HasDraftByLegacyPredicate: Only get changes with drafts, not the comments

HasDraftByLegacyPredicate is only interested in changes with draft
comments, but not in the comments itself. Save some work and give
HasDraftByLegacyPredicate only what it needs.

Change-Id: Iee2154229f835ad656bda21aa4f70a7342844bc0
Signed-off-by: Edwin Kempin <ekempin@google.com>

gerrit-server/src/main/java/com/google/gerrit/server/PatchLineCommentsUtil.java

@@ -20,6 +20,7 @@ import static java.util.stream.Collectors.toList;
 
 import com.google.common.base.Optional;
 import com.google.common.collect.ComparisonChain;
+import com.google.common.collect.FluentIterable;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Ordering;
@@ -38,7 +39,6 @@ import com.google.gerrit.server.config.AllUsersName;
 import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.gerrit.server.notedb.ChangeNotes;
 import com.google.gerrit.server.notedb.ChangeUpdate;
-import com.google.gerrit.server.notedb.DraftCommentNotes;
 import com.google.gerrit.server.notedb.NotesMigration;
 import com.google.gerrit.server.patch.PatchListCache;
 import com.google.gerrit.server.patch.PatchListNotAvailableException;
@@ -113,17 +113,14 @@ public class PatchLineCommentsUtil {
 
   private final GitRepositoryManager repoManager;
   private final AllUsersName allUsers;
-  private final DraftCommentNotes.Factory draftFactory;
   private final NotesMigration migration;
 
   @Inject
   PatchLineCommentsUtil(GitRepositoryManager repoManager,
       AllUsersName allUsers,
-      DraftCommentNotes.Factory draftFactory,
       NotesMigration migration) {
     this.repoManager = repoManager;
     this.allUsers = allUsers;
-    this.draftFactory = draftFactory;
     this.migration = migration;
   }
 
@@ -275,13 +272,14 @@ public class PatchLineCommentsUtil {
   }
 
   @Deprecated // To be used only by HasDraftByLegacyPredicate.
-  public List<PatchLineComment> draftByAuthor(ReviewDb db,
+  public List<Change.Id> changesWithDraftsByAuthor(ReviewDb db,
       Account.Id author) throws OrmException {
     if (!migration.readChanges()) {
-      return sort(db.patchComments().draftByAuthor(author).toList());
+      return FluentIterable.from(db.patchComments().draftByAuthor(author))
+          .transform(plc -> plc.getPatchSetId().getParentKey()).toList();
     }
 
-    List<PatchLineComment> comments = new ArrayList<>();
+    List<Change.Id> changes = new ArrayList<>();
     try (Repository repo = repoManager.openRepository(allUsers)) {
       for (String refName : repo.getRefDatabase()
           .getRefs(RefNames.REFS_DRAFT_COMMENTS).keySet()) {
@@ -290,17 +288,12 @@ public class PatchLineCommentsUtil {
         if (accountId == null || changeId == null) {
           continue;
         }
-        // Avoid loading notes for all affected changes just to be able to auto-
-        // rebuild. This is only used in a corner case in the search codepath,
-        // so returning slightly stale values is ok.
-        DraftCommentNotes notes =
-            draftFactory.createWithAutoRebuildingDisabled(changeId, author);
-        comments.addAll(notes.load().getComments().values());
+        changes.add(changeId);
       }
     } catch (IOException e) {
       throw new OrmException(e);
     }
-    return sort(comments);
+    return changes;
   }
 
   public void putComments(ReviewDb db, ChangeUpdate update,

gerrit-server/src/main/java/com/google/gerrit/server/query/change/HasDraftByLegacyPredicate.java

@@ -16,7 +16,6 @@ package com.google.gerrit.server.query.change;
 
 import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.reviewdb.client.Change;
-import com.google.gerrit.reviewdb.client.PatchLineComment;
 import com.google.gerrit.server.query.change.ChangeQueryBuilder.Arguments;
 import com.google.gwtorm.server.ListResultSet;
 import com.google.gwtorm.server.OrmException;
@@ -50,9 +49,9 @@ class HasDraftByLegacyPredicate extends ChangeOperatorPredicate
   @Override
   public ResultSet<ChangeData> read() throws OrmException {
     Set<Change.Id> ids = new HashSet<>();
-    for (PatchLineComment sc :
-        args.plcUtil.draftByAuthor(args.db.get(), accountId)) {
-      ids.add(sc.getKey().getParentKey().getParentKey().getParentKey());
+    for (Change.Id changeId : args.plcUtil
+        .changesWithDraftsByAuthor(args.db.get(), accountId)) {
+      ids.add(changeId);
     }
 
     List<ChangeData> r = new ArrayList<>(ids.size());