// 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.change;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.auto.value.AutoValue;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ListMultimap;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.common.collect.MultimapBuilder;
import com.google.gerrit.reviewdb.client.Change;
import com.google.gerrit.reviewdb.client.PatchSet;
import com.google.gerrit.reviewdb.client.Project;
import com.google.gerrit.server.git.GitRepositoryManager;
import com.google.gerrit.server.project.ProjectControl;
import com.google.gerrit.server.query.change.ChangeData;
import com.google.gwtorm.server.OrmException;
import com.google.inject.Inject;
import com.google.inject.Singleton;
import java.io.IOException;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Deque;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevWalk;
@Singleton
class RelatedChangesSorter {
private final GitRepositoryManager repoManager;
@Inject
RelatedChangesSorter(GitRepositoryManager repoManager) {
this.repoManager = repoManager;
}
public List<PatchSetData> sort(List<ChangeData> in, PatchSet startPs)
throws OrmException, IOException {
checkArgument(!in.isEmpty(), "Input may not be empty");
// Map of all patch sets, keyed by commit SHA-1.
Map<String, PatchSetData> byId = collectById(in);
PatchSetData start = byId.get(startPs.getRevision().get());
checkArgument(start != null, "%s not found in %s", startPs, in);
ProjectControl ctl = start.data().changeControl().getProjectControl();
// Map of patch set -> immediate parent.
ListMultimap<PatchSetData, PatchSetData> parents =
MultimapBuilder.hashKeys(in.size()).arrayListValues(3).build();
// Map of patch set -> immediate children.
ListMultimap<PatchSetData, PatchSetData> children =
MultimapBuilder.hashKeys(in.size()).arrayListValues(3).build();
// All other patch sets of the same change as startPs.
List<PatchSetData> otherPatchSetsOfStart = new ArrayList<>();
for (ChangeData cd : in) {
for (PatchSet ps : cd.patchSets()) {
PatchSetData thisPsd = checkNotNull(byId.get(ps.getRevision().get()));
if (cd.getId().equals(start.id()) && !ps.getId().equals(start.psId())) {
otherPatchSetsOfStart.add(thisPsd);
}
for (RevCommit p : thisPsd.commit().getParents()) {
PatchSetData parentPsd = byId.get(p.name());
if (parentPsd != null) {
parents.put(thisPsd, parentPsd);
children.put(parentPsd, thisPsd);
}
}
}
}
Collection<PatchSetData> ancestors = walkAncestors(ctl, parents, start);
List<PatchSetData> descendants =
walkDescendants(ctl, children, start, otherPatchSetsOfStart, ancestors);
List<PatchSetData> result = new ArrayList<>(ancestors.size() + descendants.size() - 1);
result.addAll(Lists.reverse(descendants));
result.addAll(ancestors);
return result;
}
private Map<String, PatchSetData> collectById(List<ChangeData> in)
throws OrmException, IOException {
Project.NameKey project = in.get(0).change().getProject();
Map<String, PatchSetData> result = Maps.newHashMapWithExpectedSize(in.size() * 3);
try (Repository repo = repoManager.openRepository(project);
RevWalk rw = new RevWalk(repo)) {
rw.setRetainBody(true);
for (ChangeData cd : in) {
checkArgument(
cd.change().getProject().equals(project),
"Expected change %s in project %s, found %s",
cd.getId(),
project,
cd.change().getProject());
for (PatchSet ps : cd.patchSets()) {
String id = ps.getRevision().get();
RevCommit c = rw.parseCommit(ObjectId.fromString(id));
PatchSetData psd = PatchSetData.create(cd, ps, c);
result.put(id, psd);
}
}
}
return result;
}
private static Collection<PatchSetData> walkAncestors(
ProjectControl ctl, ListMultimap<PatchSetData, PatchSetData> parents, PatchSetData start)
throws OrmException {
LinkedHashSet<PatchSetData> result = new LinkedHashSet<>();
Deque<PatchSetData> pending = new ArrayDeque<>();
pending.add(start);
while (!pending.isEmpty()) {
PatchSetData psd = pending.remove();
if (result.contains(psd) || !isVisible(psd, ctl)) {
continue;
}
result.add(psd);
pending.addAll(Lists.reverse(parents.get(psd)));
}
return result;
}
private static List<PatchSetData> walkDescendants(
ProjectControl ctl,
ListMultimap<PatchSetData, PatchSetData> children,
PatchSetData start,
List<PatchSetData> otherPatchSetsOfStart,
Iterable<PatchSetData> ancestors)
throws OrmException {
Set<Change.Id> alreadyEmittedChanges = new HashSet<>();
addAllChangeIds(alreadyEmittedChanges, ancestors);
// Prefer descendants found by following the original patch set passed in.
List<PatchSetData> result =
walkDescendentsImpl(ctl, alreadyEmittedChanges, children, ImmutableList.of(start));
addAllChangeIds(alreadyEmittedChanges, result);
// Then, go back and add new indirect descendants found by following any
// other patch sets of start. These show up after all direct descendants,
// because we wouldn't know where in the walk to insert them.
result.addAll(walkDescendentsImpl(ctl, alreadyEmittedChanges, children, otherPatchSetsOfStart));
return result;
}
private static void addAllChangeIds(
Collection<Change.Id> changeIds, Iterable<PatchSetData> psds) {
for (PatchSetData psd : psds) {
changeIds.add(psd.id());
}
}
private static List<PatchSetData> walkDescendentsImpl(
ProjectControl ctl,
Set<Change.Id> alreadyEmittedChanges,
ListMultimap<PatchSetData, PatchSetData> children,
List<PatchSetData> start)
throws OrmException {
if (start.isEmpty()) {
return ImmutableList.of();
}
Map<Change.Id, PatchSet.Id> maxPatchSetIds = new HashMap<>();
Set<PatchSetData> seen = new HashSet<>();
List<PatchSetData> allPatchSets = new ArrayList<>();
Deque<PatchSetData> pending = new ArrayDeque<>();
pending.addAll(start);
while (!pending.isEmpty()) {
PatchSetData psd = pending.remove();
if (seen.contains(psd) || !isVisible(psd, ctl)) {
continue;
}
seen.add(psd);
if (!alreadyEmittedChanges.contains(psd.id())) {
// Don't emit anything for changes that were previously emitted, even
// though different patch sets might show up later. However, do
// continue walking through them for the purposes of finding indirect
// descendants.
PatchSet.Id oldMax = maxPatchSetIds.get(psd.id());
if (oldMax == null || psd.psId().get() > oldMax.get()) {
maxPatchSetIds.put(psd.id(), psd.psId());
}
allPatchSets.add(psd);
}
// Depth-first search with newest children first.
for (PatchSetData child : children.get(psd)) {
pending.addFirst(child);
}
}
// If we saw the same change multiple times, prefer the latest patch set.
List<PatchSetData> result = new ArrayList<>(allPatchSets.size());
for (PatchSetData psd : allPatchSets) {
if (checkNotNull(maxPatchSetIds.get(psd.id())).equals(psd.psId())) {
result.add(psd);
}
}
return result;
}
private static boolean isVisible(PatchSetData psd, ProjectControl ctl) throws OrmException {
// Reuse existing project control rather than lazily creating a new one for
// each ChangeData.
return ctl.controlFor(psd.data().notes()).isPatchVisible(psd.patchSet(), psd.data());
}
@AutoValue
abstract static class PatchSetData {
@VisibleForTesting
static PatchSetData create(ChangeData cd, PatchSet ps, RevCommit commit) {
return new AutoValue_RelatedChangesSorter_PatchSetData(cd, ps, commit);
}
abstract ChangeData data();
abstract PatchSet patchSet();
abstract RevCommit commit();
PatchSet.Id psId() {
return patchSet().getId();
}
Change.Id id() {
return psId().getParentKey();
}
@Override
public int hashCode() {
return Objects.hash(patchSet().getId(), commit());
}
}
}