Populate results of DiffusionQueryCommitsConduitAPIMethod with DiffusionLowLevelCommitQuery

Summary:
Ref T2783.  This populates the following fields in DiffusionQueryCommitsConduitAPIMethod using DiffusionLowLevelCommitQuery when `bypassCache` is set to true:

  * `authorName`
  * `authorEmail`
  * `committerName`
  * `committerEmail`
  * `message`
  * `hashes`

The original outline called for `authorPHID` and `committerPHID` as well (but no `message` field).  As far as I can tell, the PHIDs aren't actual a property on `DiffusionCommitRef`, and since the intention of this is to be able to populate a `DiffusionCommitRef`, I haven't included them.  Let me know if we really do need the PHIDs here.

Test Plan: Tested using 3 Phabricator instances (one web, one taskmaster and one storage).  The web and taskmaster tiers are directed at the Conduit API of the storage tier.  Made a `diffusion.querycommits` from the Conduit app on the web tier instance and saw the data populated from the raw VCS data (located on the storage tier).

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Maniphest Tasks: T2783

Differential Revision: https://secure.phabricator.com/D10399

src/applications/diffusion/conduit/DiffusionQueryCommitsConduitAPIMethod.php

@@ -22,6 +22,7 @@ final class DiffusionQueryCommitsConduitAPIMethod
       'names'             => 'optional list<string>',
       'repositoryPHID'    => 'optional phid',
       'needMessages'      => 'optional bool',
+      'bypassCache'       => 'optional bool',
     ) + $this->getPagerParamTypes();
   }
 
@@ -31,6 +32,7 @@ final class DiffusionQueryCommitsConduitAPIMethod
 
   protected function execute(ConduitAPIRequest $request) {
     $need_messages = $request->getValue('needMessages');
+    $bypass_cache = $request->getValue('bypassCache');
 
     $query = id(new DiffusionCommitQuery())
       ->setViewer($request->getUser());
@@ -87,8 +89,35 @@ final class DiffusionQueryCommitsConduitAPIMethod
         'uri' => $uri,
         'isImporting' => !$commit->isImported(),
         'summary' => $commit->getSummary(),
+        'authorName' => '',
+        'authorEmail' => '',
+        'committerName' => '',
+        'committerEmail' => '',
+        'hashes' => array(),
       );
 
+      if ($bypass_cache) {
+        $lowlevel_commitref = id(new DiffusionLowLevelCommitQuery())
+          ->setRepository($commit->getRepository())
+          ->withIdentifier($commit->getCommitIdentifier())
+          ->execute();
+
+        $dict['authorName'] = $lowlevel_commitref->getAuthorName();
+        $dict['authorEmail'] = $lowlevel_commitref->getAuthorEmail();
+        $dict['committerName'] = $lowlevel_commitref->getCommitterName();
+        $dict['committerEmail'] = $lowlevel_commitref->getCommitterEmail();
+
+        if ($need_messages) {
+          $dict['message'] = $lowlevel_commitref->getMessage();
+        }
+
+        foreach ($lowlevel_commitref->getHashes() as $hash) {
+          $dict['hashes'][] = array(
+            'type' => $hash->getHashType(),
+            'value' => $hash->getHashValue());
+        }
+      }
+
       if ($need_messages) {
         $commit_data = $commit->getCommitData();
         if ($commit_data) {