// 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.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static org.eclipse.jgit.lib.ObjectIdSerialization.readNotNull;
import static org.eclipse.jgit.lib.ObjectIdSerialization.writeNotNull;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.cache.Cache;
import com.google.common.cache.Weigher;
import com.google.common.collect.FluentIterable;
import com.google.gerrit.common.Nullable;
import com.google.gerrit.extensions.client.ChangeKind;
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.reviewdb.server.ReviewDb;
import com.google.gerrit.server.cache.CacheModule;
import com.google.gerrit.server.config.GerritServerConfig;
import com.google.gerrit.server.git.GitRepositoryManager;
import com.google.gerrit.server.git.InMemoryInserter;
import com.google.gerrit.server.git.MergeUtil;
import com.google.gerrit.server.query.change.ChangeData;
import com.google.gwtorm.server.OrmException;
import com.google.inject.Inject;
import com.google.inject.Module;
import com.google.inject.name.Named;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.Arrays;
import java.util.Collection;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import org.eclipse.jgit.errors.LargeObjectException;
import org.eclipse.jgit.lib.Config;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectInserter;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.merge.ThreeWayMerger;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevWalk;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class ChangeKindCacheImpl implements ChangeKindCache {
private static final Logger log = LoggerFactory.getLogger(ChangeKindCacheImpl.class);
private static final String ID_CACHE = "change_kind";
public static Module module() {
return new CacheModule() {
@Override
protected void configure() {
bind(ChangeKindCache.class).to(ChangeKindCacheImpl.class);
persist(ID_CACHE, Key.class, ChangeKind.class)
.maximumWeight(2 << 20)
.weigher(ChangeKindWeigher.class);
}
};
}
@VisibleForTesting
public static class NoCache implements ChangeKindCache {
private final boolean useRecursiveMerge;
private final ChangeData.Factory changeDataFactory;
private final GitRepositoryManager repoManager;
@Inject
NoCache(
@GerritServerConfig Config serverConfig,
ChangeData.Factory changeDataFactory,
GitRepositoryManager repoManager) {
this.useRecursiveMerge = MergeUtil.useRecursiveMerge(serverConfig);
this.changeDataFactory = changeDataFactory;
this.repoManager = repoManager;
}
@Override
public ChangeKind getChangeKind(
Project.NameKey project,
@Nullable RevWalk rw,
@Nullable Config repoConfig,
ObjectId prior,
ObjectId next) {
try {
Key key = new Key(prior, next, useRecursiveMerge);
return new Loader(key, repoManager, project, rw, repoConfig).call();
} catch (IOException e) {
log.warn(
"Cannot check trivial rebase of new patch set " + next.name() + " in " + project, e);
return ChangeKind.REWORK;
}
}
@Override
public ChangeKind getChangeKind(ReviewDb db, Change change, PatchSet patch) {
return getChangeKindInternal(this, db, change, patch, changeDataFactory, repoManager);
}
@Override
public ChangeKind getChangeKind(
@Nullable RevWalk rw, @Nullable Config repoConfig, ChangeData cd, PatchSet patch) {
return getChangeKindInternal(this, rw, repoConfig, cd, patch);
}
}
public static class Key implements Serializable {
private static final long serialVersionUID = 1L;
private transient ObjectId prior;
private transient ObjectId next;
private transient String strategyName;
private Key(ObjectId prior, ObjectId next, boolean useRecursiveMerge) {
checkNotNull(next, "next");
String strategyName = MergeUtil.mergeStrategyName(true, useRecursiveMerge);
this.prior = prior.copy();
this.next = next.copy();
this.strategyName = strategyName;
}
public Key(ObjectId prior, ObjectId next, String strategyName) {
this.prior = prior;
this.next = next;
this.strategyName = strategyName;
}
public ObjectId getPrior() {
return prior;
}
public ObjectId getNext() {
return next;
}
public String getStrategyName() {
return strategyName;
}
@Override
public boolean equals(Object o) {
if (o instanceof Key) {
Key k = (Key) o;
return Objects.equals(prior, k.prior)
&& Objects.equals(next, k.next)
&& Objects.equals(strategyName, k.strategyName);
}
return false;
}
@Override
public int hashCode() {
return Objects.hash(prior, next, strategyName);
}
private void writeObject(ObjectOutputStream out) throws IOException {
writeNotNull(out, prior);
writeNotNull(out, next);
out.writeUTF(strategyName);
}
private void readObject(ObjectInputStream in) throws IOException {
prior = readNotNull(in);
next = readNotNull(in);
strategyName = in.readUTF();
}
}
private static class Loader implements Callable<ChangeKind> {
private final Key key;
private final GitRepositoryManager repoManager;
private final Project.NameKey projectName;
private final RevWalk alreadyOpenRw;
private final Config repoConfig;
private Loader(
Key key,
GitRepositoryManager repoManager,
Project.NameKey projectName,
@Nullable RevWalk rw,
@Nullable Config repoConfig) {
checkArgument(
(rw == null && repoConfig == null) || (rw != null && repoConfig != null),
"must either provide both revwalk/config, or neither; got %s/%s",
rw,
repoConfig);
this.key = key;
this.repoManager = repoManager;
this.projectName = projectName;
this.alreadyOpenRw = rw;
this.repoConfig = repoConfig;
}
@SuppressWarnings("resource") // Resources are manually managed.
@Override
public ChangeKind call() throws IOException {
if (Objects.equals(key.prior, key.next)) {
return ChangeKind.NO_CODE_CHANGE;
}
RevWalk rw = alreadyOpenRw;
Config config = repoConfig;
Repository repo = null;
if (alreadyOpenRw == null) {
repo = repoManager.openRepository(projectName);
rw = new RevWalk(repo);
config = repo.getConfig();
}
try {
RevCommit prior = rw.parseCommit(key.prior);
rw.parseBody(prior);
RevCommit next = rw.parseCommit(key.next);
rw.parseBody(next);
if (!next.getFullMessage().equals(prior.getFullMessage())) {
if (isSameDeltaAndTree(prior, next)) {
return ChangeKind.NO_CODE_CHANGE;
}
return ChangeKind.REWORK;
}
if (isSameDeltaAndTree(prior, next)) {
return ChangeKind.NO_CHANGE;
}
if ((prior.getParentCount() != 1 || next.getParentCount() != 1)
&& (!onlyFirstParentChanged(prior, next) || prior.getParentCount() == 0)) {
// Trivial rebases done by machine only work well on 1 parent.
return ChangeKind.REWORK;
}
// A trivial rebase can be detected by looking for the next commit
// having the same tree as would exist when the prior commit is
// cherry-picked onto the next commit's new first parent.
try (ObjectInserter ins = new InMemoryInserter(rw.getObjectReader())) {
ThreeWayMerger merger = MergeUtil.newThreeWayMerger(ins, config, key.strategyName);
merger.setBase(prior.getParent(0));
if (merger.merge(next.getParent(0), prior)
&& merger.getResultTreeId().equals(next.getTree())) {
if (prior.getParentCount() == 1) {
return ChangeKind.TRIVIAL_REBASE;
}
return ChangeKind.MERGE_FIRST_PARENT_UPDATE;
}
} catch (LargeObjectException e) {
// Some object is too large for the merge attempt to succeed. Assume
// it was a rework.
}
return ChangeKind.REWORK;
} finally {
if (repo != null) {
rw.close();
repo.close();
}
}
}
public static boolean onlyFirstParentChanged(RevCommit prior, RevCommit next) {
return !sameFirstParents(prior, next) && sameRestOfParents(prior, next);
}
private static boolean sameFirstParents(RevCommit prior, RevCommit next) {
if (prior.getParentCount() == 0) {
return next.getParentCount() == 0;
}
return prior.getParent(0).equals(next.getParent(0));
}
private static boolean sameRestOfParents(RevCommit prior, RevCommit next) {
Set<RevCommit> priorRestParents = allExceptFirstParent(prior.getParents());
Set<RevCommit> nextRestParents = allExceptFirstParent(next.getParents());
return priorRestParents.equals(nextRestParents);
}
private static Set<RevCommit> allExceptFirstParent(RevCommit[] parents) {
return FluentIterable.from(Arrays.asList(parents)).skip(1).toSet();
}
private static boolean isSameDeltaAndTree(RevCommit prior, RevCommit next) {
if (next.getTree() != prior.getTree()) {
return false;
}
if (prior.getParentCount() != next.getParentCount()) {
return false;
} else if (prior.getParentCount() == 0) {
return true;
}
// Make sure that the prior/next delta is the same - not just the tree.
// This is done by making sure that the parent trees are equal.
for (int i = 0; i < prior.getParentCount(); i++) {
if (next.getParent(i).getTree() != prior.getParent(i).getTree()) {
return false;
}
}
return true;
}
}
public static class ChangeKindWeigher implements Weigher<Key, ChangeKind> {
@Override
public int weigh(Key key, ChangeKind changeKind) {
return 16
+ 2 * 36
+ 2 * key.strategyName.length() // Size of Key, 64 bit JVM
+ 2 * changeKind.name().length(); // Size of ChangeKind, 64 bit JVM
}
}
private final Cache<Key, ChangeKind> cache;
private final boolean useRecursiveMerge;
private final ChangeData.Factory changeDataFactory;
private final GitRepositoryManager repoManager;
@Inject
ChangeKindCacheImpl(
@GerritServerConfig Config serverConfig,
@Named(ID_CACHE) Cache<Key, ChangeKind> cache,
ChangeData.Factory changeDataFactory,
GitRepositoryManager repoManager) {
this.cache = cache;
this.useRecursiveMerge = MergeUtil.useRecursiveMerge(serverConfig);
this.changeDataFactory = changeDataFactory;
this.repoManager = repoManager;
}
@Override
public ChangeKind getChangeKind(
Project.NameKey project,
@Nullable RevWalk rw,
@Nullable Config repoConfig,
ObjectId prior,
ObjectId next) {
try {
Key key = new Key(prior, next, useRecursiveMerge);
return cache.get(key, new Loader(key, repoManager, project, rw, repoConfig));
} catch (ExecutionException e) {
log.warn("Cannot check trivial rebase of new patch set " + next.name() + " in " + project, e);
return ChangeKind.REWORK;
}
}
@Override
public ChangeKind getChangeKind(ReviewDb db, Change change, PatchSet patch) {
return getChangeKindInternal(this, db, change, patch, changeDataFactory, repoManager);
}
@Override
public ChangeKind getChangeKind(
@Nullable RevWalk rw, @Nullable Config repoConfig, ChangeData cd, PatchSet patch) {
return getChangeKindInternal(this, rw, repoConfig, cd, patch);
}
private static ChangeKind getChangeKindInternal(
ChangeKindCache cache,
@Nullable RevWalk rw,
@Nullable Config repoConfig,
ChangeData change,
PatchSet patch) {
ChangeKind kind = ChangeKind.REWORK;
// Trivial case: if we're on the first patch, we don't need to use
// the repository.
if (patch.getId().get() > 1) {
try {
Collection<PatchSet> patchSetCollection = change.patchSets();
PatchSet priorPs = patch;
for (PatchSet ps : patchSetCollection) {
if (ps.getId().get() < patch.getId().get()
&& (ps.getId().get() > priorPs.getId().get() || priorPs == patch)) {
// We only want the previous patch set, so walk until the last one
priorPs = ps;
}
}
// If we still think the previous patch is the current patch,
// we only have one patch set. Return the default.
// This can happen if a user creates a draft, uploads a second patch,
// and deletes the draft.
if (priorPs != patch) {
kind =
cache.getChangeKind(
change.project(),
rw,
repoConfig,
ObjectId.fromString(priorPs.getRevision().get()),
ObjectId.fromString(patch.getRevision().get()));
}
} catch (OrmException e) {
// Do nothing; assume we have a complex change
log.warn(
"Unable to get change kind for patchSet "
+ patch.getPatchSetId()
+ "of change "
+ change.getId(),
e);
}
}
return kind;
}
private static ChangeKind getChangeKindInternal(
ChangeKindCache cache,
ReviewDb db,
Change change,
PatchSet patch,
ChangeData.Factory changeDataFactory,
GitRepositoryManager repoManager) {
// TODO - dborowitz: add NEW_CHANGE type for default.
ChangeKind kind = ChangeKind.REWORK;
// Trivial case: if we're on the first patch, we don't need to open
// the repository.
if (patch.getId().get() > 1) {
try (Repository repo = repoManager.openRepository(change.getProject());
RevWalk rw = new RevWalk(repo)) {
kind =
getChangeKindInternal(
cache, rw, repo.getConfig(), changeDataFactory.create(db, change), patch);
} catch (IOException e) {
// Do nothing; assume we have a complex change
log.warn(
"Unable to get change kind for patchSet "
+ patch.getPatchSetId()
+ "of change "
+ change.getChangeId(),
e);
}
}
return kind;
}
}