// Copyright (C) 2009 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.common.base.Function;
import com.google.common.cache.CacheLoader;
import com.google.common.collect.FluentIterable;
import com.google.gerrit.reviewdb.client.AccountDiffPreference.Whitespace;
import com.google.gerrit.reviewdb.client.Patch;
import com.google.gerrit.reviewdb.client.RefNames;
import com.google.gerrit.server.git.GitRepositoryManager;
import com.google.inject.Inject;
import org.eclipse.jgit.diff.DiffEntry;
import org.eclipse.jgit.diff.DiffFormatter;
import org.eclipse.jgit.diff.Edit;
import org.eclipse.jgit.diff.EditList;
import org.eclipse.jgit.diff.HistogramDiff;
import org.eclipse.jgit.diff.RawText;
import org.eclipse.jgit.diff.RawTextComparator;
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.Constants;
import org.eclipse.jgit.lib.FileMode;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectInserter;
import org.eclipse.jgit.lib.ObjectReader;
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.MergeStrategy;
import org.eclipse.jgit.merge.ResolveMerger;
import org.eclipse.jgit.patch.FileHeader;
import org.eclipse.jgit.patch.FileHeader.PatchType;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevObject;
import org.eclipse.jgit.revwalk.RevTree;
import org.eclipse.jgit.revwalk.RevWalk;
import org.eclipse.jgit.util.TemporaryBuffer;
import org.eclipse.jgit.util.io.DisabledOutputStream;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
public class PatchListLoader extends CacheLoader<PatchListKey, PatchList> {
static final Logger log = LoggerFactory.getLogger(PatchListLoader.class);
private final GitRepositoryManager repoManager;
private final PatchListCache patchListCache;
@Inject
PatchListLoader(GitRepositoryManager mgr, PatchListCache plc) {
repoManager = mgr;
patchListCache = plc;
}
@Override
public PatchList load(final PatchListKey key) throws IOException,
PatchListNotAvailableException {
final Repository repo = repoManager.openRepository(key.projectKey);
try {
return readPatchList(key, repo);
} finally {
repo.close();
}
}
private static RawTextComparator comparatorFor(Whitespace ws) {
switch (ws) {
case IGNORE_ALL_SPACE:
return RawTextComparator.WS_IGNORE_ALL;
case IGNORE_SPACE_AT_EOL:
return RawTextComparator.WS_IGNORE_TRAILING;
case IGNORE_SPACE_CHANGE:
return RawTextComparator.WS_IGNORE_CHANGE;
case IGNORE_NONE:
default:
return RawTextComparator.DEFAULT;
}
}
private PatchList readPatchList(final PatchListKey key, final Repository repo)
throws IOException, PatchListNotAvailableException {
final RawTextComparator cmp = comparatorFor(key.getWhitespace());
final ObjectReader reader = repo.newObjectReader();
try {
final RevWalk rw = new RevWalk(reader);
final RevCommit b = rw.parseCommit(key.getNewId());
final RevObject a = aFor(key, repo, rw, b);
if (a == null) {
// TODO(sop) Remove this case.
// This is a merge commit, compared to its ancestor.
//
final PatchListEntry[] entries = new PatchListEntry[1];
entries[0] = newCommitMessage(cmp, repo, reader, null, b);
return new PatchList(a, b, true, entries);
}
final boolean againstParent =
b.getParentCount() > 0 && b.getParent(0) == a;
RevCommit aCommit = a instanceof RevCommit ? (RevCommit) a : null;
RevTree aTree = rw.parseTree(a);
RevTree bTree = b.getTree();
DiffFormatter df = new DiffFormatter(DisabledOutputStream.INSTANCE);
df.setRepository(repo);
df.setDiffComparator(cmp);
df.setDetectRenames(true);
List<DiffEntry> diffEntries = df.scan(aTree, bTree);
Set<String> paths = key.getOldId() != null
? FluentIterable.from(patchListCache.get(
new PatchListKey(key.projectKey, null, key.getNewId(),
key.getWhitespace())).getPatches())
.transform(new Function<PatchListEntry, String>() {
@Override
public String apply(PatchListEntry entry) {
return entry.getNewName();
}
})
.toSet()
: null;
int cnt = diffEntries.size();
List<PatchListEntry> entries = new ArrayList<>();
entries.add(newCommitMessage(cmp, repo, reader, //
againstParent ? null : aCommit, b));
for (int i = 0; i < cnt; i++) {
DiffEntry diffEntry = diffEntries.get(i);
if (paths == null || paths.contains(diffEntry.getNewPath())
|| paths.contains(diffEntry.getOldPath())) {
FileHeader fh = df.toFileHeader(diffEntry);
entries.add(newEntry(aTree, fh));
}
}
return new PatchList(a, b, againstParent,
entries.toArray(new PatchListEntry[entries.size()]));
} finally {
reader.release();
}
}
private PatchListEntry newCommitMessage(final RawTextComparator cmp,
final Repository db, final ObjectReader reader,
final RevCommit aCommit, final RevCommit bCommit) throws IOException {
StringBuilder hdr = new StringBuilder();
hdr.append("diff --git");
if (aCommit != null) {
hdr.append(" a/").append(Patch.COMMIT_MSG);
} else {
hdr.append(" ").append(FileHeader.DEV_NULL);
}
hdr.append(" b/").append(Patch.COMMIT_MSG);
hdr.append("\n");
if (aCommit != null) {
hdr.append("--- a/").append(Patch.COMMIT_MSG).append("\n");
} else {
hdr.append("--- ").append(FileHeader.DEV_NULL).append("\n");
}
hdr.append("+++ b/").append(Patch.COMMIT_MSG).append("\n");
Text aText =
aCommit != null ? Text.forCommit(db, reader, aCommit) : Text.EMPTY;
Text bText = Text.forCommit(db, reader, bCommit);
byte[] rawHdr = hdr.toString().getBytes("UTF-8");
RawText aRawText = new RawText(aText.getContent());
RawText bRawText = new RawText(bText.getContent());
EditList edits = new HistogramDiff().diff(cmp, aRawText, bRawText);
FileHeader fh = new FileHeader(rawHdr, edits, PatchType.UNIFIED);
return new PatchListEntry(fh, edits);
}
private PatchListEntry newEntry(RevTree aTree, FileHeader fileHeader) {
final FileMode oldMode = fileHeader.getOldMode();
final FileMode newMode = fileHeader.getNewMode();
if (oldMode == FileMode.GITLINK || newMode == FileMode.GITLINK) {
return new PatchListEntry(fileHeader, Collections.<Edit> emptyList());
}
if (aTree == null // want combined diff
|| fileHeader.getPatchType() != PatchType.UNIFIED
|| fileHeader.getHunks().isEmpty()) {
return new PatchListEntry(fileHeader, Collections.<Edit> emptyList());
}
List<Edit> edits = fileHeader.toEditList();
if (edits.isEmpty()) {
return new PatchListEntry(fileHeader, Collections.<Edit> emptyList());
} else {
return new PatchListEntry(fileHeader, edits);
}
}
private static RevObject aFor(final PatchListKey key,
final Repository repo, final RevWalk rw, final RevCommit b)
throws IOException {
if (key.getOldId() != null) {
return rw.parseAny(key.getOldId());
}
switch (b.getParentCount()) {
case 0:
return rw.parseAny(emptyTree(repo));
case 1: {
RevCommit r = b.getParent(0);
rw.parseBody(r);
return r;
}
case 2:
return automerge(repo, rw, b);
default:
// TODO(sop) handle an octopus merge.
return null;
}
}
public static RevTree automerge(Repository repo, RevWalk rw, RevCommit b)
throws IOException {
return automerge(repo, rw, b, true);
}
public static RevTree automerge(Repository repo, RevWalk rw, RevCommit b,
boolean save) throws IOException {
String hash = b.name();
String refName = RefNames.REFS_CACHE_AUTOMERGE
+ hash.substring(0, 2)
+ "/"
+ hash.substring(2);
Ref ref = repo.getRef(refName);
if (ref != null && ref.getObjectId() != null) {
return rw.parseTree(ref.getObjectId());
}
ObjectId treeId;
ResolveMerger m = (ResolveMerger) MergeStrategy.RESOLVE.newMerger(repo, true);
final ObjectInserter ins = repo.newObjectInserter();
try {
DirCache dc = DirCache.newInCore();
m.setDirCache(dc);
m.setObjectInserter(new ObjectInserter.Filter() {
@Override
protected ObjectInserter delegate() {
return ins;
}
@Override
public void flush() {
}
@Override
public void release() {
}
});
boolean couldMerge;
try {
couldMerge = m.merge(b.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;
}
if (couldMerge) {
treeId = m.getResultTreeId();
} else {
RevCommit ours = b.getParent(0);
RevCommit theirs = b.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();
TemporaryBuffer buf = new TemporaryBuffer.LocalFile(10 * 1024 * 1024);
try {
fmt.formatMerge(buf, p, "BASE", oursName, theirsName, "UTF-8");
buf.close();
InputStream in = buf.openInputStream();
try {
resolved.put(entry.getKey(), ins.insert(Constants.OBJ_BLOB, buf.length(), in));
} finally {
in.close();
}
} finally {
buf.destroy();
}
}
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);
}
ins.flush();
} finally {
ins.release();
}
if (save) {
RefUpdate update = repo.updateRef(refName);
update.setNewObjectId(treeId);
update.disableRefLog();
update.forceUpdate();
}
return rw.parseTree(treeId);
}
private static ObjectId emptyTree(final Repository repo) throws IOException {
ObjectInserter oi = repo.newObjectInserter();
try {
ObjectId id = oi.insert(Constants.OBJ_TREE, new byte[] {});
oi.flush();
return id;
} finally {
oi.release();
}
}
}