Make PackWriterBitmapWalker public

Make PackWriterBitmapWriter class public and move it to a more central
location, in preparation for its use by another class (in a subsequent
commit).

One of its inner static classes, AddUnseenToBitmapFilter, previously
package-private, is also used directly in its former package. Therefore,
AddUnseenToBitmapFilter and its sibling class have been moved to an
internal package instead.

Change-Id: I740bc4bfc4e4e3c857d1ee7d25fe45e90cd22a75
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>

5 files changed, 273 insertions, 122 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/revwalk/AddToBitmapFilter.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/revwalk/AddToBitmapFilter.java
new file mode 100644
index 0000000000..3145de1849
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/revwalk/AddToBitmapFilter.java
@@ -0,0 +1,105 @@
+/*
+ * Copyright (C) 2017, 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.internal.revwalk;
+
+import org.eclipse.jgit.lib.BitmapIndex.Bitmap;
+import org.eclipse.jgit.lib.BitmapIndex.BitmapBuilder;
+import org.eclipse.jgit.lib.Constants;
+import org.eclipse.jgit.revwalk.filter.RevFilter;
+import org.eclipse.jgit.revwalk.RevWalk;
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevFlag;
+
+/**
+ * A RevFilter that adds the visited commits to {@code bitmap} as a side
+ * effect.
+ * <p>
+ * When the walk hits a commit that is part of {@code bitmap}'s
+ * BitmapIndex, that entire bitmap is ORed into {@code bitmap} and the
+ * commit and its parents are marked as SEEN so that the walk does not
+ * have to visit its ancestors.  This ensures the walk is very short if
+ * there is good bitmap coverage.
+ */
+public class AddToBitmapFilter extends RevFilter {
+	private final BitmapBuilder bitmap;
+
+	/**
+	 * Create a filter that adds visited commits to the given bitmap.
+	 *
+	 * @param bitmap bitmap to write visited commits to
+	 */
+	public AddToBitmapFilter(BitmapBuilder bitmap) {
+		this.bitmap = bitmap;
+	}
+
+	@Override
+	public final boolean include(RevWalk walker, RevCommit cmit) {
+		Bitmap visitedBitmap;
+
+		if (bitmap.contains(cmit)) {
+			// already included
+		} else if ((visitedBitmap = bitmap.getBitmapIndex()
+				.getBitmap(cmit)) != null) {
+			bitmap.or(visitedBitmap);
+		} else {
+			bitmap.addObject(cmit, Constants.OBJ_COMMIT);
+			return true;
+		}
+
+		for (RevCommit p : cmit.getParents()) {
+			p.add(RevFlag.SEEN);
+		}
+		return false;
+	}
+
+	@Override
+	public final RevFilter clone() {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public final boolean requiresCommitBody() {
+		return false;
+	}
+}
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/revwalk/AddUnseenToBitmapFilter.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/revwalk/AddUnseenToBitmapFilter.java
new file mode 100644
index 0000000000..6cb19ba00f
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/revwalk/AddUnseenToBitmapFilter.java
@@ -0,0 +1,113 @@
+/*
+ * Copyright (C) 2017, 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.internal.revwalk;
+
+import org.eclipse.jgit.lib.BitmapIndex.Bitmap;
+import org.eclipse.jgit.lib.BitmapIndex.BitmapBuilder;
+import org.eclipse.jgit.lib.Constants;
+import org.eclipse.jgit.revwalk.filter.RevFilter;
+import org.eclipse.jgit.revwalk.RevWalk;
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevFlag;
+
+/**
+ * A RevFilter that adds the visited commits to {@code bitmap} as a side
+ * effect.
+ * <p>
+ * When the walk hits a commit that is part of {@code bitmap}'s
+ * BitmapIndex, that entire bitmap is ORed into {@code bitmap} and the
+ * commit and its parents are marked as SEEN so that the walk does not
+ * have to visit its ancestors.  This ensures the walk is very short if
+ * there is good bitmap coverage.
+ * <p>
+ * Commits named in {@code seen} are considered already seen.  If one is
+ * encountered, that commit and its parents will be marked with the SEEN
+ * flag to prevent the walk from visiting its ancestors.
+ */
+public class AddUnseenToBitmapFilter extends RevFilter {
+	private final BitmapBuilder seen;
+	private final BitmapBuilder bitmap;
+
+	/**
+	 * Create a filter that adds visited commits to the given bitmap, but does not walk
+	 * through the objects in {@code seen}.
+	 *
+	 * @param seen objects that are already seen
+	 * @param bitmap bitmap to write visited commits to
+	 */
+	public AddUnseenToBitmapFilter(BitmapBuilder seen, BitmapBuilder bitmap) {
+		this.seen = seen;
+		this.bitmap = bitmap;
+	}
+
+	@Override
+	public final boolean include(RevWalk walker, RevCommit cmit) {
+		Bitmap visitedBitmap;
+
+		if (seen.contains(cmit) || bitmap.contains(cmit)) {
+			// already seen or included
+		} else if ((visitedBitmap = bitmap.getBitmapIndex()
+				.getBitmap(cmit)) != null) {
+			bitmap.or(visitedBitmap);
+		} else {
+			bitmap.addObject(cmit, Constants.OBJ_COMMIT);
+			return true;
+		}
+
+		for (RevCommit p : cmit.getParents()) {
+			p.add(RevFlag.SEEN);
+		}
+		return false;
+	}
+
+	@Override
+	public final RevFilter clone() {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public final boolean requiresCommitBody() {
+		return false;
+	}
+}
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/PackWriter.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/PackWriter.java
index 7271560e3c..2c1d475aea 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/PackWriter.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/PackWriter.java
@@ -107,6 +107,7 @@ import org.eclipse.jgit.lib.ProgressMonitor;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.lib.ThreadSafeProgressMonitor;
 import org.eclipse.jgit.revwalk.AsyncRevObjectQueue;
+import org.eclipse.jgit.revwalk.BitmapWalker;
 import org.eclipse.jgit.revwalk.DepthWalk;
 import org.eclipse.jgit.revwalk.ObjectWalk;
 import org.eclipse.jgit.revwalk.RevCommit;
@@ -1714,7 +1715,7 @@ public class PackWriter implements AutoCloseable {
 		if (!shallowPack && useBitmaps) {
 			BitmapIndex bitmapIndex = reader.getBitmapIndex();
 			if (bitmapIndex != null) {
-				PackWriterBitmapWalker bitmapWalker = new PackWriterBitmapWalker(
+				BitmapWalker bitmapWalker = new BitmapWalker(
 						walker, bitmapIndex, countingMonitor);
 				findObjectsToPackUsingBitmaps(bitmapWalker, want, have);
 				endPhase(countingMonitor);
@@ -1917,7 +1918,7 @@ public class PackWriter implements AutoCloseable {
 	}
 
 	private void findObjectsToPackUsingBitmaps(
-			PackWriterBitmapWalker bitmapWalker, Set<? extends ObjectId> want,
+			BitmapWalker bitmapWalker, Set<? extends ObjectId> want,
 			Set<? extends ObjectId> have)
 			throws MissingObjectException, IncorrectObjectTypeException,
 			IOException {
@@ -2123,7 +2124,7 @@ public class PackWriter implements AutoCloseable {
 
 		beginPhase(PackingPhase.BUILDING_BITMAPS, pm, selectedCommits.size());
 
-		PackWriterBitmapWalker walker = bitmapPreparer.newBitmapWalker();
+		BitmapWalker walker = bitmapPreparer.newBitmapWalker();
 		AnyObjectId last = null;
 		for (PackWriterBitmapPreparer.BitmapCommit cmit : selectedCommits) {
 			if (!cmit.isReuseWalker()) {
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/PackWriterBitmapPreparer.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/PackWriterBitmapPreparer.java
index 8bedddb935..38d3458cf9 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/PackWriterBitmapPreparer.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/PackWriterBitmapPreparer.java
@@ -59,18 +59,19 @@ import java.util.Set;
 import org.eclipse.jgit.errors.IncorrectObjectTypeException;
 import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.internal.JGitText;
+import org.eclipse.jgit.internal.revwalk.AddUnseenToBitmapFilter;
 import org.eclipse.jgit.internal.storage.file.BitmapIndexImpl;
 import org.eclipse.jgit.internal.storage.file.BitmapIndexImpl.CompressedBitmap;
 import org.eclipse.jgit.internal.storage.file.PackBitmapIndex;
 import org.eclipse.jgit.internal.storage.file.PackBitmapIndexBuilder;
 import org.eclipse.jgit.internal.storage.file.PackBitmapIndexRemapper;
-import org.eclipse.jgit.internal.storage.pack.PackWriterBitmapWalker.AddUnseenToBitmapFilter;
 import org.eclipse.jgit.lib.AnyObjectId;
 import org.eclipse.jgit.lib.BitmapIndex.BitmapBuilder;
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectReader;
 import org.eclipse.jgit.lib.ProgressMonitor;
+import org.eclipse.jgit.revwalk.BitmapWalker;
 import org.eclipse.jgit.revwalk.ObjectWalk;
 import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.revwalk.RevObject;
@@ -508,8 +509,8 @@ class PackWriterBitmapPreparer {
 		return Math.max(next, recentCommitSpan);
 	}
 
-	PackWriterBitmapWalker newBitmapWalker() {
-		return new PackWriterBitmapWalker(
+	BitmapWalker newBitmapWalker() {
+		return new BitmapWalker(
 				new ObjectWalk(reader), bitmapIndex, null);
 	}
 
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/PackWriterBitmapWalker.java b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/BitmapWalker.java
index a5c3b71eb2..787cf3588e 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/PackWriterBitmapWalker.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/BitmapWalker.java
@@ -41,29 +41,28 @@
  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package org.eclipse.jgit.internal.storage.pack;
+package org.eclipse.jgit.revwalk;
 
 import java.io.IOException;
 import java.util.Arrays;
 
 import org.eclipse.jgit.errors.IncorrectObjectTypeException;
 import org.eclipse.jgit.errors.MissingObjectException;
-import org.eclipse.jgit.lib.BitmapIndex;
+import org.eclipse.jgit.internal.revwalk.AddToBitmapFilter;
+import org.eclipse.jgit.internal.revwalk.AddUnseenToBitmapFilter;
 import org.eclipse.jgit.lib.BitmapIndex.Bitmap;
 import org.eclipse.jgit.lib.BitmapIndex.BitmapBuilder;
-import org.eclipse.jgit.lib.Constants;
+import org.eclipse.jgit.lib.BitmapIndex;
 import org.eclipse.jgit.lib.NullProgressMonitor;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ProgressMonitor;
-import org.eclipse.jgit.revwalk.ObjectWalk;
-import org.eclipse.jgit.revwalk.RevCommit;
-import org.eclipse.jgit.revwalk.RevFlag;
-import org.eclipse.jgit.revwalk.RevObject;
-import org.eclipse.jgit.revwalk.RevWalk;
-import org.eclipse.jgit.revwalk.filter.RevFilter;
 
-/** Helper class for PackWriter to do ObjectWalks with pack index bitmaps. */
-final class PackWriterBitmapWalker {
+/**
+ * Helper class to do ObjectWalks with pack index bitmaps.
+ *
+ * @since 4.10
+ */
+public final class BitmapWalker {
 
 	private final ObjectWalk walker;
 
@@ -73,18 +72,52 @@ final class PackWriterBitmapWalker {
 
 	private long countOfBitmapIndexMisses;
 
-	PackWriterBitmapWalker(
+	/**
+	 * Create a BitmapWalker.
+	 *
+	 * @param walker walker to use when traversing the object graph.
+	 * @param bitmapIndex index to obtain bitmaps from.
+	 * @param pm progress monitor to report progress on.
+	 */
+	public BitmapWalker(
 			ObjectWalk walker, BitmapIndex bitmapIndex, ProgressMonitor pm) {
 		this.walker = walker;
 		this.bitmapIndex = bitmapIndex;
 		this.pm = (pm == null) ? NullProgressMonitor.INSTANCE : pm;
 	}
 
-	long getCountOfBitmapIndexMisses() {
+	/**
+	 * Return the number of objects that had to be walked because they were not covered by a
+	 * bitmap.
+	 *
+	 * @return the number of objects that had to be walked because they were not covered by a
+	 *     bitmap.
+	 */
+	public long getCountOfBitmapIndexMisses() {
 		return countOfBitmapIndexMisses;
 	}
 
-	BitmapBuilder findObjects(Iterable<? extends ObjectId> start, BitmapBuilder seen,
+	/**
+	 * Return, as a bitmap, the objects reachable from the objects in start.
+	 *
+	 * @param start the objects to start the object traversal from.
+	 * @param seen the objects to skip if encountered during traversal.
+	 * @param ignoreMissing true to ignore missing objects, false otherwise.
+	 * @return as a bitmap, the objects reachable from the objects in start.
+	 * @throws MissingObjectException
+	 *             the object supplied is not available from the object
+	 *             database. This usually indicates the supplied object is
+	 *             invalid, but the reference was constructed during an earlier
+	 *             invocation to {@link RevWalk#lookupAny(AnyObjectId, int)}.
+	 * @throws IncorrectObjectTypeException
+	 *             the object was not parsed yet and it was discovered during
+	 *             parsing that it is not actually the type of the instance
+	 *             passed in. This usually indicates the caller used the wrong
+	 *             type in a {@link RevWalk#lookupAny(AnyObjectId, int)} call.
+	 * @throws IOException
+	 *             a pack file or loose object could not be read.
+	 */
+	public BitmapBuilder findObjects(Iterable<? extends ObjectId> start, BitmapBuilder seen,
 			boolean ignoreMissing)
 			throws MissingObjectException, IncorrectObjectTypeException,
 				   IOException {
@@ -191,106 +224,4 @@ final class PackWriterBitmapWalker {
 
 		return bitmapResult;
 	}
-
-	/**
-	 * A RevFilter that adds the visited commits to {@code bitmap} as a side
-	 * effect.
-	 * <p>
-	 * When the walk hits a commit that is part of {@code bitmap}'s
-	 * BitmapIndex, that entire bitmap is ORed into {@code bitmap} and the
-	 * commit and its parents are marked as SEEN so that the walk does not
-	 * have to visit its ancestors.  This ensures the walk is very short if
-	 * there is good bitmap coverage.
-	 */
-	static class AddToBitmapFilter extends RevFilter {
-		private final BitmapBuilder bitmap;
-
-		AddToBitmapFilter(BitmapBuilder bitmap) {
-			this.bitmap = bitmap;
-		}
-
-		@Override
-		public final boolean include(RevWalk walker, RevCommit cmit) {
-			Bitmap visitedBitmap;
-
-			if (bitmap.contains(cmit)) {
-				// already included
-			} else if ((visitedBitmap = bitmap.getBitmapIndex()
-					.getBitmap(cmit)) != null) {
-				bitmap.or(visitedBitmap);
-			} else {
-				bitmap.addObject(cmit, Constants.OBJ_COMMIT);
-				return true;
-			}
-
-			for (RevCommit p : cmit.getParents()) {
-				p.add(RevFlag.SEEN);
-			}
-			return false;
-		}
-
-		@Override
-		public final RevFilter clone() {
-			throw new UnsupportedOperationException();
-		}
-
-		@Override
-		public final boolean requiresCommitBody() {
-			return false;
-		}
-	}
-
-	/**
-	 * A RevFilter that adds the visited commits to {@code bitmap} as a side
-	 * effect.
-	 * <p>
-	 * When the walk hits a commit that is part of {@code bitmap}'s
-	 * BitmapIndex, that entire bitmap is ORed into {@code bitmap} and the
-	 * commit and its parents are marked as SEEN so that the walk does not
-	 * have to visit its ancestors.  This ensures the walk is very short if
-	 * there is good bitmap coverage.
-	 * <p>
-	 * Commits named in {@code seen} are considered already seen.  If one is
-	 * encountered, that commit and its parents will be marked with the SEEN
-	 * flag to prevent the walk from visiting its ancestors.
-	 */
-	static class AddUnseenToBitmapFilter extends RevFilter {
-		private final BitmapBuilder seen;
-		private final BitmapBuilder bitmap;
-
-		AddUnseenToBitmapFilter(BitmapBuilder seen, BitmapBuilder bitmapResult) {
-			this.seen = seen;
-			this.bitmap = bitmapResult;
-		}
-
-		@Override
-		public final boolean include(RevWalk walker, RevCommit cmit) {
-			Bitmap visitedBitmap;
-
-			if (seen.contains(cmit) || bitmap.contains(cmit)) {
-				// already seen or included
-			} else if ((visitedBitmap = bitmap.getBitmapIndex()
-					.getBitmap(cmit)) != null) {
-				bitmap.or(visitedBitmap);
-			} else {
-				bitmap.addObject(cmit, Constants.OBJ_COMMIT);
-				return true;
-			}
-
-			for (RevCommit p : cmit.getParents()) {
-				p.add(RevFlag.SEEN);
-			}
-			return false;
-		}
-
-		@Override
-		public final RevFilter clone() {
-			throw new UnsupportedOperationException();
-		}
-
-		@Override
-		public final boolean requiresCommitBody() {
-			return false;
-		}
-	}
 }