PackWriter: offer to write an object-size index for the pack

PackWriter callers tell the writer what do the want to include in the
pack and invoke #writePack(). Afterwards, they can invoke #writeIndex()
to write the corresponding pack index.

Mirror this for the object-size index, adding a #writeObjectSizeIndex()
method.

Change-Id: Ic319975c72c239cd6488303f7d4cced797e6fe00

2 files changed, 82 insertions, 0 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 3fe8f52fba..2a403c7699 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
@@ -505,6 +505,43 @@ public class PackWriterTest extends SampleDataRepositoryTestCase {
 	}
 
 	@Test
+	public void testWriteObjectSizeIndex_noDeltas() throws Exception {
+		config.setMinBytesForObjSizeIndex(0);
+		HashSet<ObjectId> interesting = new HashSet<>();
+		interesting.add(ObjectId
+				.fromString("82c6b885ff600be425b4ea96dee75dca255b69e7"));
+
+		NullProgressMonitor m1 = NullProgressMonitor.INSTANCE;
+		writer = new PackWriter(config, db.newObjectReader());
+		writer.setUseBitmaps(false);
+		writer.setThin(false);
+		writer.setIgnoreMissingUninteresting(false);
+		writer.preparePack(m1, interesting, NONE);
+		writer.writePack(m1, m1, os);
+
+		PackIndex idx;
+		try (ByteArrayOutputStream is = new ByteArrayOutputStream()) {
+			writer.writeIndex(is);
+			idx = PackIndex.read(new ByteArrayInputStream(is.toByteArray()));
+		}
+
+		PackObjectSizeIndex objSizeIdx;
+		try (ByteArrayOutputStream objSizeStream = new ByteArrayOutputStream()) {
+			writer.writeObjectSizeIndex(objSizeStream);
+			objSizeIdx = PackObjectSizeIndexLoader.load(
+					new ByteArrayInputStream(objSizeStream.toByteArray()));
+		}
+		writer.close();
+
+		ObjectId knownBlob1 = ObjectId
+				.fromString("5b6e7c66c276e7610d4a73c70ec1a1f7c1003259");
+		ObjectId knownBlob2 = ObjectId
+				.fromString("6ff87c4664981e4397625791c8ea3bbb5f2279a3");
+		assertEquals(18009, objSizeIdx.getSize(idx.findPosition(knownBlob1)));
+		assertEquals(18787, objSizeIdx.getSize(idx.findPosition(knownBlob2)));
+	}
+
+	@Test
 	public void testExclude() throws Exception {
 		// TestRepository closes repo
 		FileRepository repo = createBareRepository();
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 d42d348a1c..bad572459a 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
@@ -61,6 +61,7 @@ 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.lib.AnyObjectId;
 import org.eclipse.jgit.lib.AsyncObjectSizeQueue;
 import org.eclipse.jgit.lib.BatchingProgressMonitor;
@@ -1092,6 +1093,50 @@ public class PackWriter implements AutoCloseable {
 	}
 
 	/**
+	 * Create an object size index file for the contents of the pack file just
+	 * written.
+	 * <p>
+	 * Called after
+	 * {@link #writePack(ProgressMonitor, ProgressMonitor, OutputStream)} that
+	 * populates the list of objects to pack and before
+	 * {@link #writeBitmapIndex(OutputStream)} 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.
+	 *
+	 * @param objIdxStream
+	 *            output for the object size index data. Caller is responsible
+	 *            for closing this stream.
+	 * @throws IOException
+	 *             errors while writing
+	 */
+	public void writeObjectSizeIndex(OutputStream objIdxStream)
+			throws IOException {
+		if (config.getMinBytesForObjSizeIndex() < 0) {
+			return;
+		}
+
+		long writeStart = System.currentTimeMillis();
+		// We only need to populate the size of blobs
+		AsyncObjectSizeQueue<ObjectToPack> sizeQueue = reader
+				.getObjectSize(objectsLists[OBJ_BLOB], /* reportMissing= */false);
+		try {
+			while (sizeQueue.next()) {
+				ObjectToPack otp = sizeQueue.getCurrent();
+				long sz = sizeQueue.getSize();
+				otp.setFullSize(sz);
+			}
+		} finally {
+			sizeQueue.release();
+		}
+		PackObjectSizeIndexWriter iw = PackObjectSizeIndexWriter.createWriter(
+				objIdxStream, config.getMinBytesForObjSizeIndex());
+		// All indexed objects because their positions must match primary index order
+		iw.write(sortByName());
+		stats.timeWriting += System.currentTimeMillis() - writeStart;
+	}
+
+	/**
 	 * Create a bitmap index file to match the pack file just written.
 	 * <p>
 	 * Called after {@link #prepareBitmapIndex(ProgressMonitor)}.