From 5e8fcfa853d99e036df9c9dc638370e40804fd38 Mon Sep 17 00:00:00 2001
From: Ivan Frade <ifrade@google.com>
Date: Fri, 31 May 2024 12:20:07 -0700
Subject: [PATCH] CommitGraphWriter: use ANY_DIFF instead of idEquals inside
 next()

Calculating the paths modified in a commit respect its parents is
taking undue amount of time in big trees.

Use ANY_DIFF filter, instead of #idEquals() inside the #next(). This
shorcuts the tree browsing earlier.

Change-Id: I318eee3ae817b7b9004d60bdb8d0f1bf19b9962d
---
 .../storage/commitgraph/CommitGraphWriterTest.java    |  2 ++
 .../storage/commitgraph/CommitGraphWriter.java        | 11 ++++++++---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/commitgraph/CommitGraphWriterTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/commitgraph/CommitGraphWriterTest.java
index 7130d59b95..80a0f0cea5 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/commitgraph/CommitGraphWriterTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/commitgraph/CommitGraphWriterTest.java
@@ -435,6 +435,8 @@ public class CommitGraphWriterTest extends RepositoryTestCase {
 				.map(b -> StandardCharsets.UTF_8.decode(b).toString())
 				.collect(toList());
 		assertThat(asString, containsInAnyOrder("d", "d/sd2", "d/sd2/f2"));
+		// We don't walk into d/sd1/f1
+		assertEquals(1, c.stepCounter);
 	}
 
 	RevCommit commit(RevCommit... parents) throws Exception {
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/commitgraph/CommitGraphWriter.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/commitgraph/CommitGraphWriter.java
index 37a0de84c4..55539e2a66 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/commitgraph/CommitGraphWriter.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/commitgraph/CommitGraphWriter.java
@@ -52,6 +52,7 @@ import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.revwalk.RevWalk;
 import org.eclipse.jgit.treewalk.EmptyTreeIterator;
 import org.eclipse.jgit.treewalk.TreeWalk;
+import org.eclipse.jgit.treewalk.filter.TreeFilter;
 import org.eclipse.jgit.util.NB;
 
 /**
@@ -447,12 +448,18 @@ public class CommitGraphWriter {
 
 	// Visible for testing
 	static class PathDiffCalculator {
+
+		// Walk steps in the last invocation of changedPaths
+		int stepCounter;
+
 		Optional<HashSet<ByteBuffer>> changedPaths(
 				ObjectReader or, RevCommit cmit) throws MissingObjectException,
 				IncorrectObjectTypeException, CorruptObjectException, IOException {
+			stepCounter = 0;
 			HashSet<ByteBuffer> paths = new HashSet<>();
 			try (TreeWalk walk = new TreeWalk(null, or)) {
 				walk.setRecursive(true);
+				walk.setFilter(TreeFilter.ANY_DIFF);
 				if (cmit.getParentCount() == 0) {
 					walk.addTree(new EmptyTreeIterator());
 				} else {
@@ -460,9 +467,7 @@ public class CommitGraphWriter {
 				}
 				walk.addTree(cmit.getTree());
 				while (walk.next()) {
-					if (walk.idEqual(0, 1)) {
-						continue;
-					}
+					stepCounter += 1;
 					byte[] rawPath = walk.getRawPath();
 					paths.add(ByteBuffer.wrap(rawPath));
 					for (int i = 0; i < rawPath.length; i++) {
-- 
2.39.5