Adds fallback support for HystrixCommand, Observable, and Single results

Jimmy Lu · Adrian Cole · commit 07dcd87fc09e · 2016-03-05T11:06:32.000+08:00
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,5 +1,6 @@
 ### Version 8.16
 * Adds `@QueryMap` annotation to support dynamic query parameters
+* Adds fallback support for HystrixCommand, Observable, and Single results
 
 ### Version 8.15
 * Supports PUT without a body parameter
diff --git a/hystrix/src/main/java/feign/hystrix/HystrixInvocationHandler.java b/hystrix/src/main/java/feign/hystrix/HystrixInvocationHandler.java
@@ -29,6 +29,7 @@
 import feign.Target;
 import rx.Observable;
 import rx.Single;
+import rx.functions.Action1;
 
 import static feign.Util.checkNotNull;
 
@@ -68,7 +69,18 @@ protected Object run() throws Exception {
       protected Object getFallback() {
         if (fallback == null) return super.getFallback();
         try {
-          return method.invoke(fallback, args);
+			Object result = method.invoke(fallback, args);
+			if (isReturnsHystrixCommand(method)) {
+				return ((HystrixCommand) result).execute();
+			} else if (isReturnsObservable(method)) {
+				// Create a cold Observable
+				return ((Observable) result).toBlocking().first();
+			} else if (isReturnsSingle(method)) {
+				// Create a cold Observable as a Single
+				return ((Single) result).toObservable().toBlocking().first();
+			} else {
+				return result;
+			}
         } catch (IllegalAccessException e) {
           // shouldn't happen as method is public due to being an interface
           throw new AssertionError(e);
@@ -79,18 +91,30 @@ protected Object getFallback() {
       }
     };
 
-    if (HystrixCommand.class.isAssignableFrom(method.getReturnType())) {
+    if (isReturnsHystrixCommand(method)) {
       return hystrixCommand;
-    } else if (Observable.class.isAssignableFrom(method.getReturnType())) {
+    } else if (isReturnsObservable(method)) {
       // Create a cold Observable
       return hystrixCommand.toObservable();
-    } else if (Single.class.isAssignableFrom(method.getReturnType())) {
+    } else if (isReturnsSingle(method)) {
       // Create a cold Observable as a Single
       return hystrixCommand.toObservable().toSingle();
     }
     return hystrixCommand.execute();
   }
 
+	private boolean isReturnsHystrixCommand(Method method) {
+		return HystrixCommand.class.isAssignableFrom(method.getReturnType());
+	}
+
+	private boolean isReturnsObservable(Method method) {
+		return Observable.class.isAssignableFrom(method.getReturnType());
+	}
+
+	private boolean isReturnsSingle(Method method) {
+		return Single.class.isAssignableFrom(method.getReturnType());
+	}
+
   static final class Factory implements InvocationHandlerFactory {
 
     @Override
diff --git a/hystrix/src/test/java/feign/hystrix/HystrixBuilderTest.java b/hystrix/src/test/java/feign/hystrix/HystrixBuilderTest.java
