INT-4473: Support prefix bean names with flow id

JIRA: https://jira.spring.io/browse/INT-4473

Previously, dynamic registration of integration flows with components configured
with the same `id` would fail with duplicate bean names.

Add `useFlowIdAsPrefix()` to the registration builder to enable the option.
Then, in the BPP, check the flag before naming the beans.

**cherry-pick to 5.0.x**

* Polishing according PR comments
* Widen `flowNamePrefix` responsibility in the
`IntegrationFlowBeanPostProcessor` since we may have many other
components in the dynamic flow with the same id, not only consumer
endpoints

spring-integration-core/src/main/java/org/springframework/integration/dsl/IntegrationFlowBeanPostProcessor.java

@@ -44,6 +44,7 @@ import org.springframework.integration.config.ConsumerEndpointFactoryBean;
 import org.springframework.integration.config.IntegrationConfigUtils;
 import org.springframework.integration.config.SourcePollingChannelAdapterFactoryBean;
 import org.springframework.integration.core.MessageSource;
+import org.springframework.integration.dsl.context.IntegrationFlowContext;
 import org.springframework.integration.dsl.support.MessageChannelReference;
 import org.springframework.integration.gateway.AnnotationGatewayProxyFactoryBean;
 import org.springframework.integration.support.context.NamedComponent;
@@ -67,6 +68,8 @@ public class IntegrationFlowBeanPostProcessor
 
 	private ConfigurableListableBeanFactory beanFactory;
 
+	private IntegrationFlowContext flowContext;
+
 	@Override
 	public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
 		Assert.isInstanceOf(ConfigurableListableBeanFactory.class, beanFactory,
@@ -75,6 +78,8 @@ public class IntegrationFlowBeanPostProcessor
 		);
 
 		this.beanFactory = (ConfigurableListableBeanFactory) beanFactory;
+		this.flowContext = this.beanFactory.getBean(IntegrationFlowContext.class);
+		Assert.notNull(this.flowContext, "There must be an IntegrationFlowContext in the application context");
 	}
 
 	@Override
@@ -100,7 +105,7 @@ public class IntegrationFlowBeanPostProcessor
 					throw new BeanCreationNotAllowedException(beanName, "IntegrationFlows can not be scoped beans. " +
 							"Any dependant beans are registered as singletons, meanwhile IntegrationFlow is just a " +
 							"logical container for them. \n" +
-							"Consider to use [IntegrationFlowContext] for manual registration of IntegrationFlows.");
+							"Consider using [IntegrationFlowContext] for manual registration of IntegrationFlows.");
 				}
 			}
 		}
@@ -108,6 +113,7 @@ public class IntegrationFlowBeanPostProcessor
 
 	private Object processStandardIntegrationFlow(StandardIntegrationFlow flow, String flowBeanName) {
 		String flowNamePrefix = flowBeanName + ".";
+		boolean useFlowIdAsPrefix = this.flowContext.isUseIdAsPrefix(flowBeanName);
 		int subFlowNameIndex = 0;
 		int channelNameIndex = 0;
 
@@ -123,7 +129,10 @@ public class IntegrationFlowBeanPostProcessor
 				String id = endpointSpec.getId();
 
 				if (id == null) {
-					id = generateBeanName(endpoint, flowNamePrefix, entry.getValue());
+					id = generateBeanName(endpoint, flowNamePrefix, entry.getValue(), useFlowIdAsPrefix);
+				}
+				else if (useFlowIdAsPrefix) {
+					id = flowNamePrefix + id;
 				}
 
 				Collection<?> messageHandlers =
@@ -185,13 +194,19 @@ public class IntegrationFlowBeanPostProcessor
 													.contains(o.getKey()))
 									.forEach(o ->
 											registerComponent(o.getKey(),
-													generateBeanName(o.getKey(), flowNamePrefix, o.getValue())));
+													generateBeanName(o.getKey(), flowNamePrefix, o.getValue(),
+															useFlowIdAsPrefix)));
 						}
 						SourcePollingChannelAdapterFactoryBean pollingChannelAdapterFactoryBean = spec.get().getT1();
 						String id = spec.getId();
-						if (!StringUtils.hasText(id)) {
-							id = generateBeanName(pollingChannelAdapterFactoryBean, flowNamePrefix, entry.getValue());
+						if (id == null) {
+							id = generateBeanName(pollingChannelAdapterFactoryBean, flowNamePrefix, entry.getValue(),
+									useFlowIdAsPrefix);
 						}
+						else if (useFlowIdAsPrefix) {
+							id = flowNamePrefix + id;
+						}
+
 						registerComponent(pollingChannelAdapterFactoryBean, id, flowBeanName);
 						targetIntegrationComponents.put(pollingChannelAdapterFactoryBean, id);
 
@@ -236,7 +251,9 @@ public class IntegrationFlowBeanPostProcessor
 						targetIntegrationComponents.put(component, gatewayId);
 					}
 					else {
-						String generatedBeanName = generateBeanName(component, flowNamePrefix, entry.getValue());
+						String generatedBeanName =
+								generateBeanName(component, flowNamePrefix, entry.getValue(), useFlowIdAsPrefix);
+
 						registerComponent(component, generatedBeanName, flowBeanName);
 						targetIntegrationComponents.put(component, generatedBeanName);
 					}
@@ -334,15 +351,19 @@ public class IntegrationFlowBeanPostProcessor
 	}
 
 	private String generateBeanName(Object instance, String prefix) {
-		return generateBeanName(instance, prefix, null);
+		return generateBeanName(instance, prefix, null, false);
 	}
 
-	private String generateBeanName(Object instance, String prefix, String fallbackId) {
+	private String generateBeanName(Object instance, String prefix, String fallbackId, boolean useFlowIdAsPrefix) {
 		if (instance instanceof NamedComponent && ((NamedComponent) instance).getComponentName() != null) {
-			return ((NamedComponent) instance).getComponentName();
+			return useFlowIdAsPrefix
+					? prefix + ((NamedComponent) instance).getComponentName()
+					: ((NamedComponent) instance).getComponentName();
 		}
 		else if (fallbackId != null) {
-			return fallbackId;
+			return useFlowIdAsPrefix
+					? prefix + fallbackId
+					: fallbackId;
 		}
 
 		String generatedBeanName = prefix + instance.getClass().getName();

spring-integration-core/src/main/java/org/springframework/integration/dsl/context/IntegrationFlowContext.java

@@ -95,6 +95,16 @@ public interface IntegrationFlowContext {
 	 */
 	Map<String, IntegrationFlowRegistration> getRegistry();
 
+	/**
+	 * Return true to prefix flow bean names with the flow id and a period.
+	 * @param flowId the flow id.
+	 * @return true to use as a prefix.
+	 * @since 5.0.6
+	 */
+	default boolean isUseIdAsPrefix(String flowId) {
+		return false;
+	}
+
 	/**
 	 * @author Gary Russell
 	 * @since 5.1
@@ -209,6 +219,19 @@ public interface IntegrationFlowContext {
 		 */
 		IntegrationFlowRegistrationBuilder addBean(String name, Object bean);
 
+		/**
+		 * Invoke this method to prefix bean names in the flow with the (required) flow id
+		 * and a period. This is useful if you wish to register the same flow multiple times
+		 * while retaining the ability to reference beans within the flow; adding the unique
+		 * flow id to the bean name makes the name unique.
+		 * @return the current builder instance.
+		 * @see #id(String)
+		 * @since 5.0.6
+		 */
+		default IntegrationFlowRegistrationBuilder useFlowIdAsPrefix() {
+			return this;
+		}
+
 		/**
 		 * Register an {@link IntegrationFlow} and all the dependant and support components
 		 * in the application context and return an associated {@link IntegrationFlowRegistration}

spring-integration-core/src/main/java/org/springframework/integration/dsl/context/StandardIntegrationFlowContext.java

@@ -37,6 +37,7 @@ import org.springframework.integration.dsl.IntegrationFlow;
 import org.springframework.integration.support.context.NamedComponent;
 import org.springframework.messaging.MessageChannel;
 import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
 
 /**
  * Standard implementation of {@link IntegrationFlowContext}.
@@ -51,6 +52,8 @@ public final class StandardIntegrationFlowContext implements IntegrationFlowCont
 
 	private final Map<String, IntegrationFlowRegistration> registry = new ConcurrentHashMap<>();
 
+	private final Map<String, Boolean> useFlowIdAsPrefix = new ConcurrentHashMap<>();
+
 	private final Lock registerFlowsLock = new ReentrantLock();
 
 	private ConfigurableListableBeanFactory beanFactory;
@@ -78,6 +81,11 @@ public final class StandardIntegrationFlowContext implements IntegrationFlowCont
 		return new StandardIntegrationFlowRegistrationBuilder(integrationFlow);
 	}
 
+	@Override
+	public boolean isUseIdAsPrefix(String flowId) {
+		return Boolean.TRUE.equals(this.useFlowIdAsPrefix.get(flowId));
+	}
+
 	private void register(StandardIntegrationFlowRegistrationBuilder builder) {
 		IntegrationFlow integrationFlow = builder.integrationFlowRegistration.getIntegrationFlow();
 		String flowId = builder.integrationFlowRegistration.getId();
@@ -224,6 +232,8 @@ public final class StandardIntegrationFlowContext implements IntegrationFlowCont
 
 		private boolean autoStartup = true;
 
+		private boolean idAsPrefix;
+
 		StandardIntegrationFlowRegistrationBuilder(IntegrationFlow integrationFlow) {
 			this.integrationFlowRegistration = new StandardIntegrationFlowRegistration(integrationFlow);
 			this.integrationFlowRegistration.setBeanFactory(StandardIntegrationFlowContext.this.beanFactory);
@@ -282,6 +292,12 @@ public final class StandardIntegrationFlowContext implements IntegrationFlowCont
 			return this;
 		}
 
+		@Override
+		public IntegrationFlowRegistrationBuilder useFlowIdAsPrefix() {
+			this.idAsPrefix = true;
+			return this;
+		}
+
 		/**
 		 * Register an {@link IntegrationFlow} and all the dependant and support components
 		 * in the application context and return an associated {@link IntegrationFlowRegistration}
@@ -290,6 +306,12 @@ public final class StandardIntegrationFlowContext implements IntegrationFlowCont
 		 */
 		@Override
 		public IntegrationFlowRegistration register() {
+			String id = this.integrationFlowRegistration.getId();
+			Assert.state(!this.idAsPrefix || StringUtils.hasText(id),
+					"An 'id' must be present to use 'useFlowIdAsPrefix'");
+			if (this.idAsPrefix) {
+				StandardIntegrationFlowContext.this.useFlowIdAsPrefix.put(id, this.idAsPrefix);
+			}
 			StandardIntegrationFlowContext.this.register(this);
 			return this.integrationFlowRegistration;
 		}

spring-integration-core/src/test/java/org/springframework/integration/dsl/manualflow/ManualFlowTests.java

@@ -171,12 +171,13 @@ public class ManualFlowTests {
 								.fixedDelay(10)
 								.maxMessagesPerPoll(1)
 								.receiveTimeout(10)))
-				.handle(new BeanFactoryHandler());
+				.handle(new BeanFactoryHandler(), e -> e.id("anId"));
 
 		BeanFactoryHandler additionalBean = new BeanFactoryHandler();
 		IntegrationFlowRegistration flowRegistration =
 				this.integrationFlowContext.registration(myFlow)
 						.id(flowId)
+						.useFlowIdAsPrefix()
 						.addBean(additionalBean)
 						.register();
 
@@ -185,6 +186,7 @@ public class ManualFlowTests {
 						BeanFactoryHandler.class);
 		assertSame(additionalBean, bean);
 		assertSame(this.beanFactory, bean.beanFactory);
+		bean = this.beanFactory.getBean(flowRegistration.getId() + "." + "anId.handler", BeanFactoryHandler.class);
 
 		MessagingTemplate messagingTemplate = flowRegistration.getMessagingTemplate();
 		messagingTemplate.setReceiveTimeout(10000);

src/reference/asciidoc/dsl.adoc

@@ -580,7 +580,7 @@ And Lambda flow can't start from `MessageSource` or `MessageProducer`.
 
 Starting _version 5.1_, this kind of `IntegrationFlow` are wrapped to the proxy for exposing lifecycle control and provide access to the `inputChannel` of the internally associated `StandardIntegrationFlow`.
 
-Starting with _version 5.0.5_, the generated bean names for the components in an `IntegrationFlow` include the flow bean followed by a dot as a prefix.
+Starting with _version 5.0.6_, the generated bean names for the components in an `IntegrationFlow` include the flow bean followed by a dot as a prefix.
 For example the `ConsumerEndpointFactoryBean` for the `.transform("Hello "::concat)` in the sample above, will end up with te bean name like `lambdaFlow.org.springframework.integration.config.ConsumerEndpointFactoryBean#0`.
 The `Transformer` implementation bean for that endpoint will have a bean name such as `lambdaFlow.org.springframework.integration.transformer.MethodInvokingTransformer#0`.
 These generated bean names are prepended with the flow id prefix for purposes such as parsing logs or grouping components together in some analysis tool, as well as to avoid a race condition when we concurrently register integration flows at runtime.
@@ -933,10 +933,46 @@ Usually those additional beans are connection factories (AMQP, JMS, (S)FTP, TCP/
 Such a dynamically registered `IntegrationFlow` and all its dependant beans can be removed afterwards using `IntegrationFlowRegistration.destroy()` callback.
 See `IntegrationFlowContext` JavaDocs for more information.
 
-NOTE: Starting with _version 5.0.5_, all generated bean names in an `IntegrationFlow` definition are prepended with flow id as a prefix.
+NOTE: Starting with _version 5.0.6_, all generated bean names in an `IntegrationFlow` definition are prepended with flow id as a prefix.
 It is recommended to always specify an explicit flow id, otherwise a synchronization barrier is initiated in the `IntegrationFlowContext` to generate the bean name for the `IntegrationFlow` and register its beans.
 We synchronize on these two operations to avoid a race condition when the same generated bean name may be used for different `IntegrationFlow` instances.
 
+Also, starting with _version 5.0.6_, the registration builder API has a new method `useFlowIdAsPrefix()`.
+This is useful if you wish to declare multiple instances of the same flow and avoid bean name collisions if components in the flows have the same id.
+
+For example:
+
+[source, java]
+----
+private void registerFlows() {
+    IntegrationFlowRegistration flow1 =
+              this.flowContext.registration(buildFlow(1234))
+                    .id("tcp1")
+                    .useFlowIdAsPrefix()
+                    .register();
+
+    IntegrationFlowRegistration flow2 =
+              this.flowContext.registration(buildFlow(1235))
+                    .id("tcp2")
+                    .useFlowIdAsPrefix()
+                    .register();
+}
+
+private IntegrationFlow buildFlow(int port) {
+    return f -> f
+            .handle(Tcp.outboundGateway(Tcp.netClient("localhost", port)
+                    .serializer(TcpCodecs.crlf())
+                    .deserializer(TcpCodecs.lengthHeader1())
+                    .id("client"))
+                .remoteTimeout(m -> 5000))
+            .transform(Transformers.objectToString());
+}
+----
+
+In this case, the message handler for the first flow can be referenced with bean name `tcp1.client.handler`.
+
+NOTE: an `id` is required when using `useFlowIdAsPrefix()`.
+
 [[java-dsl-gateway]]
 === IntegrationFlow as Gateway