Factor out writing of commit for notedb updates

For the sake of rebuilding the notedb, we would like to write all
commits for all AbstractChangeUpdates on a project to the object
database, before committing a single BatchRefUpdate to update all the
refs.  This refactoring makes that possible.

Change-Id: I864b2845b32426a55a3f62910ae09910bc25901e

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

@@ -25,6 +25,7 @@ import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.gerrit.server.git.MetaDataUpdate;
 import com.google.gerrit.server.git.VersionedMetaData;
 import com.google.gerrit.server.project.ChangeControl;
+import com.google.gwtorm.server.OrmException;
 
 import org.eclipse.jgit.errors.ConfigInvalidException;
 import org.eclipse.jgit.lib.BatchRefUpdate;
@@ -178,6 +179,10 @@ public abstract class AbstractChangeUpdate extends VersionedMetaData {
         anonymousCowardName);
   }
 
+  /** Writes commit to a BatchMetaDataUpdate without committing the batch. */
+  abstract public void writeCommit(BatchMetaDataUpdate batch)
+      throws OrmException, IOException;
+
   /**
    * @return the NameKey for the project where the update will be stored,
    *    which is not necessarily the same as the change's project.

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

@@ -262,19 +262,7 @@ public class ChangeDraftUpdate extends AbstractChangeUpdate {
   public RevCommit commit() throws IOException {
     BatchMetaDataUpdate batch = openUpdate();
     try {
-      CommitBuilder builder = new CommitBuilder();
+      writeCommit(batch);
-      if (migration.write()) {
-        AtomicBoolean removedAllComments = new AtomicBoolean();
-        ObjectId treeId = storeCommentsInNotes(removedAllComments);
-        if (treeId != null) {
-          if (removedAllComments.get()) {
-            batch.removeRef(getRefName());
-          } else {
-            builder.setTreeId(treeId);
-            batch.write(builder);
-          }
-        }
-      }
       return batch.commit();
     } catch (OrmException e) {
       throw new IOException(e);
@@ -283,6 +271,24 @@ public class ChangeDraftUpdate extends AbstractChangeUpdate {
     }
   }
 
+  @Override
+  public void writeCommit(BatchMetaDataUpdate batch)
+      throws OrmException, IOException {
+    CommitBuilder builder = new CommitBuilder();
+    if (migration.write()) {
+      AtomicBoolean removedAllComments = new AtomicBoolean();
+      ObjectId treeId = storeCommentsInNotes(removedAllComments);
+      if (treeId != null) {
+        if (removedAllComments.get()) {
+          batch.removeRef(getRefName());
+        } else {
+          builder.setTreeId(treeId);
+          batch.write(builder);
+        }
+      }
+    }
+  }
+
   @Override
   protected Project.NameKey getProjectName() {
     return draftsProject;

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

@@ -389,14 +389,7 @@ public class ChangeUpdate extends AbstractChangeUpdate {
   public RevCommit commit() throws IOException {
     BatchMetaDataUpdate batch = openUpdate();
     try {
-      CommitBuilder builder = new CommitBuilder();
+      writeCommit(batch);
-      if (migration.write()) {
-        ObjectId treeId = storeCommentsInNotes();
-        if (treeId != null) {
-          builder.setTreeId(treeId);
-        }
-      }
-      batch.write(builder);
       if (draftUpdate != null) {
         draftUpdate.commit();
       }
@@ -409,6 +402,19 @@ public class ChangeUpdate extends AbstractChangeUpdate {
     }
   }
 
+  @Override
+  public void writeCommit(BatchMetaDataUpdate batch) throws OrmException,
+      IOException {
+    CommitBuilder builder = new CommitBuilder();
+    if (migration.write()) {
+      ObjectId treeId = storeCommentsInNotes();
+      if (treeId != null) {
+        builder.setTreeId(treeId);
+      }
+    }
+    batch.write(builder);
+  }
+
   @Override
   protected String getRefName() {
     return ChangeNoteUtil.changeRefName(getChange().getId());