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Adds Hystrix SetterFactory to customize group and command keys (OpenFeign#447)
This exposes means to customize group and command keys, for example to use non-default conventions from configuration or custom annotation processing. Ex. ```java SetterFactory commandKeyIsRequestLine = (target, method) -> { String groupKey = target.name(); String commandKey = method.getAnnotation(RequestLine.class).value(); return HystrixCommand.Setter .withGroupKey(HystrixCommandGroupKey.Factory.asKey(groupKey)) .andCommandKey(HystrixCommandKey.Factory.asKey(commandKey)); }; api = HystrixFeign.builder() .setterFactory(commandKeyIsRequestLine) ... ``` This also makes the default's more unique to avoid clashing in Hystrix's cache.
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‎CHANGELOG.md‎

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### Version 9.2
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* Adds Hystrix `SetterFactory` to customize group and command keys
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* Supports context path when using Ribbon `LoadBalancingTarget`
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* Adds builder methods for the Response object
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* Deprecates Response factory methods

‎hystrix/README.md‎

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@@ -50,6 +50,34 @@ api.getYourType("a").execute();
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api.getYourTypeSynchronous("a");
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```
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### Group and Command keys
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By default, Hystrix group keys match the target name, and the target name is usually the base url.
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Hystrix command keys are the same as logging keys, which are equivalent to javadoc references.
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For example, for the canonical GitHub example...
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* the group key would be "https://api.github.com" and
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* the command key would be "GitHub#contributors(String,String)"
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You can use `HystrixFeign.Builder#setterFactory(SetterFactory)` to customize this, for example, to
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read key mappings from configuration or annotations.
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Ex.
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```java
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SetterFactory commandKeyIsRequestLine = (target, method) -> {
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String groupKey = target.name();
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String commandKey = method.getAnnotation(RequestLine.class).value();
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return HystrixCommand.Setter
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.withGroupKey(HystrixCommandGroupKey.Factory.asKey(groupKey))
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.andCommandKey(HystrixCommandKey.Factory.asKey(commandKey));
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};
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api = HystrixFeign.builder()
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.setterFactory(commandKeyIsRequestLine)
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...
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```
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### Fallback support
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Fallbacks are known values, which you return when there's an error invoking an http method.
@@ -77,4 +105,4 @@ GitHub fallback = (owner, repo) -> {
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GitHub github = HystrixFeign.builder()
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...
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.target(GitHub.class, "https://api.github.com", fallback);
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```
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```

‎hystrix/src/main/java/feign/hystrix/HystrixFeign.java‎

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@@ -33,6 +33,15 @@ public static Builder builder() {
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public static final class Builder extends Feign.Builder {
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private Contract contract = new Contract.Default();
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private SetterFactory setterFactory = new SetterFactory.Default();
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/**
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* Allows you to override hystrix properties such as thread pools and command keys.
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*/
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public Builder setterFactory(SetterFactory setterFactory) {
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this.setterFactory = setterFactory;
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return this;
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}
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/**
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* @see #target(Class, String, Object)
@@ -101,7 +110,7 @@ Feign buildWithFallback(final Object nullableFallback) {
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super.invocationHandlerFactory(new InvocationHandlerFactory() {
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@Override public InvocationHandler create(Target target,
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Map<Method, MethodHandler> dispatch) {
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return new HystrixInvocationHandler(target, dispatch, nullableFallback);
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return new HystrixInvocationHandler(target, dispatch, setterFactory, nullableFallback);
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}
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});
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super.contract(new HystrixDelegatingContract(contract));

‎hystrix/src/main/java/feign/hystrix/HystrixInvocationHandler.java‎

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package feign.hystrix;
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import com.netflix.hystrix.HystrixCommand;
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import com.netflix.hystrix.HystrixCommandGroupKey;
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import com.netflix.hystrix.HystrixCommandKey;
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import com.netflix.hystrix.HystrixCommand.Setter;
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import java.lang.reflect.InvocationHandler;
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import java.lang.reflect.InvocationTargetException;
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import java.lang.reflect.Method;
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import java.lang.reflect.Proxy;
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import java.util.LinkedHashMap;
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import java.util.Map;
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import java.util.Set;
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import feign.InvocationHandlerFactory.MethodHandler;
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import feign.Target;
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private final Map<Method, MethodHandler> dispatch;
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private final Object fallback; // Nullable
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private final Map<Method, Method> fallbackMethodMap;
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private final Map<Method, Setter> setterMethodMap;
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HystrixInvocationHandler(Target<?> target, Map<Method, MethodHandler> dispatch, Object fallback) {
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HystrixInvocationHandler(Target<?> target, Map<Method, MethodHandler> dispatch,
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SetterFactory setterFactory, Object fallback) {
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this.target = checkNotNull(target, "target");
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this.dispatch = checkNotNull(dispatch, "dispatch");
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this.fallback = fallback;
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this.fallbackMethodMap = toFallbackMethod(dispatch);
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this.setterMethodMap = toSetters(setterFactory, target, dispatch.keySet());
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}
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/**
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* If the method param of InvocationHandler.invoke is not accessible, i.e in a package-private
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* interface, the fallback call in hystrix command will fail cause of access restrictions.
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* But methods in dispatch are copied methods. So setting access to dispatch method doesn't take
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* effect to the method in InvocationHandler.invoke. Use map to store a copy of method
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* to invoke the fallback to bypass this and reducing the count of reflection calls.
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* interface, the fallback call in hystrix command will fail cause of access restrictions. But
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* methods in dispatch are copied methods. So setting access to dispatch method doesn't take
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* effect to the method in InvocationHandler.invoke. Use map to store a copy of method to invoke
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* the fallback to bypass this and reducing the count of reflection calls.
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*
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* @return cached methods map for fallback invoking
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*/
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private Map<Method, Method> toFallbackMethod(Map<Method, MethodHandler> dispatch) {
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static Map<Method, Method> toFallbackMethod(Map<Method, MethodHandler> dispatch) {
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Map<Method, Method> result = new LinkedHashMap<Method, Method>();
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for (Method method : dispatch.keySet()) {
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method.setAccessible(true);
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return result;
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}
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/**
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* Process all methods in the target so that appropriate setters are created.
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*/
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static Map<Method, Setter> toSetters(SetterFactory setterFactory, Target<?> target,
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Set<Method> methods) {
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Map<Method, Setter> result = new LinkedHashMap<Method, Setter>();
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for (Method method : methods) {
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method.setAccessible(true);
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result.put(method, setterFactory.create(target, method));
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}
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return result;
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}
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@Override
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public Object invoke(final Object proxy, final Method method, final Object[] args)
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throws Throwable {
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return toString();
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}
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String groupKey = this.target.name();
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String commandKey = method.getName();
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HystrixCommand.Setter setter = HystrixCommand.Setter
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.withGroupKey(HystrixCommandGroupKey.Factory.asKey(groupKey))
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.andCommandKey(HystrixCommandKey.Factory.asKey(commandKey));
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HystrixCommand<Object> hystrixCommand = new HystrixCommand<Object>(setter) {
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HystrixCommand<Object> hystrixCommand = new HystrixCommand<Object>(setterMethodMap.get(method)) {
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@Override
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protected Object run() throws Exception {
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try {
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} else if (isReturnsSingle(method)) {
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// Create a cold Observable as a Single
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return hystrixCommand.toObservable().toSingle();
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} else if(isReturnsCompletable(method)) {
155+
} else if (isReturnsCompletable(method)) {
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return hystrixCommand.toObservable().toCompletable();
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}
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return hystrixCommand.execute();

‎hystrix/src/main/java/feign/hystrix/SetterFactory.java‎

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package feign.hystrix;
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import com.netflix.hystrix.HystrixCommand;
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import com.netflix.hystrix.HystrixCommandGroupKey;
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import com.netflix.hystrix.HystrixCommandKey;
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import java.lang.reflect.Method;
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import feign.Feign;
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import feign.Target;
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/**
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* Used to control properties of a hystrix command. Use cases include reading from static
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* configuration or custom annotations.
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*
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* <p>This is parsed up-front, like {@link feign.Contract}, so will not be invoked for each command
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* invocation.
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*
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* <p>Note: when deciding the {@link com.netflix.hystrix.HystrixCommand.Setter#andCommandKey(HystrixCommandKey)
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* command key}, recall it lives in a shared cache, so make sure it is unique.
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*/
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public interface SetterFactory {
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/**
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* Returns a hystrix setter appropriate for the given target and method
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*/
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HystrixCommand.Setter create(Target<?> target, Method method);
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/**
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* Default behavior is to derive the group key from {@link Target#name()} and the command key from
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* {@link Feign#configKey(Class, Method)}.
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*/
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final class Default implements SetterFactory {
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@Override
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public HystrixCommand.Setter create(Target<?> target, Method method) {
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String groupKey = target.name();
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String commandKey = Feign.configKey(target.type(), method);
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return HystrixCommand.Setter
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.withGroupKey(HystrixCommandGroupKey.Factory.asKey(groupKey))
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.andCommandKey(HystrixCommandKey.Factory.asKey(commandKey));
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}
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}
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}

‎hystrix/src/test/java/feign/hystrix/HystrixBuilderTest.java‎

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@@ -148,7 +148,7 @@ public List<String> contributors(String owner, String repo) {
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@Test
149149
public void errorInFallbackHasExpectedBehavior() {
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thrown.expect(HystrixRuntimeException.class);
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thrown.expectMessage("contributors failed and fallback failed.");
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thrown.expectMessage("GitHub#contributors(String,String) failed and fallback failed.");
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thrown.expectCause(
153153
isA(FeignException.class)); // as opposed to RuntimeException (from the fallback)
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@@ -170,7 +170,7 @@ public List<String> contributors(String owner, String repo) {
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@Test
171171
public void hystrixRuntimeExceptionPropagatesOnException() {
172172
thrown.expect(HystrixRuntimeException.class);
173-
thrown.expectMessage("contributors failed and no fallback available.");
173+
thrown.expectMessage("GitHub#contributors(String,String) failed and no fallback available.");
174174
thrown.expectCause(isA(FeignException.class));
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176176
server.enqueue(new MockResponse().setResponseCode(500));
@@ -301,7 +301,7 @@ public void rxObservableListFall_noFallback() {
301301
assertThat(testSubscriber.getOnNextEvents()).isEmpty();
302302
assertThat(testSubscriber.getOnErrorEvents().get(0))
303303
.isInstanceOf(HystrixRuntimeException.class)
304-
.hasMessage("listObservable failed and no fallback available.");
304+
.hasMessage("TestInterface#listObservable() failed and no fallback available.");
305305
}
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307307
@Test

‎hystrix/src/test/java/feign/hystrix/SetterFactoryTest.java‎

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package feign.hystrix;
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3+
import com.netflix.hystrix.HystrixCommand;
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import com.netflix.hystrix.HystrixCommandGroupKey;
5+
import com.netflix.hystrix.HystrixCommandKey;
6+
import com.netflix.hystrix.exception.HystrixRuntimeException;
7+
8+
import org.junit.Rule;
9+
import org.junit.Test;
10+
import org.junit.rules.ExpectedException;
11+
12+
import feign.RequestLine;
13+
import okhttp3.mockwebserver.MockResponse;
14+
import okhttp3.mockwebserver.MockWebServer;
15+
16+
public class SetterFactoryTest {
17+
18+
interface TestInterface {
19+
@RequestLine("POST /")
20+
String invoke();
21+
}
22+
23+
@Rule
24+
public final ExpectedException thrown = ExpectedException.none();
25+
@Rule
26+
public final MockWebServer server = new MockWebServer();
27+
28+
@Test
29+
public void customSetter() {
30+
thrown.expect(HystrixRuntimeException.class);
31+
thrown.expectMessage("POST / failed and no fallback available.");
32+
33+
server.enqueue(new MockResponse().setResponseCode(500));
34+
35+
SetterFactory commandKeyIsRequestLine = (target, method) -> {
36+
String groupKey = target.name();
37+
String commandKey = method.getAnnotation(RequestLine.class).value();
38+
return HystrixCommand.Setter
39+
.withGroupKey(HystrixCommandGroupKey.Factory.asKey(groupKey))
40+
.andCommandKey(HystrixCommandKey.Factory.asKey(commandKey));
41+
};
42+
43+
TestInterface api = HystrixFeign.builder()
44+
.setterFactory(commandKeyIsRequestLine)
45+
.target(TestInterface.class, "http://localhost:" + server.getPort());
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api.invoke();
48+
}
49+
}

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