PackWriter: Display totals after sending objects

CGit pack-objects displays a totals line after the pack data
was fully written.  This can be useful to understand some of
the decisions made by the packer, and has been a great tool
for helping to debug some of that code.

Track some of the basic values, and send it to the client when
packing is done:

  remote: Counting objects: 1826776, done
  remote: Finding sources: 100% (55121/55121)
  remote: Getting sizes: 100% (25654/25654)
  remote: Compressing objects: 100% (11434/11434)
  remote: Total 1861830 (delta 3926), reused 1854705 (delta 38306)
  Receiving objects: 100% (1861830/1861830), 386.03 MiB | 30.32 MiB/s, done.

Change-Id: If3b039017a984ed5d5ae80940ce32bda93652df5
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

org.eclipse.jgit/resources/org/eclipse/jgit/JGitText.properties

@@ -329,6 +329,7 @@ packetSizeMustBeAtMost=packet size {0} must be <= {1}
 packfileCorruptionDetected=Packfile corruption detected: {0}
 packfileIsTruncated=Packfile is truncated.
 packingCancelledDuringObjectsWriting=Packing cancelled during objects writing
+packWriterStatistics=Total {0,number,#0} (delta {1,number,#0}), reused {2,number,#0} (delta {3,number,#0})
 pathIsNotInWorkingDir=Path is not in working dir
 peeledLineBeforeRef=Peeled line before ref.
 peerDidNotSupplyACompleteObjectGraph=peer did not supply a complete object graph

org.eclipse.jgit/src/org/eclipse/jgit/JGitText.java

@@ -389,6 +389,7 @@ public class JGitText extends TranslationBundle {
 	/***/ public String packfileCorruptionDetected;
 	/***/ public String packfileIsTruncated;
 	/***/ public String packingCancelledDuringObjectsWriting;
+	/***/ public String packWriterStatistics;
 	/***/ public String pathIsNotInWorkingDir;
 	/***/ public String peeledLineBeforeRef;
 	/***/ public String peerDidNotSupplyACompleteObjectGraph;

org.eclipse.jgit/src/org/eclipse/jgit/storage/pack/PackWriter.java

@@ -50,6 +50,7 @@ import static org.eclipse.jgit.storage.pack.StoredObjectRepresentation.PACK_WHOL
 import java.io.IOException;
 import java.io.OutputStream;
 import java.security.MessageDigest;
+import java.text.MessageFormat;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -155,6 +156,8 @@ public class PackWriter {
 
 	private final PackConfig config;
 
+	private final Statistics stats;
+
 	private List<ObjectToPack> sortedByName;
 
 	private byte packcsum[];
@@ -229,6 +232,7 @@ public class PackWriter {
 
 		deltaBaseAsOffset = config.isDeltaBaseAsOffset();
 		reuseDeltas = config.isReuseDeltas();
+		stats = new Statistics();
 	}
 
 	/**
@@ -498,6 +502,7 @@ public class PackWriter {
 				packStream, this);
 
 		int objCnt = getObjectsNumber();
+		stats.totalObjects = objCnt;
 		writeMonitor.beginTask(JGitText.get().writingObjects, objCnt);
 		out.writeFileHeader(PACK_VERSION_GENERATED, objCnt);
 		out.flush();
@@ -508,6 +513,15 @@ public class PackWriter {
 		writeMonitor.endTask();
 	}
 
+	/**
+	 * @return description of what this PackWriter did in order to create the
+	 *         final pack stream. The object is only available to callers after
+	 *         {@link #writePack(ProgressMonitor, ProgressMonitor, OutputStream)}
+	 */
+	public Statistics getStatistics() {
+		return stats;
+	}
+
 	/** Release all resources used by this writer. */
 	public void release() {
 		reader.release();
@@ -846,6 +860,9 @@ public class PackWriter {
 				reuseSupport.copyObjectAsIs(out, otp);
 				out.endObject();
 				otp.setCRC(out.getCRC32());
+				stats.reusedObjects++;
+				if (otp.isDeltaRepresentation())
+					stats.reusedDeltas++;
 				return;
 			} catch (StoredObjectRepresentationNotAvailableException gone) {
 				if (otp.getOffset() == out.length()) {
@@ -940,6 +957,7 @@ public class PackWriter {
 		DeflaterOutputStream dst = new DeflaterOutputStream(out, deflater);
 		delta.writeTo(dst, null);
 		dst.finish();
+		stats.totalDeltas++;
 	}
 
 	private TemporaryBuffer.Heap delta(final ObjectToPack otp)
@@ -1167,4 +1185,22 @@ public class PackWriter {
 
 		otp.select(next);
 	}
+
+	/** Summary of how PackWriter created the pack. */
+	public static class Statistics {
+		long totalObjects;
+
+		long totalDeltas;
+
+		long reusedObjects;
+
+		long reusedDeltas;
+
+		/** @return formatted message string for display to clients. */
+		public String getMessage() {
+			return MessageFormat.format(JGitText.get().packWriterStatistics, //
+					totalObjects, totalDeltas, //
+					reusedObjects, reusedDeltas);
+		}
+	}
 }

org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java

@@ -57,6 +57,7 @@ import java.util.Set;
 import org.eclipse.jgit.JGitText;
 import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.errors.PackProtocolException;
+import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.NullProgressMonitor;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ProgressMonitor;
@@ -614,6 +615,7 @@ public class UploadPack {
 
 		ProgressMonitor pm = NullProgressMonitor.INSTANCE;
 		OutputStream packOut = rawOut;
+		SideBandOutputStream msgOut = null;
 
 		if (sideband) {
 			int bufsz = SideBandOutputStream.SMALL_BUF;
@@ -622,9 +624,11 @@ public class UploadPack {
 
 			packOut = new SideBandOutputStream(SideBandOutputStream.CH_DATA,
 					bufsz, rawOut);
-			if (!options.contains(OPTION_NO_PROGRESS))
+			if (!options.contains(OPTION_NO_PROGRESS)) {
-				pm = new SideBandProgressMonitor(new SideBandOutputStream(
+				msgOut = new SideBandOutputStream(
-						SideBandOutputStream.CH_PROGRESS, bufsz, rawOut));
+						SideBandOutputStream.CH_PROGRESS, bufsz, rawOut);
+				pm = new SideBandProgressMonitor(msgOut);
+			}
 		}
 
 		PackConfig cfg = packConfig;
@@ -650,11 +654,19 @@ public class UploadPack {
 						pw.addObject(t);
 				}
 			}
+
 			pw.writePack(pm, NullProgressMonitor.INSTANCE, packOut);
+			packOut.flush();
+
+			if (msgOut != null) {
+				String msg = pw.getStatistics().getMessage() + '\n';
+				msgOut.write(Constants.encode(msg));
+				msgOut.flush();
+			}
+
 		} finally {
 			pw.release();
 		}
-		packOut.flush();
 
 		if (sideband)
 			pckOut.end();