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// Copyright (C) 2013 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.gerrit.server.change;
import static com.google.common.collect.ImmutableSortedSet.toImmutableSortedSet;
import static java.util.Comparator.comparing;
import static java.util.Comparator.naturalOrder;
import static java.util.stream.Collectors.toList;
import com.google.auto.value.AutoValue;
import com.google.common.collect.ImmutableSortedSet;
import com.google.common.collect.LinkedListMultimap;
import com.google.common.collect.ListMultimap;
import com.google.common.collect.Lists;
import com.google.common.flogger.FluentLogger;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import org.eclipse.jgit.errors.IncorrectObjectTypeException;
import org.eclipse.jgit.errors.MissingObjectException;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.Ref;
import org.eclipse.jgit.lib.RefDatabase;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevFlag;
import org.eclipse.jgit.revwalk.RevWalk;
/** Resolve in which tags and branches a commit is included. */
public class IncludedInResolver {
private static final FluentLogger logger = FluentLogger.forEnclosingClass();
public static Result resolve(Repository repo, RevWalk rw, RevCommit commit) throws IOException {
RevFlag flag = newFlag(rw);
try {
return new IncludedInResolver(repo, rw, commit, flag).resolve();
} finally {
rw.disposeFlag(flag);
}
}
public static boolean includedInAny(
final Repository repo, RevWalk rw, RevCommit commit, Collection<Ref> refs)
throws IOException {
if (refs.isEmpty()) {
return false;
}
RevFlag flag = newFlag(rw);
try {
return new IncludedInResolver(repo, rw, commit, flag).includedInOne(refs);
} finally {
rw.disposeFlag(flag);
}
}
private static RevFlag newFlag(RevWalk rw) {
return rw.newFlag("CONTAINS_TARGET");
}
private final Repository repo;
private final RevWalk rw;
private final RevCommit target;
private final RevFlag containsTarget;
private ListMultimap<RevCommit, String> commitToRef;
private List<RevCommit> tipsByCommitTime;
private IncludedInResolver(
Repository repo, RevWalk rw, RevCommit target, RevFlag containsTarget) {
this.repo = repo;
this.rw = rw;
this.target = target;
this.containsTarget = containsTarget;
}
private Result resolve() throws IOException {
RefDatabase refDb = repo.getRefDatabase();
Collection<Ref> tags = refDb.getRefsByPrefix(Constants.R_TAGS);
Collection<Ref> branches = refDb.getRefsByPrefix(Constants.R_HEADS);
List<Ref> allTagsAndBranches = Lists.newArrayListWithCapacity(tags.size() + branches.size());
allTagsAndBranches.addAll(tags);
allTagsAndBranches.addAll(branches);
parseCommits(allTagsAndBranches);
Set<String> allMatchingTagsAndBranches = includedIn(tipsByCommitTime, 0);
return new AutoValue_IncludedInResolver_Result(
getMatchingRefNames(allMatchingTagsAndBranches, branches),
getMatchingRefNames(allMatchingTagsAndBranches, tags));
}
private boolean includedInOne(Collection<Ref> refs) throws IOException {
parseCommits(refs);
List<RevCommit> before = new ArrayList<>();
List<RevCommit> after = new ArrayList<>();
partition(before, after);
rw.reset();
// It is highly likely that the target is reachable from the "after" set
// Within the "before" set we are trying to handle cases arising from clock skew
return !includedIn(after, 1).isEmpty() || !includedIn(before, 1).isEmpty();
}
/** Resolves which tip refs include the target commit. */
private Set<String> includedIn(Collection<RevCommit> tips, int limit)
throws IOException, MissingObjectException, IncorrectObjectTypeException {
Set<String> result = new HashSet<>();
for (RevCommit tip : tips) {
boolean commitFound = false;
rw.resetRetain(RevFlag.UNINTERESTING, containsTarget);
rw.markStart(tip);
for (RevCommit commit : rw) {
if (commit.equals(target) || commit.has(containsTarget)) {
commitFound = true;
tip.add(containsTarget);
result.addAll(commitToRef.get(tip));
break;
}
}
if (!commitFound) {
rw.markUninteresting(tip);
} else if (0 < limit && limit < result.size()) {
break;
}
}
return result;
}
/**
* Partition the reference tips into two sets:
*
* <ul>
* <li>before = commits with time < target.getCommitTime()
* <li>after = commits with time >= target.getCommitTime()
* </ul>
*
* Each of the before/after lists is sorted by the commit time.
*
* @param before
* @param after
*/
private void partition(List<RevCommit> before, List<RevCommit> after) {
int insertionPoint =
Collections.binarySearch(tipsByCommitTime, target, comparing(RevCommit::getCommitTime));
if (insertionPoint < 0) {
insertionPoint = -(insertionPoint + 1);
}
if (0 < insertionPoint) {
before.addAll(tipsByCommitTime.subList(0, insertionPoint));
}
if (insertionPoint < tipsByCommitTime.size()) {
after.addAll(tipsByCommitTime.subList(insertionPoint, tipsByCommitTime.size()));
}
}
/**
* Returns the short names of refs which are as well in the matchingRefs list as well as in the
* allRef list.
*/
private static ImmutableSortedSet<String> getMatchingRefNames(
Set<String> matchingRefs, Collection<Ref> allRefs) {
return allRefs
.stream()
.map(Ref::getName)
.filter(matchingRefs::contains)
.map(Repository::shortenRefName)
.collect(toImmutableSortedSet(naturalOrder()));
}
/** Parse commit of ref and store the relation between ref and commit. */
private void parseCommits(Collection<Ref> refs) throws IOException {
if (commitToRef != null) {
return;
}
commitToRef = LinkedListMultimap.create();
for (Ref ref : refs) {
final RevCommit commit;
try {
commit = rw.parseCommit(ref.getObjectId());
} catch (IncorrectObjectTypeException notCommit) {
// Its OK for a tag reference to point to a blob or a tree, this
// is common in the Linux kernel or git.git repository.
//
continue;
} catch (MissingObjectException notHere) {
// Log the problem with this branch, but keep processing.
//
logger.atWarning().log(
"Reference %s in %s points to dangling object %s",
ref.getName(), repo.getDirectory(), ref.getObjectId());
continue;
}
commitToRef.put(commit, ref.getName());
}
tipsByCommitTime =
commitToRef.keySet().stream().sorted(comparing(RevCommit::getCommitTime)).collect(toList());
}
@AutoValue
public abstract static class Result {
public abstract ImmutableSortedSet<String> branches();
public abstract ImmutableSortedSet<String> tags();
}
}
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