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// 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 java.util.Objects.requireNonNull;
import static java.util.stream.Collectors.toMap;
import com.google.auto.value.AutoValue;
import com.google.auto.value.extension.memoized.Memoized;
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.entities.Change;
import com.google.gerrit.entities.PatchSet;
import com.google.gerrit.entities.Project;
import com.google.gerrit.extensions.restapi.AuthException;
import com.google.gerrit.server.git.GitRepositoryManager;
import com.google.gerrit.server.permissions.ChangePermission;
import com.google.gerrit.server.permissions.PermissionBackend;
import com.google.gerrit.server.permissions.PermissionBackendException;
import com.google.gerrit.server.project.ProjectCache;
import com.google.gerrit.server.project.ProjectState;
import com.google.gerrit.server.query.change.ChangeData;
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
public class RelatedChangesSorter {
private final GitRepositoryManager repoManager;
private final PermissionBackend permissionBackend;
private final ProjectCache projectCache;
@Inject
RelatedChangesSorter(
GitRepositoryManager repoManager,
PermissionBackend permissionBackend,
ProjectCache projectCache) {
this.repoManager = repoManager;
this.permissionBackend = permissionBackend;
this.projectCache = projectCache;
}
public List sort(List in, PatchSet startPs)
throws IOException, PermissionBackendException {
checkArgument(!in.isEmpty(), "Input may not be empty");
// Map of all patch sets, keyed by commit SHA-1.
Map byId = collectById(in);
PatchSetData start = byId.get(startPs.commitId());
requireNonNull(
start,
() ->
String.format(
"commit %s of patch set %s not found in %s",
startPs.commitId().name(),
startPs.id(),
byId.entrySet().stream()
.collect(toMap(e -> e.getKey().name(), e -> e.getValue().patchSet().id()))));
// Map of patch set -> immediate parent.
ListMultimap parents =
MultimapBuilder.hashKeys(in.size()).arrayListValues(3).build();
// Map of patch set -> immediate children.
ListMultimap children =
MultimapBuilder.hashKeys(in.size()).arrayListValues(3).build();
// All other patch sets of the same change as startPs.
List otherPatchSetsOfStart = new ArrayList<>();
for (ChangeData cd : in) {
for (PatchSet ps : cd.patchSets()) {
PatchSetData thisPsd = requireNonNull(byId.get(ps.commitId()));
if (cd.getId().equals(start.id()) && !ps.id().equals(start.psId())) {
otherPatchSetsOfStart.add(thisPsd);
}
for (RevCommit p : thisPsd.commit().getParents()) {
PatchSetData parentPsd = byId.get(p);
if (parentPsd != null) {
parents.put(thisPsd, parentPsd);
children.put(parentPsd, thisPsd);
}
}
}
}
Collection ancestors = walkAncestors(parents, start);
List descendants =
walkDescendants(children, start, otherPatchSetsOfStart, ancestors);
List result = new ArrayList<>(ancestors.size() + descendants.size() - 1);
result.addAll(Lists.reverse(descendants));
result.addAll(ancestors);
return result;
}
private Map collectById(List in) throws IOException {
Project.NameKey project = in.get(0).change().getProject();
Map 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()) {
RevCommit c = rw.parseCommit(ps.commitId());
PatchSetData psd = PatchSetData.create(cd, ps, c);
result.put(ps.commitId(), psd);
}
}
}
return result;
}
private Collection walkAncestors(
ListMultimap parents, PatchSetData start)
throws PermissionBackendException {
LinkedHashSet result = new LinkedHashSet<>();
Deque pending = new ArrayDeque<>();
pending.add(start);
while (!pending.isEmpty()) {
PatchSetData psd = pending.remove();
if (result.contains(psd) || !isVisible(psd)) {
continue;
}
result.add(psd);
pending.addAll(Lists.reverse(parents.get(psd)));
}
return result;
}
private List walkDescendants(
ListMultimap children,
PatchSetData start,
List otherPatchSetsOfStart,
Iterable ancestors)
throws PermissionBackendException {
Set alreadyEmittedChanges = new HashSet<>();
addAllChangeIds(alreadyEmittedChanges, ancestors);
// Prefer descendants found by following the original patch set passed in.
List result =
walkDescendentsImpl(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(alreadyEmittedChanges, children, otherPatchSetsOfStart));
return result;
}
private static void addAllChangeIds(
Collection changeIds, Iterable psds) {
for (PatchSetData psd : psds) {
changeIds.add(psd.id());
}
}
private List walkDescendentsImpl(
Set alreadyEmittedChanges,
ListMultimap children,
List start)
throws PermissionBackendException {
if (start.isEmpty()) {
return new ArrayList<>();
}
Map maxPatchSetIds = new HashMap<>();
Set seen = new HashSet<>();
List allPatchSets = new ArrayList<>();
Deque pending = new ArrayDeque<>();
pending.addAll(start);
while (!pending.isEmpty()) {
PatchSetData psd = pending.remove();
if (seen.contains(psd) || !isVisible(psd)) {
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 result = new ArrayList<>(allPatchSets.size());
for (PatchSetData psd : allPatchSets) {
if (requireNonNull(maxPatchSetIds.get(psd.id())).equals(psd.psId())) {
result.add(psd);
}
}
return result;
}
private boolean isVisible(PatchSetData psd) throws PermissionBackendException {
PermissionBackend.WithUser perm = permissionBackend.currentUser();
try {
perm.change(psd.data()).check(ChangePermission.READ);
} catch (AuthException e) {
return false;
}
return projectCache.get(psd.data().project()).map(ProjectState::statePermitsRead).orElse(false);
}
@AutoValue
public abstract static class PatchSetData {
@VisibleForTesting
static PatchSetData create(ChangeData cd, PatchSet ps, RevCommit commit) {
return new AutoValue_RelatedChangesSorter_PatchSetData(cd, ps, commit);
}
public abstract ChangeData data();
public abstract PatchSet patchSet();
public abstract RevCommit commit();
public PatchSet.Id psId() {
return patchSet().id();
}
public Change.Id id() {
return psId().changeId();
}
@Memoized
@Override
public int hashCode() {
return Objects.hash(patchSet().id(), commit());
}
@Override
public final boolean equals(Object obj) {
if (!(obj instanceof PatchSetData)) {
return false;
}
PatchSetData o = (PatchSetData) obj;
return Objects.equals(patchSet().id(), o.patchSet().id())
&& Objects.equals(commit(), o.commit());
}
}
}
