revwalk: Introduce bitmap-based object reachability checker
Change-Id: I0b1a2bd21f98894862aab339f8c2e4a417897b89 Signed-off-by: Ivan Frade <ifrade@google.com>
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/*
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* Copyright (C) 2020, Google LLC and others
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*
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* This program and the accompanying materials are made available under the
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* terms of the Eclipse Distribution License v. 1.0 which is available at
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* https://www.eclipse.org/org/documents/edl-v10.php.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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package org.eclipse.jgit.revwalk;
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import org.eclipse.jgit.internal.storage.file.FileRepository;
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import org.eclipse.jgit.internal.storage.file.GC;
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import org.eclipse.jgit.junit.TestRepository;
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public class BitmappedObjectReachabilityTest
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extends ObjectReachabilityTestCase {
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@Override
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ObjectReachabilityChecker getChecker(
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TestRepository<FileRepository> repository) throws Exception {
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// GC generates the bitmaps
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GC gc = new GC(repository.getRepository());
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gc.setAuto(false);
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gc.gc();
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return new BitmappedObjectReachabilityChecker(
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repository.getRevWalk().toObjectWalkWithSameObjects());
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}
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}
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/*
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* Copyright (C) 2020, Google LLC and others
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*
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* This program and the accompanying materials are made available under the
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* terms of the Eclipse Distribution License v. 1.0 which is available at
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* https://www.eclipse.org/org/documents/edl-v10.php.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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package org.eclipse.jgit.revwalk;
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import java.io.IOException;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.Collection;
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import java.util.Iterator;
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import java.util.List;
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import java.util.Optional;
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import java.util.stream.Stream;
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import org.eclipse.jgit.errors.IncorrectObjectTypeException;
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import org.eclipse.jgit.errors.MissingObjectException;
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import org.eclipse.jgit.lib.BitmapIndex.BitmapBuilder;
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/**
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* Checks if all objects are reachable from certain starting points using
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* bitmaps.
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*/
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public class BitmappedObjectReachabilityChecker
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implements ObjectReachabilityChecker {
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private ObjectWalk walk;
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/**
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* New instance of the reachability checker using a existing walk.
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*
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* @param walk
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* ObjectWalk instance to reuse. Caller retains ownership.
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*/
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public BitmappedObjectReachabilityChecker(ObjectWalk walk) {
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this.walk = walk;
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}
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/**
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* {@inheritDoc}
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*
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* This implementation tries to shortcut the check adding starters
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* incrementally. Ordering the starters by relevance can improve performance
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* in the average case.
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*/
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@Override
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public Optional<RevObject> areAllReachable(Collection<RevObject> targets,
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Stream<RevObject> starters) throws IOException {
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try {
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List<RevObject> remainingTargets = new ArrayList<>(targets);
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BitmapWalker bitmapWalker = new BitmapWalker(walk,
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walk.getObjectReader().getBitmapIndex(), null);
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Iterator<RevObject> starterIt = starters.iterator();
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BitmapBuilder seen = null;
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while (starterIt.hasNext()) {
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List<RevObject> asList = Arrays.asList(starterIt.next());
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BitmapBuilder visited = bitmapWalker.findObjects(asList, seen,
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true);
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seen = seen == null ? visited : seen.or(visited);
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remainingTargets.removeIf(seen::contains);
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if (remainingTargets.isEmpty()) {
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return Optional.empty();
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}
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}
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return Optional.of(remainingTargets.get(0));
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} catch (MissingObjectException | IncorrectObjectTypeException e) {
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throw new IllegalStateException(e);
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}
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}
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}
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