[JGIT PATCH 3/4] Micro-optimize TreeWalk's exitSubtree implementation

["Shawn O. Pearce" <spearce@spearce.org>]

Rather than recomputing the min over again we can take the hint that
the prior min (the one that describes the tree we just left) must be
one that matches itself.  There may be more than one such case, as a
min could be found and match itself and later another min is found.
So we fall back into a pathCompare if we identify more than one.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
---
 .../src/org/spearce/jgit/treewalk/TreeWalk.java    |   12 ++++++++++--
 1 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/org.spearce.jgit/src/org/spearce/jgit/treewalk/TreeWalk.java b/org.spearce.jgit/src/org/spearce/jgit/treewalk/TreeWalk.java
index 6d0ef02..ef27e4e 100644
--- a/org.spearce.jgit/src/org/spearce/jgit/treewalk/TreeWalk.java
+++ b/org.spearce.jgit/src/org/spearce/jgit/treewalk/TreeWalk.java
@@ -722,11 +722,19 @@ void skipEntriesEqual() throws CorruptObjectException {
 		}
 	}
 
-	private void exitSubtree() throws CorruptObjectException {
+	private void exitSubtree() {
 		depth--;
 		for (int i = 0; i < trees.length; i++)
 			trees[i] = trees[i].parent;
-		currentHead = min();
+
+		AbstractTreeIterator minRef = null;
+		for (final AbstractTreeIterator t : trees) {
+			if (t.matches != t)
+				continue;
+			if (minRef == null || t.pathCompare(minRef) < 0)
+				minRef = t;
+		}
+		currentHead = minRef;
 	}
 
 	private CanonicalTreeParser parserFor(final ObjectId id)
-- 
1.6.0.112.g9c75