sanha commented on a change in pull request #115: [NEMO-96] Modularize DataSkewPolicy to use MetricVertex and BarrierVertex URL: https://github.com/apache/incubator-nemo/pull/115#discussion_r214376120
########## File path: common/src/main/java/edu/snu/nemo/common/coder/KVDecoderFactory.java ########## @@ -0,0 +1,87 @@ +/* + * Copyright (C) 2018 Seoul National University + * + * Licensed 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 edu.snu.nemo.common.coder; + +import java.io.IOException; +import java.io.InputStream; + +/** + * A kv decoder factory object which generates kv decoders that decode byte streams to values of type {@code T}. + * To avoid generating instance-based coder such as Spark serializer for every decoding, + * user need to explicitly instantiate an kv decoder instance and use it. + * + * @param <T> element type. + */ +public interface KVDecoderFactory<T> extends DecoderFactory { + @Override + KVDecoder<T> create(InputStream inputStream) throws IOException; + DecoderFactory getKeyDecoderFactory(); + + /** + * Interface of the Decoder. + * + * @param <T> element type. + */ + interface KVDecoder<T> extends Decoder<T> { + /** + * Decodes the given value onto the specified input stream. + * It has to be able to decode the given stream consequently by calling this method repeatedly. + * Because the user can want to keep a single input stream and continuously concatenate elements, + * the input stream should not be closed. + * + * @throws IOException if fail to decode + */ + T decode() throws IOException; + } + + /** + * Dummy kv decoder factory. + */ + KVDecoderFactory DUMMY_KVDECODER_FACTORY = new DummyKVDecoderFactory(); + + /** + * Dummy kv decoder factory implementation which is not supposed to be used. + */ + final class DummyKVDecoderFactory implements KVDecoderFactory { + private final DecoderFactory keyDecoderFactory = null; Review comment: How about use dummy decoder factory instead of `null`? ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
