| /** |
| * 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.crunch; |
| |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.mapreduce.TaskInputOutputContext; |
| |
| import java.io.IOException; |
| import java.io.Serializable; |
| import java.util.Set; |
| |
| /** |
| * Represents the contents of a data source that can be read on the cluster from within one |
| * of the tasks running as part of a Crunch pipeline. |
| */ |
| public interface ReadableData<T> extends Serializable { |
| |
| /** |
| * @return Any {@code SourceTarget} instances that must exist before the data in |
| * this instance can be read. Used by the planner in sequencing job processing. |
| */ |
| Set<SourceTarget<?>> getSourceTargets(); |
| |
| /** |
| * Allows this instance to specify any additional configuration settings that may |
| * be needed by the job that it is launched in. |
| * |
| * @param conf The {@code Configuration} object for the job |
| */ |
| void configure(Configuration conf); |
| |
| /** |
| * Read the data referenced by this instance within the given context. |
| * |
| * @param context The context of the task that is reading the data |
| * @return An iterable reference to the data in this instance |
| * @throws IOException If the data cannot be read |
| */ |
| Iterable<T> read(TaskInputOutputContext<?, ?, ?, ?> context) throws IOException; |
| } |