Merge tag 'v2.3.20' into testing

[gpl/argeo-jcr.git] / org.argeo.slc.repo / src / org / eclipse / aether / SyncContext.java

diff --git a/org.argeo.slc.repo/src/org/eclipse/aether/SyncContext.java b/org.argeo.slc.repo/src/org/eclipse/aether/SyncContext.java
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+/*******************************************************************************
+ * Copyright (c) 2010, 2011 Sonatype, Inc.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Sonatype, Inc. - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.aether;
+
+import java.io.Closeable;
+import java.util.Collection;
+
+import org.eclipse.aether.artifact.Artifact;
+import org.eclipse.aether.metadata.Metadata;
+
+/**
+ * A synchronization context used to coordinate concurrent access to artifacts or metadatas. The typical usage of a
+ * synchronization context looks like this:
+ * 
+ * <pre>
+ * SyncContext syncContext = repositorySystem.newSyncContext( ... );
+ * try {
+ *     syncContext.acquire( artifacts, metadatas );
+ *     // work with the artifacts and metadatas
+ * } finally {
+ *     syncContext.close();
+ * }
+ * </pre>
+ * 
+ * Within one thread, synchronization contexts may be nested which can naturally happen in a hierarchy of method calls.
+ * The nested synchronization contexts may also acquire overlapping sets of artifacts/metadatas as long as the following
+ * conditions are met. If the outer-most context holding a particular resource is exclusive, that resource can be
+ * reacquired in any nested context. If however the outer-most context is shared, the resource may only be reacquired by
+ * nested contexts if these are also shared.
+ * <p>
+ * A synchronization context is meant to be utilized by only one thread and as such is not thread-safe.
+ * <p>
+ * Note that the level of actual synchronization is subject to the implementation and might range from OS-wide to none.
+ * 
+ * @see RepositorySystem#newSyncContext(RepositorySystemSession, boolean)
+ */
+public interface SyncContext
+    extends Closeable
+{
+
+    /**
+     * Acquires synchronized access to the specified artifacts and metadatas. The invocation will potentially block
+     * until all requested resources can be acquired by the calling thread. Acquiring resources that are already
+     * acquired by this synchronization context has no effect. Please also see the class-level documentation for
+     * information regarding reentrancy. The method may be invoked multiple times on a synchronization context until all
+     * desired resources have been acquired.
+     * 
+     * @param artifacts The artifacts to acquire, may be {@code null} or empty if none.
+     * @param metadatas The metadatas to acquire, may be {@code null} or empty if none.
+     */
+    void acquire( Collection<? extends Artifact> artifacts, Collection<? extends Metadata> metadatas );
+
+    /**
+     * Releases all previously acquired artifacts/metadatas. If no resources have been acquired before or if this
+     * synchronization context has already been closed, this method does nothing.
+     */
+    void close();
+
+}