Add a listener for changes to a DfsObjDatabase's pack files

Intended for cross-request use, so only refers to
DfsRepositoryDescriptions rather than DfsRepositorys.

Change-Id: I2633e472c9264d91d632069f608d53d4bdd0fc09

org.eclipse.jgit/src/org/eclipse/jgit/storage/dfs/DfsObjDatabase.java

@@ -147,7 +147,7 @@ public abstract class DfsObjDatabase extends ObjectDatabase {
 	}
 
 	/**
-	 * List all available pack files in the repository.
+	 * Scan and list all available pack files in the repository.
 	 *
 	 * @return list of available packs. The returned array is shared with the
 	 *         implementation and must not be modified by the caller.
@@ -163,6 +163,16 @@ public abstract class DfsObjDatabase extends ObjectDatabase {
 		return repository;
 	}
 
+	/**
+	 * List currently known pack files in the repository, without scanning.
+	 *
+	 * @return list of available packs. The returned array is shared with the
+	 *         implementation and must not be modified by the caller.
+	 */
+	public DfsPackFile[] getCurrentPacks() {
+		return packList.get().packs;
+	}
+
 	/**
 	 * Generate a new unique name for a pack file.
 	 *
@@ -318,8 +328,8 @@ public abstract class DfsObjDatabase extends ObjectDatabase {
 	}
 
 	private PackList scanPacks(final PackList original) throws IOException {
+		PackList o, n;
 		synchronized (packList) {
-			PackList o, n;
 			do {
 				o = packList.get();
 				if (o != original) {
@@ -332,8 +342,9 @@ public abstract class DfsObjDatabase extends ObjectDatabase {
 				if (n == o)
 					return n;
 			} while (!packList.compareAndSet(o, n));
-			return n;
 		}
+		getRepository().fireEvent(new DfsPacksChangedEvent());
+		return n;
 	}
 
 	private PackList scanPacksImpl(PackList old) throws IOException {

org.eclipse.jgit/src/org/eclipse/jgit/storage/dfs/DfsPacksChangedEvent.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2011, Google Inc.
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ *   names of its contributors may be used to endorse or promote
+ *   products derived from this software without specific prior
+ *   written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package org.eclipse.jgit.storage.dfs;
+
+import org.eclipse.jgit.events.RepositoryEvent;
+
+/** Describes a change to the list of packs in a {@link DfsRepository}. */
+public class DfsPacksChangedEvent
+		extends RepositoryEvent<DfsPacksChangedListener> {
+	@Override
+	public Class<DfsPacksChangedListener> getListenerType() {
+		return DfsPacksChangedListener.class;
+	}
+
+	@Override
+	public void dispatch(DfsPacksChangedListener listener) {
+		listener.onPacksChanged(this);
+	}
+}

org.eclipse.jgit/src/org/eclipse/jgit/storage/dfs/DfsPacksChangedListener.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) 2011, Google Inc.
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ *   names of its contributors may be used to endorse or promote
+ *   products derived from this software without specific prior
+ *   written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package org.eclipse.jgit.storage.dfs;
+
+import org.eclipse.jgit.events.RepositoryListener;
+
+/** Receives {@link DfsPacksChangedEvent}s. */
+public interface DfsPacksChangedListener extends RepositoryListener {
+	/**
+	 * Invoked when all packs in a repository are listed.
+	 *
+	 * @param event
+	 *            information about the packs.
+	 */
+	void onPacksChanged(DfsPacksChangedEvent event);
+}