GH-355 Added support for deffered initialization of Function Catalog

Resolves #355

spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/catalog/AbstractComposableFunctionRegistry.java

@@ -77,9 +77,12 @@ public abstract class AbstractComposableFunctionRegistry implements FunctionRegi
 
 	protected ApplicationEventPublisher applicationEventPublisher;
 
+	private AtomicBoolean initialized = new AtomicBoolean();
+
 	@SuppressWarnings("unchecked")
 	@Override
 	public <T> T lookup(Class<?> type, String name) {
+		initializeIfNecessary();
 		String functionDefinitionName = !StringUtils.hasText(name)
 				&& this.environment.containsProperty("spring.cloud.function.definition")
 						? this.environment.getProperty("spring.cloud.function.definition")
@@ -90,6 +93,7 @@ public abstract class AbstractComposableFunctionRegistry implements FunctionRegi
 	@SuppressWarnings("serial")
 	@Override
 	public Set<String> getNames(Class<?> type) {
+		initializeIfNecessary();
 		if (type == null) {
 			return new HashSet<String>(getSupplierNames()) {
 				{
@@ -111,6 +115,7 @@ public abstract class AbstractComposableFunctionRegistry implements FunctionRegi
 	 * @return immutable {@link Set} of available {@link Supplier} names.
 	 */
 	public Set<String> getSupplierNames() {
+		initializeIfNecessary();
 		return this.functions.entrySet().stream()
 				.filter(entry -> entry.getValue() instanceof Supplier)
 				.map(entry -> entry.getKey())
@@ -122,6 +127,7 @@ public abstract class AbstractComposableFunctionRegistry implements FunctionRegi
 	 * @return immutable {@link Set} of available {@link Function} names.
 	 */
 	public Set<String> getFunctionNames() {
+		initializeIfNecessary();
 		return this.functions.entrySet().stream()
 				.filter(entry -> !(entry.getValue() instanceof Supplier))
 				.map(entry -> entry.getKey())
@@ -129,10 +135,12 @@ public abstract class AbstractComposableFunctionRegistry implements FunctionRegi
 	}
 
 	public boolean hasSuppliers() {
+		initializeIfNecessary();
 		return !CollectionUtils.isEmpty(getSupplierNames());
 	}
 
 	public boolean hasFunctions() {
+		initializeIfNecessary();
 		return !CollectionUtils.isEmpty(getFunctionNames());
 	}
 
@@ -144,10 +152,12 @@ public abstract class AbstractComposableFunctionRegistry implements FunctionRegi
 	 */
 	@Override
 	public int size() {
+		initializeIfNecessary();
 		return this.functions.size();
 	}
 
 	public FunctionType getFunctionType(String name) {
+		initializeIfNecessary();
 		return this.types.get(name);
 	}
 
@@ -158,6 +168,7 @@ public abstract class AbstractComposableFunctionRegistry implements FunctionRegi
 	 * @return the name of the function or null.
 	 */
 	public String lookupFunctionName(Object function) {
+		initializeIfNecessary();
 		return this.names.containsKey(function) ? this.names.get(function) : null;
 	}
 
@@ -174,6 +185,7 @@ public abstract class AbstractComposableFunctionRegistry implements FunctionRegi
 
 	@Override
 	public FunctionRegistration<?> getRegistration(Object function) {
+		initializeIfNecessary();
 		String functionName = function == null ? null
 				: this.lookupFunctionName(function);
 		if (StringUtils.hasText(functionName)) {
@@ -189,10 +201,19 @@ public abstract class AbstractComposableFunctionRegistry implements FunctionRegi
 	public <T> void register(FunctionRegistration<T> functionRegistration) {
 		Assert.notEmpty(functionRegistration.getNames(),
 				"'registration' must contain at least one name before it is registered in catalog.");
+		initializeIfNecessary();
 		register(functionRegistration, functionRegistration.getNames().iterator().next());
 	}
 
+	private void initializeIfNecessary() {
+		if (initialized.compareAndSet(false, true)) {
+			doInitialize();
+		}
+	}
 
+	protected void doInitialize() {
+
+	}
 
 	/**
 	 * Registers function wrapped by the provided FunctionRegistration with

spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/config/ContextFunctionCatalogAutoConfiguration.java

@@ -36,7 +36,6 @@ import com.google.gson.Gson;
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.BeanFactoryAware;
-import org.springframework.beans.factory.SmartInitializingSingleton;
 import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
@@ -86,7 +85,7 @@ public class ContextFunctionCatalogAutoConfiguration {
 
 	protected static class BeanFactoryFunctionCatalog
 			extends AbstractComposableFunctionRegistry
-		implements SmartInitializingSingleton, BeanFactoryAware {
+		implements BeanFactoryAware {
 
 		private ApplicationEventPublisher applicationEventPublisher;
 
@@ -96,18 +95,21 @@ public class ContextFunctionCatalogAutoConfiguration {
 		 * Will collect all suppliers, functions, consumers and function registration as
 		 * late as possible in the lifecycle.
 		 */
+		@SuppressWarnings("rawtypes")
 		@Override
-		public void afterSingletonsInstantiated() {
-			Map<String, Supplier> supplierBeans = this.beanFactory
-				.getBeansOfType(Supplier.class);
-			Map<String, Function> functionBeans = this.beanFactory
-				.getBeansOfType(Function.class);
-			Map<String, Consumer> consumerBeans = this.beanFactory
-				.getBeansOfType(Consumer.class);
-			Map<String, FunctionRegistration> functionRegistrationBeans = this.beanFactory
-				.getBeansOfType(FunctionRegistration.class);
-			this.doMerge(functionRegistrationBeans, consumerBeans, supplierBeans,
-				functionBeans);
+		protected void doInitialize() {
+			if (this.beanFactory != null) {
+				Map<String, Supplier> supplierBeans = this.beanFactory
+						.getBeansOfType(Supplier.class);
+					Map<String, Function> functionBeans = this.beanFactory
+						.getBeansOfType(Function.class);
+					Map<String, Consumer> consumerBeans = this.beanFactory
+						.getBeansOfType(Consumer.class);
+					Map<String, FunctionRegistration> functionRegistrationBeans = this.beanFactory
+						.getBeansOfType(FunctionRegistration.class);
+					this.doMerge(functionRegistrationBeans, consumerBeans, supplierBeans,
+						functionBeans);
+			}
 		}
 
 		@Override

spring-cloud-function-context/src/test/java/org/springframework/cloud/function/context/config/ContextFunctionCatalogAutoConfigurationTests.java

@@ -297,6 +297,7 @@ public class ContextFunctionCatalogAutoConfigurationTests {
 	@Test(expected = IllegalArgumentException.class)
 	public void monoToMonoNonVoidFunction() {
 		create(MonoToMonoNonVoidConfiguration.class);
+		this.catalog.lookup("anything-doesn't-matter");
 	}
 
 	@Test