himanshug commented on a change in pull request #7363: Implementing dropwizard emitter for druid URL: https://github.com/apache/incubator-druid/pull/7363#discussion_r321015861
########## File path: extensions-contrib/dropwizard-emitter/src/main/java/org/apache/druid/emitter/dropwizard/DropwizardEmitter.java ########## @@ -0,0 +1,165 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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.apache.druid.emitter.dropwizard; + +import com.codahale.metrics.Gauge; +import com.codahale.metrics.MetricRegistry; +import com.fasterxml.jackson.databind.ObjectMapper; +import com.google.common.base.Joiner; +import com.google.common.collect.ImmutableList; +import org.apache.druid.java.util.common.ISE; +import org.apache.druid.java.util.common.StringUtils; +import org.apache.druid.java.util.common.logger.Logger; +import org.apache.druid.java.util.emitter.core.Emitter; +import org.apache.druid.java.util.emitter.core.Event; +import org.apache.druid.java.util.emitter.service.AlertEvent; +import org.apache.druid.java.util.emitter.service.ServiceMetricEvent; + +import java.util.LinkedHashMap; +import java.util.List; +import java.util.Map; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.atomic.AtomicBoolean; + +public class DropwizardEmitter implements Emitter +{ + private static Logger log = new Logger(DropwizardEmitter.class); + private final MetricRegistry metricsRegistry = new MetricRegistry(); + private final AtomicBoolean started = new AtomicBoolean(false); + private final DropwizardConverter converter; + private final List<Emitter> alertEmitters; + private final List<DropwizardReporter> reporters; + private final DropwizardEmitterConfig config; + // Note: the gauges do not represent the actual instantaneous value for the metrics. + // Instead they have the last known value for it. + private final ConcurrentHashMap<String, Number> gagues = new ConcurrentHashMap<>(); + + public DropwizardEmitter( + DropwizardEmitterConfig config, + ObjectMapper mapper, + List<Emitter> alertEmitters + ) + { + this.alertEmitters = alertEmitters; + this.config = config; + this.reporters = config.getReporters(); + this.converter = new DropwizardConverter(mapper, config.getDimensionMapPath()); + } + + + @Override + public void start() + { + for (DropwizardReporter reporter : reporters) { + reporter.start(metricsRegistry); + } + started.set(true); + } + + @Override + public void emit(Event event) + { + if (event instanceof ServiceMetricEvent) { + ServiceMetricEvent metricEvent = (ServiceMetricEvent) event; + String host = metricEvent.getHost(); + String service = metricEvent.getService(); + String metric = metricEvent.getMetric(); + Map<String, Object> userDims = metricEvent.getUserDims(); + Number value = metricEvent.getValue(); + ImmutableList.Builder<String> nameBuilder = new ImmutableList.Builder<>(); + LinkedHashMap<String, String> dims = new LinkedHashMap<>(); + final DropwizardMetricSpec metricSpec = converter.addFilteredUserDims(service, metric, userDims, dims); + + if (metricSpec != null) { + if (config.isIncludeDimensionNames()) { + if (config.getPrefix() != null) { + nameBuilder.add(config.getPrefix()); + } + nameBuilder.add("metric=" + metric); + nameBuilder.add("service=" + service); + if (config.getIncludeHost()) { + nameBuilder.add("hostname=" + host); + } + dims.forEach((key, value1) -> nameBuilder.add(key + "=" + value1)); + } else { + nameBuilder.add(metric); + nameBuilder.add(service); + if (config.getIncludeHost()) { + nameBuilder.add(host); + } + nameBuilder.addAll(dims.values()); + } + + String fullName = StringUtils.replaceChar(Joiner.on(",").join(nameBuilder.build()), '/', "."); + updateMetric(fullName, value, metricSpec); + } else { + log.debug("Service=[%s], Metric=[%s] has no mapping", service, metric); + } + } else if (event instanceof AlertEvent) { + for (Emitter emitter : alertEmitters) { + emitter.emit(event); + } + } else { + throw new ISE("unknown event type [%s]", event.getClass()); + } + } + + private void updateMetric(String name, Number value, DropwizardMetricSpec metricSpec) + { + switch (metricSpec.getType()) { + case meter: + metricsRegistry.meter(name).mark(value.longValue()); + break; + case timer: + metricsRegistry.timer(name) + .update(value.longValue(), metricSpec.getTimeUnit()); + break; + case counter: + metricsRegistry.counter(name).inc(value.longValue()); + break; + case histogram: + metricsRegistry.histogram(name).update(value.longValue()); + break; + case gauge: + Number prevVal = gagues.put(name, value); + // It is the first time we get this metric, register it with metricsRegistry + if (prevVal == null) { + metricsRegistry.register(name, (Gauge<Number>) () -> gagues.get(name)); + } + } + } + + @Override + public void flush() + { + for (DropwizardReporter reporter : reporters) { + reporter.flush(); Review comment: we could mention that it must be non blocking in the javadoc of `DropwizardReporter.flush()`, so that if someone implements another then they know about it. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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