Minor cleanup and improvements in new GCF adapter

Resolves #468

spring-cloud-function-adapters/spring-cloud-function-adapter-gcp/src/main/java/org/springframework/cloud/function/adapter/gcloud/FunctionInvoker.java

@@ -0,0 +1,89 @@
+/*
+ * Copyright 2020-2020 the original author or 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
+ *
+ *      https://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.function.adapter.gcloud;
+
+import java.io.BufferedReader;
+import java.nio.charset.StandardCharsets;
+import java.util.Map.Entry;
+import java.util.function.Function;
+
+import com.google.cloud.functions.HttpFunction;
+import com.google.cloud.functions.HttpRequest;
+import com.google.cloud.functions.HttpResponse;
+
+import org.springframework.cloud.function.context.AbstractSpringFunctionAdapterInitializer;
+import org.springframework.messaging.Message;
+import org.springframework.messaging.support.MessageBuilder;
+import org.springframework.util.Assert;
+import org.springframework.util.MimeTypeUtils;
+
+/**
+ * Implementation of {@link HttpFunction} for Google Cloud Function (GCF).
+ * This is the Spring Cloud Function adapter for GCF HTTP function.
+ *
+ * @author Dmitry Solomakha
+ * @author Mike Eltsufin
+ * @author Oleg Zhurakousky
+ *
+ * @since 3.0.4
+ */
+public class FunctionInvoker
+	extends AbstractSpringFunctionAdapterInitializer<HttpRequest> implements HttpFunction {
+
+	public FunctionInvoker() {
+		super();
+	}
+
+	public FunctionInvoker(Class<?> configurationClass) {
+		super(configurationClass);
+		System.setProperty("spring.http.converters.preferred-json-mapper", "gson");
+		Thread.currentThread() //TODO investigate if it is necessary
+			.setContextClassLoader(FunctionInvoker.class.getClassLoader());
+		initialize(null);
+	}
+
+	/**
+	 * The implementation of a GCF {@link HttpFunction} that will be used as the entry point from GCF.
+	 */
+	@Override
+	public void service(HttpRequest httpRequest, HttpResponse httpResponse) throws Exception {
+		try {
+			String functionName = System.getenv().containsKey("spring.cloud.function.definition")
+					? System.getenv("spring.cloud.function.definition") : "";
+
+			Function<Message<BufferedReader>, Message<byte[]>> function =
+					this.catalog.lookup(functionName, MimeTypeUtils.APPLICATION_JSON.toString());
+			Assert.notNull(function, "'function' with name '" + functionName + "' must not be null");
+
+			Message<BufferedReader> message = getInputType() == Void.class
+					? null : MessageBuilder.withPayload(httpRequest.getReader())
+								.copyHeaders(httpRequest.getHeaders())
+								.build();
+			Message<byte[]> result = function.apply(message);
+
+			if (result != null) {
+				httpResponse.getWriter().write(new String(result.getPayload(), StandardCharsets.UTF_8));
+				for (Entry<String, Object> header : result.getHeaders().entrySet()) {
+					httpResponse.appendHeader(header.getKey(), header.getValue().toString());
+				}
+			}
+		}
+		finally {
+			httpResponse.getWriter().close();
+		}
+	}
+}

spring-cloud-function-adapters/spring-cloud-function-adapter-gcp/src/main/java/org/springframework/cloud/function/adapter/gcloud/GcfSpringBootHttpRequestHandler.java

@@ -1,73 +0,0 @@
-/*
- * Copyright 2020-2020 the original author or 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
- *
- *      https://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.function.adapter.gcloud;
-
-import com.google.cloud.functions.HttpFunction;
-import com.google.cloud.functions.HttpRequest;
-import com.google.cloud.functions.HttpResponse;
-import com.google.gson.Gson;
-import org.reactivestreams.Publisher;
-import reactor.core.publisher.Mono;
-
-import org.springframework.cloud.function.context.AbstractSpringFunctionAdapterInitializer;
-
-/**
- * Implementation of {@link HttpFunction} for Google Cloud Function (GCF).
- * This is the Spring Cloud Function adapter for GCF HTTP function.
- *
- * @author Dmitry Solomakha
- * @author Mike Eltsufin
- */
-public class GcfSpringBootHttpRequestHandler
-	extends AbstractSpringFunctionAdapterInitializer<HttpRequest> implements HttpFunction {
-
-	private final Gson gson = new Gson();
-
-	public GcfSpringBootHttpRequestHandler() {
-		super();
-	}
-
-	public GcfSpringBootHttpRequestHandler(Class<?> configurationClass) {
-		super(configurationClass);
-	}
-
-	/**
-	 * The implementation of a GCF {@link HttpFunction} that will be used as the entrypoint from GCF.
-	 */
-	@Override
-	public void service(HttpRequest httpRequest, HttpResponse httpResponse) throws Exception {
-		Thread.currentThread()
-			.setContextClassLoader(GcfSpringBootHttpRequestHandler.class.getClassLoader());
-
-		initialize(httpRequest);
-
-		Publisher<?> input;
-		if (getInputType() == Void.class) {
-			input = Mono.empty();
-		}
-		else {
-			input = Mono.just(gson.fromJson(httpRequest.getReader(), getInputType()));
-		}
-
-		Publisher<?> output = this.apply(input);
-
-		Object result = this.result(input, output);
-
-		httpResponse.getWriter().write(gson.toJson(result));
-		httpResponse.getWriter().close();
-	}
-}

spring-cloud-function-adapters/spring-cloud-function-adapter-gcp/src/test/java/org/springframework/cloud/function/adapter/gcloud/FunctionInvokerTests.java

@@ -34,6 +34,8 @@ import org.springframework.cloud.function.context.config.ContextFunctionCatalogA
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
+import org.springframework.messaging.Message;
+import org.springframework.messaging.support.MessageBuilder;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.Mockito.when;
@@ -44,7 +46,7 @@ import static org.mockito.Mockito.when;
  * @author Dmitry Solomakha
  * @author Mike Eltsufin
  */
-public class GcfSpringBootHttpRequestHandlerTests {
+public class FunctionInvokerTests {
 
 	private static final Gson gson = new Gson();
 
@@ -71,21 +73,23 @@ public class GcfSpringBootHttpRequestHandlerTests {
 	}
 
 	private <I, O> void testFunction(Class<?> configurationClass, I input, O expectedOutput) throws Exception {
-		GcfSpringBootHttpRequestHandler handler = new GcfSpringBootHttpRequestHandler(configurationClass);
+		try (FunctionInvoker handler = new FunctionInvoker(configurationClass);) {
 
-		HttpRequest request = Mockito.mock(HttpRequest.class);
+			HttpRequest request = Mockito.mock(HttpRequest.class);
 
-		if (input != null) {
-			when(request.getReader()).thenReturn(new BufferedReader(new StringReader(gson.toJson(input))));
+			if (input != null) {
+				when(request.getReader()).thenReturn(new BufferedReader(new StringReader(gson.toJson(input))));
+			}
+
+			HttpResponse response = Mockito.mock(HttpResponse.class);
+			StringWriter writer = new StringWriter();
+			when(response.getWriter()).thenReturn(new BufferedWriter(writer));
+
+			handler.service(request, response);
+			if (expectedOutput != null) {
+				assertThat(writer.toString()).isEqualTo(gson.toJson(expectedOutput));
+			}
 		}
-
-		HttpResponse response = Mockito.mock(HttpResponse.class);
-		StringWriter writer = new StringWriter();
-		when(response.getWriter()).thenReturn(new BufferedWriter(writer));
-
-		handler.service(request, response);
-
-		assertThat(writer.toString()).isEqualTo(gson.toJson(expectedOutput));
 	}
 
 	@Configuration
@@ -110,8 +114,11 @@ public class GcfSpringBootHttpRequestHandlerTests {
 	@Import({ ContextFunctionCatalogAutoConfiguration.class })
 	protected static class JsonInputOutputFunction {
 		@Bean
-		public Function<IncomingRequest, OutgoingResponse> function() {
-			return (in) -> new OutgoingResponse("Thank you for sending the message: " + in.message);
+		public Function<IncomingRequest, Message<OutgoingResponse>> function() {
+			return (in) -> {
+				return MessageBuilder.withPayload(new OutgoingResponse("Thank you for sending the message: " + in.message))
+						.setHeader("foo", "bar").build();
+			};
 		}
 	}