gc: Add options to preserve and prune old pack files

The new --preserve-oldpacks option moves old pack files into the
preserved subdirectory instead of deleting them after repacking.

The new --prune-preserved option prunes old pack files from the
preserved subdirectory after repacking, but before potentially
moving the latest old packfiles to this subdirectory.

These options are designed to prevent stale file handle exceptions
during git operations which can happen on users of NFS repos when
repacking is done on them. The strategy is to preserve old pack files
around until the next repack with the hopes that they will become
unreferenced by then and not cause any exceptions to running processes
when they are finally deleted (pruned).

Change-Id: If3f729f0d9ce920ee2c3e6acdde46f2068be61d2
Signed-off-by: James Melvin <jmelvin@codeaurora.org>

1 files changed, 42 insertions, 1 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/GcBasicPackingTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/GcBasicPackingTest.java
index 762feed3c2..8a9ad89600 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/GcBasicPackingTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/GcBasicPackingTest.java
@@ -44,6 +44,8 @@
 package org.eclipse.jgit.internal.storage.file;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
 
 import java.io.File;
 import java.io.IOException;
@@ -233,7 +235,45 @@ public class GcBasicPackingTest extends GcTestCase {
 
 	}
 
-	private void configureGc(GC myGc, boolean aggressive) {
+	@Test
+	public void testPreserveAndPruneOldPacks() throws Exception {
+		testPreserveOldPacks();
+		configureGc(gc, false).setPrunePreserved(true);
+		gc.gc();
+
+		assertFalse(repo.getObjectDatabase().getPreservedDirectory().exists());
+	}
+
+	private void testPreserveOldPacks() throws Exception {
+		BranchBuilder bb = tr.branch("refs/heads/master");
+		bb.commit().message("P").add("P", "P").create();
+
+		// pack loose object into packfile
+		gc.setExpireAgeMillis(0);
+		gc.gc();
+		File oldPackfile = tr.getRepository().getObjectDatabase().getPacks()
+				.iterator().next().getPackFile();
+		assertTrue(oldPackfile.exists());
+
+		fsTick();
+		bb.commit().message("B").add("B", "Q").create();
+
+		// repack again but now without a grace period for packfiles. We should
+		// end up with a new packfile and the old one should be placed in the
+		// preserved directory
+		gc.setPackExpireAgeMillis(0);
+		configureGc(gc, false).setPreserveOldPacks(true);
+		gc.gc();
+
+		File oldPackDir = repo.getObjectDatabase().getPreservedDirectory();
+		String oldPackFileName = oldPackfile.getName();
+		String oldPackName = oldPackFileName.substring(0,
+				oldPackFileName.lastIndexOf('.')) + ".old-pack";  //$NON-NLS-1$
+		File preservePackFile = new File(oldPackDir, oldPackName);
+		assertTrue(preservePackFile.exists());
+	}
+
+	private PackConfig configureGc(GC myGc, boolean aggressive) {
 		PackConfig pconfig = new PackConfig(repo);
 		if (aggressive) {
 			pconfig.setDeltaSearchWindowSize(250);
@@ -242,5 +282,6 @@ public class GcBasicPackingTest extends GcTestCase {
 		} else
 			pconfig = new PackConfig(repo);
 		myGc.setPackConfig(pconfig);
+		return pconfig;
 	}
 }