/*
* 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.flink.streaming.api.functions.source;
import org.apache.flink.annotation.Public;
import org.apache.flink.api.common.functions.AbstractRichFunction;
/**
* Base class for implementing a parallel data source that has access to context information
* (via {@link #getRuntimeContext()}) and additional life-cycle methods
* ({@link #open(org.apache.flink.configuration.Configuration)} and {@link #close()}.
*
* <p>This class is useful when implementing parallel sources where different parallel subtasks
* need to perform different work. Typical patterns for that are:
* <ul>
* <li>Use {@link #getRuntimeContext()} to obtain the runtime context.</li>
* <li>Use {@link org.apache.flink.api.common.functions.RuntimeContext#getNumberOfParallelSubtasks()}
* to determine the current parallelism. It is strongly encouraged to use this method, rather than
* hard-wiring the parallelism, because the configured parallelism may change depending on
* program configuration. The parallelism may also change after recovering failures, when fewer than
* desired parallel worker as available.</li>
* <li>Use {@link org.apache.flink.api.common.functions.RuntimeContext#getIndexOfThisSubtask()} to
* determine which subtask the current instance of the function executes.</li>
* </ul>
*
* @param <OUT> The type of the records produced by this source.
*/
@Public
public abstract class RichSourceFunction<OUT> extends AbstractRichFunction implements SourceFunction<OUT> {
private static final long serialVersionUID = 1L;
}