskTimed(Object m) { if (!(m instanceof HandlerMethod)) return Collections.emptySet(); Set<Timed> timed = TimedUtils.findTimed(((HandlerMethod) m).getMethod()).filter(Timed::longTask) .collect(toSet()); if (timed.isEmpty()) { return TimedUtils.findTimed(((HandlerMethod) m).getBeanType()).filter(Timed::longTask).collect(toSet()); } return timed; } private Set<Timed> timed(Object m) { if (!(m instanceof HandlerMethod)) return Collections.emptySet(); Set<Timed> timed = TimedUtils.findTimed(((HandlerMethod) m).getMethod()).filter(t -> !t.longTask()) .collect(toSet()); if (timed.isEmpty()) { return TimedUtils.findTimed(((HandlerMethod) m).getBeanType()).filter(t -> !t.longTask()) .collect(toSet()); } return timed; } }