001/*
002 *  Licensed to the Apache Software Foundation (ASF) under one or more
003 *  contributor license agreements.  See the NOTICE file distributed with
004 *  this work for additional information regarding copyright ownership.
005 *  The ASF licenses this file to You under the Apache License, Version 2.0
006 *  (the "License"); you may not use this file except in compliance with
007 *  the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 *  Unless required by applicable law or agreed to in writing, software
012 *  distributed under the License is distributed on an "AS IS" BASIS,
013 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 *  See the License for the specific language governing permissions and
015 *  limitations under the License.
016 *
017 */
018package org.apache.commons.compress.parallel;
019
020import java.io.Closeable;
021import java.io.IOException;
022import java.io.InputStream;
023
024/**
025 * <p>Store intermediate payload in a scatter-gather scenario.
026 * Multiple threads write their payload to a backing store, which can
027 * subsequently be reversed to an {@link InputStream} to be used as input in the
028 * gather phase.</p>
029 *
030 * <p>It is the responsibility of the allocator of an instance of this class
031 * to close this. Closing it should clear off any allocated structures
032 * and preferably delete files.</p>
033 *
034 * @since 1.10
035 */
036public interface ScatterGatherBackingStore extends Closeable {
037
038    /**
039     * Closes this backing store for further writing.
040     * @throws IOException when something fails
041     */
042    void closeForWriting() throws IOException;
043
044    /**
045     * An input stream that contains the scattered payload
046     *
047     * @return An InputStream, should be closed by the caller of this method.
048     * @throws IOException when something fails
049     */
050    InputStream getInputStream() throws IOException;
051
052    /**
053     * Writes a piece of payload.
054     *
055     * @param data the data to write
056     * @param offset offset inside data to start writing from
057     * @param length the amount of data to write
058     * @throws IOException when something fails
059     */
060    void writeOut(byte[] data, int offset, int length) throws IOException;
061}