Fix MetricWriterMessageHandler to deal with reset

Update MetricWriterMessageHandler to deal with 'reset' messages and to
log unsupported payload types.

Fixes gh-3378

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

 /*
- * Copyright 2012-2013 the original author or authors.
+ * Copyright 2012-2015 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.
@@ -18,7 +18,6 @@ package org.springframework.boot.actuate.metrics.writer;
 
 import org.springframework.boot.actuate.metrics.Metric;
 import org.springframework.messaging.MessageChannel;
-import org.springframework.messaging.support.MessageBuilder;
 
 /**
  * A {@link MetricWriter} that publishes the metric updates on a {@link MessageChannel}.
@@ -26,13 +25,10 @@ import org.springframework.messaging.support.MessageBuilder;
  * carry an additional header "metricName" with the name of the metric in it.
  *
  * @author Dave Syer
+ * @see MetricWriterMessageHandler
  */
 public class MessageChannelMetricWriter implements MetricWriter {
 
-	private static final String METRIC_NAME = "metricName";
-
-	private final String DELETE = "delete";
-
 	private final MessageChannel channel;
 
 	public MessageChannelMetricWriter(MessageChannel channel) {
@@ -41,20 +37,17 @@ public class MessageChannelMetricWriter implements MetricWriter {
 
 	@Override
 	public void increment(Delta<?> delta) {
-		this.channel.send(MessageBuilder.withPayload(delta)
-				.setHeader(METRIC_NAME, delta.getName()).build());
+		this.channel.send(MetricMessage.forIncrement(delta));
 	}
 
 	@Override
 	public void set(Metric<?> value) {
-		this.channel.send(MessageBuilder.withPayload(value)
-				.setHeader(METRIC_NAME, value.getName()).build());
+		this.channel.send(MetricMessage.forSet(value));
 	}
 
 	@Override
 	public void reset(String metricName) {
-		this.channel.send(MessageBuilder.withPayload(this.DELETE)
-				.setHeader(METRIC_NAME, metricName).build());
+		this.channel.send(MetricMessage.forReset(metricName));
 	}
 
 }

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

+/*
+ * Copyright 2012-2015 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.writer;
+
+import org.springframework.boot.actuate.metrics.Metric;
+import org.springframework.messaging.Message;
+import org.springframework.messaging.support.MessageBuilder;
+
+/**
+ * A metric message sent via Spring Integration.
+ *
+ * @author Phillip Webb
+ */
+class MetricMessage {
+
+	private static final String METRIC_NAME = "metricName";
+
+	private static final String DELETE = "delete";
+
+	private final Message<?> message;
+
+	public MetricMessage(Message<?> message) {
+		this.message = message;
+	}
+
+	public boolean isReset() {
+		return DELETE.equals(getPayload());
+	}
+
+	public Object getPayload() {
+		return this.message.getPayload();
+	}
+
+	public String getMetricName() {
+		return this.message.getHeaders().get(METRIC_NAME, String.class);
+	}
+
+	public static Message<?> forIncrement(Delta<?> delta) {
+		return forPayload(delta.getName(), delta);
+	}
+
+	public static Message<?> forSet(Metric<?> value) {
+		return forPayload(value.getName(), value);
+	}
+
+	public static Message<?> forReset(String metricName) {
+		return forPayload(metricName, DELETE);
+	}
+
+	private static Message<?> forPayload(String metricName, Object payload) {
+		MessageBuilder<Object> builder = MessageBuilder.withPayload(payload);
+		builder.setHeader(METRIC_NAME, metricName);
+		return builder.build();
+	}
+
+}

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

 /*
- * Copyright 2012-2013 the original author or authors.
+ * Copyright 2012-2015 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.
@@ -16,6 +16,8 @@
 
 package org.springframework.boot.actuate.metrics.writer;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.springframework.boot.actuate.metrics.Metric;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHandler;
@@ -26,9 +28,12 @@ import org.springframework.messaging.MessagingException;
  * {@link MetricWriter}.
  *
  * @author Dave Syer
+ * @see MessageChannelMetricWriter
  */
 public final class MetricWriterMessageHandler implements MessageHandler {
 
+	private static final Log logger = LogFactory.getLog(MetricWriterMessageHandler.class);
+
 	private final MetricWriter observer;
 
 	public MetricWriterMessageHandler(MetricWriter observer) {
@@ -37,14 +42,28 @@ public final class MetricWriterMessageHandler implements MessageHandler {
 
 	@Override
 	public void handleMessage(Message<?> message) throws MessagingException {
+		handleMessage(new MetricMessage(message));
+	}
+
+	private void handleMessage(MetricMessage message) {
 		Object payload = message.getPayload();
-		if (payload instanceof Delta) {
+		if (message.isReset()) {
+			this.observer.reset(message.getMetricName());
+		}
+		else if (payload instanceof Delta) {
 			Delta<?> value = (Delta<?>) payload;
 			this.observer.increment(value);
 		}
-		else {
+		else if (payload instanceof Metric) {
 			Metric<?> value = (Metric<?>) payload;
 			this.observer.set(value);
 		}
+		else {
+			if (logger.isWarnEnabled()) {
+				logger.warn("Unsupported metric payload "
+						+ (payload == null ? "null" : payload.getClass().getName()));
+			}
+		}
 	}
-}
+
\ No newline at end of file
+}

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/metrics/writer/MessageChannelMetricWriterTests.java

 /*
- * Copyright 2012-2013 the original author or authors.
+ * Copyright 2012-2015 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.
@@ -16,35 +16,73 @@
 
 package org.springframework.boot.actuate.metrics.writer;
 
+import org.junit.Before;
 import org.junit.Test;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.mockito.invocation.InvocationOnMock;
+import org.mockito.stubbing.Answer;
 import org.springframework.boot.actuate.metrics.Metric;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageChannel;
 
+import static org.mockito.BDDMockito.given;
 import static org.mockito.Matchers.any;
-import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 
 /**
+ * Tests for {@link MessageChannelMetricWriter} and {@link MetricWriterMessageHandler}.
+ *
  * @author Dave Syer
  */
 public class MessageChannelMetricWriterTests {
 
-	private final MessageChannel channel = mock(MessageChannel.class);
+	@Mock
+	private MessageChannel channel;
+
+	@Mock
+	private MetricWriter observer;
+
+	private MessageChannelMetricWriter writer;
 
-	private final MessageChannelMetricWriter observer = new MessageChannelMetricWriter(
-			this.channel);
+	private MetricWriterMessageHandler handler;
+
+	@Before
+	public void setup() {
+		MockitoAnnotations.initMocks(this);
+		given(this.channel.send(any(Message.class))).willAnswer(new Answer<Object>() {
+
+			@Override
+			public Object answer(InvocationOnMock invocation) throws Throwable {
+				MessageChannelMetricWriterTests.this.handler.handleMessage(invocation
+						.getArgumentAt(0, Message.class));
+				return true;
+			}
+
+		});
+		this.writer = new MessageChannelMetricWriter(this.channel);
+		this.handler = new MetricWriterMessageHandler(this.observer);
+	}
 
 	@Test
 	public void messageSentOnAdd() {
-		this.observer.increment(new Delta<Integer>("foo", 1));
+		this.writer.increment(new Delta<Integer>("foo", 1));
 		verify(this.channel).send(any(Message.class));
+		verify(this.observer).increment(any(Delta.class));
 	}
 
 	@Test
 	public void messageSentOnSet() {
-		this.observer.set(new Metric<Double>("foo", 1d));
+		this.writer.set(new Metric<Double>("foo", 1d));
+		verify(this.channel).send(any(Message.class));
+		verify(this.observer).set(any(Metric.class));
+	}
+
+	@Test
+	public void messageSentOnReset() throws Exception {
+		this.writer.reset("foo");
 		verify(this.channel).send(any(Message.class));
+		verify(this.observer).reset("foo");
 	}
 
 }