// 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;
import com.google.common.base.Objects;
import org.eclipse.jgit.dircache.DirCache;
import org.eclipse.jgit.dircache.DirCacheBuilder;
import org.eclipse.jgit.dircache.DirCacheEditor;
import org.eclipse.jgit.dircache.DirCacheEditor.DeletePath;
import org.eclipse.jgit.dircache.DirCacheEditor.PathEdit;
import org.eclipse.jgit.dircache.DirCacheEntry;
import org.eclipse.jgit.errors.ConfigInvalidException;
import org.eclipse.jgit.errors.IncorrectObjectTypeException;
import org.eclipse.jgit.errors.MissingObjectException;
import org.eclipse.jgit.lib.AnyObjectId;
import org.eclipse.jgit.lib.CommitBuilder;
import org.eclipse.jgit.lib.Config;
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.ObjectLoader;
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.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevTree;
import org.eclipse.jgit.revwalk.RevWalk;
import org.eclipse.jgit.treewalk.TreeWalk;
import org.eclipse.jgit.util.RawParseUtils;
import java.io.IOException;
/**
* Support for metadata stored within a version controlled branch.
* <p>
* Implementors are responsible for supplying implementations of the onLoad and
* onSave methods to read from the repository, or format an update that can
* later be written back to the repository.
*/
public abstract class VersionedMetaData {
private RevCommit revision;
protected ObjectReader reader;
protected ObjectInserter inserter;
protected DirCache newTree;
/** @return name of the reference storing this configuration. */
protected abstract String getRefName();
/** Set up the metadata, parsing any state from the loaded revision. */
protected abstract void onLoad() throws IOException, ConfigInvalidException;
/**
* Save any changes to the metadata in a commit.
*
* @return true if the commit should proceed, false to abort.
* @throws IOException
* @throws ConfigInvalidException
*/
protected abstract boolean onSave(CommitBuilder commit) throws IOException,
ConfigInvalidException;
/** @return revision of the metadata that was loaded. */
public ObjectId getRevision() {
return revision != null ? revision.copy() : null;
}
/**
* Load the current version from the branch.
* <p>
* The repository is not held after the call completes, allowing the
* application to retain this object for long periods of time.
*
* @param db repository to access.
* @throws IOException
* @throws ConfigInvalidException
*/
public void load(Repository db) throws IOException, ConfigInvalidException {
Ref ref = db.getRef(getRefName());
load(db, ref != null ? ref.getObjectId() : null);
}
/**
* Load a specific version from the repository.
* <p>
* This method is primarily useful for applying updates to a specific revision
* that was shown to an end-user in the user interface. If there are conflicts
* with another user's concurrent changes, these will be automatically
* detected at commit time.
* <p>
* The repository is not held after the call completes, allowing the
* application to retain this object for long periods of time.
*
* @param db repository to access.
* @param id revision to load.
* @throws IOException
* @throws ConfigInvalidException
*/
public void load(Repository db, ObjectId id) throws IOException,
ConfigInvalidException {
reader = db.newObjectReader();
try {
revision = id != null ? new RevWalk(reader).parseCommit(id) : null;
onLoad();
} finally {
reader.release();
reader = null;
}
}
public void load(MetaDataUpdate update) throws IOException,
ConfigInvalidException {
load(update.getRepository());
}
public void load(MetaDataUpdate update, ObjectId id) throws IOException,
ConfigInvalidException {
load(update.getRepository(), id);
}
/**
* Update this metadata branch, recording a new commit on its reference.
*
* @param update helper information to define the update that will occur.
* @return the commit that was created
* @throws IOException if there is a storage problem and the update cannot be
* executed as requested or if it failed because of a concurrent
* update to the same reference
*/
public RevCommit commit(MetaDataUpdate update) throws IOException {
BatchMetaDataUpdate batch = openUpdate(update);
try {
batch.write(update.getCommitBuilder());
return batch.commit();
} finally {
batch.close();
}
}
/**
* Creates a new commit and a new ref based on this commit.
*
* @param update helper information to define the update that will occur.
* @param refName name of the ref that should be created
* @return the commit that was created
* @throws IOException if there is a storage problem and the update cannot be
* executed as requested or if it failed because of a concurrent
* update to the same reference
*/
public RevCommit commitToNewRef(MetaDataUpdate update, String refName) throws IOException {
BatchMetaDataUpdate batch = openUpdate(update);
try {
batch.write(update.getCommitBuilder());
return batch.createRef(refName);
} finally {
batch.close();
}
}
public interface BatchMetaDataUpdate {
void write(CommitBuilder commit) throws IOException;
void write(VersionedMetaData config, CommitBuilder commit) throws IOException;
RevCommit createRef(String refName) throws IOException;
RevCommit commit() throws IOException;
RevCommit commitAt(ObjectId revision) throws IOException;
void close();
}
public BatchMetaDataUpdate openUpdate(final MetaDataUpdate update) throws IOException {
final Repository db = update.getRepository();
reader = db.newObjectReader();
inserter = db.newObjectInserter();
final RevWalk rw = new RevWalk(reader);
final RevTree tree = revision != null ? rw.parseTree(revision) : null;
newTree = readTree(tree);
return new BatchMetaDataUpdate() {
AnyObjectId src = revision;
AnyObjectId srcTree = tree;
@Override
public void write(CommitBuilder commit) throws IOException {
write(VersionedMetaData.this, commit);
}
private boolean doSave(VersionedMetaData config, CommitBuilder commit) throws IOException {
DirCache nt = config.newTree;
ObjectReader r = config.reader;
ObjectInserter i = config.inserter;
try {
config.newTree = newTree;
config.reader = reader;
config.inserter = inserter;
return config.onSave(commit);
} catch (ConfigInvalidException e) {
throw new IOException("Cannot update " + getRefName() + " in "
+ db.getDirectory() + ": " + e.getMessage(), e);
} finally {
config.newTree = nt;
config.reader = r;
config.inserter = i;
}
}
@Override
public void write(VersionedMetaData config, CommitBuilder commit) throws IOException {
if (!doSave(config, commit)) {
return;
}
final ObjectId res = newTree.writeTree(inserter);
if (res.equals(srcTree) && !update.allowEmpty()) {
// If there are no changes to the content, don't create the commit.
return;
}
commit.setTreeId(res);
if (src != null) {
commit.addParentId(src);
}
src = inserter.insert(commit);
srcTree = res;
}
@Override
public RevCommit createRef(String refName) throws IOException {
if (Objects.equal(src, revision)) {
return revision;
}
RefUpdate ru = db.updateRef(refName);
ru.setExpectedOldObjectId(ObjectId.zeroId());
ru.setNewObjectId(src);
ru.disableRefLog();
inserter.flush();
RefUpdate.Result result = ru.update();
switch (result) {
case NEW:
revision = rw.parseCommit(ru.getNewObjectId());
update.fireGitRefUpdatedEvent(ru);
return revision;
default:
throw new IOException("Cannot update " + ru.getName() + " in "
+ db.getDirectory() + ": " + ru.getResult());
}
}
@Override
public RevCommit commit() throws IOException {
return commitAt(revision);
}
@Override
public RevCommit commitAt(ObjectId expected) throws IOException {
if (Objects.equal(src, expected)) {
return revision;
}
RefUpdate ru = db.updateRef(getRefName());
if (expected != null) {
ru.setExpectedOldObjectId(expected);
} else {
ru.setExpectedOldObjectId(ObjectId.zeroId());
}
ru.setNewObjectId(src);
ru.disableRefLog();
inserter.flush();
switch (ru.update(rw)) {
case NEW:
case FAST_FORWARD:
revision = rw.parseCommit(ru.getNewObjectId());
update.fireGitRefUpdatedEvent(ru);
return revision;
default:
throw new IOException("Cannot update " + ru.getName() + " in "
+ db.getDirectory() + ": " + ru.getResult());
}
}
@Override
public void close() {
newTree = null;
if (inserter != null) {
inserter.release();
inserter = null;
}
if (reader != null) {
reader.release();
reader = null;
}
}
};
}
protected DirCache readTree(RevTree tree) throws IOException,
MissingObjectException, IncorrectObjectTypeException {
DirCache dc = DirCache.newInCore();
if (tree != null) {
DirCacheBuilder b = dc.builder();
b.addTree(new byte[0], DirCacheEntry.STAGE_0, reader, tree);
b.finish();
}
return dc;
}
protected Config readConfig(String fileName) throws IOException,
ConfigInvalidException {
Config rc = new Config();
String text = readUTF8(fileName);
if (!text.isEmpty()) {
try {
rc.fromText(text);
} catch (ConfigInvalidException err) {
throw new ConfigInvalidException("Invalid config file " + fileName
+ " in commit " + revision.name(), err);
}
}
return rc;
}
protected String readUTF8(String fileName) throws IOException {
byte[] raw = readFile(fileName);
return raw.length != 0 ? RawParseUtils.decode(raw) : "";
}
protected byte[] readFile(String fileName) throws IOException {
if (revision == null) {
return new byte[] {};
}
TreeWalk tw = TreeWalk.forPath(reader, fileName, revision.getTree());
if (tw != null) {
ObjectLoader obj = reader.open(tw.getObjectId(0), Constants.OBJ_BLOB);
return obj.getCachedBytes(Integer.MAX_VALUE);
} else {
return new byte[] {};
}
}
protected ObjectId getObjectId(String fileName) throws IOException {
if (revision == null) {
return null;
}
TreeWalk tw = TreeWalk.forPath(reader, fileName, revision.getTree());
if (tw != null) {
return tw.getObjectId(0);
}
return null;
}
protected static void set(Config rc, String section, String subsection,
String name, String value) {
if (value != null) {
rc.setString(section, subsection, name, value);
} else {
rc.unset(section, subsection, name);
}
}
protected static void set(Config rc, String section, String subsection,
String name, boolean value) {
if (value) {
rc.setBoolean(section, subsection, name, value);
} else {
rc.unset(section, subsection, name);
}
}
protected static <E extends Enum<?>> void set(Config rc, String section,
String subsection, String name, E value, E defaultValue) {
if (value != defaultValue) {
rc.setEnum(section, subsection, name, value);
} else {
rc.unset(section, subsection, name);
}
}
protected void saveConfig(String fileName, Config cfg) throws IOException {
saveUTF8(fileName, cfg.toText());
}
protected void saveUTF8(String fileName, String text) throws IOException {
saveFile(fileName, text != null ? Constants.encode(text) : null);
}
protected void saveFile(String fileName, byte[] raw) throws IOException {
DirCacheEditor editor = newTree.editor();
if (raw != null && 0 < raw.length) {
final ObjectId blobId = inserter.insert(Constants.OBJ_BLOB, raw);
editor.add(new PathEdit(fileName) {
@Override
public void apply(DirCacheEntry ent) {
ent.setFileMode(FileMode.REGULAR_FILE);
ent.setObjectId(blobId);
}
});
} else {
editor.add(new DeletePath(fileName));
}
editor.finish();
}
}