Add a --repair flag to "bin/repository discover"

Summary:
If a repository is missing commits because they mysteriously vanished, there's no reasonable way to get them back right now. Provide a way to ignore the state in the database and rediscover the entire repository unconditionally.

We don't queue any reparses or anything, but when I move reparse into this script we can hook things up or something. This generally shouldn't be too important anyway.

Test Plan: Ran `repository discover --repair` on Phabricator.

Reviewers: jungejason, nh, vrana

Reviewed By: vrana

CC: aran

Differential Revision: https://secure.phabricator.com/D2850

src/applications/repository/daemon/PhabricatorRepositoryPullLocalDaemon.php

@@ -46,6 +46,12 @@ final class PhabricatorRepositoryPullLocalDaemon
   extends PhabricatorDaemon {
 
   private $commitCache = array();
+  private $repair;
+
+  public function setRepair($repair) {
+    $this->repair = $repair;
+    return $this;
+  }
 
 
 /* -(  Pulling Repositories  )----------------------------------------------- */
@@ -238,6 +244,13 @@ final class PhabricatorRepositoryPullLocalDaemon
       return true;
     }
 
+    if ($this->repair) {
+      // In repair mode, rediscover the entire repository, ignoring the
+      // database state. We can hit the local cache above, but if we miss it
+      // stop the script from going to the database cache.
+      return false;
+    }
+
     $commit = id(new PhabricatorRepositoryCommit())->loadOneWhere(
       'repositoryID = %s AND commitIdentifier = %s',
       $repository->getID(),
@@ -316,6 +329,12 @@ final class PhabricatorRepositoryPullLocalDaemon
         $commit->getID(),
         $epoch);
 
+      if ($this->repair) {
+        // Normally, the query should throw a duplicate key exception. If we
+        // reach this in repair mode, we've actually performed a repair.
+        $this->log("Repaired commit '%s'.", $commit_identifier);
+      }
+
       $this->setCache($repository, $commit_identifier);
     } catch (AphrontQueryDuplicateKeyException $ex) {
       // Ignore. This can happen because we discover the same new commit

src/applications/repository/management/PhabricatorRepositoryManagementDiscoverWorkflow.php

@@ -22,7 +22,7 @@ final class PhabricatorRepositoryManagementDiscoverWorkflow
   public function didConstruct() {
     $this
       ->setName('discover')
-      ->setExamples('**discover** __repository__ ...')
+      ->setExamples('**discover** [__options__] __repository__ ...')
       ->setSynopsis('Discover __repository__, named by callsign or PHID.')
       ->setArguments(
         array(
@@ -30,6 +30,11 @@ final class PhabricatorRepositoryManagementDiscoverWorkflow
             'name'        => 'verbose',
             'help'        => 'Show additional debugging information.',
           ),
+          array(
+            'name'        => 'repair',
+            'help'        => 'Repair a repository with gaps in commit '.
+                             'history.',
+          ),
           array(
             'name'        => 'repos',
             'wildcard'    => true,
@@ -52,6 +57,7 @@ final class PhabricatorRepositoryManagementDiscoverWorkflow
 
       $daemon = new PhabricatorRepositoryPullLocalDaemon(array());
       $daemon->setVerbose($args->getArg('verbose'));
+      $daemon->setRepair($args->getArg('repair'));
       $daemon->discoverRepository($repo);
     }