1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, 13 * software distributed under the License is distributed on an 14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 15 * KIND, either express or implied. See the License for the 16 * specific language governing permissions and limitations 17 * under the License. 18 */ 19 package org.eclipse.aether; 20 21 import java.io.Closeable; 22 import java.util.Collection; 23 24 import org.eclipse.aether.artifact.Artifact; 25 import org.eclipse.aether.metadata.Metadata; 26 27 /** 28 * A synchronization context used to coordinate concurrent access to artifacts or metadatas. The typical usage of a 29 * synchronization context looks like this: 30 * 31 * <pre> 32 * SyncContext syncContext = repositorySystem.newSyncContext( ... ); 33 * try { 34 * syncContext.acquire( artifacts, metadatas ); 35 * // work with the artifacts and metadatas 36 * } finally { 37 * syncContext.close(); 38 * } 39 * </pre> 40 * 41 * Within one thread, synchronization contexts may be nested which can naturally happen in a hierarchy of method calls. 42 * The nested synchronization contexts may also acquire overlapping sets of artifacts/metadatas as long as the following 43 * conditions are met. If the outer-most context holding a particular resource is exclusive, that resource can be 44 * reacquired in any nested context. If however the outer-most context is shared, the resource may only be reacquired by 45 * nested contexts if these are also shared. 46 * <p> 47 * A synchronization context is meant to be utilized by only one thread and as such is not thread-safe. 48 * <p> 49 * Note that the level of actual synchronization is subject to the implementation and might range from OS-wide to none. 50 * 51 * @see RepositorySystem#newSyncContext(RepositorySystemSession, boolean) 52 */ 53 public interface SyncContext extends Closeable { 54 55 /** 56 * Acquires synchronized access to the specified artifacts and metadatas. The invocation will potentially block 57 * until all requested resources can be acquired by the calling thread. Acquiring resources that are already 58 * acquired by this synchronization context has no effect. Please also see the class-level documentation for 59 * information regarding reentrancy. The method may be invoked multiple times on a synchronization context until all 60 * desired resources have been acquired. 61 * 62 * @param artifacts The artifacts to acquire, may be {@code null} or empty if none. 63 * @param metadatas The metadatas to acquire, may be {@code null} or empty if none. 64 */ 65 void acquire(Collection<? extends Artifact> artifacts, Collection<? extends Metadata> metadatas); 66 67 /** 68 * Releases all previously acquired artifacts/metadatas. If no resources have been acquired before or if this 69 * synchronization context has already been closed, this method does nothing. 70 */ 71 void close(); 72 }