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Add support for CompletableFuture for method return types (OpenFeign#638)
Implements support for `CompletableFuture` on method return types by converting through RxJava `Observable`
1 parent f16553d commit 9dfd9b4

5 files changed

Lines changed: 135 additions & 3 deletions

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‎hystrix/README.md‎

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Original file line numberDiff line numberDiff line change
@@ -10,11 +10,11 @@ GitHub github = HystrixFeign.builder()
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.target(GitHub.class, "https://api.github.com");
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```
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For asynchronous or reactive use, return `HystrixCommand<YourType>`.
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For asynchronous or reactive use, return `HystrixCommand<YourType>` or `CompletableFuture<YourType>`.
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For RxJava compatibility, use `rx.Observable<YourType>` or `rx.Single<YourType>`. Rx types are <a href="http://reactivex.io/documentation/observable.html">cold</a>, which means a http call isn't made until there's a subscriber.
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Methods that do *not* return [`HystrixCommand`](https://netflix.github.io/Hystrix/javadoc/com/netflix/hystrix/HystrixCommand.html), [`rx.Observable`](http://reactivex.io/RxJava/javadoc/rx/Observable.html) or [`rx.Single`] are still wrapped in a `HystrixCommand`, but `execute()` is automatically called for you.
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Methods that do *not* return [`HystrixCommand`](https://netflix.github.io/Hystrix/javadoc/com/netflix/hystrix/HystrixCommand.html), `CompletableFuture`, [`rx.Observable`](http://reactivex.io/RxJava/javadoc/rx/Observable.html) or `rx.Single` are still wrapped in a `HystrixCommand`, but `execute()` is automatically called for you.
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```java
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interface YourApi {
@@ -27,6 +27,9 @@ interface YourApi {
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@RequestLine("GET /yourtype/{id}")
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Single<YourType> getYourTypeSingle(@Param("id") String id);
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@RequestLine("GET /yourtype/{id}")
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CompletableFuture<YourType> getYourTypeCompletableFuture(@Param("id") String id);
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@RequestLine("GET /yourtype/{id}")
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YourType getYourTypeSynchronous(@Param("id") String id);
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}
@@ -46,6 +49,9 @@ api.getYourType("a").queue();
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// for synchronous
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api.getYourType("a").execute();
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// or for a CompletableFuture
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api.getYourTypeCompletableFuture("a").thenApply(o -> "b");
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// or to apply hystrix to existing feign methods.
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api.getYourTypeSynchronous("a");
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```

‎hystrix/src/main/java/feign/hystrix/HystrixDelegatingContract.java‎

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@@ -17,6 +17,7 @@
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import java.lang.reflect.ParameterizedType;
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import java.lang.reflect.Type;
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import java.util.List;
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import java.util.concurrent.CompletableFuture;
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import com.netflix.hystrix.HystrixCommand;
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import feign.Contract;
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import feign.MethodMetadata;
@@ -63,6 +64,9 @@ public List<MethodMetadata> parseAndValidatateMetadata(Class<?> targetType) {
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} else if (type instanceof ParameterizedType
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&& ((ParameterizedType) type).getRawType().equals(Completable.class)) {
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metadata.returnType(void.class);
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} else if (type instanceof ParameterizedType
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&& ((ParameterizedType) type).getRawType().equals(CompletableFuture.class)) {
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metadata.returnType(resolveLastTypeParameter(type, CompletableFuture.class));
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}
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}
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‎hystrix/src/main/java/feign/hystrix/HystrixInvocationHandler.java‎

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@@ -22,6 +22,9 @@
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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 java.util.concurrent.CompletableFuture;
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import java.util.concurrent.ExecutionException;
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import java.util.concurrent.Future;
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import feign.InvocationHandlerFactory.MethodHandler;
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import feign.Target;
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import feign.Util;
@@ -130,15 +133,21 @@ protected Object getFallback() {
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} else if (isReturnsCompletable(method)) {
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((Completable) result).await();
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return null;
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} else if (isReturnsCompletableFuture(method)) {
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return ((Future) result).get();
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} else {
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return result;
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}
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} catch (IllegalAccessException e) {
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// shouldn't happen as method is public due to being an interface
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throw new AssertionError(e);
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} catch (InvocationTargetException e) {
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} catch (InvocationTargetException | ExecutionException e) {
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// Exceptions on fallback are tossed by Hystrix
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throw new AssertionError(e.getCause());
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} catch (InterruptedException e) {
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// Exceptions on fallback are tossed by Hystrix
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Thread.currentThread().interrupt();
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throw new AssertionError(e.getCause());
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}
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}
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};
@@ -155,6 +164,8 @@ protected Object getFallback() {
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return hystrixCommand.toObservable().toSingle();
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} else if (isReturnsCompletable(method)) {
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return hystrixCommand.toObservable().toCompletable();
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} else if (isReturnsCompletableFuture(method)) {
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return new ObservableCompletableFuture<>(hystrixCommand);
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}
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return hystrixCommand.execute();
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}
@@ -171,6 +182,10 @@ private boolean isReturnsObservable(Method method) {
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return Observable.class.isAssignableFrom(method.getReturnType());
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}
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185+
private boolean isReturnsCompletableFuture(Method method) {
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return CompletableFuture.class.isAssignableFrom(method.getReturnType());
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}
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private boolean isReturnsSingle(Method method) {
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return Single.class.isAssignableFrom(method.getReturnType());
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}

‎hystrix/src/main/java/feign/hystrix/ObservableCompletableFuture.java‎

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@@ -0,0 +1,35 @@
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/**
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* Copyright 2012-2018 The Feign Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
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* in compliance with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software distributed under the License
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* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
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* or implied. See the License for the specific language governing permissions and limitations under
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* the License.
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*/
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package feign.hystrix;
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import com.netflix.hystrix.HystrixCommand;
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import rx.Subscription;
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import java.util.concurrent.CompletableFuture;
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final class ObservableCompletableFuture<T> extends CompletableFuture<T> {
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private final Subscription sub;
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ObservableCompletableFuture(final HystrixCommand<T> command) {
25+
this.sub = command.toObservable().single().subscribe(ObservableCompletableFuture.this::complete,
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ObservableCompletableFuture.this::completeExceptionally);
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}
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@Override
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public boolean cancel(final boolean b) {
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sub.unsubscribe();
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return super.cancel(b);
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}
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}

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

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@@ -26,6 +26,10 @@
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import java.util.Arrays;
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import java.util.Collections;
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import java.util.List;
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import java.util.concurrent.CompletableFuture;
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import java.util.concurrent.ExecutionException;
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import java.util.concurrent.TimeUnit;
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import java.util.concurrent.TimeoutException;
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import feign.FeignException;
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import feign.Headers;
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import feign.Param;
@@ -427,6 +431,66 @@ public void rxSingleListFallback() {
427431
assertThat(testSubscriber.getOnNextEvents().get(0)).containsExactly("fallback");
428432
}
429433

434+
@Test
435+
public void completableFutureEmptyBody()
436+
throws InterruptedException, ExecutionException, TimeoutException {
437+
server.enqueue(new MockResponse());
438+
439+
TestInterface api = target();
440+
441+
CompletableFuture<String> completable = api.completableFuture();
442+
443+
assertThat(completable).isNotNull();
444+
445+
completable.get(5, TimeUnit.SECONDS);
446+
}
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448+
@Test
449+
public void completableFutureWithBody()
450+
throws InterruptedException, ExecutionException, TimeoutException {
451+
server.enqueue(new MockResponse().setBody("foo"));
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453+
TestInterface api = target();
454+
455+
CompletableFuture<String> completable = api.completableFuture();
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457+
assertThat(completable).isNotNull();
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459+
assertThat(completable.get(5, TimeUnit.SECONDS)).isEqualTo("foo");
460+
}
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462+
@Test
463+
public void completableFutureFailWithoutFallback() throws TimeoutException, InterruptedException {
464+
server.enqueue(new MockResponse().setResponseCode(500));
465+
466+
TestInterface api = HystrixFeign.builder()
467+
.target(TestInterface.class, "http://localhost:" + server.getPort());
468+
469+
CompletableFuture<String> completable = api.completableFuture();
470+
471+
assertThat(completable).isNotNull();
472+
473+
try {
474+
completable.get(5, TimeUnit.SECONDS);
475+
} catch (ExecutionException e) {
476+
assertThat(e).hasCauseInstanceOf(HystrixRuntimeException.class);
477+
}
478+
}
479+
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@Test
481+
public void completableFutureFallback()
482+
throws InterruptedException, ExecutionException, TimeoutException {
483+
server.enqueue(new MockResponse().setResponseCode(500));
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485+
TestInterface api = target();
486+
487+
CompletableFuture<String> completable = api.completableFuture();
488+
489+
assertThat(completable).isNotNull();
490+
491+
assertThat(completable.get(5, TimeUnit.SECONDS)).isEqualTo("fallback");
492+
}
493+
430494
@Test
431495
public void rxCompletableEmptyBody() {
432496
server.enqueue(new MockResponse());
@@ -657,6 +721,9 @@ default HystrixCommand<String> defaultMethodReturningCommand() {
657721

658722
@RequestLine("GET /")
659723
Completable completable();
724+
725+
@RequestLine("GET /")
726+
CompletableFuture<String> completableFuture();
660727
}
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662729
class FallbackTestInterface implements TestInterface {
@@ -742,5 +809,10 @@ public List<String> getList() {
742809
public Completable completable() {
743810
return Completable.complete();
744811
}
812+
813+
@Override
814+
public CompletableFuture<String> completableFuture() {
815+
return CompletableFuture.completedFuture("fallback");
816+
}
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}
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}

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