SPR-6368 The parser for the 'executor' element in the task namespace now creates a FactoryBean so that the pool-size range can be configured after property placeholder resolution when necessary.

org.springframework.context/src/main/java/org/springframework/scheduling/config/ExecutorBeanDefinitionParser.java

@@ -22,7 +22,6 @@ import org.springframework.beans.factory.support.BeanDefinitionBuilder;
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.beans.factory.xml.AbstractSingleBeanDefinitionParser;
 import org.springframework.beans.factory.xml.ParserContext;
-import org.springframework.core.JdkVersion;
 import org.springframework.util.StringUtils;
 
 /**
@@ -36,12 +35,7 @@ public class ExecutorBeanDefinitionParser extends AbstractSingleBeanDefinitionPa
 
 	@Override
 	protected String getBeanClassName(Element element) {
-		if (shouldUseBackport(element)) {
+		return "org.springframework.scheduling.config.TaskExecutorFactoryBean";
-			return "org.springframework.scheduling.backportconcurrent.ThreadPoolTaskExecutor";
-		}
-		else {
-			return "org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor";
-		}
 	}
 
 	@Override
@@ -56,48 +50,8 @@ public class ExecutorBeanDefinitionParser extends AbstractSingleBeanDefinitionPa
 		}
 		configureRejectionPolicy(element, builder);
 		String poolSize = element.getAttribute("pool-size");
-		if (!StringUtils.hasText(poolSize)) {
+		if (StringUtils.hasText(poolSize)) {
-			return;
+			builder.addPropertyValue("poolSize", poolSize);
-		}
-		Integer[] range = null;
-		try {
-			int separatorIndex = poolSize.indexOf('-');
-			if (separatorIndex != -1) {
-				range = new Integer[2];
-				range[0] = Integer.valueOf(poolSize.substring(0, separatorIndex));
-				range[1] = Integer.valueOf(poolSize.substring(separatorIndex + 1, poolSize.length()));
-				if (range[0] > range[1]) {
-					parserContext.getReaderContext().error(
-							"Lower bound of pool-size range must not exceed the upper bound.", element);
-				}
-				if (!StringUtils.hasText(queueCapacity)) {
-					// no queue-capacity provided, so unbounded
-					if (range[0] == 0) {
-						// actually set 'corePoolSize' to the upper bound of the range
-						// but allow core threads to timeout
-						builder.addPropertyValue("allowCoreThreadTimeOut", true);
-						range[0] = range[1];
-					}
-					else {
-						// non-zero lower bound implies a core-max size range
-						parserContext.getReaderContext().error(
-								"A non-zero lower bound for the size range requires a queue-capacity value.", element);
-					}
-				}
-			}
-			else {
-				Integer value = Integer.valueOf(poolSize);
-				range = new Integer[] {value, value};
-			}
-		}
-		catch (NumberFormatException ex) {
-			parserContext.getReaderContext().error("Invalid pool-size value [" + poolSize + "]: only single " +
-					"maximum integer (e.g. \"5\") and minimum-maximum range (e.g. \"3-5\") are supported.",
-					element, ex);
-		}
-		if (range != null) {
-			builder.addPropertyValue("corePoolSize", range[0]);
-			builder.addPropertyValue("maxPoolSize", range[1]);
 		}
 	}
 
@@ -129,10 +83,4 @@ public class ExecutorBeanDefinitionParser extends AbstractSingleBeanDefinitionPa
 		builder.addPropertyValue("rejectedExecutionHandler", new RootBeanDefinition(policyClassName));
 	}
 
-	private boolean shouldUseBackport(Element element) {
-		String poolSize = element.getAttribute("pool-size");
-		return (StringUtils.hasText(poolSize) && poolSize.startsWith("0") &&
-				JdkVersion.getMajorJavaVersion() < JdkVersion.JAVA_16);
-	}
-
 }

org.springframework.context/src/main/java/org/springframework/scheduling/config/TaskExecutorFactoryBean.java

@@ -0,0 +1,169 @@
+/*
+ * Copyright 2002-2009 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
+ *
+ *      http://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.scheduling.config;
+
+import org.springframework.beans.BeanWrapper;
+import org.springframework.beans.BeanWrapperImpl;
+import org.springframework.beans.factory.BeanCreationException;
+import org.springframework.beans.factory.BeanNameAware;
+import org.springframework.beans.factory.FactoryBean;
+import org.springframework.core.JdkVersion;
+import org.springframework.core.task.TaskExecutor;
+import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
+
+/**
+ * FactoryBean for creating TaskExecutor instances.
+ *
+ * @author Mark Fisher
+ * @since 3.0
+ */
+public class TaskExecutorFactoryBean implements FactoryBean<TaskExecutor>, BeanNameAware {
+
+	private volatile TaskExecutor target;
+
+	private volatile BeanWrapper beanWrapper;
+
+	private volatile String poolSize;
+
+	private volatile Integer queueCapacity;
+
+	private volatile Object rejectedExecutionHandler;
+
+	private volatile Integer keepAliveSeconds;
+
+	private volatile String beanName;
+
+	private final Object initializationMonitor = new Object();
+
+
+	public void setPoolSize(String poolSize) {
+		this.poolSize = poolSize;
+	}
+
+	public void setQueueCapacity(int queueCapacity) {
+		this.queueCapacity = queueCapacity;
+	}
+
+	public void setRejectedExecutionHandler(Object rejectedExecutionHandler) {
+		this.rejectedExecutionHandler = rejectedExecutionHandler;
+	}
+
+	public void setKeepAliveSeconds(int keepAliveSeconds) {
+		this.keepAliveSeconds = keepAliveSeconds;
+	}
+
+	public void setBeanName(String beanName) {
+		this.beanName = beanName;
+	}
+
+	public Class<? extends TaskExecutor> getObjectType() {
+		if (this.target != null) {
+			return this.target.getClass();
+		}
+		return TaskExecutor.class;
+	}
+
+	public TaskExecutor getObject() throws Exception {
+		if (this.target == null) {
+			this.initializeExecutor();
+		}
+		return this.target;
+	}
+
+	public boolean isSingleton() {
+		return true;
+	}
+
+	private void initializeExecutor() throws Exception {
+		synchronized (this.initializationMonitor) {
+			if (this.target != null) {
+				return;
+			}
+			String executorClassName = (shouldUseBackport(this.poolSize))
+					? "org.springframework.scheduling.backportconcurrent.ThreadPoolTaskExecutor"
+					: "org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor";
+			Class<?> executorClass = getClass().getClassLoader().loadClass(executorClassName);
+			this.beanWrapper = new BeanWrapperImpl(executorClass);
+			this.setValueIfNotNull("queueCapacity", this.queueCapacity);
+			this.setValueIfNotNull("keepAliveSeconds", this.keepAliveSeconds);
+			this.setValueIfNotNull("rejectedExecutionHandler", this.rejectedExecutionHandler);
+			Integer[] range = this.determinePoolSizeRange();
+			if (range != null) {
+				this.setValueIfNotNull("corePoolSize", range[0]);
+				this.setValueIfNotNull("maxPoolSize", range[1]);
+			}
+			this.target = (TaskExecutor) this.beanWrapper.getWrappedInstance();
+		}
+	}
+
+	private void setValueIfNotNull(String name, Object value) {
+		Assert.notNull(this.beanWrapper, "Property values cannot be set until the BeanWrapper has been created.");
+		if (value != null) {
+			this.beanWrapper.setPropertyValue(name, value);
+		}
+	}
+
+	private Integer[] determinePoolSizeRange() {
+		if (!StringUtils.hasText(this.poolSize)) {
+			return null;
+		}
+		Integer[] range = null;
+		try {
+			int separatorIndex = poolSize.indexOf('-');
+			if (separatorIndex != -1) {
+				range = new Integer[2];
+				range[0] = Integer.valueOf(poolSize.substring(0, separatorIndex));
+				range[1] = Integer.valueOf(poolSize.substring(separatorIndex + 1, poolSize.length()));
+				if (range[0] > range[1]) {
+					throw new BeanCreationException(this.beanName,
+							"Lower bound of pool-size range must not exceed the upper bound.");
+				}
+				if (this.queueCapacity == null) {
+					// no queue-capacity provided, so unbounded
+					if (range[0] == 0) {
+						// actually set 'corePoolSize' to the upper bound of the range
+						// but allow core threads to timeout
+						this.setValueIfNotNull("allowCoreThreadTimeOut", true);
+						range[0] = range[1];
+					}
+					else {
+						// non-zero lower bound implies a core-max size range
+						throw new BeanCreationException(this.beanName,
+								"A non-zero lower bound for the size range requires a queue-capacity value.");
+					}
+				}
+			}
+			else {
+				Integer value = Integer.valueOf(poolSize);
+				range = new Integer[] {value, value};
+			}
+		}
+		catch (NumberFormatException ex) {
+			throw new BeanCreationException(this.beanName,
+					"Invalid pool-size value [" + poolSize + "]: only single maximum integer " +
+					"(e.g. \"5\") and minimum-maximum range (e.g. \"3-5\") are supported.", ex);
+		}
+		return range;
+	}
+
+	private boolean shouldUseBackport(String poolSize) {
+		return (StringUtils.hasText(poolSize) && poolSize.startsWith("0") &&
+				JdkVersion.getMajorJavaVersion() < JdkVersion.JAVA_16);
+	}
+
+}

org.springframework.context/src/test/java/org/springframework/scheduling/config/ExecutorBeanDefinitionParserTests.java

@@ -22,6 +22,7 @@ import org.junit.Before;
 import org.junit.Test;
 
 import org.springframework.beans.DirectFieldAccessor;
+import org.springframework.beans.factory.BeanCreationException;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.support.ClassPathXmlApplicationContext;
 
@@ -56,6 +57,11 @@ public class ExecutorBeanDefinitionParserTests {
 		assertEquals(42, this.getMaxPoolSize(executor));
 	}
 
+	@Test(expected = BeanCreationException.class)
+	public void invalidPoolSize() {
+		this.context.getBean("invalidPoolSize");
+	}
+
 	@Test
 	public void rangeWithBoundedQueue() {
 		Object executor = this.context.getBean("rangeWithBoundedQueue");
@@ -74,6 +80,38 @@ public class ExecutorBeanDefinitionParserTests {
 		assertEquals(Integer.MAX_VALUE, this.getQueueCapacity(executor));
 	}
 
+	@Test
+	public void propertyPlaceholderWithSingleSize() {
+		Object executor = this.context.getBean("propertyPlaceholderWithSingleSize");
+		assertEquals(123, this.getCorePoolSize(executor));
+		assertEquals(123, this.getMaxPoolSize(executor));
+		assertEquals(60, this.getKeepAliveSeconds(executor));
+		assertEquals(false, this.getAllowCoreThreadTimeOut(executor));
+		assertEquals(Integer.MAX_VALUE, this.getQueueCapacity(executor));
+	}
+
+	@Test
+	public void propertyPlaceholderWithRange() {
+		Object executor = this.context.getBean("propertyPlaceholderWithRange");
+		assertEquals(5, this.getCorePoolSize(executor));
+		assertEquals(25, this.getMaxPoolSize(executor));
+		assertEquals(false, this.getAllowCoreThreadTimeOut(executor));
+		assertEquals(10, this.getQueueCapacity(executor));
+	}
+
+	@Test
+	public void propertyPlaceholderWithRangeAndCoreThreadTimeout() {
+		Object executor = this.context.getBean("propertyPlaceholderWithRangeAndCoreThreadTimeout");
+		assertEquals(99, this.getCorePoolSize(executor));
+		assertEquals(99, this.getMaxPoolSize(executor));
+		assertEquals(true, this.getAllowCoreThreadTimeOut(executor));
+	}
+
+	@Test(expected = BeanCreationException.class)
+	public void propertyPlaceholderWithInvalidPoolSize() {
+		this.context.getBean("propertyPlaceholderWithInvalidPoolSize");
+	}
+
 
 	private int getCorePoolSize(Object executor) {
 		return (Integer) new DirectFieldAccessor(executor).getPropertyValue("corePoolSize");

org.springframework.context/src/test/resources/org/springframework/scheduling/config/executorContext.xml

@@ -1,11 +1,13 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <beans xmlns="http://www.springframework.org/schema/beans"
-	   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-	   xmlns:task="http://www.springframework.org/schema/task"
+	xmlns:task="http://www.springframework.org/schema/task"
-	   xsi:schemaLocation="http://www.springframework.org/schema/beans
+	xmlns:context="http://www.springframework.org/schema/context"
-	   			http://www.springframework.org/schema/beans/spring-beans.xsd
+	xmlns:util="http://www.springframework.org/schema/util"
-				http://www.springframework.org/schema/task
+	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
-				http://www.springframework.org/schema/task/spring-task.xsd">
+		http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task.xsd
+		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
+		http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd">
 
 	<task:executor id="default"/>
 
@@ -15,4 +17,23 @@
 
 	<task:executor id="rangeWithUnboundedQueue" pool-size="0-9" keep-alive="37"/>
 
+	<task:executor id="invalidPoolSize" pool-size="zzz"/>
+
+	<task:executor id="propertyPlaceholderWithSingleSize" pool-size="${size.single}"/>
+
+	<task:executor id="propertyPlaceholderWithRange" pool-size="${size.range}" queue-capacity="10"/>
+
+	<task:executor id="propertyPlaceholderWithRangeAndCoreThreadTimeout" pool-size="${size.rangeFromZero}"/>
+
+	<task:executor id="propertyPlaceholderWithInvalidPoolSize" pool-size="${size.invalid}"/>
+
+	<context:property-placeholder properties-ref="props"/>
+
+	<util:properties id="props">
+		<prop key="size.single">123</prop>
+		<prop key="size.range">5-25</prop>
+		<prop key="size.rangeFromZero">0-99</prop>
+		<prop key="size.invalid">22-abc</prop>
+	</util:properties>
+
 </beans>