com.datatorrent.api.Component 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 com.datatorrent.api;
/**
* Basic interface which is implemented by almost all entities in the system.
* This interface provides a convenient way of setting up and tearing down most
* entities in the system.
*
* @param Context used for the current run of the component.
* @since 0.3.2
*/
public interface Component
{
/**
* It's recommended to use this separator to create scoped names for the components.
* e.g. Port p on Operator o can be identified as o.concat(CONCAT_SEPARATOR).concat(p).
*/
public static final String CONCAT_SEPARATOR = ".";
/**
* It's recommended to use this separator to split the scoped names into individual components.
* e.g. o.concat(CONCAT_SEPARATOR).concat(p).split(SPLIT_SEPARATOR) will return String[]{o, p}.
*
*/
public static final String SPLIT_SEPARATOR = "\\.";
/**
* Callback to give the component a chance to perform tasks required as part of setting itself up.
* This callback is made exactly once during the operator lifetime. If you want to perform certain
* setup tasks every time the operator is activated/deactivated, please implement ActivationListener.
*
* @param context - context in which the operator executues.
*/
public void setup(CONTEXT context);
/**
* Callback to give the component a chance to perform tasks required as part of tearing itself down.
* A recommended practice is to reciprocate the tasks in setup by doing exactly opposite.
*/
public void teardown();
/**
* A utility class to club component along with the entity such as context or configuration.
*
* We use ComponentComplementPair for better readability of the code compared to using a bare
* pair where first and second do not have semantic meaning.
*
* @param
* @param
* @since 0.3.2
*/
public static abstract class ComponentComplementPair, COMPLEMENT>
{
public final COMPONENT component;
/**
* Constructor for ComponentComplementPair.
*/
public ComponentComplementPair(COMPONENT component)
{
super();
this.component = component;
}
/** {@inheritDoc} */
@Override
public int hashCode()
{
int hash = 7;
hash = 73 * hash + (this.component != null ? this.component.hashCode() : 0);
hash = 73 * hash + (this.getComplement() != null ? this.getComplement().hashCode() : 0);
return hash;
}
/** {@inheritDoc} */
@Override
public boolean equals(Object obj)
{
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
@SuppressWarnings(value = "unchecked")
final ComponentComplementPair other = (ComponentComplementPair)obj;
if (this.component != other.component && (this.component == null || !this.component.equals(other.component))) {
return false;
}
if (this.getComplement() != other.getComplement() && (this.getComplement() == null || !this.getComplement().equals(other.getComplement()))) {
return false;
}
return true;
}
/**
* getComplement.
*/
public abstract COMPLEMENT getComplement();
}
}