/*
 * 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
 *
 *   https://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.commons.compress.parallel;

import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;

/**
 * Store intermediate payload in a scatter-gather scenario. Multiple threads write their payload to a backing store, which can subsequently be reversed to an
 * {@link InputStream} to be used as input in the gather phase.
 * <p>
 * It is the responsibility of the allocator of an instance of this class to close this. Closing it should clear off any allocated structures and preferably
 * delete files.
 * </p>
 *
 * @since 1.10
 */
public interface ScatterGatherBackingStore extends Closeable {

    /**
     * Closes this backing store for further writing.
     *
     * @throws IOException if an I/O error occurs.
     */
    void closeForWriting() throws IOException;

    /**
     * An input stream that contains the scattered payload
     *
     * @return An InputStream, should be closed by the caller of this method.
     * @throws IOException if an I/O error occurs.
     */
    InputStream getInputStream() throws IOException;

    /**
     * Writes a piece of payload.
     *
     * @param data   the data to write
     * @param offset offset inside data to start writing from
     * @param length the amount of data to write
     * @throws IOException if an I/O error occurs.
     */
    void writeOut(byte[] data, int offset, int length) throws IOException;
}
