Merge changes from topic 'reachability-2'

* changes:
  UploadPack: Use reachability checker to validate non-advertised wants
  BitmappedReachabilityChecker: Reachability check using bitmaps
  BitmapCalculator: Get the reachability bitmap of a commit
  ReachabilityChecker: Default implementation with a RevWalk

4 files changed, 433 insertions, 0 deletions

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 0000000000..3a78e1e623
--- /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<FileRepository> 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.test/tst/org/eclipse/jgit/revwalk/BitmappedReachabilityCheckerTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/BitmappedReachabilityCheckerTest.java
new file mode 100644
index 0000000000..5d3adf5eab
--- /dev/null
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/BitmappedReachabilityCheckerTest.java
@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2019, Google LLC
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ *   names of its contributors may be used to endorse or promote
+ *   products derived from this software without specific prior
+ *   written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.eclipse.jgit.revwalk;
+
+import static org.junit.Assert.assertNotNull;
+
+import org.eclipse.jgit.internal.storage.file.FileRepository;
+import org.eclipse.jgit.internal.storage.file.GC;
+import org.eclipse.jgit.junit.TestRepository;
+
+public class BitmappedReachabilityCheckerTest
+		extends ReachabilityCheckerTestCase {
+
+	@Override
+	protected ReachabilityChecker getChecker(
+			TestRepository<FileRepository> repository) throws Exception {
+		// GC generates the bitmaps
+		GC gc = new GC(repo.getRepository());
+		gc.setAuto(false);
+		gc.gc();
+
+		// This is null when the test didn't create any branch
+		assertNotNull("Probably the test didn't define any ref",
+				repo.getRevWalk().getObjectReader().getBitmapIndex());
+
+		return new BitmappedReachabilityChecker(repository.getRevWalk());
+	}
+
+}
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/PedestrianReachabilityCheckerTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/PedestrianReachabilityCheckerTest.java
new file mode 100644
index 0000000000..8d3e78c1fe
--- /dev/null
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/PedestrianReachabilityCheckerTest.java
@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) 2019, Google LLC.
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ *   names of its contributors may be used to endorse or promote
+ *   products derived from this software without specific prior
+ *   written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.eclipse.jgit.revwalk;
+
+import org.eclipse.jgit.internal.storage.file.FileRepository;
+import org.eclipse.jgit.junit.TestRepository;
+
+public class PedestrianReachabilityCheckerTest
+		extends ReachabilityCheckerTestCase {
+
+	@Override
+	protected ReachabilityChecker getChecker(
+			TestRepository<FileRepository> repository) {
+		return new PedestrianReachabilityChecker(true, repository.getRevWalk());
+	}
+
+}
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/ReachabilityCheckerTestCase.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/ReachabilityCheckerTestCase.java
new file mode 100644
index 0000000000..dd73e35727
--- /dev/null
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/ReachabilityCheckerTestCase.java
@@ -0,0 +1,168 @@
+/*
+ * Copyright (C) 2019, Google LLC.
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ *   names of its contributors may be used to endorse or promote
+ *   products derived from this software without specific prior
+ *   written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.eclipse.jgit.revwalk;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import java.util.Arrays;
+import java.util.Optional;
+
+import org.eclipse.jgit.internal.storage.file.FileRepository;
+import org.eclipse.jgit.junit.LocalDiskRepositoryTestCase;
+import org.eclipse.jgit.junit.TestRepository;
+import org.junit.Before;
+import org.junit.Test;
+
+public abstract class ReachabilityCheckerTestCase
+		extends LocalDiskRepositoryTestCase {
+
+	protected abstract ReachabilityChecker getChecker(
+			TestRepository<FileRepository> repository) throws Exception;
+
+	TestRepository<FileRepository> repo;
+
+	/** {@inheritDoc} */
+	@Override
+	@Before
+	public void setUp() throws Exception {
+		super.setUp();
+		FileRepository db = createWorkRepository();
+		repo = new TestRepository<>(db);
+	}
+
+	@Test
+	public void reachable() throws Exception {
+		RevCommit a = repo.commit().create();
+		RevCommit b1 = repo.commit(a);
+		RevCommit b2 = repo.commit(b1);
+		RevCommit c1 = repo.commit(a);
+		RevCommit c2 = repo.commit(c1);
+		repo.update("refs/heads/checker", b2);
+
+		ReachabilityChecker checker = getChecker(repo);
+
+		assertReachable("reachable from one tip",
+				checker.areAllReachable(Arrays.asList(a), Arrays.asList(c2)));
+		assertReachable("reachable from another tip",
+				checker.areAllReachable(Arrays.asList(a), Arrays.asList(b2)));
+		assertReachable("reachable from itself",
+				checker.areAllReachable(Arrays.asList(a), Arrays.asList(b2)));
+	}
+
+	@Test
+	public void reachable_merge() throws Exception {
+		RevCommit a = repo.commit().create();
+		RevCommit b1 = repo.commit(a);
+		RevCommit b2 = repo.commit(b1);
+		RevCommit c1 = repo.commit(a);
+		RevCommit c2 = repo.commit(c1);
+		RevCommit merge = repo.commit(c2, b2);
+		repo.update("refs/heads/checker", merge);
+
+		ReachabilityChecker checker = getChecker(repo);
+
+		assertReachable("reachable through one branch",
+				checker.areAllReachable(Arrays.asList(b1),
+						Arrays.asList(merge)));
+		assertReachable("reachable through another branch",
+				checker.areAllReachable(Arrays.asList(c1),
+						Arrays.asList(merge)));
+		assertReachable("reachable, before the branching",
+				checker.areAllReachable(Arrays.asList(a),
+						Arrays.asList(merge)));
+	}
+
+	@Test
+	public void unreachable_isLaterCommit() throws Exception {
+		RevCommit a = repo.commit().create();
+		RevCommit b1 = repo.commit(a);
+		RevCommit b2 = repo.commit(b1);
+		repo.update("refs/heads/checker", b2);
+
+		ReachabilityChecker checker = getChecker(repo);
+
+		assertUnreachable("unreachable from the future",
+				checker.areAllReachable(Arrays.asList(b2), Arrays.asList(b1)));
+	}
+
+	@Test
+	public void unreachable_differentBranch() throws Exception {
+		RevCommit a = repo.commit().create();
+		RevCommit b1 = repo.commit(a);
+		RevCommit b2 = repo.commit(b1);
+		RevCommit c1 = repo.commit(a);
+		repo.update("refs/heads/checker", b2);
+
+		ReachabilityChecker checker = getChecker(repo);
+
+		assertUnreachable("unreachable from different branch",
+				checker.areAllReachable(Arrays.asList(c1), Arrays.asList(b2)));
+	}
+
+	@Test
+	public void reachable_longChain() throws Exception {
+		RevCommit root = repo.commit().create();
+		RevCommit head = root;
+		for (int i = 0; i < 10000; i++) {
+			head = repo.commit(head);
+		}
+		repo.update("refs/heads/master", head);
+
+		ReachabilityChecker checker = getChecker(repo);
+
+		assertReachable("reachable with long chain in the middle", checker
+				.areAllReachable(Arrays.asList(root), Arrays.asList(head)));
+	}
+
+	private static void assertReachable(String msg,
+			Optional<RevCommit> result) {
+		assertFalse(msg, result.isPresent());
+	}
+
+	private static void assertUnreachable(String msg,
+			Optional<RevCommit> result) {
+		assertTrue(msg, result.isPresent());
+	}
+
+}