PackWriter: writeBitmapIndex takes bitmap index writer

PackWriter.writeBitmapIndex now takes an interface which will perform
the writing of the bitmap index to an arbitrary backing storage.

Change-Id: Icba89321d56f7b652bbcbfcd5ed3ec74999cb8c4

6 files changed, 76 insertions, 22 deletions

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 62b55d4734..a177669788 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
@@ -17,7 +17,6 @@ import static org.eclipse.jgit.internal.storage.dfs.DfsObjDatabase.PackSource.IN
 import static org.eclipse.jgit.internal.storage.dfs.DfsObjDatabase.PackSource.RECEIVE;
 import static org.eclipse.jgit.internal.storage.dfs.DfsObjDatabase.PackSource.UNREACHABLE_GARBAGE;
 import static org.eclipse.jgit.internal.storage.dfs.DfsPackCompactor.configureReftable;
-import static org.eclipse.jgit.internal.storage.pack.PackExt.BITMAP_INDEX;
 import static org.eclipse.jgit.internal.storage.pack.PackExt.COMMIT_GRAPH;
 import static org.eclipse.jgit.internal.storage.pack.PackExt.INDEX;
 import static org.eclipse.jgit.internal.storage.pack.PackExt.OBJECT_SIZE_INDEX;
@@ -709,13 +708,7 @@ public class DfsGarbageCollector {
 		}
 
 		if (pw.prepareBitmapIndex(pm)) {
-			try (DfsOutputStream out = objdb.writeFile(pack, BITMAP_INDEX)) {
-				CountingOutputStream cnt = new CountingOutputStream(out);
-				pw.writeBitmapIndex(cnt);
-				pack.addFileExt(BITMAP_INDEX);
-				pack.setFileSize(BITMAP_INDEX, cnt.getCount());
-				pack.setBlockSize(BITMAP_INDEX, out.blockSize());
-			}
+			pw.writeBitmapIndex(objdb.getPackBitmapIndexWriter(pack));
 		}
 
 		PackStatistics stats = pw.getStatistics();
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsObjDatabase.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsObjDatabase.java
index 9f6eb10256..616563ffdd 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsObjDatabase.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsObjDatabase.java
@@ -11,6 +11,7 @@
 package org.eclipse.jgit.internal.storage.dfs;
 
 import static java.util.stream.Collectors.joining;
+import static org.eclipse.jgit.internal.storage.pack.PackExt.BITMAP_INDEX;
 
 import java.io.FileNotFoundException;
 import java.io.IOException;
@@ -26,11 +27,14 @@ import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicReference;
 
+import org.eclipse.jgit.internal.storage.file.PackBitmapIndexWriterV1;
+import org.eclipse.jgit.internal.storage.pack.PackBitmapIndexWriter;
 import org.eclipse.jgit.internal.storage.pack.PackExt;
 import org.eclipse.jgit.lib.AnyObjectId;
 import org.eclipse.jgit.lib.ObjectDatabase;
 import org.eclipse.jgit.lib.ObjectInserter;
 import org.eclipse.jgit.lib.ObjectReader;
+import org.eclipse.jgit.util.io.CountingOutputStream;
 
 /**
  * Manages objects stored in
@@ -743,4 +747,28 @@ public abstract class DfsObjDatabase extends ObjectDatabase {
 			dirty = true;
 		}
 	}
+
+	/**
+	 * Returns a writer to store the bitmap index in this object database.
+	 *
+	 * @param pack
+	 *            Pack file to which the bitmaps are associated.
+	 * @return a writer to store bitmaps associated with the pack
+	 * @throws IOException
+	 *             when some I/O problem occurs while creating or writing to
+	 *             output stream
+	 */
+	public PackBitmapIndexWriter getPackBitmapIndexWriter(
+			DfsPackDescription pack) throws IOException {
+		return (bitmaps, packDataChecksum) -> {
+			try (DfsOutputStream out = writeFile(pack, BITMAP_INDEX)) {
+				CountingOutputStream cnt = new CountingOutputStream(out);
+				PackBitmapIndexWriterV1 iw = new PackBitmapIndexWriterV1(cnt);
+				iw.write(bitmaps, packDataChecksum);
+				pack.addFileExt(BITMAP_INDEX);
+				pack.setFileSize(BITMAP_INDEX, cnt.getCount());
+				pack.setBlockSize(BITMAP_INDEX, out.blockSize());
+			}
+		};
+	}
 }
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/GC.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/GC.java
index fc058abcca..4c996730e8 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/GC.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/GC.java
@@ -1399,7 +1399,7 @@ public class GC {
 						FileChannel idxChannel = fos.getChannel();
 						OutputStream idxStream = Channels
 								.newOutputStream(idxChannel)) {
-					pw.writeBitmapIndex(idxStream);
+					pw.writeBitmapIndex(new PackBitmapIndexWriterV1(idxStream));
 					idxChannel.force(true);
 				}
 			}
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackBitmapIndexWriterV1.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackBitmapIndexWriterV1.java
index a5c8423dfd..84326d5e62 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackBitmapIndexWriterV1.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackBitmapIndexWriterV1.java
@@ -19,6 +19,7 @@ import java.text.MessageFormat;
 
 import org.eclipse.jgit.internal.JGitText;
 import org.eclipse.jgit.internal.storage.file.PackBitmapIndexBuilder.StoredEntry;
+import org.eclipse.jgit.internal.storage.pack.PackBitmapIndexWriter;
 import org.eclipse.jgit.lib.Constants;
 
 import com.googlecode.javaewah.EWAHCompressedBitmap;
@@ -28,7 +29,7 @@ import com.googlecode.javaewah.EWAHCompressedBitmap;
  *
  * @see PackBitmapIndexV1
  */
-public class PackBitmapIndexWriterV1 {
+public class PackBitmapIndexWriterV1 implements PackBitmapIndexWriter {
 	private final DigestOutputStream out;
 	private final DataOutput dataOutput;
 
@@ -60,6 +61,7 @@ public class PackBitmapIndexWriterV1 {
 	 *             an error occurred while writing to the output stream, or this
 	 *             index format cannot store the object data supplied.
 	 */
+	@Override
 	public void write(PackBitmapIndexBuilder bitmaps, byte[] packDataChecksum)
 			throws IOException {
 		if (bitmaps == null || packDataChecksum.length != 20)
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/PackBitmapIndexWriter.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/PackBitmapIndexWriter.java
new file mode 100644
index 0000000000..9cf8c7f2b5
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/PackBitmapIndexWriter.java
@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2024, Google Inc.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Distribution License v. 1.0 which is available at
+ * https://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+package org.eclipse.jgit.internal.storage.pack;
+
+import java.io.IOException;
+
+import org.eclipse.jgit.internal.storage.file.PackBitmapIndexBuilder;
+
+/**
+ * Represents a function that accepts a collection of bitmaps and write them
+ * into storage.
+ */
+@FunctionalInterface
+public interface PackBitmapIndexWriter {
+	/**
+	 * @param bitmaps
+	 *            list of bitmaps to be written to a bitmap index
+	 * @param packChecksum
+	 *            checksum of the pack that the bitmap index refers to
+	 * @throws IOException
+	 *             thrown in case of IO errors while writing the bitmap index
+	 */
+	public void write(PackBitmapIndexBuilder bitmaps, byte[] packChecksum)
+			throws IOException;
+}
\ No newline at end of file
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 9e95231253..4350f97915 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
@@ -58,11 +58,10 @@ import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.errors.SearchForReuseTimeout;
 import org.eclipse.jgit.errors.StoredObjectRepresentationNotAvailableException;
 import org.eclipse.jgit.internal.JGitText;
-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.internal.storage.file.PackBitmapIndexBuilder;
 import org.eclipse.jgit.lib.AnyObjectId;
 import org.eclipse.jgit.lib.AsyncObjectSizeQueue;
 import org.eclipse.jgit.lib.BatchingProgressMonitor;
@@ -121,7 +120,7 @@ import org.eclipse.jgit.util.TemporaryBuffer;
  * pack is being stored as a file the matching index can be written out after
  * writing the pack by {@link #writeIndex(OutputStream)}. An optional bitmap
  * index can be made by calling {@link #prepareBitmapIndex(ProgressMonitor)}
- * followed by {@link #writeBitmapIndex(OutputStream)}.
+ * followed by {@link #writeBitmapIndex(PackBitmapIndexWriter)}.
  * </p>
  * <p>
  * Class provide set of configurable options and
@@ -1130,7 +1129,7 @@ public class PackWriter implements AutoCloseable {
 	 * Called after
 	 * {@link #writePack(ProgressMonitor, ProgressMonitor, OutputStream)} that
 	 * populates the list of objects to pack and before
-	 * {@link #writeBitmapIndex(OutputStream)} that destroys it.
+	 * {@link #writeBitmapIndex(PackBitmapIndexWriter)} that destroys it.
 	 * <p>
 	 * Writing this index is only required for local pack storage. Packs sent on
 	 * the network do not need to create an object size index.
@@ -1204,20 +1203,18 @@ public class PackWriter implements AutoCloseable {
 	 * <p>
 	 * Called after {@link #prepareBitmapIndex(ProgressMonitor)}.
 	 *
-	 * @param bitmapIndexStream
-	 *            output for the bitmap index data. Caller is responsible for
-	 *            closing this stream.
+	 * @param bitmapIndexWriter
+	 *            a writer to store the bitmap index in this object database
 	 * @throws java.io.IOException
-	 *             the index data could not be written to the supplied stream.
+	 *             the index data could not be written using the supplied writer
 	 */
-	public void writeBitmapIndex(OutputStream bitmapIndexStream)
+	public void writeBitmapIndex(PackBitmapIndexWriter bitmapIndexWriter)
 			throws IOException {
 		if (writeBitmaps == null)
 			throw new IOException(JGitText.get().bitmapsMustBePrepared);
 
 		long writeStart = System.currentTimeMillis();
-		final PackBitmapIndexWriterV1 iw = new PackBitmapIndexWriterV1(bitmapIndexStream);
-		iw.write(writeBitmaps, packcsum);
+		bitmapIndexWriter.write(writeBitmaps, packcsum);
 		stats.timeWriting += System.currentTimeMillis() - writeStart;
 	}
 
@@ -2468,7 +2465,8 @@ public class PackWriter implements AutoCloseable {
 	 * <p>
 	 * To reduce memory internal state is cleared during this method, rendering
 	 * the PackWriter instance useless for anything further than a call to write
-	 * out the new bitmaps with {@link #writeBitmapIndex(OutputStream)}.
+	 * out the new bitmaps with
+	 * {@link #writeBitmapIndex(PackBitmapIndexWriter)}.
 	 *
 	 * @param pm
 	 *            progress monitor to report bitmap building work.