Merge changes I9ba0e70f,I1f38e055,Idb55a303

* changes:
  Do not rewrite parents in RevWalkTextBuiltins
  RevWalk: Allow disabling parent rewriting
  RevWalkTextBuiltin: Add -n to limit number of commits returned

org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/RevWalkTextBuiltin.java

@@ -146,6 +146,9 @@ abstract class RevWalkTextBuiltin extends TextBuiltin {
 		revLimiter.add(MessageRevFilter.create(msg));
 	}
 
+	@Option(name = "--max-count", aliases = "-n", metaVar = "metaVar_n")
+	private int maxCount = -1;
+
 	@Override
 	protected void run() throws Exception {
 		walk = createWalk();
@@ -208,17 +211,22 @@ abstract class RevWalkTextBuiltin extends TextBuiltin {
 	}
 
 	protected RevWalk createWalk() {
+		RevWalk result;
 		if (objects)
-			return new ObjectWalk(db);
-		if (argWalk != null)
-			return argWalk;
-		return argWalk = new RevWalk(db);
+			result = new ObjectWalk(db);
+		else if (argWalk != null)
+			result = argWalk;
+		else
+		  result = argWalk = new RevWalk(db);
+		result.setRewriteParents(false);
+		return result;
 	}
 
 	protected int walkLoop() throws Exception {
 		int n = 0;
 		for (final RevCommit c : walk) {
-			n++;
+			if (++n > maxCount && maxCount >= 0)
+				break;
 			show(c);
 		}
 		if (walk instanceof ObjectWalk) {

org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevWalkPathFilter1Test.java

@@ -128,6 +128,25 @@ public class RevWalkPathFilter1Test extends RevWalkTestCase {
 		assertNull(rw.next());
 	}
 
+	@Test
+	public void testStringOfPearls_FilePath1_NoParentRewriting()
+			throws Exception {
+		final RevCommit a = commit(tree(file("d/f", blob("a"))));
+		final RevCommit b = commit(tree(file("d/f", blob("a"))), a);
+		final RevCommit c = commit(tree(file("d/f", blob("b"))), b);
+		filter("d/f");
+		markStart(c);
+		rw.setRewriteParents(false);
+
+		assertCommit(c, rw.next());
+		assertEquals(1, c.getParentCount());
+		assertCommit(b, c.getParent(0));
+
+		assertCommit(a, rw.next()); // b was skipped
+		assertEquals(0, a.getParentCount());
+		assertNull(rw.next());
+	}
+
 	@Test
 	public void testStringOfPearls_FilePath2() throws Exception {
 		final RevCommit a = commit(tree(file("d/f", blob("a"))));
@@ -147,6 +166,28 @@ public class RevWalkPathFilter1Test extends RevWalkTestCase {
 		assertNull(rw.next());
 	}
 
+	@Test
+	public void testStringOfPearls_FilePath2_NoParentRewriting()
+	throws Exception {
+		final RevCommit a = commit(tree(file("d/f", blob("a"))));
+		final RevCommit b = commit(tree(file("d/f", blob("a"))), a);
+		final RevCommit c = commit(tree(file("d/f", blob("b"))), b);
+		final RevCommit d = commit(tree(file("d/f", blob("b"))), c);
+		filter("d/f");
+		markStart(d);
+		rw.setRewriteParents(false);
+
+		// d was skipped
+		assertCommit(c, rw.next());
+		assertEquals(1, c.getParentCount());
+		assertCommit(b, c.getParent(0));
+
+		// b was skipped
+		assertCommit(a, rw.next());
+		assertEquals(0, a.getParentCount());
+		assertNull(rw.next());
+	}
+
 	@Test
 	public void testStringOfPearls_DirPath2() throws Exception {
 		final RevCommit a = commit(tree(file("d/f", blob("a"))));
@@ -166,6 +207,28 @@ public class RevWalkPathFilter1Test extends RevWalkTestCase {
 		assertNull(rw.next());
 	}
 
+	@Test
+	public void testStringOfPearls_DirPath2_NoParentRewriting()
+			throws Exception {
+		final RevCommit a = commit(tree(file("d/f", blob("a"))));
+		final RevCommit b = commit(tree(file("d/f", blob("a"))), a);
+		final RevCommit c = commit(tree(file("d/f", blob("b"))), b);
+		final RevCommit d = commit(tree(file("d/f", blob("b"))), c);
+		filter("d");
+		markStart(d);
+		rw.setRewriteParents(false);
+
+		// d was skipped
+		assertCommit(c, rw.next());
+		assertEquals(1, c.getParentCount());
+		assertCommit(b, c.getParent(0));
+
+		// b was skipped
+		assertCommit(a, rw.next());
+		assertEquals(0, a.getParentCount());
+		assertNull(rw.next());
+	}
+
 	@Test
 	public void testStringOfPearls_FilePath3() throws Exception {
 		final RevCommit a = commit(tree(file("d/f", blob("a"))));
@@ -192,4 +255,35 @@ public class RevWalkPathFilter1Test extends RevWalkTestCase {
 		assertEquals(0, a.getParentCount());
 		assertNull(rw.next());
 	}
+
+	@Test
+	public void testStringOfPearls_FilePath3_NoParentRewriting()
+			throws Exception {
+		final RevCommit a = commit(tree(file("d/f", blob("a"))));
+		final RevCommit b = commit(tree(file("d/f", blob("a"))), a);
+		final RevCommit c = commit(tree(file("d/f", blob("b"))), b);
+		final RevCommit d = commit(tree(file("d/f", blob("b"))), c);
+		final RevCommit e = commit(tree(file("d/f", blob("b"))), d);
+		final RevCommit f = commit(tree(file("d/f", blob("b"))), e);
+		final RevCommit g = commit(tree(file("d/f", blob("b"))), f);
+		final RevCommit h = commit(tree(file("d/f", blob("b"))), g);
+		final RevCommit i = commit(tree(file("d/f", blob("c"))), h);
+		filter("d/f");
+		markStart(i);
+		rw.setRewriteParents(false);
+
+		assertCommit(i, rw.next());
+		assertEquals(1, i.getParentCount());
+		assertCommit(h, i.getParent(0));
+
+		// h..d was skipped
+		assertCommit(c, rw.next());
+		assertEquals(1, c.getParentCount());
+		assertCommit(b, c.getParent(0));
+
+		// b was skipped
+		assertCommit(a, rw.next());
+		assertEquals(0, a.getParentCount());
+		assertNull(rw.next());
+	}
 }

org.eclipse.jgit/src/org/eclipse/jgit/revwalk/RevWalk.java

@@ -190,6 +190,8 @@ public class RevWalk implements Iterable<RevCommit> {
 
 	private boolean retainBody;
 
+	private boolean rewriteParents = true;
+
 	boolean shallowCommitsInitialized;
 
 	/**
@@ -533,8 +535,9 @@ public class RevWalk implements Iterable<RevCommit> {
 	 * will not be simplified.
 	 * <p>
 	 * If non-null and not {@link TreeFilter#ALL} then the tree filter will be
-	 * installed and commits will have their ancestry simplified to hide commits
-	 * that do not contain tree entries matched by the filter.
+	 * installed. Commits will have their ancestry simplified to hide commits that
+	 * do not contain tree entries matched by the filter, unless
+	 * {@code setRewriteParents(false)} is called.
 	 * <p>
 	 * Usually callers should be inserting a filter graph including
 	 * {@link TreeFilter#ANY_DIFF} along with one or more
@@ -550,6 +553,28 @@ public class RevWalk implements Iterable<RevCommit> {
 		treeFilter = newFilter != null ? newFilter : TreeFilter.ALL;
 	}
 
+	/**
+	 * Set whether to rewrite parent pointers when filtering by modified paths.
+	 * <p>
+	 * By default, when {@link #setTreeFilter(TreeFilter)} is called with non-
+	 * null and non-{@link TreeFilter#ALL} filter, commits will have their
+	 * ancestry simplified and parents rewritten to hide commits that do not match
+	 * the filter.
+	 * <p>
+	 * This behavior can be bypassed by passing false to this method.
+	 *
+	 * @param rewrite
+	 *            whether to rewrite parents; defaults to true.
+	 * @since 3.4
+	 */
+	public void setRewriteParents(boolean rewrite) {
+		rewriteParents = rewrite;
+	}
+
+	boolean getRewriteParents() {
+		return rewriteParents;
+	}
+
 	/**
 	 * Should the body of a commit or tag be retained after parsing its headers?
 	 * <p>

org.eclipse.jgit/src/org/eclipse/jgit/revwalk/StartGenerator.java

@@ -128,7 +128,9 @@ class StartGenerator extends Generator {
 			pending = new DateRevQueue(q);
 		if (tf != TreeFilter.ALL) {
 			rf = AndRevFilter.create(new RewriteTreeFilter(w, tf), rf);
-			pendingOutputType |= HAS_REWRITE | NEEDS_REWRITE;
+			pendingOutputType |= HAS_REWRITE;
+			if (w.getRewriteParents())
+				pendingOutputType |= NEEDS_REWRITE;
 		}
 
 		walker.queue = q;