Fix calculation of pack files and objects since bitmap

Fix a logic issue where pack files and objects created since the most
recent bitmap were incorrectly counted, ignoring their modification
time.

Since pack files are processed in order from most recent to oldest, we
can reliably stop counting as soon as we encounter the first bitmap. By
definition, all subsequent pack files are older and should not be
included in the count.

This ensures accurate repository statistics and prevents overcounting.

Bug: jgit-140
Change-Id: I99d85fb70bc7eb42a8d24c74a1fdb8e03334099e

2 files changed, 33 insertions, 8 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/GcSinceBitmapStatisticsTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/GcSinceBitmapStatisticsTest.java
index 3cd766c4e9..af52e2cb85 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/GcSinceBitmapStatisticsTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/GcSinceBitmapStatisticsTest.java
@@ -20,6 +20,7 @@ import java.util.stream.StreamSupport;
 import org.eclipse.jgit.internal.storage.file.GC.RepoStatistics;
 import org.eclipse.jgit.lib.PersonIdent;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.storage.pack.PackConfig;
 import org.junit.Test;
 
 public class GcSinceBitmapStatisticsTest extends GcTestCase {
@@ -51,11 +52,19 @@ public class GcSinceBitmapStatisticsTest extends GcTestCase {
 	}
 
 	@Test
-	public void testShouldReportNoPacksDirectlyAfterGc() throws Exception {
-		// given
+	public void testShouldReportNoPacksFilesSinceBitmapWhenPackfilesAreOlderThanBitmapFile()
+			throws Exception {
 		addCommit(null);
-		gc.gc().get();
+		configureGC(/* buildBitmap */ false).gc().get();
+		assertEquals(1L, gc.getStatistics().numberOfPackFiles);
+		assertEquals(0L, repositoryBitmapFiles());
+		assertEquals(1L, gc.getStatistics().numberOfPackFilesSinceBitmap);
+
+		addCommit(null);
+		configureGC(/* buildBitmap */ true).gc().get();
+
 		assertEquals(1L, repositoryBitmapFiles());
+		assertEquals(2L, gc.getStatistics().numberOfPackFiles);
 		assertEquals(0L, gc.getStatistics().numberOfPackFilesSinceBitmap);
 	}
 
@@ -79,8 +88,11 @@ public class GcSinceBitmapStatisticsTest extends GcTestCase {
 
 		// progress & pack
 		addCommit(parent);
-		tr.packAndPrune();
+		assertEquals(1L, gc.getStatistics().numberOfPackFiles);
+		assertEquals(0L, gc.getStatistics().numberOfPackFilesSinceBitmap);
 
+		tr.packAndPrune();
+		assertEquals(2L, gc.getStatistics().numberOfPackFiles);
 		assertEquals(1L, gc.getStatistics().numberOfPackFilesSinceBitmap);
 	}
 
@@ -90,13 +102,17 @@ public class GcSinceBitmapStatisticsTest extends GcTestCase {
 		// commit & gc
 		RevCommit parent = addCommit(null);
 		gc.gc().get();
+		assertEquals(0L, gc.getStatistics().numberOfLooseObjects);
 		assertEquals(0L, gc.getStatistics().numberOfObjectsSinceBitmap);
 
 		// progress & pack
 		addCommit(parent);
+		assertEquals(1L, gc.getStatistics().numberOfLooseObjects);
 		assertEquals(1L, gc.getStatistics().numberOfObjectsSinceBitmap);
 
 		tr.packAndPrune();
+		assertEquals(0L, gc.getStatistics().numberOfLooseObjects);
+		// Number of objects contained in the newly created PackFile
 		assertEquals(3L, gc.getStatistics().numberOfObjectsSinceBitmap);
 	}
 
@@ -164,4 +180,11 @@ public class GcSinceBitmapStatisticsTest extends GcTestCase {
 			}
 		}).sum();
 	}
+
+	private GC configureGC(boolean buildBitmap) {
+		PackConfig pc = new PackConfig(repo.getObjectDatabase().getConfig());
+		pc.setBuildBitmaps(buildBitmap);
+		gc.setPackConfig(pc);
+		return gc;
+	}
 }
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/GC.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/GC.java
index b33afed131..3cc43ebb04 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/GC.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/GC.java
@@ -1579,7 +1579,7 @@ public class GC {
 	public RepoStatistics getStatistics() throws IOException {
 		RepoStatistics ret = new RepoStatistics();
 		Collection<Pack> packs = repo.getObjectDatabase().getPacks();
-		long latestBitmapTime = Long.MIN_VALUE;
+		long latestBitmapTime = 0L;
 		for (Pack p : packs) {
 			long packedObjects = p.getIndex().getObjectCount();
 			ret.numberOfPackedObjects += packedObjects;
@@ -1587,9 +1587,11 @@ public class GC {
 			ret.sizeOfPackedObjects += p.getPackFile().length();
 			if (p.getBitmapIndex() != null) {
 				ret.numberOfBitmaps += p.getBitmapIndex().getBitmapCount();
-				latestBitmapTime = p.getFileSnapshot().lastModifiedInstant()
-						.toEpochMilli();
-			} else {
+				if (latestBitmapTime == 0L) {
+					latestBitmapTime = p.getFileSnapshot().lastModifiedInstant().toEpochMilli();
+				}
+			}
+			else if (latestBitmapTime == 0L) {
 				ret.numberOfPackFilesSinceBitmap++;
 				ret.numberOfObjectsSinceBitmap += packedObjects;
 			}