Java tutorial
/* * Copyright 2013-2015 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.reader; import java.beans.PropertyDescriptor; import java.util.HashSet; import java.util.Iterator; import java.util.List; import java.util.Map; import java.util.Set; import java.util.concurrent.ConcurrentHashMap; import java.util.concurrent.TimeUnit; import com.codahale.metrics.Counter; import com.codahale.metrics.Gauge; import com.codahale.metrics.Histogram; import com.codahale.metrics.Meter; import com.codahale.metrics.MetricRegistry; import com.codahale.metrics.MetricRegistryListener; import com.codahale.metrics.Sampling; import com.codahale.metrics.Timer; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.beans.BeanUtils; import org.springframework.beans.BeanWrapperImpl; import org.springframework.boot.actuate.metrics.Metric; import org.springframework.util.ClassUtils; import org.springframework.util.LinkedMultiValueMap; import org.springframework.util.MultiValueMap; import org.springframework.util.StringUtils; /** * A Spring Boot {@link MetricReader} that reads metrics from a Dropwizard * {@link MetricRegistry}. Gauges and Counters are reflected as a single value. Timers, * Meters and Histograms are expanded into sets of metrics containing all the properties * of type Number. * * @author Dave Syer * @author Andy Wilkinson */ public class MetricRegistryMetricReader implements MetricReader, MetricRegistryListener { private static Log logger = LogFactory.getLog(MetricRegistryMetricReader.class); private static final Map<Class<?>, Set<String>> numberKeys = new ConcurrentHashMap<Class<?>, Set<String>>(); private final Object monitor = new Object(); private final Map<String, String> names = new ConcurrentHashMap<String, String>(); private final MultiValueMap<String, String> reverse = new LinkedMultiValueMap<String, String>(); private final MetricRegistry registry; public MetricRegistryMetricReader(MetricRegistry registry) { this.registry = registry; registry.addListener(this); } @Override public Metric<?> findOne(String metricName) { String name = this.names.get(metricName); if (name == null) { return null; } com.codahale.metrics.Metric metric = this.registry.getMetrics().get(name); if (metric == null) { return null; } if (metric instanceof Counter) { Counter counter = (Counter) metric; return new Metric<Number>(metricName, counter.getCount()); } if (metric instanceof Gauge) { @SuppressWarnings("unchecked") Gauge<Number> value = (Gauge<Number>) metric; return new Metric<Number>(metricName, value.getValue()); } if (metric instanceof Sampling) { if (metricName.contains(".snapshot.")) { Number value = getMetric(((Sampling) metric).getSnapshot(), metricName); if (metric instanceof Timer) { // convert back to MILLISEC value = TimeUnit.MILLISECONDS.convert(value.longValue(), TimeUnit.NANOSECONDS); } return new Metric<Number>(metricName, value); } } return new Metric<Number>(metricName, getMetric(metric, metricName)); } @Override public Iterable<Metric<?>> findAll() { return new Iterable<Metric<?>>() { @Override public Iterator<Metric<?>> iterator() { Set<Metric<?>> metrics = new HashSet<Metric<?>>(); for (String name : MetricRegistryMetricReader.this.names.keySet()) { Metric<?> metric = findOne(name); if (metric != null) { metrics.add(metric); } } return metrics.iterator(); } }; } @Override public long count() { return this.names.size(); } @Override public void onGaugeAdded(String name, Gauge<?> gauge) { if (!(gauge.getValue() instanceof Number)) { if (logger.isDebugEnabled()) { logger.debug("Ignoring gauge '" + name + "' (" + gauge + ") as its value is not a Number"); } return; } this.names.put(name, name); synchronized (this.monitor) { this.reverse.add(name, name); } } @Override public void onGaugeRemoved(String name) { remove(name); } @Override public void onCounterAdded(String name, Counter counter) { this.names.put(name, name); synchronized (this.monitor) { this.reverse.add(name, name); } } @Override public void onCounterRemoved(String name) { remove(name); } @Override public void onHistogramAdded(String name, Histogram histogram) { for (String key : getNumberKeys(histogram)) { String metricName = name + "." + key; this.names.put(metricName, name); synchronized (this.monitor) { this.reverse.add(name, metricName); } } for (String key : getNumberKeys(histogram.getSnapshot())) { String metricName = name + ".snapshot." + key; this.names.put(metricName, name); synchronized (this.monitor) { this.reverse.add(name, metricName); } } } @Override public void onHistogramRemoved(String name) { remove(name); } @Override public void onMeterAdded(String name, Meter meter) { for (String key : getNumberKeys(meter)) { String metricName = name + "." + key; this.names.put(metricName, name); synchronized (this.monitor) { this.reverse.add(name, metricName); } } } @Override public void onMeterRemoved(String name) { remove(name); } @Override public void onTimerAdded(String name, Timer timer) { for (String key : getNumberKeys(timer)) { String metricName = name + "." + key; this.names.put(metricName, name); synchronized (this.monitor) { this.reverse.add(name, metricName); } } for (String key : getNumberKeys(timer.getSnapshot())) { String metricName = name + ".snapshot." + key; this.names.put(metricName, name); synchronized (this.monitor) { this.reverse.add(name, metricName); } } } @Override public void onTimerRemoved(String name) { remove(name); } private void remove(String name) { List<String> keys; synchronized (this.monitor) { keys = this.reverse.remove(name); } if (keys != null) { for (String key : keys) { this.names.remove(name + "." + key); } } } private static Set<String> getNumberKeys(Object metric) { Set<String> result = numberKeys.get(metric.getClass()); if (result == null) { result = new HashSet<String>(); } if (result.isEmpty()) { for (PropertyDescriptor descriptor : BeanUtils.getPropertyDescriptors(metric.getClass())) { if (ClassUtils.isAssignable(Number.class, descriptor.getPropertyType())) { result.add(descriptor.getName()); } } numberKeys.put(metric.getClass(), result); } return result; } private static Number getMetric(Object metric, String metricName) { String key = StringUtils.getFilenameExtension(metricName); return (Number) new BeanWrapperImpl(metric).getPropertyValue(key); } }