PackWriter: write the PackReverseIndex file

PackWriter offers the ability to write out the pack file and its various
index files, except for the newly introduced file-based reverse index.

Now that PackReverseIndexWriter can write reverse index files,
PackWriter#writeReverseIndex will write one for a pack if the
corresponding config flag PackConfig#writeReverseIndex is on.

Change-Id: Ib75dd2bbfb9ee9366d5aacb46700d8cf8af4823a
Signed-off-by: Anna Papitto <annapapitto@google.com>

5 files changed, 117 insertions, 3 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/PackWriterTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/PackWriterTest.java
index 2a403c7699..24a81b6715 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/PackWriterTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/PackWriterTest.java
@@ -542,6 +542,39 @@ public class PackWriterTest extends SampleDataRepositoryTestCase {
 	}
 
 	@Test
+	public void testWriteReverseIndexConfig() {
+		assertFalse(config.isWriteReverseIndex());
+		config.setWriteReverseIndex(true);
+		assertTrue(config.isWriteReverseIndex());
+	}
+
+	@Test
+	public void testWriteReverseIndexOff() throws Exception {
+		config.setWriteReverseIndex(false);
+		writer = new PackWriter(config, db.newObjectReader());
+		ByteArrayOutputStream reverseIndexOutput = new ByteArrayOutputStream();
+
+		writer.writeReverseIndex(reverseIndexOutput);
+
+		assertEquals(0, reverseIndexOutput.size());
+	}
+
+	@Test
+	public void testWriteReverseIndexOn() throws Exception {
+		config.setWriteReverseIndex(true);
+		writeVerifyPack4(false);
+		ByteArrayOutputStream reverseIndexOutput = new ByteArrayOutputStream();
+		int headerBytes = 12;
+		int bodyBytes = 12;
+		int footerBytes = 40;
+
+		writer.writeReverseIndex(reverseIndexOutput);
+
+		assertTrue(reverseIndexOutput.size() == headerBytes + bodyBytes
+				+ footerBytes);
+	}
+
+	@Test
 	public void testExclude() throws Exception {
 		// TestRepository closes repo
 		FileRepository repo = createBareRepository();
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsGarbageCollector.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsGarbageCollector.java
index 66bcf73987..92e23b8b40 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsGarbageCollector.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsGarbageCollector.java
@@ -577,6 +577,7 @@ public class DfsGarbageCollector {
 		cfg.setReuseObjects(true);
 		cfg.setDeltaCompress(false);
 		cfg.setBuildBitmaps(false);
+		cfg.setWriteReverseIndex(false);
 
 		try (PackWriter pw = new PackWriter(cfg, ctx);
 				RevWalk pool = new RevWalk(ctx)) {
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 bad572459a..666e9d8cbc 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
@@ -62,6 +62,7 @@ import org.eclipse.jgit.internal.storage.file.PackBitmapIndexBuilder;
 import org.eclipse.jgit.internal.storage.file.PackBitmapIndexWriterV1;
 import org.eclipse.jgit.internal.storage.file.PackIndexWriter;
 import org.eclipse.jgit.internal.storage.file.PackObjectSizeIndexWriter;
+import org.eclipse.jgit.internal.storage.file.PackReverseIndexWriter;
 import org.eclipse.jgit.lib.AnyObjectId;
 import org.eclipse.jgit.lib.AsyncObjectSizeQueue;
 import org.eclipse.jgit.lib.BatchingProgressMonitor;
@@ -1137,6 +1138,38 @@ public class PackWriter implements AutoCloseable {
 	}
 
 	/**
+	 * Whether the writer will write a reverse index file. The configuration
+	 * flag must be on and the writer must be able to write corresponding
+	 * forward index.
+	 *
+	 * @return whether the writer will write a reverse index file
+	 */
+	public boolean isReverseIndexEnabled() {
+		// Only write the reverse index if the writer is configured to and the
+		// forward index that it would correspond to will be written.
+		return config.isWriteReverseIndex() && !isIndexDisabled();
+	}
+
+	/**
+	 * Write the pack's reverse index file to the output stream.
+	 *
+	 * @param stream
+	 *            where to write the file contents to
+	 * @throws IOException
+	 *             if writing to the stream fails
+	 */
+	public void writeReverseIndex(OutputStream stream) throws IOException {
+		if (!isReverseIndexEnabled()) {
+			return;
+		}
+		long writeStart = System.currentTimeMillis();
+		PackReverseIndexWriter writer = PackReverseIndexWriter
+				.createWriter(stream);
+		writer.write(sortByName(), packcsum);
+		stats.timeWriting += System.currentTimeMillis() - writeStart;
+	}
+
+	/**
 	 * Create a bitmap index file to match the pack file just written.
 	 * <p>
 	 * Called after {@link #prepareBitmapIndex(ProgressMonitor)}.
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/lib/ConfigConstants.java b/org.eclipse.jgit/src/org/eclipse/jgit/lib/ConfigConstants.java
index c4b6bf955e..4c080f4761 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/lib/ConfigConstants.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/lib/ConfigConstants.java
@@ -745,6 +745,13 @@ public final class ConfigConstants {
 	public static final String CONFIG_KEY_BITMAP_RECENT_COMMIT_COUNT = "bitmaprecentcommitspan";
 
 	/**
+	 * The "pack.writeReverseIndex" key
+	 *
+	 * @since 6.6
+	 */
+	public static final String CONFIG_KEY_WRITE_REVERSE_INDEX = "writeReverseIndex";
+
+	/**
 	 * The "pack.buildBitmaps" key
 	 * @since 5.8
 	 */
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/storage/pack/PackConfig.java b/org.eclipse.jgit/src/org/eclipse/jgit/storage/pack/PackConfig.java
index a0c978f6ea..8177425665 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/storage/pack/PackConfig.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/storage/pack/PackConfig.java
@@ -27,7 +27,10 @@ import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_DELTA_CACHE_SIZE;
 import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_DELTA_COMPRESSION;
 import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_DEPTH;
 import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_INDEXVERSION;
+import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_MIN_BYTES_OBJ_SIZE_INDEX;
 import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_MIN_SIZE_PREVENT_RACYPACK;
+import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_PRESERVE_OLD_PACKS;
+import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_PRUNE_PRESERVED;
 import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_REUSE_DELTAS;
 import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_REUSE_OBJECTS;
 import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_SEARCH_FOR_REUSE_TIMEOUT;
@@ -36,10 +39,8 @@ import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_THREADS;
 import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_WAIT_PREVENT_RACYPACK;
 import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_WINDOW;
 import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_WINDOW_MEMORY;
-import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_MIN_BYTES_OBJ_SIZE_INDEX;
+import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_WRITE_REVERSE_INDEX;
 import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_PACK_SECTION;
-import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_PRESERVE_OLD_PACKS;
-import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_PRUNE_PRESERVED;
 
 import java.time.Duration;
 import java.util.concurrent.Executor;
@@ -162,6 +163,14 @@ public class PackConfig {
 	public static final int DEFAULT_INDEX_VERSION = 2;
 
 	/**
+	 * Default value of the write reverse index option: {@value}
+	 *
+	 * @see #setWriteReverseIndex(boolean)
+	 * @since 6.6
+	 */
+	public static final boolean DEFAULT_WRITE_REVERSE_INDEX = false;
+
+	/**
 	 * Default value of the build bitmaps option: {@value}
 	 *
 	 * @see #setBuildBitmaps(boolean)
@@ -292,6 +301,8 @@ public class PackConfig {
 
 	private int indexVersion = DEFAULT_INDEX_VERSION;
 
+	private boolean writeReverseIndex = DEFAULT_WRITE_REVERSE_INDEX;
+
 	private boolean buildBitmaps = DEFAULT_BUILD_BITMAPS;
 
 	private int bitmapContiguousCommitCount = DEFAULT_BITMAP_CONTIGUOUS_COMMIT_COUNT;
@@ -373,6 +384,7 @@ public class PackConfig {
 		this.threads = cfg.threads;
 		this.executor = cfg.executor;
 		this.indexVersion = cfg.indexVersion;
+		this.writeReverseIndex = cfg.writeReverseIndex;
 		this.buildBitmaps = cfg.buildBitmaps;
 		this.bitmapContiguousCommitCount = cfg.bitmapContiguousCommitCount;
 		this.bitmapRecentCommitCount = cfg.bitmapRecentCommitCount;
@@ -974,6 +986,31 @@ public class PackConfig {
 	}
 
 	/**
+	 * True if the writer should write reverse index files.
+	 *
+	 * Default setting: {@value #DEFAULT_WRITE_REVERSE_INDEX}
+	 *
+	 * @return whether the writer should write reverse index files
+	 * @since 6.6
+	 */
+	public boolean isWriteReverseIndex() {
+		return writeReverseIndex;
+	}
+
+	/**
+	 * Set whether the writer will write reverse index files.
+	 *
+	 * Default setting: {@value #DEFAULT_WRITE_REVERSE_INDEX}
+	 *
+	 * @param writeReverseIndex
+	 *            whether the writer should write reverse index files
+	 * @since 6.6
+	 */
+	public void setWriteReverseIndex(boolean writeReverseIndex) {
+		this.writeReverseIndex = writeReverseIndex;
+	}
+
+	/**
 	 * True if writer is allowed to build bitmaps for indexes.
 	 *
 	 * Default setting: {@value #DEFAULT_BUILD_BITMAPS}
@@ -1286,6 +1323,8 @@ public class PackConfig {
 		setSinglePack(rc.getBoolean(CONFIG_PACK_SECTION,
 				CONFIG_KEY_SINGLE_PACK,
 				getSinglePack()));
+		setWriteReverseIndex(rc.getBoolean(CONFIG_PACK_SECTION,
+				CONFIG_KEY_WRITE_REVERSE_INDEX, isWriteReverseIndex()));
 		setBuildBitmaps(rc.getBoolean(CONFIG_PACK_SECTION,
 				CONFIG_KEY_BUILD_BITMAPS, isBuildBitmaps()));
 		setBitmapContiguousCommitCount(rc.getInt(CONFIG_PACK_SECTION,
@@ -1347,6 +1386,7 @@ public class PackConfig {
 		b.append(", reuseDeltas=").append(isReuseDeltas()); //$NON-NLS-1$
 		b.append(", reuseObjects=").append(isReuseObjects()); //$NON-NLS-1$
 		b.append(", deltaCompress=").append(isDeltaCompress()); //$NON-NLS-1$
+		b.append(", writeReverseIndex=").append(isWriteReverseIndex()); // $NON-NLS-1$
 		b.append(", buildBitmaps=").append(isBuildBitmaps()); //$NON-NLS-1$
 		b.append(", bitmapContiguousCommitCount=") //$NON-NLS-1$
 				.append(getBitmapContiguousCommitCount());