ChangeNotes: Add special factory method for new changes

When a new change is created the Change instance must be passed into
ChangeNotes, because there is no notes branch yet from which the
change can be read. Add an extra factory method for this so that this
case can be differentiated from instantiating ChangeNotes for
existing changes. Then in a later step we can change the method
signature of the factory method for existing changes to require a
project name + a change ID instead of a change.

Change-Id: I3adc5c5814c4201541834d25f48b50a1d886895a
Signed-off-by: Edwin Kempin <ekempin@google.com>

gerrit-server/src/main/java/com/google/gerrit/server/git/BatchUpdate.java

@@ -397,6 +397,7 @@ public class BatchUpdate implements AutoCloseable {
   private final GitRepositoryManager repoManager;
   private final ChangeIndexer indexer;
   private final ChangeControl.GenericFactory changeControlFactory;
+  private final ChangeNotes.Factory changeNotesFactory;
   private final ChangeUpdate.Factory changeUpdateFactory;
   private final GitReferenceUpdated gitRefUpdated;
   private final NotesMigration notesMigration;
@@ -424,6 +425,7 @@ public class BatchUpdate implements AutoCloseable {
   BatchUpdate(GitRepositoryManager repoManager,
       ChangeIndexer indexer,
       ChangeControl.GenericFactory changeControlFactory,
+      ChangeNotes.Factory changeNotesFactory,
       ChangeUpdate.Factory changeUpdateFactory,
       GitReferenceUpdated gitRefUpdated,
       NotesMigration notesMigration,
@@ -437,6 +439,7 @@ public class BatchUpdate implements AutoCloseable {
     this.repoManager = repoManager;
     this.indexer = indexer;
     this.changeControlFactory = changeControlFactory;
+    this.changeNotesFactory = changeNotesFactory;
     this.changeUpdateFactory = changeUpdateFactory;
     this.gitRefUpdated = gitRefUpdated;
     this.notesMigration = notesMigration;
@@ -628,8 +631,9 @@ public class BatchUpdate implements AutoCloseable {
     // Pass in preloaded change to controlFor, to avoid:
     //  - reading from a db that does not belong to this update
     //  - attempting to read a change that doesn't exist yet
+    ChangeNotes notes = changeNotesFactory.createForNew(c);
     ChangeContext ctx = new ChangeContext(
-      changeControlFactory.controlFor(c, user), new BatchUpdateReviewDb(db));
+      changeControlFactory.controlFor(notes, user), new BatchUpdateReviewDb(db));
     if (notesMigration.readChanges()) {
       ctx.getNotes().load();
     }

gerrit-server/src/main/java/com/google/gerrit/server/notedb/AbstractChangeNotes.java

@@ -89,7 +89,7 @@ public abstract class AbstractChangeNotes<T> extends VersionedMetaData {
    * @return the NameKey for the project where the notes should be stored,
    *    which is not necessarily the same as the change's project.
    */
-  protected abstract Project.NameKey getProjectName();
+  public abstract Project.NameKey getProjectName();
 
   @SuppressWarnings("unchecked")
   protected final T self() {

gerrit-server/src/main/java/com/google/gerrit/server/notedb/ChangeNotes.java

@@ -118,6 +118,10 @@ public class ChangeNotes extends AbstractChangeNotes<ChangeNotes> {
     public ChangeNotes create(Change change) {
       return new ChangeNotes(repoManager, migration, allUsersProvider, change);
     }
+
+    public ChangeNotes createForNew(Change change) {
+      return new ChangeNotes(repoManager, migration, allUsersProvider, change);
+    }
   }
 
   private final Change change;
@@ -345,7 +349,7 @@ public class ChangeNotes extends AbstractChangeNotes<ChangeNotes> {
   }
 
   @Override
-  protected Project.NameKey getProjectName() {
+  public Project.NameKey getProjectName() {
     return getChange().getProject();
   }
 }

gerrit-server/src/main/java/com/google/gerrit/server/notedb/DraftCommentNotes.java

@@ -134,7 +134,7 @@ public class DraftCommentNotes extends AbstractChangeNotes<DraftCommentNotes> {
   }
 
   @Override
-  protected Project.NameKey getProjectName() {
+  public Project.NameKey getProjectName() {
     return draftsProject;
   }
 }

gerrit-server/src/main/java/com/google/gerrit/server/project/ChangeControl.java

@@ -77,6 +77,16 @@ public class ChangeControl {
       }
     }
 
+    public ChangeControl controlFor(ChangeNotes notes, CurrentUser user)
+        throws NoSuchChangeException {
+      try {
+        return projectControl.controlFor(notes.getProjectName(), user)
+            .controlFor(notes);
+      } catch (NoSuchProjectException | IOException e) {
+        throw new NoSuchChangeException(notes.getChangeId(), e);
+      }
+    }
+
     public ChangeControl validateFor(Change.Id changeId, CurrentUser user)
         throws NoSuchChangeException, OrmException {
       Change change = db.get().changes().get(changeId);

gerrit-server/src/main/java/com/google/gerrit/server/project/ProjectControl.java

@@ -43,6 +43,7 @@ import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.gerrit.server.git.TagCache;
 import com.google.gerrit.server.git.VisibleRefFilter;
 import com.google.gerrit.server.group.SystemGroupBackend;
+import com.google.gerrit.server.notedb.ChangeNotes;
 import com.google.inject.Inject;
 import com.google.inject.Provider;
 import com.google.inject.assistedinject.Assisted;
@@ -196,6 +197,11 @@ public class ProjectControl {
     return changeControlFactory.create(controlForRef(change.getDest()), change);
   }
 
+  public ChangeControl controlFor(ChangeNotes notes) {
+    return changeControlFactory
+        .create(controlForRef(notes.getChange().getDest()), notes);
+  }
+
   public RefControl controlForRef(Branch.NameKey ref) {
     return controlForRef(ref.get());
   }