org.argeo.slc.repo/src/org/eclipse/aether/SyncContext.java

   1 /*******************************************************************************
   2  * Copyright (c) 2010, 2011 Sonatype, Inc.
   3  * All rights reserved. This program and the accompanying materials
   4  * are made available under the terms of the Eclipse Public License v1.0
   5  * which accompanies this distribution, and is available at
   6  * http://www.eclipse.org/legal/epl-v10.html
   7  *
   8  * Contributors:
   9  *    Sonatype, Inc. - initial API and implementation
  10  *******************************************************************************/
  11 package org.eclipse.aether;
  12
  13 import java.io.Closeable;
  14 import java.util.Collection;
  15
  16 import org.eclipse.aether.artifact.Artifact;
  17 import org.eclipse.aether.metadata.Metadata;
  18
  19 /**
  20  * A synchronization context used to coordinate concurrent access to artifacts or metadatas. The typical usage of a
  21  * synchronization context looks like this:
  22  *
  23  * <pre>
  24  * SyncContext syncContext = repositorySystem.newSyncContext( ... );
  25  * try {
  26  *     syncContext.acquire( artifacts, metadatas );
  27  *     // work with the artifacts and metadatas
  28  * } finally {
  29  *     syncContext.close();
  30  * }
  31  * </pre>
  32  *
  33  * Within one thread, synchronization contexts may be nested which can naturally happen in a hierarchy of method calls.
  34  * The nested synchronization contexts may also acquire overlapping sets of artifacts/metadatas as long as the following
  35  * conditions are met. If the outer-most context holding a particular resource is exclusive, that resource can be
  36  * reacquired in any nested context. If however the outer-most context is shared, the resource may only be reacquired by
  37  * nested contexts if these are also shared.
  38  * <p>
  39  * A synchronization context is meant to be utilized by only one thread and as such is not thread-safe.
  40  * <p>
  41  * Note that the level of actual synchronization is subject to the implementation and might range from OS-wide to none.
  42  *
  43  * @see RepositorySystem#newSyncContext(RepositorySystemSession, boolean)
  44  */
  45 public interface SyncContext
  46     extends Closeable
  47 {
  48
  49     /**
  50      * Acquires synchronized access to the specified artifacts and metadatas. The invocation will potentially block
  51      * until all requested resources can be acquired by the calling thread. Acquiring resources that are already
  52      * acquired by this synchronization context has no effect. Please also see the class-level documentation for
  53      * information regarding reentrancy. The method may be invoked multiple times on a synchronization context until all
  54      * desired resources have been acquired.
  55      *
  56      * @param artifacts The artifacts to acquire, may be {@code null} or empty if none.
  57      * @param metadatas The metadatas to acquire, may be {@code null} or empty if none.
  58      */
  59     void acquire( Collection<? extends Artifact> artifacts, Collection<? extends Metadata> metadatas );
  60
  61     /**
  62      * Releases all previously acquired artifacts/metadatas. If no resources have been acquired before or if this
  63      * synchronization context has already been closed, this method does nothing.
  64      */
  65     void close();
  66
  67 }