pack-refs: Add sorted flag

packed-refs are already sorted but jgit isn't adding
the headers, so cgit performs extra work.

Add coverage to verify header contents and refs order.

Change-Id: I5ee0781a435295d3d6db3ecafc3177c15d90f5d4

org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/RefDirectoryTest.java

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/RefDirectoryTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/RefDirectoryTest.java
index baa0182..6552bac 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/RefDirectoryTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/RefDirectoryTest.java
@@ -37,6 +37,7 @@
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicReference;
 
+import org.eclipse.jgit.api.PackRefsCommand;
 import org.eclipse.jgit.errors.LockFailedException;
 import org.eclipse.jgit.events.ListenerHandle;
 import org.eclipse.jgit.events.RefsChangedEvent;
@@ -44,6 +45,7 @@
 import org.eclipse.jgit.junit.Repeat;
 import org.eclipse.jgit.junit.TestRepository;
 import org.eclipse.jgit.lib.AnyObjectId;
+import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.Ref;
 import org.eclipse.jgit.lib.Ref.Storage;
 import org.eclipse.jgit.lib.RefDatabase;
@@ -1062,6 +1064,60 @@ public void test_repack() throws Exception {
 	}
 
 	@Test
+	public void testPackedRefsHeaderWithSorted() throws Exception {
+		writeLooseRef("refs/heads/master", A);
+		writeLooseRef("refs/heads/other", B);
+		writeLooseRef("refs/tags/v1.0", v1_0);
+
+		PackRefsCommand packRefsCommand = new PackRefsCommand(diskRepo);
+		packRefsCommand.setAll(true);
+		packRefsCommand.call();
+
+		File packedRefsFile = new File(diskRepo.getCommonDirectory(), Constants.PACKED_REFS);
+		assertTrue("packed-refs should exist", packedRefsFile.exists());
+
+		String content = read(packedRefsFile);
+		String firstLine = content.split("\n")[0];
+		assertTrue("packed-refs should have header with sorted",
+				firstLine.contains(" sorted"));
+
+		int masterIndex = content.indexOf(A.name() + " refs/heads/master");
+		int otherIndex = content.indexOf(B.name() + " refs/heads/other");
+		int tagIndex = content.indexOf(v1_0.name() + " refs/tags/v1.0");
+		assertTrue("packed-refs should be sorted",
+				masterIndex < otherIndex && otherIndex < tagIndex);
+	}
+
+	@Test
+	public void testPackedRefsUnsortedGetsSorted() throws Exception {
+		writePackedRefs("# pack-refs with: peeled \n" + //
+				B.name() + " refs/heads/other\n" + //
+				v1_0.name() + " refs/tags/v1.0\n" + //
+				"^" + v1_0.getObject().name() + "\n" + //
+				A.name() + " refs/heads/master\n");
+
+		// extra loose-ref to trigger packing
+		writeLooseRef("refs/heads/loose", A);
+
+		PackRefsCommand packRefsCommand = new PackRefsCommand(diskRepo);
+		packRefsCommand.setAll(true);
+		packRefsCommand.call();
+
+		File packedRefsFile = new File(diskRepo.getCommonDirectory(), Constants.PACKED_REFS);
+		String content = read(packedRefsFile);
+		int looseIndex = content.indexOf(v1_0.name() + " refs/tags/loose");
+		int masterIndex = content.indexOf(A.name() + " refs/heads/master");
+		int otherIndex = content.indexOf(B.name() + " refs/heads/other");
+		int tagIndex = content.indexOf(v1_0.name() + " refs/tags/v1.0");
+		assertTrue(
+				"packed-refs should be sorted",
+				looseIndex < masterIndex &&
+						masterIndex < otherIndex &&
+						otherIndex < tagIndex
+		);
+	}
+
+	@Test
 	public void testFindRef_EmptyDatabase() throws IOException {
 		Ref r;
 

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/RefDirectory.java

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/RefDirectory.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/RefDirectory.java
index 9c262e9..9fa3ff3 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/RefDirectory.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/RefDirectory.java
@@ -121,6 +121,9 @@ public class RefDirectory extends RefDatabase {
 	/** If in the header, denotes the file has peeled data. */
 	public static final String PACKED_REFS_PEELED = " peeled"; //$NON-NLS-1$
 
+	/** If in the header, denotes the file has sorted data. */
+	public static final String PACKED_REFS_SORTED = " sorted"; //$NON-NLS-1$
+
 	@SuppressWarnings("boxing")
 	private static final List<Integer> RETRY_SLEEP_MS =
 			Collections.unmodifiableList(Arrays.asList(0, 100, 200, 400, 800, 1600));

org.eclipse.jgit/src/org/eclipse/jgit/lib/RefWriter.java

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/lib/RefWriter.java b/org.eclipse.jgit/src/org/eclipse/jgit/lib/RefWriter.java
index 41917f8..58aed82 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/lib/RefWriter.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/lib/RefWriter.java
@@ -139,6 +139,7 @@ public void writePackedRefs() throws IOException {
 		if (peeled) {
 			w.write(RefDirectory.PACKED_REFS_HEADER);
 			w.write(RefDirectory.PACKED_REFS_PEELED);
+			w.write(RefDirectory.PACKED_REFS_SORTED);
 			w.write('\n');
 		}