| // 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.patch; |
| |
| import com.google.gerrit.common.Nullable; |
| import com.google.gerrit.entities.Project; |
| import com.google.gerrit.entities.RefNames; |
| 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.update.RepoView; |
| import com.google.inject.Inject; |
| import com.google.inject.Singleton; |
| import java.io.IOException; |
| import java.util.Optional; |
| import org.eclipse.jgit.lib.Config; |
| import org.eclipse.jgit.lib.Constants; |
| import org.eclipse.jgit.lib.ObjectId; |
| import org.eclipse.jgit.lib.ObjectInserter; |
| import org.eclipse.jgit.lib.ObjectReader; |
| import org.eclipse.jgit.lib.Repository; |
| import org.eclipse.jgit.revwalk.RevCommit; |
| import org.eclipse.jgit.revwalk.RevObject; |
| import org.eclipse.jgit.revwalk.RevWalk; |
| |
| /** A utility class for computing the base commit / parent for a specific patchset commit. */ |
| @Singleton |
| class BaseCommitUtil { |
| private final AutoMerger autoMerger; |
| private final GitRepositoryManager repoManager; |
| |
| /** If true, auto-merge results are stored in the repository. */ |
| private final boolean saveAutomerge; |
| |
| @Inject |
| BaseCommitUtil(AutoMerger am, @GerritServerConfig Config cfg, GitRepositoryManager repoManager) { |
| this.autoMerger = am; |
| this.saveAutomerge = AutoMerger.cacheAutomerge(cfg); |
| this.repoManager = repoManager; |
| } |
| |
| RevObject getBaseCommit(Project.NameKey project, ObjectId newCommit, @Nullable Integer parentNum) |
| throws IOException { |
| try (Repository repo = repoManager.openRepository(project); |
| ObjectInserter ins = newInserter(repo); |
| ObjectReader reader = ins.newReader(); |
| RevWalk rw = new RevWalk(reader)) { |
| return getParentCommit(repo, ins, rw, parentNum, newCommit); |
| } |
| } |
| |
| /** |
| * Returns the number of parent commits of the commit represented by the commitId parameter. |
| * |
| * @param project a specific git repository. |
| * @param commitId 20 bytes commitId SHA-1 hash. |
| * @return an integer representing the number of parents of the designated commit. |
| */ |
| int getNumParents(Project.NameKey project, ObjectId commitId) throws IOException { |
| try (Repository repo = repoManager.openRepository(project); |
| ObjectInserter ins = repo.newObjectInserter(); |
| ObjectReader reader = ins.newReader(); |
| RevWalk rw = new RevWalk(reader)) { |
| RevCommit current = rw.parseCommit(commitId); |
| return current.getParentCount(); |
| } |
| } |
| |
| /** |
| * Returns the parent commit Object of the commit represented by the commitId parameter. |
| * |
| * @param repo a git repository. |
| * @param ins a git object inserter in the database. |
| * @param rw a {@link RevWalk} object of the repository. |
| * @param parentNum used to identify the parent number for merge commits. If parentNum is null and |
| * {@code commitId} has two parents, the auto-merge commit will be returned. If {@code |
| * commitId} has a single parent, it will be returned. |
| * @param commitId 20 bytes commitId SHA-1 hash. |
| * @return Returns the parent commit of the commit represented by the commitId parameter. Note |
| * that auto-merge is not supported for commits having more than two parents. |
| */ |
| RevObject getParentCommit( |
| Repository repo, |
| ObjectInserter ins, |
| RevWalk rw, |
| @Nullable Integer parentNum, |
| ObjectId commitId) |
| throws IOException { |
| RevCommit current = rw.parseCommit(commitId); |
| switch (current.getParentCount()) { |
| case 0: |
| return rw.parseAny(emptyTree(ins)); |
| case 1: |
| return current.getParent(0); |
| default: |
| if (parentNum != null) { |
| RevCommit r = current.getParent(parentNum - 1); |
| rw.parseBody(r); |
| return r; |
| } |
| // Only support auto-merge for 2 parents, not octopus merges |
| if (current.getParentCount() == 2) { |
| if (!saveAutomerge) { |
| throw new IOException( |
| "diff against auto-merge commits is only supported if 'change.cacheAutomerge' config is set to true."); |
| } |
| // TODO(ghareeb): Avoid persisting auto-merge commits. |
| return getAutoMergeFromGitOrCreate(repo, ins, rw, current); |
| } |
| return null; |
| } |
| } |
| |
| /** |
| * Gets the auto-merge commit from git if it already exists. If not, the auto-merge is created, |
| * persisted in git and the cache-automerge ref is updated for the merge commit. |
| * |
| * @return the auto-merge {@link RevCommit} |
| */ |
| private RevCommit getAutoMergeFromGitOrCreate( |
| Repository repo, ObjectInserter ins, RevWalk rw, RevCommit mergeCommit) throws IOException { |
| String refName = RefNames.refsCacheAutomerge(mergeCommit.name()); |
| Optional<RevCommit> autoMergeCommit = autoMerger.lookupCommit(repo, rw, refName); |
| if (autoMergeCommit.isPresent()) { |
| return autoMergeCommit.get(); |
| } |
| ObjectId autoMergeId = |
| autoMerger.createAutoMergeCommit(new RepoView(repo, rw, ins), rw, ins, mergeCommit); |
| ins.flush(); |
| return rw.parseCommit(autoMergeId); |
| } |
| |
| private ObjectInserter newInserter(Repository repo) { |
| return saveAutomerge ? repo.newObjectInserter() : new InMemoryInserter(repo); |
| } |
| |
| private static ObjectId emptyTree(ObjectInserter ins) throws IOException { |
| ObjectId id = ins.insert(Constants.OBJ_TREE, new byte[] {}); |
| ins.flush(); |
| return id; |
| } |
| } |