| /* |
| * 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 opennlp.tools.ml.model; |
| |
| import java.io.IOException; |
| import java.nio.charset.StandardCharsets; |
| import java.util.zip.CRC32C; |
| import java.util.zip.Checksum; |
| |
| import opennlp.tools.util.AbstractObjectStream; |
| import opennlp.tools.util.ObjectStream; |
| |
| /** |
| * A {@link Checksum}-based {@link AbstractObjectStream event stream} implementation. |
| * Computes the checksum while consuming the event stream. |
| * By default, this implementation will use {@link CRC32C} for checksum calculations |
| * as it can use of CPU-specific acceleration instructions at runtime. |
| * |
| * @see Event |
| * @see Checksum |
| * @see AbstractObjectStream |
| */ |
| public class ChecksumEventStream extends AbstractObjectStream<Event> { |
| |
| private final Checksum checksum; |
| |
| |
| /** |
| * Initializes an {@link ChecksumEventStream}. |
| * |
| * @param eventStream The {@link ObjectStream} that provides the {@link Event} samples. |
| */ |
| public ChecksumEventStream(ObjectStream<Event> eventStream) { |
| super(eventStream); |
| // CRC32C supports CPU-specific acceleration instructions |
| checksum = new CRC32C(); |
| } |
| |
| @Override |
| public Event read() throws IOException { |
| Event event = super.read(); |
| if (event != null) { |
| checksum.update(event.toString().getBytes(StandardCharsets.UTF_8)); |
| } |
| return event; |
| } |
| |
| /** |
| * Calculates and returns the (current) checksum. |
| * <p> |
| * Note: This should be called once the underlying stream has been (fully) consumed. |
| * |
| * @return The calculated checksum as {@code long}. |
| */ |
| public long calculateChecksum() { |
| return checksum.getValue(); |
| } |
| } |