gerrit-server/src/main/java/com/google/gerrit/server/git/NotesBranchUtil.java - gerrit - Git at Google

 // Copyright (C) 2012 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.gerrit.reviewdb.client.Project;
 import com.google.gerrit.server.GerritPersonIdent;
 import com.google.gerrit.server.extensions.events.GitReferenceUpdated;
 import com.google.inject.Inject;
 import com.google.inject.assistedinject.Assisted;

 import org.eclipse.jgit.api.errors.ConcurrentRefUpdateException;
 import org.eclipse.jgit.errors.CorruptObjectException;
 import org.eclipse.jgit.errors.IncorrectObjectTypeException;
 import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.lib.CommitBuilder;
 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.RefUpdate.Result;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.merge.MergeStrategy;
 import org.eclipse.jgit.notes.Note;
 import org.eclipse.jgit.notes.NoteMap;
 import org.eclipse.jgit.notes.NoteMapMerger;
 import org.eclipse.jgit.notes.NoteMerger;
 import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.revwalk.RevWalk;

 import java.io.IOException;

 /**
  * A utility class for updating a notes branch with automatic merge of note
  * trees.
  */
 public class NotesBranchUtil {
   public interface Factory {
     NotesBranchUtil create(Project.NameKey project, Repository db,
         ObjectInserter inserter);
   }

   private static final int MAX_LOCK_FAILURE_CALLS = 10;
   private static final int SLEEP_ON_LOCK_FAILURE_MS = 25;

   private final PersonIdent gerritIdent;
   private final GitReferenceUpdated gitRefUpdated;
   private final Project.NameKey project;
   private final Repository db;
   private final ObjectInserter inserter;

   private RevCommit baseCommit;
   private NoteMap base;

   private RevCommit oursCommit;
   private NoteMap ours;

   private RevWalk revWalk;
   private ObjectReader reader;
   private boolean overwrite;

   private ReviewNoteMerger noteMerger;

   @Inject
   public NotesBranchUtil(@GerritPersonIdent final PersonIdent gerritIdent,
       final GitReferenceUpdated gitRefUpdated,
       @Assisted Project.NameKey project,
       @Assisted Repository db,
       @Assisted ObjectInserter inserter) {
     this.gerritIdent = gerritIdent;
     this.gitRefUpdated = gitRefUpdated;
     this.project = project;
     this.db = db;
     this.inserter = inserter;
   }

   /**
    * Create a new commit in the {@code notesBranch} by updating existing
    * or creating new notes from the {@code notes} map.
    *
    * @param notes map of notes
    * @param notesBranch notes branch to update
    * @param commitAuthor author of the commit in the notes branch
    * @param commitMessage for the commit in the notes branch
    * @throws IOException
    * @throws ConcurrentRefUpdateException
    */
   public final void commitAllNotes(NoteMap notes, String notesBranch,
       PersonIdent commitAuthor, String commitMessage) throws IOException,
       ConcurrentRefUpdateException {
     this.overwrite = true;
     commitNotes(notes, notesBranch, commitAuthor, commitMessage);
   }

   /**
    * Create a new commit in the {@code notesBranch} by creating not yet
    * existing notes from the {@code notes} map. The notes from the
    * {@code notes} map which already exist in the note-tree of the
    * tip of the {@code notesBranch} will not be updated.
    *
    * @param notes map of notes
    * @param notesBranch notes branch to update
    * @param commitAuthor author of the commit in the notes branch
    * @param commitMessage for the commit in the notes branch
    * @return map with those notes from the {@code notes} that were newly
    *         created
    * @throws IOException
    * @throws ConcurrentRefUpdateException
    */
   public final NoteMap commitNewNotes(NoteMap notes, String notesBranch,
       PersonIdent commitAuthor, String commitMessage) throws IOException,
       ConcurrentRefUpdateException {
     this.overwrite = false;
     commitNotes(notes, notesBranch, commitAuthor, commitMessage);
     NoteMap newlyCreated = NoteMap.newEmptyMap();
     for (Note n : notes) {
       if (base == null || !base.contains(n)) {
         newlyCreated.set(n, n.getData());
       }
     }
     return newlyCreated;
   }

   private void commitNotes(NoteMap notes, String notesBranch,
       PersonIdent commitAuthor, String commitMessage) throws IOException,
       ConcurrentRefUpdateException {
     try {
       revWalk = new RevWalk(db);
       reader = db.newObjectReader();
       loadBase(notesBranch);
       if (overwrite) {
         addAllNotes(notes);
       } else {
         addNewNotes(notes);
       }
       if (base != null) {
         oursCommit = createCommit(ours, commitAuthor, commitMessage, baseCommit);
       } else {
         oursCommit = createCommit(ours, commitAuthor, commitMessage);
       }
       updateRef(notesBranch);
     } finally {
       revWalk.close();
       reader.close();
     }
   }

   private void addNewNotes(NoteMap notes) throws IOException {
     for (Note n : notes) {
       if (! ours.contains(n)) {
         ours.set(n, n.getData());
       }
     }
   }

   private void addAllNotes(NoteMap notes) throws IOException {
     for (Note n : notes) {
       if (ours.contains(n)) {
         // Merge the existing and the new note as if they are both new,
         // means: base == null
         // There is no really a common ancestry for these two note revisions
         ObjectId noteContent = getNoteMerger().merge(null, n, ours.getNote(n),
             reader, inserter).getData();
         ours.set(n, noteContent);
       } else {
         ours.set(n, n.getData());
       }
     }
   }

   private NoteMerger getNoteMerger() {
     if (noteMerger == null) {
       noteMerger = new ReviewNoteMerger();
     }
     return noteMerger;
   }

   private void loadBase(String notesBranch) throws IOException {
     Ref branch = db.getRef(notesBranch);
     if (branch != null) {
       baseCommit = revWalk.parseCommit(branch.getObjectId());
       base = NoteMap.read(revWalk.getObjectReader(), baseCommit);
     }
     if (baseCommit != null) {
       ours = NoteMap.read(revWalk.getObjectReader(), baseCommit);
     } else {
       ours = NoteMap.newEmptyMap();
     }
   }

   private RevCommit createCommit(NoteMap map, PersonIdent author,
       String message, RevCommit... parents) throws IOException {
     CommitBuilder b = new CommitBuilder();
     b.setTreeId(map.writeTree(inserter));
     b.setAuthor(author != null ? author : gerritIdent);
     b.setCommitter(gerritIdent);
     if (parents.length > 0) {
       b.setParentIds(parents);
     }
     b.setMessage(message);
     ObjectId commitId = inserter.insert(b);
     inserter.flush();
     return revWalk.parseCommit(commitId);
   }

   private void updateRef(String notesBranch) throws IOException,
       MissingObjectException, IncorrectObjectTypeException,
       CorruptObjectException, ConcurrentRefUpdateException {
     if (baseCommit != null && oursCommit.getTree().equals(baseCommit.getTree())) {
       // If the trees are identical, there is no change in the notes.
       // Avoid saving this commit as it has no new information.
       return;
     }

     int remainingLockFailureCalls = MAX_LOCK_FAILURE_CALLS;
     RefUpdate refUpdate = createRefUpdate(notesBranch, oursCommit, baseCommit);

     for (;;) {
       Result result = refUpdate.update();

       if (result == Result.LOCK_FAILURE) {
         if (--remainingLockFailureCalls > 0) {
           try {
             Thread.sleep(SLEEP_ON_LOCK_FAILURE_MS);
           } catch (InterruptedException e) {
             // ignore
           }
         } else {
           throw new ConcurrentRefUpdateException("Failed to lock the ref: "
               + notesBranch, db.getRef(notesBranch), result);
         }

       } else if (result == Result.REJECTED) {
         RevCommit theirsCommit =
             revWalk.parseCommit(refUpdate.getOldObjectId());
         NoteMap theirs =
             NoteMap.read(revWalk.getObjectReader(), theirsCommit);
         NoteMapMerger merger =
             new NoteMapMerger(db, getNoteMerger(), MergeStrategy.RESOLVE);
         NoteMap merged = merger.merge(base, ours, theirs);
         RevCommit mergeCommit =
             createCommit(merged, gerritIdent, "Merged note commits\n",
                 theirsCommit, oursCommit);
         refUpdate = createRefUpdate(notesBranch, mergeCommit, theirsCommit);
         remainingLockFailureCalls = MAX_LOCK_FAILURE_CALLS;

       } else if (result == Result.IO_FAILURE) {
         throw new IOException("Couldn't update " + notesBranch + ". "
             + result.name());
       } else {
         gitRefUpdated.fire(project, refUpdate);
         break;
       }
     }
   }

   private RefUpdate createRefUpdate(String notesBranch, ObjectId newObjectId,
       ObjectId expectedOldObjectId) throws IOException {
     RefUpdate refUpdate = db.updateRef(notesBranch);
     refUpdate.setNewObjectId(newObjectId);
     if (expectedOldObjectId == null) {
       refUpdate.setExpectedOldObjectId(ObjectId.zeroId());
     } else {
       refUpdate.setExpectedOldObjectId(expectedOldObjectId);
     }
     return refUpdate;
   }
 }
	// Copyright (C) 2012 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.gerrit.reviewdb.client.Project;
	import com.google.gerrit.server.GerritPersonIdent;
	import com.google.gerrit.server.extensions.events.GitReferenceUpdated;
	import com.google.inject.Inject;
	import com.google.inject.assistedinject.Assisted;

	import org.eclipse.jgit.api.errors.ConcurrentRefUpdateException;
	import org.eclipse.jgit.errors.CorruptObjectException;
	import org.eclipse.jgit.errors.IncorrectObjectTypeException;
	import org.eclipse.jgit.errors.MissingObjectException;
	import org.eclipse.jgit.lib.CommitBuilder;
	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.RefUpdate.Result;
	import org.eclipse.jgit.lib.Repository;
	import org.eclipse.jgit.merge.MergeStrategy;
	import org.eclipse.jgit.notes.Note;
	import org.eclipse.jgit.notes.NoteMap;
	import org.eclipse.jgit.notes.NoteMapMerger;
	import org.eclipse.jgit.notes.NoteMerger;
	import org.eclipse.jgit.revwalk.RevCommit;
	import org.eclipse.jgit.revwalk.RevWalk;

	import java.io.IOException;

	/**
	* A utility class for updating a notes branch with automatic merge of note
	* trees.
	*/
	public class NotesBranchUtil {
	public interface Factory {
	NotesBranchUtil create(Project.NameKey project, Repository db,
	ObjectInserter inserter);
	}

	private static final int MAX_LOCK_FAILURE_CALLS = 10;
	private static final int SLEEP_ON_LOCK_FAILURE_MS = 25;

	private final PersonIdent gerritIdent;
	private final GitReferenceUpdated gitRefUpdated;
	private final Project.NameKey project;
	private final Repository db;
	private final ObjectInserter inserter;

	private RevCommit baseCommit;
	private NoteMap base;

	private RevCommit oursCommit;
	private NoteMap ours;

	private RevWalk revWalk;
	private ObjectReader reader;
	private boolean overwrite;

	private ReviewNoteMerger noteMerger;

	@Inject
	public NotesBranchUtil(@GerritPersonIdent final PersonIdent gerritIdent,
	final GitReferenceUpdated gitRefUpdated,
	@Assisted Project.NameKey project,
	@Assisted Repository db,
	@Assisted ObjectInserter inserter) {
	this.gerritIdent = gerritIdent;
	this.gitRefUpdated = gitRefUpdated;
	this.project = project;
	this.db = db;
	this.inserter = inserter;
	}

	/**
	* Create a new commit in the {@code notesBranch} by updating existing
	* or creating new notes from the {@code notes} map.
	*
	* @param notes map of notes
	* @param notesBranch notes branch to update
	* @param commitAuthor author of the commit in the notes branch
	* @param commitMessage for the commit in the notes branch
	* @throws IOException
	* @throws ConcurrentRefUpdateException
	*/
	public final void commitAllNotes(NoteMap notes, String notesBranch,
	PersonIdent commitAuthor, String commitMessage) throws IOException,
	ConcurrentRefUpdateException {
	this.overwrite = true;
	commitNotes(notes, notesBranch, commitAuthor, commitMessage);
	}

	/**
	* Create a new commit in the {@code notesBranch} by creating not yet
	* existing notes from the {@code notes} map. The notes from the
	* {@code notes} map which already exist in the note-tree of the
	* tip of the {@code notesBranch} will not be updated.
	*
	* @param notes map of notes
	* @param notesBranch notes branch to update
	* @param commitAuthor author of the commit in the notes branch
	* @param commitMessage for the commit in the notes branch
	* @return map with those notes from the {@code notes} that were newly
	* created
	* @throws IOException
	* @throws ConcurrentRefUpdateException
	*/
	public final NoteMap commitNewNotes(NoteMap notes, String notesBranch,
	PersonIdent commitAuthor, String commitMessage) throws IOException,
	ConcurrentRefUpdateException {
	this.overwrite = false;
	commitNotes(notes, notesBranch, commitAuthor, commitMessage);
	NoteMap newlyCreated = NoteMap.newEmptyMap();
	for (Note n : notes) {
	if (base == null \|\| !base.contains(n)) {
	newlyCreated.set(n, n.getData());
	}
	}
	return newlyCreated;
	}

	private void commitNotes(NoteMap notes, String notesBranch,
	PersonIdent commitAuthor, String commitMessage) throws IOException,
	ConcurrentRefUpdateException {
	try {
	revWalk = new RevWalk(db);
	reader = db.newObjectReader();
	loadBase(notesBranch);
	if (overwrite) {
	addAllNotes(notes);
	} else {
	addNewNotes(notes);
	}
	if (base != null) {
	oursCommit = createCommit(ours, commitAuthor, commitMessage, baseCommit);
	} else {
	oursCommit = createCommit(ours, commitAuthor, commitMessage);
	}
	updateRef(notesBranch);
	} finally {
	revWalk.close();
	reader.close();
	}
	}

	private void addNewNotes(NoteMap notes) throws IOException {
	for (Note n : notes) {
	if (! ours.contains(n)) {
	ours.set(n, n.getData());
	}
	}
	}

	private void addAllNotes(NoteMap notes) throws IOException {
	for (Note n : notes) {
	if (ours.contains(n)) {
	// Merge the existing and the new note as if they are both new,
	// means: base == null
	// There is no really a common ancestry for these two note revisions
	ObjectId noteContent = getNoteMerger().merge(null, n, ours.getNote(n),
	reader, inserter).getData();
	ours.set(n, noteContent);
	} else {
	ours.set(n, n.getData());
	}
	}
	}

	private NoteMerger getNoteMerger() {
	if (noteMerger == null) {
	noteMerger = new ReviewNoteMerger();
	}
	return noteMerger;
	}

	private void loadBase(String notesBranch) throws IOException {
	Ref branch = db.getRef(notesBranch);
	if (branch != null) {
	baseCommit = revWalk.parseCommit(branch.getObjectId());
	base = NoteMap.read(revWalk.getObjectReader(), baseCommit);
	}
	if (baseCommit != null) {
	ours = NoteMap.read(revWalk.getObjectReader(), baseCommit);
	} else {
	ours = NoteMap.newEmptyMap();
	}
	}

	private RevCommit createCommit(NoteMap map, PersonIdent author,
	String message, RevCommit... parents) throws IOException {
	CommitBuilder b = new CommitBuilder();
	b.setTreeId(map.writeTree(inserter));
	b.setAuthor(author != null ? author : gerritIdent);
	b.setCommitter(gerritIdent);
	if (parents.length > 0) {
	b.setParentIds(parents);
	}
	b.setMessage(message);
	ObjectId commitId = inserter.insert(b);
	inserter.flush();
	return revWalk.parseCommit(commitId);
	}

	private void updateRef(String notesBranch) throws IOException,
	MissingObjectException, IncorrectObjectTypeException,
	CorruptObjectException, ConcurrentRefUpdateException {
	if (baseCommit != null && oursCommit.getTree().equals(baseCommit.getTree())) {
	// If the trees are identical, there is no change in the notes.
	// Avoid saving this commit as it has no new information.
	return;
	}

	int remainingLockFailureCalls = MAX_LOCK_FAILURE_CALLS;
	RefUpdate refUpdate = createRefUpdate(notesBranch, oursCommit, baseCommit);

	for (;;) {
	Result result = refUpdate.update();

	if (result == Result.LOCK_FAILURE) {
	if (--remainingLockFailureCalls > 0) {
	try {
	Thread.sleep(SLEEP_ON_LOCK_FAILURE_MS);
	} catch (InterruptedException e) {
	// ignore
	}
	} else {
	throw new ConcurrentRefUpdateException("Failed to lock the ref: "
	+ notesBranch, db.getRef(notesBranch), result);
	}

	} else if (result == Result.REJECTED) {
	RevCommit theirsCommit =
	revWalk.parseCommit(refUpdate.getOldObjectId());
	NoteMap theirs =
	NoteMap.read(revWalk.getObjectReader(), theirsCommit);
	NoteMapMerger merger =
	new NoteMapMerger(db, getNoteMerger(), MergeStrategy.RESOLVE);
	NoteMap merged = merger.merge(base, ours, theirs);
	RevCommit mergeCommit =
	createCommit(merged, gerritIdent, "Merged note commits\n",
	theirsCommit, oursCommit);
	refUpdate = createRefUpdate(notesBranch, mergeCommit, theirsCommit);
	remainingLockFailureCalls = MAX_LOCK_FAILURE_CALLS;

	} else if (result == Result.IO_FAILURE) {
	throw new IOException("Couldn't update " + notesBranch + ". "
	+ result.name());
	} else {
	gitRefUpdated.fire(project, refUpdate);
	break;
	}
	}
	}

	private RefUpdate createRefUpdate(String notesBranch, ObjectId newObjectId,
	ObjectId expectedOldObjectId) throws IOException {
	RefUpdate refUpdate = db.updateRef(notesBranch);
	refUpdate.setNewObjectId(newObjectId);
	if (expectedOldObjectId == null) {
	refUpdate.setExpectedOldObjectId(ObjectId.zeroId());
	} else {
	refUpdate.setExpectedOldObjectId(expectedOldObjectId);
	}
	return refUpdate;
	}
	}