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.internal.impl.synccontext.named;
020
021import java.util.Collection;
022
023import org.eclipse.aether.RepositorySystemSession;
024import org.eclipse.aether.artifact.Artifact;
025import org.eclipse.aether.metadata.Metadata;
026import org.eclipse.aether.named.NamedLockKey;
027
028/**
029 * Component mapping lock names to passed in artifacts and metadata as required.
030 */
031public interface NameMapper {
032    /**
033     * Returns {@code true} if lock names returned by this lock name mapper are file system friendly, can be used
034     * as file names and paths.
035     * <p>
036     * <em>Note:</em> The fact that name mapper is "file system friendly" means ONLY that names it produces CAN be
037     * used as file names and paths. Still, it does not mean they will work with ANY file based locking, as for example
038     * {@link org.eclipse.aether.named.providers.FileLockNamedLockFactory} expects names as string encoded
039     * {@link java.net.URI}s. The only name mapper doing it is {@link BasedirNameMapper}.
040     *
041     * @since 1.9.0
042     */
043    boolean isFileSystemFriendly();
044
045    /**
046     * Creates (opaque) names for passed in artifacts and metadata. Returned collection has max size of sum of the
047     * passed in artifacts and metadata collections, or less. If an empty collection is returned, there will be no
048     * locking happening. Never returns {@code null}. The resulting collection MUST BE "stable" (always sorted by
049     * same criteria) to avoid deadlocks by acquiring locks in same order, essentially disregarding the order of
050     * the input collections.
051     * <p>
052     * There is no requirement of any kind of "parity" between input element count (sum of two collections, that is)
053     * and output collection size, just the returned upper size limit is defined (sum of the passed in two collections
054     * size). If returned collection is empty, no locking will happen, if single element, one lock will be used, if two
055     * then two named locks will be used etc.
056     * <p>
057     * Note: name mapper must not use same string for artifacts and metadata, so even the simplest possible
058     * implementation like {@link StaticNameMapper} uses two different static strings.
059     */
060    Collection<NamedLockKey> nameLocks(
061            RepositorySystemSession session,
062            Collection<? extends Artifact> artifacts,
063            Collection<? extends Metadata> metadatas);
064}