Expose bitmap selection parameters via PackConfig

Expose the following bitmap selection parameters via PackConfig:
"bitmapContiguousCommitCount", "bitmapRecentCommitCount",
"bitmapRecentCommitSpan", "bitmapDistantCommitSpan",
"bitmapExcessiveBranchCount", and "bitmapInactiveBranchAge".

The value of bitmapContiguousCommitCount, whereby bitmaps are
created for the most recent N commits in a branch, has never
been verified. If experiments show that they are not valuable,
then we can simplify the implementation so that there is only
a concept of recent and distant commit history (defined by
"bitmapRecentCommitCount"), and the only controls we need are
"bitmapRecentCommitSpan" and "bitmapDistantCommitSpan".

Change-Id: I288bf3f97d6fbfdfcd5dde2699eff433a7307fb9
Signed-off-by: Terry Parker <tparker@google.com>

1 files changed, 136 insertions, 0 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/pack/PackWriterBitmapPreparerTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/pack/PackWriterBitmapPreparerTest.java
new file mode 100644
index 0000000000..b0f92ffa0c
--- /dev/null
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/pack/PackWriterBitmapPreparerTest.java
@@ -0,0 +1,136 @@
+package org.eclipse.jgit.internal.storage.pack;
+
+import static org.eclipse.jgit.storage.pack.PackConfig.DEFAULT_BITMAP_DISTANT_COMMIT_SPAN;
+import static org.eclipse.jgit.storage.pack.PackConfig.DEFAULT_BITMAP_RECENT_COMMIT_COUNT;
+import static org.eclipse.jgit.storage.pack.PackConfig.DEFAULT_BITMAP_RECENT_COMMIT_SPAN;
+import static org.junit.Assert.assertEquals;
+
+import java.io.IOException;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+
+import org.eclipse.jgit.errors.IncorrectObjectTypeException;
+import org.eclipse.jgit.errors.MissingObjectException;
+import org.eclipse.jgit.internal.storage.file.PackBitmapIndexBuilder;
+import org.eclipse.jgit.lib.AbbreviatedObjectId;
+import org.eclipse.jgit.lib.AnyObjectId;
+import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.lib.ObjectLoader;
+import org.eclipse.jgit.lib.ObjectReader;
+import org.eclipse.jgit.storage.pack.PackConfig;
+import org.junit.Test;
+
+/** Tests for the {@link PackWriterBitmapPreparer}. */
+public class PackWriterBitmapPreparerTest {
+	private static class StubObjectReader extends ObjectReader {
+		@Override
+		public ObjectReader newReader() {
+			return null;
+		}
+
+		@Override
+		public Collection<ObjectId> resolve(AbbreviatedObjectId id)
+				throws IOException {
+			return null;
+		}
+
+		@Override
+		public ObjectLoader open(AnyObjectId objectId, int typeHint)
+				throws MissingObjectException, IncorrectObjectTypeException,
+				IOException {
+			return null;
+		}
+
+		@Override
+		public Set<ObjectId> getShallowCommits() throws IOException {
+			return null;
+		}
+
+		@Override
+		public void close() {
+			// stub
+		}
+	}
+
+	@Test
+	public void testNextSelectionDistanceForActiveBranch() throws Exception {
+		PackWriterBitmapPreparer preparer = newPeparer(
+				DEFAULT_BITMAP_RECENT_COMMIT_COUNT, // 20000
+				DEFAULT_BITMAP_RECENT_COMMIT_SPAN, // 100
+				DEFAULT_BITMAP_DISTANT_COMMIT_SPAN); // 5000
+		int[][] distancesAndSpans = { { 0, 100 }, { 100, 100 }, { 10000, 100 },
+				{ 20000, 100 }, { 20100, 100 }, { 20102, 102 }, { 20200, 200 },
+				{ 22200, 2200 }, { 24999, 4999 }, { 25000, 5000 },
+				{ 50000, 5000 }, { 1000000, 5000 }, };
+
+		for (int[] pair : distancesAndSpans) {
+			assertEquals(pair[1], preparer.nextSpan(pair[0]));
+		}
+	}
+
+	@Test
+	public void testNextSelectionDistanceWithFewerRecentCommits()
+			throws Exception {
+		PackWriterBitmapPreparer preparer = newPeparer(1000,
+				DEFAULT_BITMAP_RECENT_COMMIT_SPAN, // 100
+				DEFAULT_BITMAP_DISTANT_COMMIT_SPAN); // 5000
+		int[][] distancesAndSpans = { { 0, 100 }, { 100, 100 }, { 1000, 100 },
+				{ 1100, 100 }, { 1111, 111 }, { 2000, 1000 }, { 5999, 4999 },
+				{ 6000, 5000 }, { 10000, 5000 }, { 50000, 5000 },
+				{ 1000000, 5000 } };
+
+		for (int[] pair : distancesAndSpans) {
+			assertEquals(pair[1], preparer.nextSpan(pair[0]));
+		}
+	}
+
+	@Test
+	public void testNextSelectionDistanceWithSmallerRecentSpan()
+			throws Exception {
+		PackWriterBitmapPreparer preparer = newPeparer(
+				DEFAULT_BITMAP_RECENT_COMMIT_COUNT, // 20000
+				10, // recent span
+				DEFAULT_BITMAP_DISTANT_COMMIT_SPAN); // 5000
+		int[][] distancesAndSpans = { { 0, 10 }, { 100, 10 }, { 10000, 10 },
+				{ 20000, 10 }, { 20010, 10 }, { 20012, 12 }, { 20050, 50 },
+				{ 20200, 200 }, { 22200, 2200 }, { 24999, 4999 },
+				{ 25000, 5000 }, { 50000, 5000 }, { 1000000, 5000 } };
+
+		for (int[] pair : distancesAndSpans) {
+			assertEquals(pair[1], preparer.nextSpan(pair[0]));
+		}
+	}
+
+	@Test
+	public void testNextSelectionDistanceWithSmallerDistantSpan()
+			throws Exception {
+		PackWriterBitmapPreparer preparer = newPeparer(
+				DEFAULT_BITMAP_RECENT_COMMIT_COUNT, // 20000
+				DEFAULT_BITMAP_RECENT_COMMIT_SPAN, // 100
+				1000);
+		int[][] distancesAndSpans = { { 0, 100 }, { 100, 100 }, { 10000, 100 },
+				{ 20000, 100 }, { 20100, 100 }, { 20102, 102 }, { 20200, 200 },
+				{ 20999, 999 }, { 21000, 1000 }, { 22000, 1000 },
+				{ 25000, 1000 }, { 50000, 1000 }, { 1000000, 1000 } };
+
+		for (int[] pair : distancesAndSpans) {
+			assertEquals(pair[1], preparer.nextSpan(pair[0]));
+		}
+	}
+
+	private PackWriterBitmapPreparer newPeparer(int recentCount, int recentSpan,
+			int distantSpan) throws IOException {
+		List<ObjectToPack> objects = Collections.emptyList();
+		Set<ObjectId> wants = Collections.emptySet();
+		PackConfig config = new PackConfig();
+		config.setBitmapRecentCommitCount(recentCount);
+		config.setBitmapRecentCommitSpan(recentSpan);
+		config.setBitmapDistantCommitSpan(distantSpan);
+		PackBitmapIndexBuilder indexBuilder = new PackBitmapIndexBuilder(
+				objects);
+		return new PackWriterBitmapPreparer(new StubObjectReader(),
+				indexBuilder, null, wants, config);
+	}
+}