Use DiffQuery instead of direct hunk loads in MessageParser daemon

Summary: Ref T5179. Ref T4045. Continue reducing the number of direct hunk loads we perform.

Test Plan: Pushed a closing commit, used `scripts/repository/reparse.php --message ...` to trigger this logic, got a sensible/accurate result.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T4045, T5179

Differential Revision: https://secure.phabricator.com/D9288

src/applications/repository/worker/commitmessageparser/PhabricatorRepositoryCommitMessageParserWorker.php

@@ -294,12 +294,22 @@ abstract class PhabricatorRepositoryCommitMessageParserWorker
 
     $repository = $this->repository;
 
+    $vs_diff = id(new DifferentialDiffQuery())
+      ->setViewer(PhabricatorUser::getOmnipotentUser())
+      ->withRevisionIDs(array($revision->getID()))
+      ->needChangesets(true)
+      ->setLimit(1)
+      ->executeOne();
+    if (!$vs_diff) {
+      return null;
+    }
+
+    if ($vs_diff->getCreationMethod() == 'commit') {
+      return null;
+    }
+
     $vs_changesets = array();
-    $vs_diff = id(new DifferentialDiff())->loadOneWhere(
-      'revisionID = %d AND creationMethod != %s ORDER BY id DESC LIMIT 1',
-      $revision->getID(),
-      'commit');
-    foreach ($vs_diff->loadChangesets() as $changeset) {
+    foreach ($vs_diff->getChangesets() as $changeset) {
       $path = $changeset->getAbsoluteRepositoryPath($repository, $vs_diff);
       $path = ltrim($path, '/');
       $vs_changesets[$path] = $changeset;
@@ -317,14 +327,6 @@ abstract class PhabricatorRepositoryCommitMessageParserWorker
       return $vs_diff;
     }
 
-    $hunks = id(new DifferentialHunk())->loadAllWhere(
-      'changesetID IN (%Ld)',
-      mpull($vs_changesets, 'getID'));
-    $hunks = mgroup($hunks, 'getChangesetID');
-    foreach ($vs_changesets as $changeset) {
-      $changeset->attachHunks(idx($hunks, $changeset->getID(), array()));
-    }
-
     $file_phids = array();
     foreach ($vs_changesets as $changeset) {
       $metadata = $changeset->getMetadata();