From b6da4b34cccc39a253d34e159a13cc2fd79a46bf Mon Sep 17 00:00:00 2001 From: Ivan Frade Date: Mon, 6 May 2019 20:39:18 -0700 Subject: [PATCH] BitmapCalculator: Get the reachability bitmap of a commit To make reachability checks with bitmaps, we need to get the reachability bitmap of a commit, which is not always precalculated. There is already a class returning such bitmap (BitmapWalker) but it does too much unnecessary work: it calculates ALL reachable objects from a commit (i.e. including trees and blobs), when for reachability the commits are just enough. Introduce BitmapCalculator to get the bitmap of a commit: either because it is precalculated or generating it with a walk only over commits. Change-Id: Ibb6c78affe9eeaf1fa362a06daf4fd2d91c1caea Signed-off-by: Ivan Frade --- .../jgit/revwalk/BitmapCalculatorTest.java | 139 ++++++++++++++++++ .../jgit/revwalk/BitmapCalculator.java | 93 ++++++++++++ 2 files changed, 232 insertions(+) create mode 100644 org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/BitmapCalculatorTest.java create mode 100644 org.eclipse.jgit/src/org/eclipse/jgit/revwalk/BitmapCalculator.java diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/BitmapCalculatorTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/BitmapCalculatorTest.java new file mode 100644 index 000000000..3a78e1e62 --- /dev/null +++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/BitmapCalculatorTest.java @@ -0,0 +1,139 @@ +package org.eclipse.jgit.revwalk; + +import static org.junit.Assert.assertEquals; +import static org.junit.Assert.assertFalse; +import static org.junit.Assert.assertTrue; + +import org.eclipse.jgit.internal.storage.file.FileRepository; +import org.eclipse.jgit.internal.storage.file.GC; +import org.eclipse.jgit.junit.LocalDiskRepositoryTestCase; +import org.eclipse.jgit.junit.TestRepository; +import org.eclipse.jgit.lib.BitmapIndex.BitmapBuilder; +import org.eclipse.jgit.lib.NullProgressMonitor; +import org.eclipse.jgit.lib.ProgressMonitor; +import org.junit.Before; +import org.junit.Test; + +public class BitmapCalculatorTest extends LocalDiskRepositoryTestCase { + TestRepository repo; + + /** {@inheritDoc} */ + @Override + @Before + public void setUp() throws Exception { + super.setUp(); + FileRepository db = createWorkRepository(); + repo = new TestRepository<>(db); + } + + @Test + public void addOnlyCommits() throws Exception { + RevBlob abBlob = repo.blob("a_b_content"); + RevCommit root = repo.commit().add("a/b", abBlob).create(); + repo.update("refs/heads/master", root); + + // GC creates bitmap index with ALL objects + GC gc = new GC(repo.getRepository()); + gc.setAuto(false); + gc.gc(); + + // These objects are not in the bitmap index. + RevBlob acBlob = repo.blob("a_c_content"); + RevCommit head = repo.commit().parent(root).add("a/c", acBlob).create(); + repo.update("refs/heads/master", head); + + BitmapCalculator bitmapWalker = new BitmapCalculator(repo.getRevWalk()); + BitmapBuilder bitmap = bitmapWalker + .getBitmap(head, NullProgressMonitor.INSTANCE); + + assertTrue(bitmap.contains(root.getId())); + assertTrue(bitmap.contains(root.getTree().getId())); + assertTrue(bitmap.contains(abBlob.getId())); + + // BitmapCalculator added only the commit, no other objects. + assertTrue(bitmap.contains(head.getId())); + assertFalse(bitmap.contains(head.getTree().getId())); + assertFalse(bitmap.contains(acBlob.getId())); + } + + @Test + public void walkUntilBitmap() throws Exception { + RevCommit root = repo.commit().create(); + repo.update("refs/heads/master", root); + + // GC creates bitmap index with ALL objects + GC gc = new GC(repo.getRepository()); + gc.setAuto(false); + gc.gc(); + + // These objects are not in the bitmap index. + RevCommit commit1 = repo.commit(root); + RevCommit commit2 = repo.commit(commit1); + repo.update("refs/heads/master", commit2); + + CounterProgressMonitor monitor = new CounterProgressMonitor(); + BitmapCalculator bitmapWalker = new BitmapCalculator(repo.getRevWalk()); + BitmapBuilder bitmap = bitmapWalker.getBitmap(commit2, monitor); + + assertTrue(bitmap.contains(root)); + assertTrue(bitmap.contains(commit1)); + assertTrue(bitmap.contains(commit2)); + assertEquals(2, monitor.getUpdates()); + } + + @Test + public void noNeedToWalk() throws Exception { + RevCommit root = repo.commit().create(); + RevCommit commit1 = repo.commit(root); + RevCommit commit2 = repo.commit(commit1); + repo.update("refs/heads/master", commit2); + + // GC creates bitmap index with ALL objects + GC gc = new GC(repo.getRepository()); + gc.setAuto(false); + gc.gc(); + + CounterProgressMonitor monitor = new CounterProgressMonitor(); + BitmapCalculator bitmapWalker = new BitmapCalculator(repo.getRevWalk()); + BitmapBuilder bitmap = bitmapWalker.getBitmap(commit2, monitor); + + assertTrue(bitmap.contains(root)); + assertTrue(bitmap.contains(commit1)); + assertTrue(bitmap.contains(commit2)); + assertEquals(0, monitor.getUpdates()); + } + + private static class CounterProgressMonitor implements ProgressMonitor { + + private int counter; + + @Override + public void start(int totalTasks) { + // Nothing to do in tests + } + + @Override + public void beginTask(String title, int totalWork) { + // Nothing to to in tests + } + + @Override + public void update(int completed) { + counter += 1; + } + + @Override + public void endTask() { + // Nothing to do in tests + } + + @Override + public boolean isCancelled() { + return false; + } + + int getUpdates() { + return counter; + } + } +} \ No newline at end of file diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/BitmapCalculator.java b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/BitmapCalculator.java new file mode 100644 index 000000000..e1d5d4ada --- /dev/null +++ b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/BitmapCalculator.java @@ -0,0 +1,93 @@ +package org.eclipse.jgit.revwalk; + +import static java.util.Objects.requireNonNull; + +import java.io.IOException; + +import org.eclipse.jgit.errors.IncorrectObjectTypeException; +import org.eclipse.jgit.errors.MissingObjectException; +import org.eclipse.jgit.internal.revwalk.AddToBitmapFilter; +import org.eclipse.jgit.lib.BitmapIndex; +import org.eclipse.jgit.lib.BitmapIndex.Bitmap; +import org.eclipse.jgit.lib.BitmapIndex.BitmapBuilder; +import org.eclipse.jgit.lib.ProgressMonitor; + +/** + * Calculate the bitmap indicating what other commits are reachable from certain + * commit. + *

+ * This bitmap refers only to commits. For a bitmap with ALL objects reachable + * from certain object, see {@code BitmapWalker}. + */ +class BitmapCalculator { + + private final RevWalk walk; + private final BitmapIndex bitmapIndex; + + BitmapCalculator(RevWalk walk) throws IOException { + this.walk = walk; + this.bitmapIndex = requireNonNull( + walk.getObjectReader().getBitmapIndex()); + } + + /** + * Get the reachability bitmap from certain commit to other commits. + *

+ * This will return a precalculated bitmap if available or walk building one + * until finding a precalculated bitmap (and returning the union). + *

+ * Beware that the returned bitmap it is guaranteed to include ONLY the + * commits reachable from the initial commit. It COULD include other objects + * (because precalculated bitmaps have them) but caller shouldn't count on + * that. See {@link BitmapWalker} for a full reachability bitmap. + * + * @param start + * the commit. Use {@code walk.parseCommit(objectId)} to get this + * object from the id. + * @param pm + * progress monitor. Updated by one per commit browsed in the + * graph + * @return the bitmap of reachable commits (and maybe some extra objects) + * for the commit + * @throws MissingObjectException + * the supplied id doesn't exist + * @throws IncorrectObjectTypeException + * the supplied id doens't refer to a commit or a tag + * @throws IOException + */ + BitmapBuilder getBitmap(RevCommit start, ProgressMonitor pm) + throws MissingObjectException, + IncorrectObjectTypeException, IOException { + Bitmap precalculatedBitmap = bitmapIndex.getBitmap(start); + if (precalculatedBitmap != null) { + return asBitmapBuilder(precalculatedBitmap); + } + + walk.reset(); + walk.sort(RevSort.TOPO); + walk.markStart(start); + // Unbounded walk. If the repo has bitmaps, it should bump into one at + // some point. + + BitmapBuilder bitmapResult = bitmapIndex.newBitmapBuilder(); + walk.setRevFilter(new AddToBitmapFilter(bitmapResult)); + while (walk.next() != null) { + // Iterate through all of the commits. The BitmapRevFilter does + // the work. + // + // filter.include returns true for commits that do not have + // a bitmap in bitmapIndex and are not reachable from a + // bitmap in bitmapIndex encountered earlier in the walk. + // Thus the number of commits returned by next() measures how + // much history was traversed without being able to make use + // of bitmaps. + pm.update(1); + } + + return bitmapResult; + } + + private BitmapBuilder asBitmapBuilder(Bitmap bitmap) { + return bitmapIndex.newBitmapBuilder().or(bitmap); + } +}