Restore and deprecate DropwizardMetricWriter

Fixes gh-3113

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/writer/DropwizardMetricWriter.java

+/*
+ * Copyright 2012-2014 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.writer;
+
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.TimeUnit;
+
+import org.springframework.boot.actuate.metrics.Metric;
+import org.springframework.boot.actuate.metrics.dropwizard.DropwizardMetricServices;
+
+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.Timer;
+
+/**
+ * A {@link MetricWriter} that send data to a Codahale {@link MetricRegistry} based on a
+ * naming convention:
+ *
+ * <ul>
+ * <li>Updates to {@link #increment(Delta)} with names in "meter.*" are treated as
+ * {@link Meter} events</li>
+ * <li>Other deltas are treated as simple {@link Counter} values</li>
+ * <li>Inputs to {@link #set(Metric)} with names in "histogram.*" are treated as
+ * {@link Histogram} updates</li>
+ * <li>Inputs to {@link #set(Metric)} with names in "timer.*" are treated as {@link Timer}
+ * updates</li>
+ * <li>Other metrics are treated as simple {@link Gauge} values (single valued
+ * measurements of type double)</li>
+ * </ul>
+ *
+ * @author Dave Syer
+ *
+ * @deprecated Use {@link DropwizardMetricServices} instead
+ */
+@Deprecated
+public class DropwizardMetricWriter implements MetricWriter {
+
+	private final MetricRegistry registry;
+
+	private final ConcurrentMap<String, Object> gaugeLocks = new ConcurrentHashMap<String, Object>();
+
+	/**
+	 * Create a new {@link DropwizardMetricWriter} instance.
+	 * @param registry the underlying metric registry
+	 */
+	public DropwizardMetricWriter(MetricRegistry registry) {
+		this.registry = registry;
+	}
+
+	@Override
+	public void increment(Delta<?> delta) {
+		String name = delta.getName();
+		long value = delta.getValue().longValue();
+		if (name.startsWith("meter")) {
+			Meter meter = this.registry.meter(name);
+			meter.mark(value);
+		}
+		else {
+			Counter counter = this.registry.counter(name);
+			counter.inc(value);
+		}
+	}
+
+	@Override
+	public void set(Metric<?> value) {
+		String name = value.getName();
+		if (name.startsWith("histogram")) {
+			long longValue = value.getValue().longValue();
+			Histogram metric = this.registry.histogram(name);
+			metric.update(longValue);
+		}
+		else if (name.startsWith("timer")) {
+			long longValue = value.getValue().longValue();
+			Timer metric = this.registry.timer(name);
+			metric.update(longValue, TimeUnit.MILLISECONDS);
+		}
+		else {
+			final double gauge = value.getValue().doubleValue();
+			// Ensure we synchronize to avoid another thread pre-empting this thread after
+			// remove causing an error in CodaHale metrics
+			// NOTE: CodaHale provides no way to do this atomically
+			synchronized (getGuageLock(name)) {
+				this.registry.remove(name);
+				this.registry.register(name, new SimpleGauge(gauge));
+			}
+		}
+	}
+
+	private Object getGuageLock(String name) {
+		Object lock = this.gaugeLocks.get(name);
+		if (lock == null) {
+			Object newLock = new Object();
+			lock = this.gaugeLocks.putIfAbsent(name, newLock);
+			lock = (lock == null ? newLock : lock);
+		}
+		return lock;
+	}
+
+	@Override
+	public void reset(String metricName) {
+		this.registry.remove(metricName);
+	}
+
+	/**
+	 * Simple {@link Gauge} implementation to {@literal double} value.
+	 */
+	private static class SimpleGauge implements Gauge<Double> {
+
+		private final double value;
+
+		private SimpleGauge(double value) {
+			this.value = value;
+		}
+
+		@Override
+		public Double getValue() {
+			return this.value;
+		}
+	}
+
+}