DfsGarbageCollector: put only GC commits into the commit graph

GC puts all commits reachable from heads and tags into the GC pack,
and commits reachable only from other refs (e.g. refs/changes) into
GC_REST. The commit-graph contains all commits in GC and GC_REST. This
produces too big commit graphs in some repos, beating the purpose of
loading the index.

Limit the commit graph to commits reachable from heads and tags
(i.e. commits in the GC pack).

Change-Id: I4962faea5a726d2ea3e548af0aeae370a6cc8588

1 files changed, 12 insertions, 10 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsGarbageCollectorTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsGarbageCollectorTest.java
index 405e12677e..16c34500a3 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsGarbageCollectorTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsGarbageCollectorTest.java
@@ -979,7 +979,7 @@ public class DfsGarbageCollectorTest {
 	}
 
 	@Test
-	public void produceCommitGraphAllRefsIncludedFromDisk() throws Exception {
+	public void produceCommitGraphOnlyHeadsAndTags() throws Exception {
 		String tag = "refs/tags/tag1";
 		String head = "refs/heads/head1";
 		String nonHead = "refs/something/nonHead";
@@ -1001,19 +1001,20 @@ public class DfsGarbageCollectorTest {
 		CommitGraph cg = gcPack.getCommitGraph(reader);
 		assertNotNull(cg);
 
-		assertTrue("all commits in commit graph", cg.getCommitCnt() == 3);
+		assertTrue("Only heads and tags reachable commits in commit graph",
+				cg.getCommitCnt() == 2);
 		// GC packed
 		assertTrue("tag referenced commit is in graph",
 				cg.findGraphPosition(rootCommitTagged) != -1);
 		assertTrue("head referenced commit is in graph",
 				cg.findGraphPosition(headTip) != -1);
-		// GC_REST packed
-		assertTrue("nonHead referenced commit is in graph",
-				cg.findGraphPosition(nonHeadTip) != -1);
+		// GC_REST not in commit graph
+		assertEquals("nonHead referenced commit is NOT in graph",
+				-1, cg.findGraphPosition(nonHeadTip));
 	}
 
 	@Test
-	public void produceCommitGraphAllRefsIncludedFromCache() throws Exception {
+	public void produceCommitGraphOnlyHeadsAndTagsIncludedFromCache() throws Exception {
 		String tag = "refs/tags/tag1";
 		String head = "refs/heads/head1";
 		String nonHead = "refs/something/nonHead";
@@ -1043,15 +1044,16 @@ public class DfsGarbageCollectorTest {
 		assertTrue("commit graph read time is recorded",
 				reader.stats.readCommitGraphMicros > 0);
 
-		assertTrue("all commits in commit graph", cachedCG.getCommitCnt() == 3);
+		assertTrue("Only heads and tags reachable commits in commit graph",
+				cachedCG.getCommitCnt() == 2);
 		// GC packed
 		assertTrue("tag referenced commit is in graph",
 				cachedCG.findGraphPosition(rootCommitTagged) != -1);
 		assertTrue("head referenced commit is in graph",
 				cachedCG.findGraphPosition(headTip) != -1);
-		// GC_REST packed
-		assertTrue("nonHead referenced commit is in graph",
-				cachedCG.findGraphPosition(nonHeadTip) != -1);
+		// GC_REST not in commit graph
+		assertEquals("nonHead referenced commit is not in graph",
+				-1, cachedCG.findGraphPosition(nonHeadTip));
 	}
 
 	@Test