PackBitmapIndex: Add AddToBitmapWithCacheFilter class
Add a new revwalk filter, AddToBitmapWithCachedFilter. This filter updates
a client-provided {@code BitmapBuilder} as a side effect of a revwalk.
Similar to {@code AddToBitmapFilter}, it short circuits the walk when it
encounters a commit which is included in the provided bitmap's BitmapIndex.
It also short circuits the walk if it encounters the client-provided
cached commit.
Change-Id: I62cb503016f4d3995d648d92b82baab7f93549a9
Signed-off-by: Yunjie Li <yunjieli@google.com>
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/revwalk/AddToBitmapWithCacheFilter.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/revwalk/AddToBitmapWithCacheFilter.java
new file mode 100644
index 0000000..d7ccadf
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/revwalk/AddToBitmapWithCacheFilter.java
@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2020, Google LLC and others
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Distribution License v. 1.0 which is available at
+ * http://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+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.lib.AnyObjectId;
+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 the same as {@code cachedCommit} or 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 AddToBitmapWithCacheFilter extends RevFilter {
+ private final AnyObjectId cachedCommit;
+
+ private final Bitmap cachedBitmap;
+
+ private final BitmapBuilder bitmap;
+
+ /**
+ * Create a filter with a cached BitmapCommit that adds visited commits to
+ * the given bitmap.
+ *
+ * @param cachedCommit
+ * the cached commit
+ * @param cachedBitmap
+ * the bitmap corresponds to {@code cachedCommit}}
+ * @param bitmap
+ * bitmap to write visited commits to
+ */
+ public AddToBitmapWithCacheFilter(AnyObjectId cachedCommit,
+ Bitmap cachedBitmap,
+ BitmapBuilder bitmap) {
+ this.cachedCommit = cachedCommit;
+ this.cachedBitmap = cachedBitmap;
+ this.bitmap = bitmap;
+ }
+
+ /** {@inheritDoc} */
+ @Override
+ public final boolean include(RevWalk rw, RevCommit c) {
+ Bitmap visitedBitmap;
+
+ if (bitmap.contains(c)) {
+ // already included
+ } else if ((visitedBitmap = bitmap.getBitmapIndex()
+ .getBitmap(c)) != null) {
+ bitmap.or(visitedBitmap);
+ } else if (cachedCommit.equals(c)) {
+ bitmap.or(cachedBitmap);
+ } else {
+ bitmap.addObject(c, Constants.OBJ_COMMIT);
+ return true;
+ }
+
+ for (RevCommit p : c.getParents()) {
+ p.add(RevFlag.SEEN);
+ }
+ return false;
+ }
+
+ /** {@inheritDoc} */
+ @Override
+ public final RevFilter clone() {
+ throw new UnsupportedOperationException();
+ }
+
+ /** {@inheritDoc} */
+ @Override
+ public final boolean requiresCommitBody() {
+ return false;
+ }
+}
+
