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// Copyright (C) 2010 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.receive;
import static com.google.common.collect.ImmutableList.toImmutableList;
import com.google.common.collect.Sets;
import com.google.common.flogger.FluentLogger;
import com.google.gerrit.entities.Account;
import com.google.gerrit.entities.PatchSet;
import com.google.gerrit.entities.Project;
import com.google.gerrit.entities.RefNames;
import com.google.gerrit.exceptions.StorageException;
import com.google.gerrit.index.query.Predicate;
import com.google.gerrit.server.git.HookUtil;
import com.google.gerrit.server.index.change.ChangeField;
import com.google.gerrit.server.query.change.ChangeData;
import com.google.gerrit.server.query.change.ChangePredicates;
import com.google.gerrit.server.query.change.ChangeStatusPredicate;
import com.google.gerrit.server.query.change.InternalChangeQuery;
import com.google.gerrit.server.util.MagicBranch;
import com.google.inject.Provider;
import java.io.IOException;
import java.util.Collections;
import java.util.Map;
import java.util.Set;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.Ref;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.transport.AdvertiseRefsHook;
import org.eclipse.jgit.transport.ReceivePack;
import org.eclipse.jgit.transport.ServiceMayNotContinueException;
import org.eclipse.jgit.transport.UploadPack;
/**
* Exposes only the non refs/changes/ reference names and provide additional haves.
*
* <p>Negotiation on Git push is suboptimal in that it tends to send more objects to the server than
* it should. This results in increased latencies for {@code git push}.
*
* <p>Ref advertisement for Git pushes still works in a "the server speaks first fashion" as Git
* Protocol V2 only addressed fetches Therefore the server needs to send all available references.
* For large repositories, this can be in the tens of megabytes to send to the client. We therefore
* remove all refs in refs/changes/* to scale down that footprint. Trivially, this would increase
* the unnecessary objects that the client has to send to the server because the common ancestor it
* finds in negotiation might be further back in history.
*
* <p>To work around this, we advertise the last 32 changes in that repository as additional {@code
* .haves}. This is a heuristical approach that aims at scaling down the number of unnecessary
* objects that client sends to the server. Unnecessary here refers to objects that the server
* already has.
*
* <p>TODO(hiesel): Instrument this heuristic and proof its value.
*/
public class ReceiveCommitsAdvertiseRefsHook implements AdvertiseRefsHook {
private static final FluentLogger logger = FluentLogger.forEnclosingClass();
private final Provider<InternalChangeQuery> queryProvider;
private final Project.NameKey projectName;
private final Account.Id user;
public ReceiveCommitsAdvertiseRefsHook(
Provider<InternalChangeQuery> queryProvider, Project.NameKey projectName, Account.Id user) {
this.queryProvider = queryProvider;
this.projectName = projectName;
this.user = user;
}
@Override
public void advertiseRefs(UploadPack us) {
throw new UnsupportedOperationException(
"ReceiveCommitsAdvertiseRefsHook cannot be used for UploadPack");
}
@Override
public void advertiseRefs(ReceivePack rp) throws ServiceMayNotContinueException {
Map<String, Ref> advertisedRefs = HookUtil.ensureAllRefsAdvertised(rp);
advertisedRefs.keySet().stream()
.filter(ReceiveCommitsAdvertiseRefsHook::skip)
.collect(toImmutableList())
.forEach(r -> advertisedRefs.remove(r));
try {
rp.setAdvertisedRefs(advertisedRefs, advertiseOpenChanges(rp.getRepository()));
} catch (IOException e) {
throw new ServiceMayNotContinueException(e);
}
}
private Set<ObjectId> advertiseOpenChanges(Repository repo)
throws ServiceMayNotContinueException {
// Advertise the user's most recent open changes. It's likely that the user has one of these in
// their local repo and they can serve as starting points to figure out the common ancestor of
// what the client and server have in common.
int limit = 32;
try {
Set<ObjectId> r = Sets.newHashSetWithExpectedSize(limit);
for (ChangeData cd :
queryProvider
.get()
.setRequestedFields(
// Required for ChangeIsVisibleToPrdicate.
ChangeField.CHANGE_SPEC,
ChangeField.REVIEWER_SPEC,
// Required during advertiseOpenChanges.
ChangeField.PATCH_SET_SPEC)
.enforceVisibility(true)
.setLimit(limit)
.query(
Predicate.and(
ChangePredicates.project(projectName),
ChangeStatusPredicate.open(),
ChangePredicates.owner(user)))) {
PatchSet ps = cd.currentPatchSet();
if (ps != null) {
// Ensure we actually observed a patch set ref pointing to this
// object, in case the database is out of sync with the repo and the
// object doesn't actually exist.
try {
Ref psRef = repo.getRefDatabase().exactRef(RefNames.patchSetRef(ps.id()));
if (psRef != null) {
r.add(ps.commitId());
}
} catch (IOException e) {
throw new ServiceMayNotContinueException(e);
}
}
}
return r;
} catch (StorageException err) {
logger.atSevere().withCause(err).log("Cannot list open changes of %s", projectName);
return Collections.emptySet();
}
}
private static boolean skip(String name) {
return name.startsWith(RefNames.REFS_CHANGES)
|| name.startsWith(RefNames.REFS_CACHE_AUTOMERGE)
|| MagicBranch.isMagicBranch(name);
}
}