/*
* Copyright 2002-2018 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.annotation;
import java.lang.annotation.Annotation;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.springframework.context.annotation.AdviceMode;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.core.Ordered;
Enables Spring's asynchronous method execution capability, similar to functionality found in Spring's <task:*> XML namespace. To be used together with @Configuration classes as follows, enabling annotation-driven async processing for an entire Spring application context:
@Configuration
@EnableAsync
public class AppConfig {
} MyAsyncBean is a user-defined type with one or more methods annotated with either Spring's @Async annotation, the EJB 3.1 @javax.ejb.Asynchronous annotation, or any custom annotation specified via the annotation attribute. The aspect is added transparently for any registered bean, for instance via this configuration: @Configuration
public class AnotherAppConfig {
@Bean
public MyAsyncBean asyncBean() {
return new MyAsyncBean();
}
}
By default, Spring will be searching for an associated thread pool definition: either a unique TaskExecutor bean in the context, or an Executor bean named "taskExecutor" otherwise. If neither of the two is resolvable, a SimpleAsyncTaskExecutor will be used to process async method invocations. Besides, annotated methods having a void return type cannot transmit any exception back to the caller. By default, such uncaught exceptions are only logged.
To customize all this, implement AsyncConfigurer and provide:
- your own
Executor through the getAsyncExecutor() method, and
- your own
AsyncUncaughtExceptionHandler through the
getAsyncUncaughtExceptionHandler() method.
NOTE: AsyncConfigurer configuration classes get initialized early in the application context bootstrap. If you need any dependencies on other beans there, make sure to declare them 'lazy' as far as possible in order to let them go through other post-processors as well.
@Configuration
@EnableAsync
public class AppConfig implements AsyncConfigurer {
@Override
public Executor getAsyncExecutor() {
ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
executor.setCorePoolSize(7);
executor.setMaxPoolSize(42);
executor.setQueueCapacity(11);
executor.setThreadNamePrefix("MyExecutor-");
executor.initialize();
return executor;
}
@Override
public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {
return new MyAsyncUncaughtExceptionHandler();
}
}
If only one item needs to be customized, null can be returned to keep the default settings. Consider also extending from AsyncConfigurerSupport when possible.
Note: In the above example the ThreadPoolTaskExecutor is not a fully managed Spring bean. Add the @Bean annotation to the getAsyncExecutor() method if you want a fully managed bean. In such circumstances it is no longer necessary to manually call the executor.initialize() method as this will be invoked automatically when the bean is initialized.
For reference, the example above can be compared to the following Spring XML
configuration:
<beans>
<task:annotation-driven executor="myExecutor" exception-handler="exceptionHandler"/>
<task:executor id="myExecutor" pool-size="7-42" queue-capacity="11"/>
<bean id="asyncBean" class="com.foo.MyAsyncBean"/>
<bean id="exceptionHandler" class="com.foo.MyAsyncUncaughtExceptionHandler"/>
</beans>
The above XML-based and JavaConfig-based examples are equivalent except for the
setting of the thread name prefix of the Executor; this is because the <task:executor> element does not expose such an attribute. This demonstrates how the JavaConfig-based approach allows for maximum configurability through direct access to actual componentry. The mode attribute controls how advice is applied: If the mode is AdviceMode.PROXY (the default), then the other attributes control the behavior of the proxying. Please note that proxy mode allows for interception of calls through the proxy only; local calls within the same class cannot get intercepted that way.
Note that if the mode is set to AdviceMode.ASPECTJ, then the value of the proxyTargetClass attribute will be ignored. Note also that in this case the spring-aspects module JAR must be present on the classpath, with compile-time weaving or load-time weaving applying the aspect to the affected classes. There is no proxy involved in such a scenario; local calls will be intercepted as well.
Author: Chris Beams, Juergen Hoeller, Stephane Nicoll, Sam Brannen See Also: Since: 3.1
/**
* Enables Spring's asynchronous method execution capability, similar to functionality
* found in Spring's {@code <task:*>} XML namespace.
*
* <p>To be used together with @{@link Configuration Configuration} classes as follows,
* enabling annotation-driven async processing for an entire Spring application context:
*
* <pre class="code">
* @Configuration
* @EnableAsync
* public class AppConfig {
*
* }</pre>
*
* {@code MyAsyncBean} is a user-defined type with one or more methods annotated with
* either Spring's {@code @Async} annotation, the EJB 3.1 {@code @javax.ejb.Asynchronous}
* annotation, or any custom annotation specified via the {@link #annotation} attribute.
* The aspect is added transparently for any registered bean, for instance via this
* configuration:
*
* <pre class="code">
* @Configuration
* public class AnotherAppConfig {
*
* @Bean
* public MyAsyncBean asyncBean() {
* return new MyAsyncBean();
* }
* }</pre>
*
* <p>By default, Spring will be searching for an associated thread pool definition:
* either a unique {@link org.springframework.core.task.TaskExecutor} bean in the context,
* or an {@link java.util.concurrent.Executor} bean named "taskExecutor" otherwise. If
* neither of the two is resolvable, a {@link org.springframework.core.task.SimpleAsyncTaskExecutor}
* will be used to process async method invocations. Besides, annotated methods having a
* {@code void} return type cannot transmit any exception back to the caller. By default,
* such uncaught exceptions are only logged.
*
* <p>To customize all this, implement {@link AsyncConfigurer} and provide:
* <ul>
* <li>your own {@link java.util.concurrent.Executor Executor} through the
* {@link AsyncConfigurer#getAsyncExecutor getAsyncExecutor()} method, and</li>
* <li>your own {@link org.springframework.aop.interceptor.AsyncUncaughtExceptionHandler
* AsyncUncaughtExceptionHandler} through the {@link AsyncConfigurer#getAsyncUncaughtExceptionHandler
* getAsyncUncaughtExceptionHandler()}
* method.</li>
* </ul>
*
* <p><b>NOTE: {@link AsyncConfigurer} configuration classes get initialized early
* in the application context bootstrap. If you need any dependencies on other beans
* there, make sure to declare them 'lazy' as far as possible in order to let them
* go through other post-processors as well.</b>
*
* <pre class="code">
* @Configuration
* @EnableAsync
* public class AppConfig implements AsyncConfigurer {
*
* @Override
* public Executor getAsyncExecutor() {
* ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
* executor.setCorePoolSize(7);
* executor.setMaxPoolSize(42);
* executor.setQueueCapacity(11);
* executor.setThreadNamePrefix("MyExecutor-");
* executor.initialize();
* return executor;
* }
*
* @Override
* public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {
* return new MyAsyncUncaughtExceptionHandler();
* }
* }</pre>
*
* <p>If only one item needs to be customized, {@code null} can be returned to
* keep the default settings. Consider also extending from {@link AsyncConfigurerSupport}
* when possible.
*
* <p>Note: In the above example the {@code ThreadPoolTaskExecutor} is not a fully managed
* Spring bean. Add the {@code @Bean} annotation to the {@code getAsyncExecutor()} method
* if you want a fully managed bean. In such circumstances it is no longer necessary to
* manually call the {@code executor.initialize()} method as this will be invoked
* automatically when the bean is initialized.
*
* <p>For reference, the example above can be compared to the following Spring XML
* configuration:
*
* <pre class="code">
* <beans>
*
* <task:annotation-driven executor="myExecutor" exception-handler="exceptionHandler"/>
*
* <task:executor id="myExecutor" pool-size="7-42" queue-capacity="11"/>
*
* <bean id="asyncBean" class="com.foo.MyAsyncBean"/>
*
* <bean id="exceptionHandler" class="com.foo.MyAsyncUncaughtExceptionHandler"/>
*
* </beans>
* </pre>
*
* The above XML-based and JavaConfig-based examples are equivalent except for the
* setting of the <em>thread name prefix</em> of the {@code Executor}; this is because
* the {@code <task:executor>} element does not expose such an attribute. This
* demonstrates how the JavaConfig-based approach allows for maximum configurability
* through direct access to actual componentry.
*
* <p>The {@link #mode} attribute controls how advice is applied: If the mode is
* {@link AdviceMode#PROXY} (the default), then the other attributes control the behavior
* of the proxying. Please note that proxy mode allows for interception of calls through
* the proxy only; local calls within the same class cannot get intercepted that way.
*
* <p>Note that if the {@linkplain #mode} is set to {@link AdviceMode#ASPECTJ}, then the
* value of the {@link #proxyTargetClass} attribute will be ignored. Note also that in
* this case the {@code spring-aspects} module JAR must be present on the classpath, with
* compile-time weaving or load-time weaving applying the aspect to the affected classes.
* There is no proxy involved in such a scenario; local calls will be intercepted as well.
*
* @author Chris Beams
* @author Juergen Hoeller
* @author Stephane Nicoll
* @author Sam Brannen
* @since 3.1
* @see Async
* @see AsyncConfigurer
* @see AsyncConfigurationSelector
*/
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Import(AsyncConfigurationSelector.class)
public @interface EnableAsync {
Indicate the 'async' annotation type to be detected at either class
or method level.
By default, both Spring's @Async annotation and the EJB 3.1 @javax.ejb.Asynchronous annotation will be detected.
This attribute exists so that developers can provide their own
custom annotation type to indicate that a method (or all methods of
a given class) should be invoked asynchronously.
/**
* Indicate the 'async' annotation type to be detected at either class
* or method level.
* <p>By default, both Spring's @{@link Async} annotation and the EJB 3.1
* {@code @javax.ejb.Asynchronous} annotation will be detected.
* <p>This attribute exists so that developers can provide their own
* custom annotation type to indicate that a method (or all methods of
* a given class) should be invoked asynchronously.
*/
Class<? extends Annotation> annotation() default Annotation.class;
Indicate whether subclass-based (CGLIB) proxies are to be created as opposed
to standard Java interface-based proxies.
Applicable only if the mode is set to AdviceMode.PROXY.
The default is false.
Note that setting this attribute to true will affect all Spring-managed beans requiring proxying, not just those marked with @Async. For example, other beans marked with Spring's @Transactional annotation will be upgraded to subclass proxying at the same time. This approach has no negative impact in practice unless one is explicitly expecting one type of proxy vs. another — for example, in tests.
/**
* Indicate whether subclass-based (CGLIB) proxies are to be created as opposed
* to standard Java interface-based proxies.
* <p><strong>Applicable only if the {@link #mode} is set to {@link AdviceMode#PROXY}</strong>.
* <p>The default is {@code false}.
* <p>Note that setting this attribute to {@code true} will affect <em>all</em>
* Spring-managed beans requiring proxying, not just those marked with {@code @Async}.
* For example, other beans marked with Spring's {@code @Transactional} annotation
* will be upgraded to subclass proxying at the same time. This approach has no
* negative impact in practice unless one is explicitly expecting one type of proxy
* vs. another — for example, in tests.
*/
boolean proxyTargetClass() default false;
Indicate how async advice should be applied.
The default is AdviceMode.PROXY. Please note that proxy mode allows for interception of calls through the proxy only. Local calls within the same class cannot get intercepted that way; an Async annotation on such a method within a local call will be ignored since Spring's interceptor does not even kick in for such a runtime scenario. For a more advanced mode of interception, consider switching this to AdviceMode.ASPECTJ.
/**
* Indicate how async advice should be applied.
* <p><b>The default is {@link AdviceMode#PROXY}.</b>
* Please note that proxy mode allows for interception of calls through the proxy
* only. Local calls within the same class cannot get intercepted that way; an
* {@link Async} annotation on such a method within a local call will be ignored
* since Spring's interceptor does not even kick in for such a runtime scenario.
* For a more advanced mode of interception, consider switching this to
* {@link AdviceMode#ASPECTJ}.
*/
AdviceMode mode() default AdviceMode.PROXY;
Indicate the order in which the AsyncAnnotationBeanPostProcessor should be applied. The default is Ordered.LOWEST_PRECEDENCE in order to run after all other post-processors, so that it can add an advisor to existing proxies rather than double-proxy.
/**
* Indicate the order in which the {@link AsyncAnnotationBeanPostProcessor}
* should be applied.
* <p>The default is {@link Ordered#LOWEST_PRECEDENCE} in order to run
* after all other post-processors, so that it can add an advisor to
* existing proxies rather than double-proxy.
*/
int order() default Ordered.LOWEST_PRECEDENCE;
}