com.google.gerrit.server.git.GroupCollector Maven / Gradle / Ivy
// Copyright (C) 2015 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.git;
import static com.google.common.base.Preconditions.checkState;
import static org.eclipse.jgit.revwalk.RevFlag.UNINTERESTING;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import com.google.common.collect.ListMultimap;
import com.google.common.collect.MultimapBuilder;
import com.google.common.collect.SetMultimap;
import com.google.common.collect.Sets;
import com.google.common.collect.SortedSetMultimap;
import com.google.common.flogger.FluentLogger;
import com.google.gerrit.entities.PatchSet;
import com.google.gerrit.entities.Project;
import com.google.gerrit.server.PatchSetUtil;
import com.google.gerrit.server.change.RevisionResource;
import com.google.gerrit.server.git.receive.ReceivePackRefCache;
import com.google.gerrit.server.notedb.ChangeNotes;
import java.io.IOException;
import java.util.ArrayDeque;
import java.util.Collection;
import java.util.Deque;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeSet;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.revwalk.RevCommit;
/**
* Helper for assigning groups to commits during {@code ReceiveCommits}.
*
* For each commit encountered along a walk between the branch tip and the tip of the push, the
* group of a commit is defined as follows:
*
*
* - If the commit is an existing patch set of a change, the group is read from the group field
* in the corresponding {@link PatchSet} record.
*
- If all of a commit's parents are merged into the branch, then its group is its own SHA-1.
*
- If the commit has a single parent that is not yet merged into the branch, then its group is
* the same as the parent's group.
*
-
*
- For a merge commit, choose a parent and use that parent's group. If one of the parents has
* a group from a patch set, use that group, otherwise, use the group from the first parent.
* In addition to setting this merge commit's group, use the chosen group for all commits that
* would otherwise use a group from the parents that were not chosen.
*
- If a merge commit has multiple parents whose group comes from separate patch sets,
* concatenate the groups from those parents together. This indicates two side branches were
* pushed separately, followed by the merge.
*
-
*
*
* Callers must call {@link #visit(RevCommit)} on all commits between the current branch tip and
* the tip of a push, in reverse topo order (parents before children). Once all commits have been
* visited, call {@link #getGroups()} for the result.
*/
public class GroupCollector {
private static final FluentLogger logger = FluentLogger.forEnclosingClass();
public static List getDefaultGroups(ObjectId commit) {
return ImmutableList.of(commit.name());
}
public static List getGroups(RevisionResource rsrc) {
if (rsrc.getEdit().isPresent()) {
// Groups for an edit are just the base revision's groups, since they have
// the same parent.
return rsrc.getEdit().get().getBasePatchSet().groups();
}
return rsrc.getPatchSet().groups();
}
interface Lookup {
List lookup(PatchSet.Id psId);
}
private final ReceivePackRefCache receivePackRefCache;
private final ListMultimap groups;
private final SetMultimap groupAliases;
private final Lookup groupLookup;
private boolean done;
/**
* Returns a new {@link GroupCollector} instance.
*
* @see GroupCollector for what this class does.
*/
public static GroupCollector create(
ReceivePackRefCache receivePackRefCache,
PatchSetUtil psUtil,
ChangeNotes.Factory notesFactory,
Project.NameKey project) {
return new GroupCollector(
receivePackRefCache,
psId -> {
// TODO(dborowitz): Reuse open repository from caller.
ChangeNotes notes = notesFactory.createChecked(project, psId.changeId());
PatchSet ps = psUtil.get(notes, psId);
return ps != null ? ps.groups() : null;
});
}
/**
* Returns a new {@link GroupCollector} instance.
*
* Used in production code by using {@link com.google.gerrit.server.notedb.ChangeNotes.Factory}
* to get a group SHA1 (40 bytes string representation) from a {@link
* com.google.gerrit.entities.PatchSet.Id}. Unit tests use this method directly by passing their
* own lookup function.
*
* @see GroupCollector for what this class does.
*/
@VisibleForTesting
GroupCollector(ReceivePackRefCache receivePackRefCache, Lookup groupLookup) {
this.receivePackRefCache = receivePackRefCache;
this.groupLookup = groupLookup;
groups = MultimapBuilder.hashKeys().arrayListValues().build();
groupAliases = MultimapBuilder.hashKeys().hashSetValues().build();
}
/**
* Process the given {@link RevCommit}. Callers must call {@link #visit(RevCommit)} on all commits
* between the current branch tip and the tip of a push, in reverse topo order (parents before
* children). Once all commits have been visited, call {@link #getGroups()} for the result.
*
* @see GroupCollector for what this class does.
*/
public void visit(RevCommit c) throws IOException {
checkState(!done, "visit() called after getGroups()");
Set interestingParents = getInterestingParents(c);
if (interestingParents.isEmpty()) {
// All parents are uninteresting: treat this commit as the root of a new
// group of related changes.
groups.put(c, c.name());
return;
} else if (interestingParents.size() == 1) {
// Only one parent is new in this push. If it is the only parent, just use
// that parent's group. If there are multiple parents, perhaps this commit
// is a merge of a side branch. This commit belongs in that parent's group
// in that case.
groups.putAll(c, groups.get(interestingParents.iterator().next()));
return;
}
// Multiple parents, merging at least two branches containing new commits in
// this push.
Set thisCommitGroups = new TreeSet<>();
Set parentGroupsNewInThisPush =
Sets.newLinkedHashSetWithExpectedSize(interestingParents.size());
for (RevCommit p : interestingParents) {
Collection parentGroups = groups.get(p);
if (parentGroups.isEmpty()) {
throw new IllegalStateException(
String.format("no group assigned to parent %s of commit %s", p.name(), c.name()));
}
for (String parentGroup : parentGroups) {
if (isGroupFromExistingPatchSet(p, parentGroup)) {
// This parent's group is from an existing patch set, i.e. the parent
// not new in this push. Use this group for the commit.
thisCommitGroups.add(parentGroup);
} else {
// This parent's group is new in this push.
parentGroupsNewInThisPush.add(parentGroup);
}
}
}
Iterable toAlias;
if (thisCommitGroups.isEmpty()) {
// All parent groups were new in this push. Pick the first one and alias
// other parents' groups to this first parent.
String firstParentGroup = parentGroupsNewInThisPush.iterator().next();
thisCommitGroups = ImmutableSet.of(firstParentGroup);
toAlias = Iterables.skip(parentGroupsNewInThisPush, 1);
} else {
// For each parent group that was new in this push, alias it to the actual
// computed group(s) for this commit.
toAlias = parentGroupsNewInThisPush;
}
groups.putAll(c, thisCommitGroups);
for (String pg : toAlias) {
groupAliases.putAll(pg, thisCommitGroups);
}
}
/**
* Returns the groups that got collected from visiting commits using {@link #visit(RevCommit)}.
*/
public SortedSetMultimap getGroups() throws IOException {
done = true;
SortedSetMultimap result =
MultimapBuilder.hashKeys(groups.keySet().size()).treeSetValues().build();
for (Map.Entry> e : groups.asMap().entrySet()) {
ObjectId id = e.getKey();
result.putAll(id.copy(), resolveGroups(id, e.getValue()));
}
return result;
}
private Set getInterestingParents(RevCommit commit) {
Set result = Sets.newLinkedHashSetWithExpectedSize(commit.getParentCount());
for (RevCommit p : commit.getParents()) {
if (!p.has(UNINTERESTING)) {
result.add(p);
}
}
return result;
}
private boolean isGroupFromExistingPatchSet(RevCommit commit, String group) throws IOException {
ObjectId id = parseGroup(commit, group);
return id != null && !receivePackRefCache.patchSetIdsFromObjectId(id).isEmpty();
}
private Set resolveGroups(ObjectId forCommit, Collection candidates)
throws IOException {
Set actual = Sets.newTreeSet();
Set done = Sets.newHashSetWithExpectedSize(candidates.size());
Set seen = Sets.newHashSetWithExpectedSize(candidates.size());
Deque todo = new ArrayDeque<>(candidates);
// BFS through all aliases to find groups that are not aliased to anything
// else.
while (!todo.isEmpty()) {
String g = todo.removeFirst();
if (!seen.add(g)) {
continue;
}
Set aliases = groupAliases.get(g);
if (aliases.isEmpty()) {
if (!done.contains(g)) {
Iterables.addAll(actual, resolveGroup(forCommit, g));
done.add(g);
}
} else {
todo.addAll(aliases);
}
}
return actual;
}
private ObjectId parseGroup(ObjectId forCommit, String group) {
try {
return ObjectId.fromString(group);
} catch (IllegalArgumentException e) {
// Shouldn't happen; some sort of corruption or manual tinkering?
logger.atWarning().log("group for commit %s is not a SHA-1: %s", forCommit.name(), group);
return null;
}
}
private Iterable resolveGroup(ObjectId forCommit, String group) throws IOException {
ObjectId id = parseGroup(forCommit, group);
if (id != null) {
PatchSet.Id psId = Iterables.getFirst(receivePackRefCache.patchSetIdsFromObjectId(id), null);
if (psId != null) {
List groups = groupLookup.lookup(psId);
// Group for existing patch set may be missing, e.g. if group has not
// been migrated yet.
if (groups != null && !groups.isEmpty()) {
return groups;
}
}
}
return ImmutableList.of(group);
}
}