Add async behavior to OkHttpClient (#1629)

* Add AsyncOkHttpClient implementation

* Make OkHttpClient implement both Client and AsyncClient

Removes the need to share code in an abstract class.

* Update mindmap

* Update CHANGELOG.md

* Remove jetbrains specific annotations

CHANGELOG.md

@@ -1,3 +1,7 @@
+### Version 11.9
+
+* `OkHttpClient` now implements `AsyncClient`
+
 ### Version 10.9
 
 * Configurable to disable streaming mode for Default client by verils (#1182) 

okhttp/pom.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!--
 
-    Copyright 2012-2021 The Feign Authors
+    Copyright 2012-2022 The Feign Authors
 
     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
@@ -54,5 +54,11 @@
       <artifactId>mockwebserver</artifactId>
       <scope>test</scope>
     </dependency>
+
+    <dependency>
+      <groupId>com.google.code.gson</groupId>
+      <artifactId>gson</artifactId>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 </project>

okhttp/src/main/java/feign/okhttp/OkHttpClient.java

@@ -19,7 +19,10 @@ import java.io.Reader;
 import java.nio.charset.Charset;
 import java.util.Collection;
 import java.util.Map;
+import java.util.Optional;
+import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.TimeUnit;
+import feign.AsyncClient;
 import feign.Client;
 import feign.Request.HttpMethod;
 import feign.Request.ProtocolVersion;
@@ -35,7 +38,7 @@ import static feign.Util.enumForName;
  * GitHub github = Feign.builder().client(new OkHttpClient()).target(GitHub.class,
  * "https://api.github.com");
  */
-public final class OkHttpClient implements Client {
+public final class OkHttpClient implements Client, AsyncClient<Object> {
 
   private final okhttp3.OkHttpClient delegate;
 
@@ -153,9 +156,7 @@ public final class OkHttpClient implements Client {
     };
   }
 
-  @Override
-  public feign.Response execute(feign.Request input, feign.Request.Options options)
-      throws IOException {
+  private okhttp3.OkHttpClient getClient(feign.Request.Options options) {
     okhttp3.OkHttpClient requestScoped;
     if (delegate.connectTimeoutMillis() != options.connectTimeoutMillis()
         || delegate.readTimeoutMillis() != options.readTimeoutMillis()
@@ -168,8 +169,39 @@ public final class OkHttpClient implements Client {
     } else {
       requestScoped = delegate;
     }
+    return requestScoped;
+  }
+
+  @Override
+  public feign.Response execute(feign.Request input, feign.Request.Options options)
+      throws IOException {
+    okhttp3.OkHttpClient requestScoped = getClient(options);
     Request request = toOkHttpRequest(input);
     Response response = requestScoped.newCall(request).execute();
     return toFeignResponse(response, input).toBuilder().request(input).build();
   }
+
+  @Override
+  public CompletableFuture<feign.Response> execute(feign.Request input,
+                                                   feign.Request.Options options,
+                                                   Optional<Object> requestContext) {
+    okhttp3.OkHttpClient requestScoped = getClient(options);
+    Request request = toOkHttpRequest(input);
+    CompletableFuture<feign.Response> responseFuture = new CompletableFuture<>();
+    requestScoped.newCall(request).enqueue(new Callback() {
+      @Override
+      public void onFailure(Call call, IOException e) {
+        responseFuture.completeExceptionally(e);
+      }
+
+      @Override
+      public void onResponse(Call call, okhttp3.Response response)
+          throws IOException {
+        final feign.Response r =
+            toFeignResponse(response, input).toBuilder().request(input).build();
+        responseFuture.complete(r);
+      }
+    });
+    return responseFuture;
+  }
 }

okhttp/src/test/java/feign/okhttp/CustomPojo.java

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2012-2022 The Feign Authors
+ *
+ * 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 feign.okhttp;
+
+public class CustomPojo {
+
+  private final String name;
+  private final Integer number;
+
+  CustomPojo(String name, Integer number) {
+    this.name = name;
+    this.number = number;
+  }
+}

src/docs/overview-mindmap.iuml

@@ -11,6 +11,7 @@
 ** async clients
 *** java.net.URL
 *** Apache HC5
+*** OkHttp
 ** contracts
 *** Feign
 *** JAX-RS