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/*
* 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 java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Optional;
import org.eclipse.jgit.errors.IncorrectObjectTypeException;
import org.eclipse.jgit.errors.MissingObjectException;
import org.eclipse.jgit.lib.BitmapIndex.BitmapBuilder;
import org.eclipse.jgit.lib.NullProgressMonitor;
/**
* Checks the reachability using bitmaps.
*/
class BitmappedReachabilityChecker implements ReachabilityChecker {
private final RevWalk walk;
/**
* @param walk
* walk on the repository to get or create the bitmaps for the
* commits. It must have bitmaps.
* @throws AssertionError
* runtime exception if walk is over a repository without
* bitmaps
* @throws IOException
* if the index or the object reader cannot be opened.
*/
public BitmappedReachabilityChecker(RevWalk walk)
throws IOException {
this.walk = walk;
if (walk.getObjectReader().getBitmapIndex() == null) {
throw new AssertionError(
"Trying to use bitmapped reachability check " //$NON-NLS-1$
+ "on a repository without bitmaps"); //$NON-NLS-1$
}
}
/**
* Check all targets are reachable from the starters.
* <p>
* In this implementation, it is recommended to put the most popular
* starters (e.g. refs/heads tips) at the beginning of the collection
*/
@Override
public Optional<RevCommit> areAllReachable(Collection<RevCommit> targets,
Collection<RevCommit> starters) throws MissingObjectException,
IncorrectObjectTypeException, IOException {
BitmapCalculator calculator = new BitmapCalculator(walk);
/**
* Iterate over starters bitmaps and remove targets as they become
* reachable.
*
* Building the total starters bitmap has the same cost (iterating over
* all starters adding the bitmaps) and this gives us the chance to
* shorcut the loop.
*
* This is based on the assuption that most of the starters will have
* the reachability bitmap precalculated. If many require a walk, the
* walk.reset() could start to take too much time.
*/
List<RevCommit> remainingTargets = new ArrayList<>(targets);
for (RevCommit starter : starters) {
BitmapBuilder starterBitmap = calculator.getBitmap(starter,
NullProgressMonitor.INSTANCE);
remainingTargets.removeIf(starterBitmap::contains);
if (remainingTargets.isEmpty()) {
return Optional.empty();
}
}
return Optional.of(remainingTargets.get(0));
}
}
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