GH-3241: MetadataStoreSelector - compare old/new (#3242)

Resolves: https://github.com/spring-projects/spring-integration/issues/3241

 * Docs and XML namespace support.

spring-integration-core/src/main/java/org/springframework/integration/config/xml/IdempotentReceiverInterceptorParser.java

@@ -59,6 +59,8 @@ public class IdempotentReceiverInterceptorParser extends AbstractBeanDefinitionP
 		boolean hasValueStrategy = StringUtils.hasText(valueStrategy);
 		String valueExpression = element.getAttribute("value-expression");
 		boolean hasValueExpression = StringUtils.hasText(valueExpression);
+		String compareValues = element.getAttribute("compare-values");
+		boolean hasCompareValues = StringUtils.hasText(compareValues);
 
 		String endpoints = element.getAttribute("endpoint");
 
@@ -68,10 +70,10 @@ public class IdempotentReceiverInterceptorParser extends AbstractBeanDefinitionP
 		}
 
 		if (hasSelector && (hasStore || hasKeyStrategy || hasKeyExpression || hasValueStrategy // NOSONAR complexity
-				|| hasValueExpression)) {
+				|| hasValueExpression || hasCompareValues)) {
 			parserContext.getReaderContext().error("The 'selector' attribute is mutually exclusive with " +
-					"'metadata-store', 'key-strategy', 'key-expression', 'value-strategy' " +
-					"or 'value-expression'", source);
+					"'metadata-store', 'key-strategy', 'key-expression', 'value-strategy', " +
+					"'value-expression', and 'compare-values'", source);
 		}
 
 		if (hasKeyStrategy && hasKeyExpression) {
@@ -133,6 +135,7 @@ public class IdempotentReceiverInterceptorParser extends AbstractBeanDefinitionP
 			else {
 				selectorBuilder.addConstructorArgValue(new RootBeanDefinition(SimpleMetadataStore.class));
 			}
+			IntegrationNamespaceUtils.setReferenceIfAttributeDefined(selectorBuilder, element, "compare-values");
 			selectorBeanDefinition = selectorBuilder.getBeanDefinition();
 		}
 

spring-integration-core/src/main/java/org/springframework/integration/selector/MetadataStoreSelector.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2019 the original author or authors.
+ * Copyright 2014-2020 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.
@@ -16,10 +16,13 @@
 
 package org.springframework.integration.selector;
 
+import java.util.function.BiPredicate;
+
 import org.springframework.integration.core.MessageSelector;
 import org.springframework.integration.handler.MessageProcessor;
 import org.springframework.integration.metadata.ConcurrentMetadataStore;
 import org.springframework.integration.metadata.SimpleMetadataStore;
+import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.util.Assert;
 
@@ -58,6 +61,9 @@ public class MetadataStoreSelector implements MessageSelector {
 
 	private final MessageProcessor<String> valueStrategy;
 
+	@Nullable
+	private BiPredicate<String, String> compareValues;
+
 	public MetadataStoreSelector(MessageProcessor<String> keyStrategy) {
 		this(keyStrategy, (MessageProcessor<String>) null);
 	}
@@ -79,6 +85,26 @@ public class MetadataStoreSelector implements MessageSelector {
 		this.valueStrategy = valueStrategy;
 	}
 
+	/**
+	 * Set a {@link BiPredicate} to compare old and new values in the metadata store for
+	 * the key. The first parameter is the old value; return true if we should accept this
+	 * message and replace the old value with the new value.
+	 * @param compareValues the {@link BiPredicate}.
+	 * @since 5.3
+	 */
+	public void setCompareValues(@Nullable BiPredicate<String, String> compareValues) {
+		this.compareValues = compareValues;
+	}
+
+	/**
+	 * Fluent version of {@link #setCompareValues(BiPredicate)}.
+	 * @param compareValues the {@link BiPredicate}.
+	 * @return this.
+	 */
+	public MetadataStoreSelector compareValues(@Nullable BiPredicate<String, String> compareValues) {
+		setCompareValues(compareValues);
+		return this;
+	}
 
 	@Override
 	public boolean accept(Message<?> message) {
@@ -88,7 +114,21 @@ public class MetadataStoreSelector implements MessageSelector {
 				? this.valueStrategy.processMessage(message)
 				: (timestamp == null ? "0" : Long.toString(timestamp));
 
-		return this.metadataStore.putIfAbsent(key, value) == null;
+		if (this.compareValues == null) {
+			return this.metadataStore.putIfAbsent(key, value) == null;
+		}
+		else {
+			synchronized (this) {
+				String oldValue = this.metadataStore.get(key);
+				if (oldValue == null) {
+					return this.metadataStore.putIfAbsent(key, value) == null;
+				}
+				if (this.compareValues.test(oldValue, value)) {
+					return this.metadataStore.replace(key, oldValue, value);
+				}
+				return false;
+			}
+		}
 	}
 
 }

spring-integration-core/src/main/resources/org/springframework/integration/config/spring-integration.xsd

@@ -4853,6 +4853,19 @@ The list of component name patterns you want to track (e.g.,  tracked-components
 				]]></xsd:documentation>
 				</xsd:annotation>
 			</xsd:attribute>
+			<xsd:attribute name="compare-values">
+				<xsd:annotation>
+					<xsd:appinfo>
+						<tool:annotation kind="ref">
+							<tool:expected-type type="java.util.function.BiPredicate"/>
+						</tool:annotation>
+					</xsd:appinfo>
+					<xsd:documentation><![CDATA[
+					A 'BiPredicate<String, String>' which is called if a value exists to determine whether the message
+					should be accepted and the old value replaced with the new value in the metadata store.
+				]]></xsd:documentation>
+				</xsd:annotation>
+			</xsd:attribute>
 			<xsd:attribute name="discard-channel" type="xsd:string">
 				<xsd:annotation>
 					<xsd:appinfo>

spring-integration-core/src/test/java/org/springframework/integration/config/xml/IdempotentReceiverParserTests-context.xml

@@ -27,9 +27,13 @@
 						 endpoint="foo"
 						 key-strategy="keyStrategy"
 						 value-strategy="valueStrategy"
+						 compare-values="valueComparator"
 						 discard-channel="nullChannel"
 						 throw-exception-on-rejection="true"/>
 
+	<beans:bean id="valueComparator"
+		class="org.springframework.integration.config.xml.IdempotentReceiverParserTests$AlwaysAccept"/>
+
 	<beans:bean id="store" class="org.springframework.integration.metadata.SimpleMetadataStore"/>
 
 	<util:properties id="properties">

spring-integration-core/src/test/java/org/springframework/integration/config/xml/IdempotentReceiverParserTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2019 the original author or authors.
+ * Copyright 2014-2020 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.
@@ -24,6 +24,7 @@ import java.io.ByteArrayInputStream;
 import java.util.List;
 import java.util.Map;
 import java.util.Properties;
+import java.util.function.BiPredicate;
 
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -77,6 +78,9 @@ public class IdempotentReceiverParserTests {
 	@Autowired
 	private MessageProcessor<String> valueStrategy;
 
+	@Autowired
+	private AlwaysAccept alwaysAccept;
+
 	@Autowired
 	@Qualifier("nullChannel")
 	private MessageChannel nullChannel;
@@ -94,8 +98,8 @@ public class IdempotentReceiverParserTests {
 		assertThat(getPropertyValue(this.selectorInterceptor, "throwExceptionOnRejection", Boolean.class)).isFalse();
 		@SuppressWarnings("unchecked")
 		Map<String, List<String>> idempotentEndpoints =
-				(Map<String, List<String>>) getPropertyValue(this.idempotentReceiverAutoProxyCreator,
-						"idempotentEndpoints", Map.class);
+				getPropertyValue(this.idempotentReceiverAutoProxyCreator,
+				"idempotentEndpoints", Map.class);
 		List<String> endpoints = idempotentEndpoints.get("selectorInterceptor");
 		assertThat(endpoints).isNotNull();
 		assertThat(endpoints.isEmpty()).isFalse();
@@ -110,10 +114,11 @@ public class IdempotentReceiverParserTests {
 		assertThat(messageSelector).isInstanceOf(MetadataStoreSelector.class);
 		assertThat(getPropertyValue(messageSelector, "keyStrategy")).isSameAs(this.keyStrategy);
 		assertThat(getPropertyValue(messageSelector, "valueStrategy")).isSameAs(this.valueStrategy);
+		assertThat(getPropertyValue(messageSelector, "compareValues")).isSameAs(this.alwaysAccept);
 		@SuppressWarnings("unchecked")
 		Map<String, List<String>> idempotentEndpoints =
-				(Map<String, List<String>>) getPropertyValue(this.idempotentReceiverAutoProxyCreator,
-						"idempotentEndpoints", Map.class);
+				getPropertyValue(this.idempotentReceiverAutoProxyCreator,
+				"idempotentEndpoints", Map.class);
 		List<String> endpoints = idempotentEndpoints.get("strategyInterceptor");
 		assertThat(endpoints).isNotNull();
 		assertThat(endpoints.isEmpty()).isFalse();
@@ -130,8 +135,8 @@ public class IdempotentReceiverParserTests {
 		assertThat(keyStrategy.toString()).contains("headers.foo");
 		@SuppressWarnings("unchecked")
 		Map<String, List<String>> idempotentEndpoints =
-				(Map<String, List<String>>) getPropertyValue(this.idempotentReceiverAutoProxyCreator,
-						"idempotentEndpoints", Map.class);
+				getPropertyValue(this.idempotentReceiverAutoProxyCreator,
+				"idempotentEndpoints", Map.class);
 		List<String> endpoints = idempotentEndpoints.get("expressionInterceptor");
 		assertThat(endpoints).isNotNull();
 		assertThat(endpoints.isEmpty()).isFalse();
@@ -172,7 +177,8 @@ public class IdempotentReceiverParserTests {
 		catch (BeanDefinitionParsingException e) {
 			assertThat(e.getMessage())
 					.contains("The 'selector' attribute is mutually exclusive with 'metadata-store', " +
-							"'key-strategy', 'key-expression', 'value-strategy' or 'value-expression'");
+							"'key-strategy', 'key-expression', 'value-strategy', 'value-expression', and "
+							+ "'compare-values'");
 		}
 	}
 
@@ -185,7 +191,8 @@ public class IdempotentReceiverParserTests {
 		catch (BeanDefinitionParsingException e) {
 			assertThat(e.getMessage())
 					.contains("The 'selector' attribute is mutually exclusive with 'metadata-store', " +
-							"'key-strategy', 'key-expression', 'value-strategy' or 'value-expression'");
+							"'key-strategy', 'key-expression', 'value-strategy', 'value-expression', and "
+							+ "'compare-values'");
 		}
 	}
 
@@ -198,7 +205,8 @@ public class IdempotentReceiverParserTests {
 		catch (BeanDefinitionParsingException e) {
 			assertThat(e.getMessage())
 					.contains("The 'selector' attribute is mutually exclusive with 'metadata-store', " +
-							"'key-strategy', 'key-expression', 'value-strategy' or 'value-expression'");
+							"'key-strategy', 'key-expression', 'value-strategy', 'value-expression', and "
+							+ "'compare-values'");
 		}
 	}
 
@@ -211,7 +219,8 @@ public class IdempotentReceiverParserTests {
 		catch (BeanDefinitionParsingException e) {
 			assertThat(e.getMessage())
 					.contains("The 'selector' attribute is mutually exclusive with 'metadata-store', " +
-							"'key-strategy', 'key-expression', 'value-strategy' or 'value-expression'");
+							"'key-strategy', 'key-expression', 'value-strategy', 'value-expression', and "
+							+ "'compare-values'");
 		}
 	}
 
@@ -224,7 +233,8 @@ public class IdempotentReceiverParserTests {
 		catch (BeanDefinitionParsingException e) {
 			assertThat(e.getMessage())
 					.contains("The 'selector' attribute is mutually exclusive with 'metadata-store', " +
-							"'key-strategy', 'key-expression', 'value-strategy' or 'value-expression'");
+							"'key-strategy', 'key-expression', 'value-strategy', 'value-expression', and "
+							+ "'compare-values'");
 		}
 	}
 
@@ -268,4 +278,13 @@ public class IdempotentReceiverParserTests {
 		return ac;
 	}
 
+	public static class AlwaysAccept implements BiPredicate<String, String> {
+
+		@Override
+		public boolean test(String t, String u) {
+			return true;
+		}
+
+	}
+
 }

spring-integration-core/src/test/java/org/springframework/integration/selector/MetadataStoreSelectorTests.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright 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.integration.selector;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.integration.metadata.SimpleMetadataStore;
+import org.springframework.messaging.support.MessageBuilder;
+
+/**
+ * @author Gary Russell
+ * @since 5.3
+ *
+ */
+public class MetadataStoreSelectorTests {
+
+	@Test
+	void lineNumbers() {
+		SimpleMetadataStore store = new SimpleMetadataStore();
+		store.put("file", "5");
+		MetadataStoreSelector selector = new MetadataStoreSelector(
+				msg -> "file", msg -> msg.getHeaders().get("lineNum").toString(), store);
+		selector.setCompareValues((oldValue, newValue) -> Integer.parseInt(oldValue) < Integer.parseInt(newValue));
+		for (int i = 0; i < 6; i++) {
+			assertThat(selector.accept(MessageBuilder.withPayload("foo").setHeader("lineNum", i).build()))
+					.isEqualTo(Boolean.FALSE);
+			assertThat(store.get("file")).isEqualTo("5");
+		}
+		assertThat(selector.accept(MessageBuilder.withPayload("foo").setHeader("lineNum", 6).build()))
+				.isEqualTo(Boolean.TRUE);
+		assertThat(store.get("file")).isEqualTo("6");
+	}
+
+}