io.micronaut.context.annotation.Parallel Maven / Gradle / Ivy
/*
* Copyright 2017-2020 original 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 io.micronaut.context.annotation;
import io.micronaut.core.annotation.Experimental;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
/**
* A hint annotation that can be added to {@link Bean} definitions or {@link Executable} methods to indicate that they can be initialized in
* parallel with the application context.
*
* This allows optimized startup time by allowing beans that have slow initialization paths to startup and without impacting the overall startup time of the application.
*
* Note that beans and methods that are processed in parallel (unlike {@link Context} scoped beans) will not initially fail the startup of the {@link io.micronaut.context.ApplicationContext}
* as they may be initialized after the {@link io.micronaut.context.ApplicationContext} has started and cannot participate in {@link io.micronaut.context.event.StartupEvent} processing. If a parallel bean fails to startup it will by default stop the {@link io.micronaut.context.ApplicationContext} with an error unless {@link #shutdownOnError()} set to to {@code false}.
*
* Adding {@link Parallel} to methods is most useful when used in conjunction with a {@link io.micronaut.context.processor.ExecutableMethodProcessor}. Be aware however, that the processor in this case should be thread safe as could be executed in parallel for different methods.
*
* NOTE: The use of {@link Parallel} generally only makes sense when combined with non {@link Prototype} scopes such as {@link jakarta.inject.Singleton} and {@link Context}
*
* @author graemerocher
* @since 1.0
* @see Context
* @see Executable
* @see io.micronaut.context.processor.ExecutableMethodProcessor
*/
@Documented
@Retention(RUNTIME)
@Target({ElementType.METHOD, ElementType.TYPE, ElementType.ANNOTATION_TYPE})
@Experimental
public @interface Parallel {
/**
* The default behaviour is to shut down the context if an error occurs on initialization. Can be set false if shutdown is not required.
*
* @return Whether to shut down the application if an error occurs.
*/
boolean shutdownOnError() default true;
}