org.apache.nifi.annotation.lifecycle.OnStopped Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.nifi.annotation.lifecycle;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.apache.nifi.controller.ConfigurationContext;
import org.apache.nifi.processor.ProcessContext;
/**
*
* Marker annotation a {@link org.apache.nifi.processor.Processor Processor} or
* {@link org.apache.nifi.reporting.ReportingTask ReportingTask} implementation
* can use to indicate that a method should be called whenever the component is
* no longer scheduled to run. Methods marked with this annotation will be
* invoked each time the component is stopped and will be invoked only after the
* last thread has returned from the onTrigger method.
*
*
*
* This means that the thread executing in this method will be the only thread
* executing in any part of the Processor. However, since other threads may
* later execute other parts of the code, member variables must still be
* protected appropriately. However, access to multiple variables need not be
* atomic.
*
*
*
* To indicate that a method should be called immediately when a component is no
* longer scheduled to run (as opposed to after all threads have returned from
* the onTrigger method), see the {@link OnUnscheduled} annotation.
*
*
*
* Methods with this annotation are permitted to take either 0 or 1 argument. If
* an argument is used, it must be of type {@link ConfigurationContext} if the
* component is a ReportingTask or of type {@link ProcessContext} if the
* component is a Processor.
*
*
* Implementation Guidelines:
*
* - Methods with this annotation are expected to perform very quick, short-lived tasks. If the function is
* expensive or long-lived, the logic should be performed in the {@code onTrigger} method instead.
* - If a method with this annotation does not return (exceptionally or otherwise) within a short period
* of time (the duration is configurable in the properties file), the Thread may be interrupted.
* - Methods that make use of this interface should honor Java's Thread interruption mechanisms and not swallow
* {@link InterruptedException}.
*
*/
@Documented
@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
public @interface OnStopped {
}