Add Hystrix data to /metrics

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/hystrix/HystrixConfiguration.java

 package org.springframework.cloud.netflix.hystrix;
 
-import com.netflix.hystrix.contrib.javanica.aop.aspectj.HystrixCommandAspect;
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.actuate.metrics.GaugeService;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.context.SmartLifecycle;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.ImportAware;
+import org.springframework.core.Ordered;
 import org.springframework.core.annotation.AnnotationAttributes;
 import org.springframework.core.type.AnnotationMetadata;
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 
-import java.util.Collection;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.netflix.hystrix.contrib.javanica.aop.aspectj.HystrixCommandAspect;
+import com.netflix.hystrix.contrib.metrics.eventstream.HystrixMetricsPoller;
+import com.netflix.hystrix.contrib.metrics.eventstream.HystrixMetricsPoller.MetricsAsJsonPollerListener;
 
 /**
  * Created by sgibb on 6/19/14.
@@ -27,29 +41,132 @@ public class HystrixConfiguration implements ImportAware {
 	}
 
 	@Bean
-    //TODO: add enable/disable
+	// TODO: add enable/disable
+	// TODO: make it @ConditionalOnWebApp (need a nested class)
 	public HystrixStreamEndpoint hystrixStreamEndpoint() {
 		return new HystrixStreamEndpoint();
 	}
 
 	@Override
 	public void setImportMetadata(AnnotationMetadata importMetadata) {
-        this.enableHystrix = AnnotationAttributes.fromMap(
-                importMetadata.getAnnotationAttributes(EnableHystrix.class.getName(), false));
-        Assert.notNull(this.enableHystrix,
-                "@EnableHystrix is not present on importing class " + importMetadata.getClassName());
+		this.enableHystrix = AnnotationAttributes.fromMap(importMetadata
+				.getAnnotationAttributes(EnableHystrix.class.getName(), false));
+		Assert.notNull(
+				this.enableHystrix,
+				"@EnableHystrix is not present on importing class "
+						+ importMetadata.getClassName());
 	}
 
-    @Autowired(required=false)
+	@Autowired(required = false)
 	void setConfigurers(Collection<HystrixConfigurer> configurers) {
 		if (CollectionUtils.isEmpty(configurers)) {
 			return;
 		}
 		if (configurers.size() > 1) {
-            throw new IllegalStateException("Only one TransactionManagementConfigurer may exist");
+			throw new IllegalStateException(
+					"Only one TransactionManagementConfigurer may exist");
 		}
-        //TODO: create CircuitBreakerConfigurer API
+		// TODO: create CircuitBreakerConfigurer API
 		// CircuitBreakerConfigurer configurer = configurers.iterator().next();
-        //this.txManager = configurer.annotationDrivenTransactionManager();
+		// this.txManager = configurer.annotationDrivenTransactionManager();
+	}
+
+	@Configuration
+	@ConditionalOnClass(GaugeService.class)
+	protected static class HystrixMetricsPollerConfiguration implements SmartLifecycle {
+
+		private static Log logger = LogFactory
+				.getLog(HystrixMetricsPollerConfiguration.class);
+
+		@Autowired
+		private GaugeService gauges;
+
+		private ObjectMapper mapper = new ObjectMapper();
+
+		private HystrixMetricsPoller poller;
+
+		private Set<String> reserved = new HashSet<String>(Arrays.asList("group", "name",
+				"type", "currentTime"));
+
+		@Override
+		public void start() {
+			MetricsAsJsonPollerListener listener = new MetricsAsJsonPollerListener() {
+				@Override
+				public void handleJsonMetric(String json) {
+					try {
+						@SuppressWarnings("unchecked")
+						Map<String, Object> map = mapper.readValue(json, Map.class);
+						if (map != null && map.containsKey("type")) {
+							addMetrics(map, "hystrix.");
+						}
+					}
+					catch (IOException e) {
+						// ignore
+					}
+				}
+
+			};
+			poller = new HystrixMetricsPoller(listener, 2000);
+			// start polling and it will write directly to the listener
+			poller.start();
+			logger.info("Starting poller");
+		}
+
+		private void addMetrics(Map<String, Object> map, String root) {
+			StringBuilder prefixBuilder = new StringBuilder(root);
+			if (map.containsKey("type")) {
+				prefixBuilder.append((String) map.get("type"));
+				if (map.containsKey("group")) {
+					prefixBuilder.append(".").append(map.get("group"));
+				}
+				prefixBuilder.append(".").append(map.get("name"));
+			}
+			String prefix = prefixBuilder.toString();
+			for (String key : map.keySet()) {
+				Object value = map.get(key);
+				if (!reserved.contains(key)) {
+					if (value instanceof Number) {
+						String name = prefix + "." + key;
+						gauges.submit(name, ((Number) value).doubleValue());
+					}
+					else if (value instanceof Map) {
+						@SuppressWarnings("unchecked")
+						Map<String, Object> sub = (Map<String, Object>) value;
+						addMetrics(sub, prefix);
+					}
+				}
+			}
+		}
+
+		@Override
+		public void stop() {
+			if (poller != null) {
+				poller.shutdown();
+			}
+		}
+
+		@Override
+		public boolean isRunning() {
+			return poller!=null ?  poller.isRunning() : false;
+		}
+
+		@Override
+		public int getPhase() {
+			return Ordered.LOWEST_PRECEDENCE;
+		}
+
+		@Override
+		public boolean isAutoStartup() {
+			return true;
+		}
+
+		@Override
+		public void stop(Runnable callback) {
+			if (poller != null) {
+				poller.shutdown();
+			}
+			callback.run();
+		}
+
 	}
 }