001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.eclipse.aether.spi.connector.checksum;
020
021import java.nio.ByteBuffer;
022
023/**
024 * Implementation performing checksum calculation for specific algorithm. Instances of this interface are stateful,
025 * non-thread safe, and should not be reused.
026 *
027 * @since 1.8.0
028 */
029public interface ChecksumAlgorithm {
030    /**
031     * Updates the checksum algorithm inner state with input.
032     */
033    void update(ByteBuffer input);
034
035    /**
036     * Returns the algorithm end result as string, never {@code null}. After invoking this method, this instance should
037     * be discarded and not reused. For new checksum calculation you have to get new instance.
038     *
039     * Values returned by this method are handled as "opaque strings", and are used for simple equality checks (matches
040     * or not matches the checksum), and are also persisted in this form (locally to file system but also uploaded as
041     * checksum files). Resolver itself never tries to "decode" or "interpret" this string in any other way.
042     */
043    String checksum();
044}