DescribeCommand.java
/*
* Copyright (C) 2013, CloudBees, Inc. and others
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0 which is available at
* https://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.eclipse.jgit.api;
import static org.eclipse.jgit.lib.Constants.R_REFS;
import static org.eclipse.jgit.lib.Constants.R_TAGS;
import static org.eclipse.jgit.lib.TypedConfigGetter.UNSET_INT;
import java.io.IOException;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.Date;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import org.eclipse.jgit.api.errors.GitAPIException;
import org.eclipse.jgit.api.errors.JGitInternalException;
import org.eclipse.jgit.api.errors.RefNotFoundException;
import org.eclipse.jgit.errors.IncorrectObjectTypeException;
import org.eclipse.jgit.errors.InvalidPatternException;
import org.eclipse.jgit.errors.MissingObjectException;
import org.eclipse.jgit.fnmatch.FileNameMatcher;
import org.eclipse.jgit.internal.JGitText;
import org.eclipse.jgit.lib.AbbrevConfig;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.Ref;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevFlag;
import org.eclipse.jgit.revwalk.RevFlagSet;
import org.eclipse.jgit.revwalk.RevTag;
import org.eclipse.jgit.revwalk.RevWalk;
/**
* Given a commit, show the most recent tag that is reachable from a commit.
*
* @since 3.2
*/
public class DescribeCommand extends GitCommand<String> {
private final RevWalk w;
/**
* Commit to describe.
*/
private RevCommit target;
/**
* How many tags we'll consider as candidates.
* This can only go up to the number of flags JGit can support in a walk,
* which is 24.
*/
private int maxCandidates = 10;
/**
* Whether to always use long output format or not.
*/
private boolean longDesc;
/**
* Pattern matchers to be applied to tags under consideration.
*/
private List<FileNameMatcher> matchers = new ArrayList<>();
/**
* Whether to use all refs in the refs/ namespace
*/
private boolean useAll;
/**
* Whether to use all tags (incl. lightweight) or not.
*/
private boolean useTags;
/**
* Whether to show a uniquely abbreviated commit hash as a fallback or not.
*/
private boolean always;
/**
* The prefix length to use when abbreviating a commit hash.
*/
private int abbrev = UNSET_INT;
/**
* Constructor for DescribeCommand.
*
* @param repo
* the {@link org.eclipse.jgit.lib.Repository}
*/
protected DescribeCommand(Repository repo) {
super(repo);
w = new RevWalk(repo);
w.setRetainBody(false);
}
/**
* Sets the commit to be described.
*
* @param target
* A non-null object ID to be described.
* @return {@code this}
* @throws MissingObjectException
* the supplied commit does not exist.
* @throws IncorrectObjectTypeException
* the supplied id is not a commit or an annotated tag.
* @throws java.io.IOException
* a pack file or loose object could not be read.
*/
public DescribeCommand setTarget(ObjectId target) throws IOException {
this.target = w.parseCommit(target);
return this;
}
/**
* Sets the commit to be described.
*
* @param rev
* Commit ID, tag, branch, ref, etc. See
* {@link org.eclipse.jgit.lib.Repository#resolve(String)} for
* allowed syntax.
* @return {@code this}
* @throws IncorrectObjectTypeException
* the supplied id is not a commit or an annotated tag.
* @throws org.eclipse.jgit.api.errors.RefNotFoundException
* the given rev didn't resolve to any object.
* @throws java.io.IOException
* a pack file or loose object could not be read.
*/
public DescribeCommand setTarget(String rev) throws IOException,
RefNotFoundException {
ObjectId id = repo.resolve(rev);
if (id == null)
throw new RefNotFoundException(MessageFormat.format(JGitText.get().refNotResolved, rev));
return setTarget(id);
}
/**
* Determine whether always to use the long format or not. When set to
* <code>true</code> the long format is used even the commit matches a tag.
*
* @param longDesc
* <code>true</code> if always the long format should be used.
* @return {@code this}
* @see <a
* href="https://www.kernel.org/pub/software/scm/git/docs/git-describe.html"
* >Git documentation about describe</a>
* @since 4.0
*/
public DescribeCommand setLong(boolean longDesc) {
this.longDesc = longDesc;
return this;
}
/**
* Instead of using only the annotated tags, use any ref found in refs/
* namespace. This option enables matching any known branch,
* remote-tracking branch, or lightweight tag.
*
* @param all
* <code>true</code> enables matching any ref found in refs/
* like setting option --all in c git
* @return {@code this}
* @since 5.10
*/
public DescribeCommand setAll(boolean all) {
this.useAll = all;
return this;
}
/**
* Instead of using only the annotated tags, use any tag found in refs/tags
* namespace. This option enables matching lightweight (non-annotated) tags
* or not.
*
* @param tags
* <code>true</code> enables matching lightweight (non-annotated)
* tags like setting option --tags in c git
* @return {@code this}
* @since 5.0
*/
public DescribeCommand setTags(boolean tags) {
this.useTags = tags;
return this;
}
/**
* Always describe the commit by eventually falling back to a uniquely
* abbreviated commit hash if no other name matches.
*
* @param always
* <code>true</code> enables falling back to a uniquely
* abbreviated commit hash
* @return {@code this}
* @since 5.4
*/
public DescribeCommand setAlways(boolean always) {
this.always = always;
return this;
}
/**
* Sets the prefix length to use when abbreviating an object SHA-1.
*
* @param abbrev
* minimum length of the abbreviated string. Must be in the range
* [{@value AbbrevConfig#MIN_ABBREV},
* {@value Constants#OBJECT_ID_STRING_LENGTH}].
* @return {@code this}
* @since 6.1
*/
public DescribeCommand setAbbrev(int abbrev) {
if (abbrev == 0) {
this.abbrev = 0;
} else {
this.abbrev = AbbrevConfig.capAbbrev(abbrev);
}
return this;
}
private String longDescription(Ref tag, int depth, ObjectId tip)
throws IOException {
if (abbrev == 0) {
return formatRefName(tag.getName());
}
return String.format("%s-%d-g%s", formatRefName(tag.getName()), //$NON-NLS-1$
Integer.valueOf(depth),
w.getObjectReader().abbreviate(tip, abbrev).name());
}
/**
* Sets one or more {@code glob(7)} patterns that tags must match to be
* considered. If multiple patterns are provided, tags only need match one
* of them.
*
* @param patterns
* the {@code glob(7)} pattern or patterns
* @return {@code this}
* @throws org.eclipse.jgit.errors.InvalidPatternException
* if the pattern passed in was invalid.
* @see <a href=
* "https://www.kernel.org/pub/software/scm/git/docs/git-describe.html"
* >Git documentation about describe</a>
* @since 4.9
*/
public DescribeCommand setMatch(String... patterns) throws InvalidPatternException {
for (String p : patterns) {
matchers.add(new FileNameMatcher(p, null));
}
return this;
}
private final Comparator<Ref> TAG_TIE_BREAKER = new Comparator<>() {
@Override
public int compare(Ref o1, Ref o2) {
try {
return tagDate(o2).compareTo(tagDate(o1));
} catch (IOException e) {
return 0;
}
}
private Date tagDate(Ref tag) throws IOException {
RevTag t = w.parseTag(tag.getObjectId());
w.parseBody(t);
return t.getTaggerIdent().getWhen();
}
};
private Optional<Ref> getBestMatch(List<Ref> tags) {
if (tags == null || tags.isEmpty()) {
return Optional.empty();
} else if (matchers.isEmpty()) {
Collections.sort(tags, TAG_TIE_BREAKER);
return Optional.of(tags.get(0));
} else {
// Find the first tag that matches in the stream of all tags
// filtered by matchers ordered by tie break order
Stream<Ref> matchingTags = Stream.empty();
for (FileNameMatcher matcher : matchers) {
Stream<Ref> m = tags.stream().filter(
tag -> {
matcher.append(formatRefName(tag.getName()));
boolean result = matcher.isMatch();
matcher.reset();
return result;
});
matchingTags = Stream.of(matchingTags, m).flatMap(i -> i);
}
return matchingTags.sorted(TAG_TIE_BREAKER).findFirst();
}
}
private ObjectId getObjectIdFromRef(Ref r) throws JGitInternalException {
try {
ObjectId key = repo.getRefDatabase().peel(r).getPeeledObjectId();
if (key == null) {
key = r.getObjectId();
}
return key;
} catch (IOException e) {
throw new JGitInternalException(e.getMessage(), e);
}
}
/**
* {@inheritDoc}
* <p>
* Describes the specified commit. Target defaults to HEAD if no commit was
* set explicitly.
*/
@Override
public String call() throws GitAPIException {
try {
checkCallable();
if (target == null) {
setTarget(Constants.HEAD);
}
if (abbrev == UNSET_INT) {
abbrev = AbbrevConfig.parseFromConfig(repo).get();
}
Collection<Ref> tagList = repo.getRefDatabase()
.getRefsByPrefix(useAll ? R_REFS : R_TAGS);
Map<ObjectId, List<Ref>> tags = tagList.stream()
.filter(this::filterLightweightTags)
.collect(Collectors.groupingBy(this::getObjectIdFromRef));
// combined flags of all the candidate instances
final RevFlagSet allFlags = new RevFlagSet();
/**
* Tracks the depth of each tag as we find them.
*/
class Candidate {
final Ref tag;
final RevFlag flag;
/**
* This field counts number of commits that are reachable from
* the tip but not reachable from the tag.
*/
int depth;
Candidate(RevCommit commit, Ref tag) {
this.tag = tag;
this.flag = w.newFlag(tag.getName());
// we'll mark all the nodes reachable from this tag accordingly
allFlags.add(flag);
w.carry(flag);
commit.add(flag);
// As of this writing, JGit carries a flag from a child to its parents
// right before RevWalk.next() returns, so all the flags that are added
// must be manually carried to its parents. If that gets fixed,
// this will be unnecessary.
commit.carry(flag);
}
/**
* Does this tag contain the given commit?
*/
boolean reaches(RevCommit c) {
return c.has(flag);
}
String describe(ObjectId tip) throws IOException {
return longDescription(tag, depth, tip);
}
}
List<Candidate> candidates = new ArrayList<>(); // all the candidates we find
// is the target already pointing to a suitable tag? if so, we are done!
Optional<Ref> bestMatch = getBestMatch(tags.get(target));
if (bestMatch.isPresent()) {
return longDesc ? longDescription(bestMatch.get(), 0, target) :
formatRefName(bestMatch.get().getName());
}
w.markStart(target);
int seen = 0; // commit seen thus far
RevCommit c;
while ((c = w.next()) != null) {
if (!c.hasAny(allFlags)) {
// if a tag already dominates this commit,
// then there's no point in picking a tag on this commit
// since the one that dominates it is always more preferable
bestMatch = getBestMatch(tags.get(c));
if (bestMatch.isPresent()) {
Candidate cd = new Candidate(c, bestMatch.get());
candidates.add(cd);
cd.depth = seen;
}
}
// if the newly discovered commit isn't reachable from a tag that we've seen
// it counts toward the total depth.
for (Candidate cd : candidates) {
if (!cd.reaches(c))
cd.depth++;
}
// if we have search going for enough tags, we will start
// closing down. JGit can only give us a finite number of bits,
// so we can't track all tags even if we wanted to.
if (candidates.size() >= maxCandidates)
break;
// TODO: if all the commits in the queue of RevWalk has allFlags
// there's no point in continuing search as we'll not discover any more
// tags. But RevWalk doesn't expose this.
seen++;
}
// at this point we aren't adding any more tags to our search,
// but we still need to count all the depths correctly.
while ((c = w.next()) != null) {
if (c.hasAll(allFlags)) {
// no point in visiting further from here, so cut the search here
for (RevCommit p : c.getParents())
p.add(RevFlag.SEEN);
} else {
for (Candidate cd : candidates) {
if (!cd.reaches(c))
cd.depth++;
}
}
}
// if all the nodes are dominated by all the tags, the walk stops
if (candidates.isEmpty()) {
return always
? w.getObjectReader()
.abbreviate(target,
AbbrevConfig.capAbbrev(abbrev))
.name()
: null;
}
Candidate best = Collections.min(candidates,
(Candidate o1, Candidate o2) -> o1.depth - o2.depth);
return best.describe(target);
} catch (IOException e) {
throw new JGitInternalException(e.getMessage(), e);
} finally {
setCallable(false);
w.close();
}
}
/**
* Removes the refs/ or refs/tags prefix from tag names
* @param name the name of the tag
* @return the tag name with its prefix removed
*/
private String formatRefName(String name) {
return name.startsWith(R_TAGS) ? name.substring(R_TAGS.length()) :
name.substring(R_REFS.length());
}
/**
* Whether we use lightweight tags or not for describe Candidates
*
* @param ref
* reference under inspection
* @return true if it should be used for describe or not regarding
* {@link org.eclipse.jgit.api.DescribeCommand#useTags}
*/
@SuppressWarnings("null")
private boolean filterLightweightTags(Ref ref) {
ObjectId id = ref.getObjectId();
try {
return this.useAll || this.useTags || (id != null && (w.parseTag(id) != null));
} catch (IOException e) {
return false;
}
}
}