| /* |
| * 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.pig; |
| |
| import java.io.IOException; |
| |
| import org.apache.pig.backend.datastorage.DataStorage; |
| |
| /** |
| * Produces independent slices of data from a given location to be processed in |
| * parallel by Pig. |
| * <p> |
| * If a class implementing this interface is given as the LoadFunc in a Pig |
| * script, it will be used to make slices for that load statement. |
| */ |
| public interface Slicer { |
| /** |
| * Checks that <code>location</code> is parsable by this Slicer, and that |
| * if the DataStorage is used by the Slicer, it's readable from there. If it |
| * isn't, an IOException with a message explaining why will be thrown. |
| * <p> |
| * This does not ensure that all the data in <code>location</code> is |
| * valid. It's a preflight check that there's some chance of the Slicer |
| * working before actual Slices are created and sent off for processing. |
| */ |
| void validate(DataStorage store, String location) throws IOException; |
| |
| /** |
| * Creates slices of data from <code>store</code> at <code>location</code>. |
| * |
| * @return the Slices to be serialized and sent out to nodes for processing. |
| */ |
| Slice[] slice(DataStorage store, String location) throws IOException; |
| } |