[#75] Working implementation of Hystrix + Feign + Sleuth. Fixes #75

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/client/SleuthHystrixInvocationHandler.java

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2015 Netflix, Inc.
+ *
+ * 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.cloud.sleuth.instrument.web.client;
+
+import static feign.Util.checkNotNull;
+
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.util.Map;
+
+import org.springframework.cloud.sleuth.TraceManager;
+import org.springframework.cloud.sleuth.instrument.hystrix.TraceCommand;
+
+import com.netflix.hystrix.HystrixCommand;
+import com.netflix.hystrix.HystrixCommandGroupKey;
+import com.netflix.hystrix.HystrixCommandKey;
+
+import feign.InvocationHandlerFactory;
+import feign.InvocationHandlerFactory.MethodHandler;
+import feign.Target;
+
+/**
+ * Wraps execution in Sleuth's TraceCommand
+ */
+final class SleuthHystrixInvocationHandler implements InvocationHandler {
+
+  private final Target target;
+  private final Map<Method, MethodHandler> dispatch;
+  private final TraceManager traceManager;
+
+  SleuthHystrixInvocationHandler(Target target, Map<Method, MethodHandler> dispatch, TraceManager traceManager) {
+    this.traceManager = checkNotNull(traceManager, "traceManager");
+    this.target = checkNotNull(target, "target");
+    this.dispatch = checkNotNull(dispatch, "dispatch");
+  }
+
+  @Override
+  public Object invoke(final Object proxy, final Method method, final Object[] args) throws Throwable {
+    String groupKey = this.target.name();
+    String commandKey = method.getName();
+    HystrixCommand.Setter setter = HystrixCommand.Setter
+        .withGroupKey(HystrixCommandGroupKey.Factory.asKey(groupKey))
+        .andCommandKey(HystrixCommandKey.Factory.asKey(commandKey));
+
+    HystrixCommand<Object> hystrixCommand = new TraceCommand<Object>(traceManager, setter) {
+      @Override
+      public Object doRun() throws Exception {
+        try {
+          return SleuthHystrixInvocationHandler.this.dispatch.get(method).invoke(args);
+        } catch (Exception e) {
+          throw e;
+        } catch (Throwable t) {
+          throw (Error)t;
+        }
+      }
+    };
+
+    if (HystrixCommand.class.isAssignableFrom(method.getReturnType())) {
+      return hystrixCommand;
+    }
+    return hystrixCommand.execute();
+  }
+
+  static final class Factory implements InvocationHandlerFactory {
+
+    private final TraceManager traceManager;
+
+    public Factory(TraceManager traceManager) {
+      this.traceManager = traceManager;
+    }
+
+    @Override
+    public InvocationHandler create(Target target, Map<Method, MethodHandler> dispatch) {
+      return new SleuthHystrixInvocationHandler(target, dispatch, traceManager);
+    }
+  }
+}

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/client/TraceFeignClientAutoConfiguration.java

@@ -26,14 +26,18 @@ import java.util.Map;
 
 import org.springframework.beans.factory.ObjectFactory;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.AutoConfigureBefore;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.autoconfigure.web.HttpMessageConverters;
+import org.springframework.cloud.netflix.feign.FeignAutoConfiguration;
 import org.springframework.cloud.netflix.feign.support.ResponseEntityDecoder;
 import org.springframework.cloud.netflix.feign.support.SpringDecoder;
 import org.springframework.cloud.sleuth.Span;
 import org.springframework.cloud.sleuth.Trace;
 import org.springframework.cloud.sleuth.TraceAccessor;
+import org.springframework.cloud.sleuth.TraceManager;
 import org.springframework.cloud.sleuth.event.ClientReceivedEvent;
 import org.springframework.cloud.sleuth.event.ClientSentEvent;
 import org.springframework.context.ApplicationEvent;
@@ -41,23 +45,28 @@ import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Primary;
+import org.springframework.context.annotation.Scope;
 
+import com.netflix.hystrix.HystrixCommand;
 import feign.Client;
+import feign.Feign;
 import feign.FeignException;
 import feign.RequestInterceptor;
 import feign.RequestTemplate;
 import feign.Response;
 import feign.codec.Decoder;
+import feign.hystrix.HystrixFeign;
 
 /**
  *
- * Configuration for ensuring that TraceID is set on the response
+ * Configuration for ensuring that Spans are propagated while using Feign
  *
  * @author Marcin Grzejszczak, 4financeIT
  */
 @Configuration
 @ConditionalOnProperty(value = "spring.sleuth.feign.enabled", matchIfMissing = true)
 @ConditionalOnClass(Client.class)
+@AutoConfigureBefore(FeignAutoConfiguration.class)
 public class TraceFeignClientAutoConfiguration {
 
 	@Autowired
@@ -69,6 +78,15 @@ public class TraceFeignClientAutoConfiguration {
 	@Autowired
 	private TraceAccessor accessor;
 
+	@Bean
+	@Scope("prototype")
+	@ConditionalOnClass(HystrixCommand.class)
+	@ConditionalOnProperty(name = "feign.hystrix.enabled", matchIfMissing = true)
+	public Feign.Builder feignHystrixBuilder(TraceManager traceManager) {
+		return HystrixFeign.builder()
+				.invocationHandlerFactory(new SleuthHystrixInvocationHandler.Factory(traceManager));
+	}
+
 	@Bean
 	@Primary
 	public Decoder feignDecoder() {