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// Copyright (C) 2020 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.notedb;
import static com.google.common.collect.ImmutableList.toImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.flogger.FluentLogger;
import com.google.gerrit.entities.Change;
import com.google.gerrit.git.RefUpdateUtil;
import com.google.gerrit.server.config.AllUsersName;
import com.google.gerrit.server.git.GitRepositoryManager;
import com.google.inject.Inject;
import com.google.inject.assistedinject.Assisted;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.function.Consumer;
import org.eclipse.jgit.lib.BatchRefUpdate;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.Ref;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.transport.ReceiveCommand;
/**
* This class can be used to clean zombie draft comments refs. More context in <a
* href="https://gerrit-review.googlesource.com/c/gerrit/+/246233">
* https://gerrit-review.googlesource.com/c/gerrit/+/246233 </a>
*
* <p>An earlier bug in the deletion of draft comments {@code
* refs/draft-comments/$change_id_short/$change_id/$user_id} caused some draft refs to remain in Git
* and not get deleted. These refs point to an empty tree.
*/
public class DeleteZombieCommentsRefs {
private static final FluentLogger logger = FluentLogger.forEnclosingClass();
private static final String EMPTY_TREE_ID = "4b825dc642cb6eb9a060e54bf8d69288fbee4904";
private static final String DRAFT_REFS_PREFIX = "refs/draft-comments";
// Number of refs deleted at once in a batch ref-update.
// Log progress after deleting every CHUNK_SIZE refs
private static final int CHUNK_SIZE = 3000;
private final GitRepositoryManager repoManager;
private final AllUsersName allUsers;
private final int cleanupPercentage;
private Repository allUsersRepo;
private final Consumer<String> uiConsumer;
public interface Factory {
DeleteZombieCommentsRefs create(int cleanupPercentage);
}
@Inject
public DeleteZombieCommentsRefs(
AllUsersName allUsers,
GitRepositoryManager repoManager,
@Assisted Integer cleanupPercentage) {
this(allUsers, repoManager, cleanupPercentage, (msg) -> {});
}
public DeleteZombieCommentsRefs(
AllUsersName allUsers,
GitRepositoryManager repoManager,
Integer cleanupPercentage,
Consumer<String> uiConsumer) {
this.allUsers = allUsers;
this.repoManager = repoManager;
this.cleanupPercentage = (cleanupPercentage == null) ? 100 : cleanupPercentage;
this.uiConsumer = uiConsumer;
}
public void execute() throws IOException {
allUsersRepo = repoManager.openRepository(allUsers);
List<Ref> draftRefs = allUsersRepo.getRefDatabase().getRefsByPrefix(DRAFT_REFS_PREFIX);
List<Ref> zombieRefs = filterZombieRefs(draftRefs);
logInfo(
String.format(
"Found a total of %d zombie draft refs in %s repo.",
zombieRefs.size(), allUsers.get()));
logInfo(String.format("Cleanup percentage = %d", cleanupPercentage));
zombieRefs =
zombieRefs.stream()
.filter(ref -> Change.Id.fromAllUsersRef(ref.getName()).get() % 100 < cleanupPercentage)
.collect(toImmutableList());
logInfo(String.format("Number of zombie refs to be cleaned = %d", zombieRefs.size()));
long zombieRefsCnt = zombieRefs.size();
long deletedRefsCnt = 0;
long startTime = System.currentTimeMillis();
for (List<Ref> refsBatch : Iterables.partition(zombieRefs, CHUNK_SIZE)) {
deleteBatchZombieRefs(refsBatch);
long elapsed = (System.currentTimeMillis() - startTime) / 1000;
deletedRefsCnt += refsBatch.size();
logProgress(deletedRefsCnt, zombieRefsCnt, elapsed);
}
}
private void deleteBatchZombieRefs(List<Ref> refsBatch) throws IOException {
List<ReceiveCommand> deleteCommands =
refsBatch.stream()
.map(
zombieRef ->
new ReceiveCommand(
zombieRef.getObjectId(), ObjectId.zeroId(), zombieRef.getName()))
.collect(toImmutableList());
BatchRefUpdate bru = allUsersRepo.getRefDatabase().newBatchUpdate();
bru.setAtomic(true);
bru.addCommand(deleteCommands);
RefUpdateUtil.executeChecked(bru, allUsersRepo);
}
private List<Ref> filterZombieRefs(List<Ref> allDraftRefs) throws IOException {
List<Ref> zombieRefs = new ArrayList<>((int) (allDraftRefs.size() * 0.5));
for (Ref ref : allDraftRefs) {
if (isZombieRef(ref)) {
zombieRefs.add(ref);
}
}
return zombieRefs;
}
private boolean isZombieRef(Ref ref) throws IOException {
return allUsersRepo.parseCommit(ref.getObjectId()).getTree().getName().equals(EMPTY_TREE_ID);
}
private void logInfo(String message) {
logger.atInfo().log("%s", message);
uiConsumer.accept(message);
}
private void logProgress(long deletedRefsCount, long allRefsCount, long elapsed) {
logInfo(
String.format(
"Deleted %d/%d zombie draft refs (%d seconds)",
deletedRefsCount, allRefsCount, elapsed));
}
}