org.apache.nifi.annotation.lifecycle.OnScheduled 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;
/**
*
* Marker annotation a {@link org.apache.nifi.processor.Processor Processor} or
* {@link org.apache.nifi.reporting.ReportingTask ReportingTask} implementation
* can use to indicate a method should be called whenever the component is
* scheduled to run. This will be called before any call to 'onTrigger' and will
* be called once each time a Processor or Reporting Task is scheduled to run.
* This occurs in one of two ways: either a user clicks to schedule the
* component to run, or NiFi is restarted with the "auto-resume state"
* configuration set to true (the default value) and the component is already
* running.
*
*
*
* Methods using this annotation must take either 0 arguments or a single
* argument.
*
*
*
* If using 1 argument and the component using the annotation is a Processor,
* that argument must be of type
* {@link org.apache.nifi.processor.ProcessContext ProcessContext}.
*
*
*
* If using 1 argument and the component using the annotation is a Reporting
* Task, that argument must be of type
* {@link org.apache.nifi.controller.ConfigurationContext ConfigurationContext}.
*
*
*
* If any method annotated with this annotation throws any Throwable, the
* framework will wait a while and then attempt to invoke the method again. This
* will continue until the method succeeds, and the component will then be
* scheduled to run after this method return successfully.
*
*
* 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 OnScheduled {
}