Forward port #969

spring-cloud-function-adapters/spring-cloud-function-adapter-azure/src/main/java/org/springframework/cloud/function/adapter/azure/AzureFunctionInstanceInjector.java

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+/*
+ * Copyright 2021-2022 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.azure;
+
+import java.util.Map;
+
+import com.microsoft.azure.functions.spi.inject.FunctionInstanceInjector;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.WebApplicationType;
+import org.springframework.cloud.function.utils.FunctionClassUtils;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.util.ClassUtils;
+import org.springframework.util.CollectionUtils;
+
+/**
+ * The instance factory used by the Spring framework to initialize Azure function instance. It is waived with the Azure
+ * Java Worker through the META-INFO/services/com.microsoft.azure.functions.spi.inject.FunctionInstanceInjector service
+ * hook. The Azure Java Worker delegates scans the classpath for service definition and delegates the function class
+ * creation to this instance factory.
+ * @author Christian Tzolov
+ * @since 3.2.9
+ */
+public class AzureFunctionInstanceInjector implements FunctionInstanceInjector {
+
+	private static Log logger = LogFactory.getLog(AzureFunctionInstanceInjector.class);
+
+	private static ConfigurableApplicationContext APPLICATION_CONTEXT;
+
+	/**
+	 * This method is called by the Azure Java Worker on every function invocation. The Worker sends in the classes
+	 * annotated with @FunctionName annotations and allows the Spring framework to initialize the function instance as a
+	 * Spring Bean and return the instance. Then the Worker uses the created instance to invoke the function.
+	 * @param functionClass the class that contains customer Azure functions (e.g. @FunctionName annotated )
+	 * @param <T> customer Azure functions class type
+	 * @return the instance that will be invoked on by azure functions java worker
+	 * @throws Exception any exception that is thrown by the Spring framework during instance creation
+	 */
+	@Override
+	public <T> T getInstance(Class<T> functionClass) throws Exception {
+		try {
+			// Backward compatibility workaround. If the function class is of type FunctionInvoker then create plain
+			// Java instance and delegate to FunctionInvoker adaptor approach.
+			if (ClassUtils.isAssignable(FunctionInvoker.class, functionClass)) {
+				return functionClass.getDeclaredConstructor().newInstance();
+			}
+
+			initialize();
+
+			Map<String, T> azureFunctionBean = APPLICATION_CONTEXT.getBeansOfType(functionClass);
+			if (CollectionUtils.isEmpty(azureFunctionBean)) {
+				throw new IllegalStateException(
+						"Failed to retrieve Bean instance for: " + functionClass
+								+ ". The class should be annotated with @Component to let the Spring framework initialize it!");
+			}
+			return azureFunctionBean.entrySet().iterator().next().getValue();
+		}
+		catch (Exception e) {
+			if (APPLICATION_CONTEXT != null) {
+				APPLICATION_CONTEXT.close();
+			}
+			throw new IllegalStateException("Failed to initialize", e);
+		}
+	}
+
+	/**
+	 * Create a static Application Context instance shared between multiple function invocations.
+	 */
+	private static void initialize() {
+		synchronized (AzureFunctionInstanceInjector.class.getName()) {
+			if (APPLICATION_CONTEXT == null) {
+				Class<?> springConfigurationClass = FunctionClassUtils.getStartClass();
+				logger.info("Initializing: " + springConfigurationClass);
+				APPLICATION_CONTEXT = springApplication(springConfigurationClass).run();
+			}
+		}
+	}
+
+	private static SpringApplication springApplication(Class<?> configurationClass) {
+		SpringApplication application = new org.springframework.cloud.function.context.FunctionalSpringApplication(
+				configurationClass);
+		application.setWebApplicationType(WebApplicationType.NONE);
+		return application;
+	}
+}

spring-cloud-function-adapters/spring-cloud-function-adapter-azure/src/main/resources/META-INF/services/com.microsoft.azure.functions.spi.inject.FunctionInstanceInjector

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+org.springframework.cloud.function.adapter.azure.AzureFunctionInstanceInjector