| // Copyright (C) 2016 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 static com.google.common.base.Preconditions.checkArgument; |
| import static java.nio.charset.StandardCharsets.UTF_8; |
| |
| import com.google.gerrit.common.Nullable; |
| import com.google.gerrit.reviewdb.client.RefNames; |
| import com.google.gerrit.server.GerritPersonIdent; |
| import com.google.gerrit.server.config.GerritServerConfig; |
| import com.google.gerrit.server.git.InMemoryInserter; |
| import com.google.inject.Inject; |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.util.HashMap; |
| import java.util.Map; |
| import org.eclipse.jgit.diff.Sequence; |
| import org.eclipse.jgit.dircache.DirCache; |
| import org.eclipse.jgit.dircache.DirCacheBuilder; |
| import org.eclipse.jgit.dircache.DirCacheEntry; |
| import org.eclipse.jgit.lib.CommitBuilder; |
| 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.PersonIdent; |
| import org.eclipse.jgit.lib.Ref; |
| import org.eclipse.jgit.lib.RefUpdate; |
| import org.eclipse.jgit.lib.Repository; |
| import org.eclipse.jgit.merge.MergeFormatter; |
| import org.eclipse.jgit.merge.MergeResult; |
| import org.eclipse.jgit.merge.ResolveMerger; |
| import org.eclipse.jgit.merge.ThreeWayMergeStrategy; |
| import org.eclipse.jgit.revwalk.RevCommit; |
| import org.eclipse.jgit.revwalk.RevObject; |
| import org.eclipse.jgit.revwalk.RevWalk; |
| import org.eclipse.jgit.util.TemporaryBuffer; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| public class AutoMerger { |
| private static final Logger log = LoggerFactory.getLogger(AutoMerger.class); |
| |
| public static boolean cacheAutomerge(Config cfg) { |
| return cfg.getBoolean("change", null, "cacheAutomerge", true); |
| } |
| |
| private final PersonIdent gerritIdent; |
| private final boolean save; |
| |
| @Inject |
| AutoMerger(@GerritServerConfig Config cfg, @GerritPersonIdent PersonIdent gerritIdent) { |
| save = cacheAutomerge(cfg); |
| this.gerritIdent = gerritIdent; |
| } |
| |
| /** |
| * Perform an auto-merge of the parents of the given merge commit. |
| * |
| * @return auto-merge commit or {@code null} if an auto-merge commit couldn't be created. Headers |
| * of the returned RevCommit are parsed. |
| */ |
| public RevCommit merge( |
| Repository repo, |
| RevWalk rw, |
| ObjectInserter ins, |
| RevCommit merge, |
| ThreeWayMergeStrategy mergeStrategy) |
| throws IOException { |
| checkArgument(rw.getObjectReader().getCreatedFromInserter() == ins); |
| InMemoryInserter tmpIns = null; |
| if (ins instanceof InMemoryInserter) { |
| // Caller gave us an in-memory inserter, so ensure anything we write from |
| // this method is visible to them. |
| tmpIns = (InMemoryInserter) ins; |
| } else if (!save) { |
| // If we don't plan on saving results, use a fully in-memory inserter. |
| // Using just a non-flushing wrapper is not sufficient, since in |
| // particular DfsInserter might try to write to storage after exceeding an |
| // internal buffer size. |
| tmpIns = new InMemoryInserter(rw.getObjectReader()); |
| } |
| |
| rw.parseHeaders(merge); |
| String refName = RefNames.refsCacheAutomerge(merge.name()); |
| Ref ref = repo.getRefDatabase().exactRef(refName); |
| if (ref != null && ref.getObjectId() != null) { |
| RevObject obj = rw.parseAny(ref.getObjectId()); |
| if (obj instanceof RevCommit) { |
| return (RevCommit) obj; |
| } |
| return commit(repo, rw, tmpIns, ins, refName, obj, merge); |
| } |
| |
| ResolveMerger m = (ResolveMerger) mergeStrategy.newMerger(repo, true); |
| DirCache dc = DirCache.newInCore(); |
| m.setDirCache(dc); |
| m.setObjectInserter(tmpIns == null ? new NonFlushingWrapper(ins) : tmpIns); |
| |
| boolean couldMerge; |
| try { |
| couldMerge = m.merge(merge.getParents()); |
| } catch (IOException e) { |
| // It is not safe to continue further down in this method as throwing |
| // an exception most likely means that the merge tree was not created |
| // and m.getMergeResults() is empty. This would mean that all paths are |
| // unmerged and Gerrit UI would show all paths in the patch list. |
| log.warn("Error attempting automerge " + refName, e); |
| return null; |
| } |
| |
| ObjectId treeId; |
| if (couldMerge) { |
| treeId = m.getResultTreeId(); |
| |
| } else { |
| RevCommit ours = merge.getParent(0); |
| RevCommit theirs = merge.getParent(1); |
| rw.parseBody(ours); |
| rw.parseBody(theirs); |
| String oursMsg = ours.getShortMessage(); |
| String theirsMsg = theirs.getShortMessage(); |
| |
| String oursName = |
| String.format( |
| "HEAD (%s %s)", |
| ours.abbreviate(6).name(), oursMsg.substring(0, Math.min(oursMsg.length(), 60))); |
| String theirsName = |
| String.format( |
| "BRANCH (%s %s)", |
| theirs.abbreviate(6).name(), |
| theirsMsg.substring(0, Math.min(theirsMsg.length(), 60))); |
| |
| MergeFormatter fmt = new MergeFormatter(); |
| Map<String, MergeResult<? extends Sequence>> r = m.getMergeResults(); |
| Map<String, ObjectId> resolved = new HashMap<>(); |
| for (Map.Entry<String, MergeResult<? extends Sequence>> entry : r.entrySet()) { |
| MergeResult<? extends Sequence> p = entry.getValue(); |
| try (TemporaryBuffer buf = new TemporaryBuffer.LocalFile(null, 10 * 1024 * 1024)) { |
| fmt.formatMerge(buf, p, "BASE", oursName, theirsName, UTF_8.name()); |
| buf.close(); |
| |
| try (InputStream in = buf.openInputStream()) { |
| resolved.put(entry.getKey(), ins.insert(Constants.OBJ_BLOB, buf.length(), in)); |
| } |
| } |
| } |
| |
| DirCacheBuilder builder = dc.builder(); |
| int cnt = dc.getEntryCount(); |
| for (int i = 0; i < cnt; ) { |
| DirCacheEntry entry = dc.getEntry(i); |
| if (entry.getStage() == 0) { |
| builder.add(entry); |
| i++; |
| continue; |
| } |
| |
| int next = dc.nextEntry(i); |
| String path = entry.getPathString(); |
| DirCacheEntry res = new DirCacheEntry(path); |
| if (resolved.containsKey(path)) { |
| // For a file with content merge conflict that we produced a result |
| // above on, collapse the file down to a single stage 0 with just |
| // the blob content, and a randomly selected mode (the lowest stage, |
| // which should be the merge base, or ours). |
| res.setFileMode(entry.getFileMode()); |
| res.setObjectId(resolved.get(path)); |
| |
| } else if (next == i + 1) { |
| // If there is exactly one stage present, shouldn't be a conflict... |
| res.setFileMode(entry.getFileMode()); |
| res.setObjectId(entry.getObjectId()); |
| |
| } else if (next == i + 2) { |
| // Two stages suggests a delete/modify conflict. Pick the higher |
| // stage as the automatic result. |
| entry = dc.getEntry(i + 1); |
| res.setFileMode(entry.getFileMode()); |
| res.setObjectId(entry.getObjectId()); |
| |
| } else { |
| // 3 stage conflict, no resolve above |
| // Punt on the 3-stage conflict and show the base, for now. |
| res.setFileMode(entry.getFileMode()); |
| res.setObjectId(entry.getObjectId()); |
| } |
| builder.add(res); |
| i = next; |
| } |
| builder.finish(); |
| treeId = dc.writeTree(ins); |
| } |
| |
| return commit(repo, rw, tmpIns, ins, refName, treeId, merge); |
| } |
| |
| private RevCommit commit( |
| Repository repo, |
| RevWalk rw, |
| @Nullable InMemoryInserter tmpIns, |
| ObjectInserter ins, |
| String refName, |
| ObjectId tree, |
| RevCommit merge) |
| throws IOException { |
| rw.parseHeaders(merge); |
| // For maximum stability, choose a single ident using the committer time of |
| // the input commit, using the server name and timezone. |
| PersonIdent ident = |
| new PersonIdent( |
| gerritIdent, merge.getCommitterIdent().getWhen(), gerritIdent.getTimeZone()); |
| CommitBuilder cb = new CommitBuilder(); |
| cb.setAuthor(ident); |
| cb.setCommitter(ident); |
| cb.setTreeId(tree); |
| cb.setMessage("Auto-merge of " + merge.name() + '\n'); |
| for (RevCommit p : merge.getParents()) { |
| cb.addParentId(p); |
| } |
| |
| if (!save) { |
| checkArgument(tmpIns != null); |
| try (ObjectReader tmpReader = tmpIns.newReader(); |
| RevWalk tmpRw = new RevWalk(tmpReader)) { |
| return tmpRw.parseCommit(tmpIns.insert(cb)); |
| } |
| } |
| |
| checkArgument(tmpIns == null); |
| checkArgument(!(ins instanceof InMemoryInserter)); |
| ObjectId commitId = ins.insert(cb); |
| ins.flush(); |
| |
| RefUpdate ru = repo.updateRef(refName); |
| ru.setNewObjectId(commitId); |
| ru.disableRefLog(); |
| ru.forceUpdate(); |
| return rw.parseCommit(commitId); |
| } |
| |
| private static class NonFlushingWrapper extends ObjectInserter.Filter { |
| private final ObjectInserter ins; |
| |
| private NonFlushingWrapper(ObjectInserter ins) { |
| this.ins = ins; |
| } |
| |
| @Override |
| protected ObjectInserter delegate() { |
| return ins; |
| } |
| |
| @Override |
| public void flush() {} |
| |
| @Override |
| public void close() {} |
| } |
| } |