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The "basic" reachability check walks the graph starting from the tips marking things as "uninteresting". If the target commit is marked as "uninteresting" it was reached; it is reachable from those tips. This requires a lot of walking and can be solved directly with bitmaps. Most of the time the bitmaps are already calculated or a short walk away. This should improve the performance of reachability checks, for example in Gitiles. Change-Id: I83d33271f58d95d2dc9ed151967b3eda513c99f7 Signed-off-by: Ivan Frade <ifrade@google.com>stable-5.5
Ivan Frade
5 years ago
2 changed files with 191 additions and 0 deletions
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/* |
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* Copyright (C) 2019, Google LLC |
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* and other copyright owners as documented in the project's IP log. |
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* |
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* This program and the accompanying materials are made available |
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* under the terms of the Eclipse Distribution License v1.0 which |
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* accompanies this distribution, is reproduced below, and is |
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* available at http://www.eclipse.org/org/documents/edl-v10.php
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* |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or |
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* without modification, are permitted provided that the following |
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* conditions are met: |
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* |
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* - Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* |
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* - Redistributions in binary form must reproduce the above |
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* copyright notice, this list of conditions and the following |
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* disclaimer in the documentation and/or other materials provided |
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* with the distribution. |
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* |
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* - Neither the name of the Eclipse Foundation, Inc. nor the |
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* names of its contributors may be used to endorse or promote |
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* products derived from this software without specific prior |
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* written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND |
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* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, |
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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*/ |
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package org.eclipse.jgit.revwalk; |
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import static org.junit.Assert.assertNotNull; |
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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 BitmappedReachabilityCheckerTest |
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extends ReachabilityCheckerTestCase { |
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@Override |
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protected ReachabilityChecker 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(repo.getRepository()); |
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gc.setAuto(false); |
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gc.gc(); |
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// This is null when the test didn't create any branch
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assertNotNull("Probably the test didn't define any ref", |
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repo.getRevWalk().getObjectReader().getBitmapIndex()); |
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return new BitmappedReachabilityChecker(repository.getRevWalk()); |
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} |
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} |
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/* |
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* Copyright (C) 2019, Google LLC |
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* and other copyright owners as documented in the project's IP log. |
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* |
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* This program and the accompanying materials are made available |
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* under the terms of the Eclipse Distribution License v1.0 which |
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* accompanies this distribution, is reproduced below, and is |
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* available at http://www.eclipse.org/org/documents/edl-v10.php
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* |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or |
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* without modification, are permitted provided that the following |
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* conditions are met: |
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* |
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* - Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* |
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* - Redistributions in binary form must reproduce the above |
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* copyright notice, this list of conditions and the following |
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* disclaimer in the documentation and/or other materials provided |
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* with the distribution. |
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* |
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* - Neither the name of the Eclipse Foundation, Inc. nor the |
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* names of its contributors may be used to endorse or promote |
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|
* products derived from this software without specific prior |
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|
* written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND |
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* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, |
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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|
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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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.Collection; |
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import java.util.List; |
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import java.util.Optional; |
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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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import org.eclipse.jgit.lib.NullProgressMonitor; |
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/** |
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* Checks the reachability using bitmaps. |
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* |
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* @since 5.5 |
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*/ |
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public class BitmappedReachabilityChecker implements ReachabilityChecker { |
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private final RevWalk walk; |
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/** |
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* @param walk |
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* walk on the repository to get or create the bitmaps for the |
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* commits. It must have bitmaps. |
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* @throws AssertionError |
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* runtime exception if walk is over a repository without |
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* bitmaps |
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* @throws IOException |
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* if the index or the object reader cannot be opened. |
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*/ |
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public BitmappedReachabilityChecker(RevWalk walk) |
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throws IOException { |
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this.walk = walk; |
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if (walk.getObjectReader().getBitmapIndex() == null) { |
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throw new AssertionError( |
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"Trying to use bitmapped reachability check " //$NON-NLS-1$
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+ "on a repository without bitmaps"); //$NON-NLS-1$
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} |
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} |
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/** |
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* Check all targets are reachable from the starters. |
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* <p> |
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* In this implementation, it is recommended to put the most popular |
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* starters (e.g. refs/heads tips) at the beginning of the collection |
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*/ |
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@Override |
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public Optional<RevCommit> areAllReachable(Collection<RevCommit> targets, |
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Collection<RevCommit> starters) throws MissingObjectException, |
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IncorrectObjectTypeException, IOException { |
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BitmapCalculator calculator = new BitmapCalculator(walk); |
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/** |
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* Iterate over starters bitmaps and remove targets as they become |
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* reachable. |
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* |
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* Building the total starters bitmap has the same cost (iterating over |
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* all starters adding the bitmaps) and this gives us the chance to |
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* shorcut the loop. |
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* |
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* This is based on the assuption that most of the starters will have |
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* the reachability bitmap precalculated. If many require a walk, the |
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* walk.reset() could start to take too much time. |
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*/ |
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List<RevCommit> remainingTargets = new ArrayList<>(targets); |
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for (RevCommit starter : starters) { |
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BitmapBuilder starterBitmap = calculator.getBitmap(starter, |
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NullProgressMonitor.INSTANCE); |
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remainingTargets.removeIf(starterBitmap::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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} |
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} |
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