diff --git a/src/applications/search/controller/PhabricatorApplicationSearchController.php b/src/applications/search/controller/PhabricatorApplicationSearchController.php
index 92a8181b4f..386be2ca8a 100644
--- a/src/applications/search/controller/PhabricatorApplicationSearchController.php
+++ b/src/applications/search/controller/PhabricatorApplicationSearchController.php
@@ -1,528 +1,557 @@
 <?php
 
 final class PhabricatorApplicationSearchController
   extends PhabricatorSearchBaseController {
 
   private $searchEngine;
   private $navigation;
   private $queryKey;
   private $preface;
 
   public function setPreface($preface) {
     $this->preface = $preface;
     return $this;
   }
 
   public function getPreface() {
     return $this->preface;
   }
 
   public function setQueryKey($query_key) {
     $this->queryKey = $query_key;
     return $this;
   }
 
   protected function getQueryKey() {
     return $this->queryKey;
   }
 
   public function setNavigation(AphrontSideNavFilterView $navigation) {
     $this->navigation = $navigation;
     return $this;
   }
 
   protected function getNavigation() {
     return $this->navigation;
   }
 
   public function setSearchEngine(
     PhabricatorApplicationSearchEngine $search_engine) {
     $this->searchEngine = $search_engine;
     return $this;
   }
 
   protected function getSearchEngine() {
     return $this->searchEngine;
   }
 
   protected function validateDelegatingController() {
     $parent = $this->getDelegatingController();
 
     if (!$parent) {
       throw new Exception(
         pht('You must delegate to this controller, not invoke it directly.'));
     }
 
     $engine = $this->getSearchEngine();
     if (!$engine) {
       throw new PhutilInvalidStateException('setEngine');
     }
 
     $engine->setViewer($this->getRequest()->getUser());
 
     $parent = $this->getDelegatingController();
   }
 
   public function processRequest() {
     $this->validateDelegatingController();
 
     $key = $this->getQueryKey();
     if ($key == 'edit') {
       return $this->processEditRequest();
     } else {
       return $this->processSearchRequest();
     }
   }
 
   private function processSearchRequest() {
     $parent = $this->getDelegatingController();
     $request = $this->getRequest();
     $user = $request->getUser();
     $engine = $this->getSearchEngine();
     $nav = $this->getNavigation();
     if (!$nav) {
       $nav = $this->buildNavigation();
     }
 
     if ($request->isFormPost()) {
       $saved_query = $engine->buildSavedQueryFromRequest($request);
       $engine->saveQuery($saved_query);
       return id(new AphrontRedirectResponse())->setURI(
         $engine->getQueryResultsPageURI($saved_query->getQueryKey()).'#R');
     }
 
     $named_query = null;
     $run_query = true;
     $query_key = $this->queryKey;
     if ($this->queryKey == 'advanced') {
       $run_query = false;
       $query_key = $request->getStr('query');
     } else if (!strlen($this->queryKey)) {
       $found_query_data = false;
 
       if ($request->isHTTPGet() || $request->isQuicksand()) {
         // If this is a GET request and it has some query data, don't
         // do anything unless it's only before= or after=. We'll build and
         // execute a query from it below. This allows external tools to build
         // URIs like "/query/?users=a,b".
         $pt_data = $request->getPassthroughRequestData();
 
         $exempt = array(
           'before' => true,
           'after' => true,
           'nux' => true,
         );
 
         foreach ($pt_data as $pt_key => $pt_value) {
           if (isset($exempt[$pt_key])) {
             continue;
           }
 
           $found_query_data = true;
           break;
         }
       }
 
       if (!$found_query_data) {
         // Otherwise, there's no query data so just run the user's default
         // query for this application.
         $query_key = head_key($engine->loadEnabledNamedQueries());
       }
     }
 
     if ($engine->isBuiltinQuery($query_key)) {
       $saved_query = $engine->buildSavedQueryFromBuiltin($query_key);
       $named_query = idx($engine->loadEnabledNamedQueries(), $query_key);
     } else if ($query_key) {
       $saved_query = id(new PhabricatorSavedQueryQuery())
         ->setViewer($user)
         ->withQueryKeys(array($query_key))
         ->executeOne();
 
       if (!$saved_query) {
         return new Aphront404Response();
       }
 
       $named_query = idx($engine->loadEnabledNamedQueries(), $query_key);
     } else {
       $saved_query = $engine->buildSavedQueryFromRequest($request);
 
       // Save the query to generate a query key, so "Save Custom Query..." and
       // other features like Maniphest's "Export..." work correctly.
       $engine->saveQuery($saved_query);
     }
 
     $nav->selectFilter(
       'query/'.$saved_query->getQueryKey(),
       'query/advanced');
 
     $form = id(new AphrontFormView())
       ->setUser($user)
       ->setAction($request->getPath());
 
     $engine->buildSearchForm($form, $saved_query);
 
     $errors = $engine->getErrors();
     if ($errors) {
       $run_query = false;
     }
 
     $submit = id(new AphrontFormSubmitControl())
       ->setValue(pht('Execute Query'));
 
     if ($run_query && !$named_query && $user->isLoggedIn()) {
       $submit->addCancelButton(
         '/search/edit/'.$saved_query->getQueryKey().'/',
         pht('Save Custom Query...'));
     }
 
     // TODO: A "Create Dashboard Panel" action goes here somewhere once
     // we sort out T5307.
 
     $form->appendChild($submit);
     $body = array();
 
     if ($this->getPreface()) {
       $body[] = $this->getPreface();
     }
 
     if ($named_query) {
       $title = $named_query->getQueryName();
     } else {
       $title = pht('Advanced Search');
     }
 
     $header = id(new PHUIHeaderView())
       ->setHeader($title)
       ->setProfileHeader(true);
 
     $box = id(new PHUIObjectBoxView())
       ->setHeader($header)
       ->addClass('application-search-results');
 
     if ($run_query || $named_query) {
       $box->setShowHide(
         pht('Edit Query'),
         pht('Hide Query'),
         $form,
         $this->getApplicationURI('query/advanced/?query='.$query_key),
         (!$named_query ? true : false));
     } else {
       $box->setForm($form);
     }
 
     $body[] = $box;
     $more_crumbs = null;
 
     if ($run_query) {
       $exec_errors = array();
 
       $box->setAnchor(
         id(new PhabricatorAnchorView())
           ->setAnchorName('R'));
 
       try {
         $engine->setRequest($request);
 
         $query = $engine->buildQueryFromSavedQuery($saved_query);
 
         $pager = $engine->newPagerForSavedQuery($saved_query);
         $pager->readFromRequest($request);
 
         $objects = $engine->executeQuery($query, $pager);
 
         $force_nux = $request->getBool('nux');
         if (!$objects || $force_nux) {
           $nux_view = $this->renderNewUserView($engine, $force_nux);
         } else {
           $nux_view = null;
         }
 
+        $is_overheated = $query->getIsOverheated();
+
         if ($nux_view) {
           $box->appendChild($nux_view);
         } else {
           $list = $engine->renderResults($objects, $saved_query);
 
           if (!($list instanceof PhabricatorApplicationSearchResultView)) {
             throw new Exception(
               pht(
                 'SearchEngines must render a "%s" object, but this engine '.
                 '(of class "%s") rendered something else.',
                 'PhabricatorApplicationSearchResultView',
                 get_class($engine)));
           }
 
           if ($list->getObjectList()) {
             $box->setObjectList($list->getObjectList());
           }
           if ($list->getTable()) {
             $box->setTable($list->getTable());
           }
           if ($list->getInfoView()) {
             $box->setInfoView($list->getInfoView());
           }
           if ($list->getContent()) {
             $box->appendChild($list->getContent());
           }
 
+          if ($is_overheated) {
+            $box->appendChild($this->newOverheatedView($objects));
+          }
+
           $result_header = $list->getHeader();
           if ($result_header) {
             $box->setHeader($result_header);
             $header = $result_header;
           }
 
           if ($list->getActions()) {
             foreach ($list->getActions() as $action) {
               $header->addActionLink($action);
             }
           }
 
           $use_actions = $engine->newUseResultsActions($saved_query);
           if ($use_actions) {
             $use_dropdown = $this->newUseResultsDropdown(
               $saved_query,
               $use_actions);
             $header->addActionLink($use_dropdown);
           }
 
           $more_crumbs = $list->getCrumbs();
 
           if ($pager->willShowPagingControls()) {
             $pager_box = id(new PHUIBoxView())
               ->setColor(PHUIBoxView::GREY)
               ->addClass('application-search-pager')
               ->appendChild($pager);
             $body[] = $pager_box;
           }
         }
       } catch (PhabricatorTypeaheadInvalidTokenException $ex) {
         $exec_errors[] = pht(
           'This query specifies an invalid parameter. Review the '.
           'query parameters and correct errors.');
       }
 
       // The engine may have encountered additional errors during rendering;
       // merge them in and show everything.
       foreach ($engine->getErrors() as $error) {
         $exec_errors[] = $error;
       }
 
       $errors = $exec_errors;
     }
 
     if ($errors) {
       $box->setFormErrors($errors, pht('Query Errors'));
     }
 
     $crumbs = $parent
       ->buildApplicationCrumbs()
       ->setBorder(true);
 
     if ($more_crumbs) {
       $query_uri = $engine->getQueryResultsPageURI($saved_query->getQueryKey());
       $crumbs->addTextCrumb($title, $query_uri);
 
       foreach ($more_crumbs as $crumb) {
         $crumbs->addCrumb($crumb);
       }
     } else {
       $crumbs->addTextCrumb($title);
     }
 
     require_celerity_resource('application-search-view-css');
 
     return $this->newPage()
       ->setApplicationMenu($this->buildApplicationMenu())
       ->setTitle(pht('Query: %s', $title))
       ->setCrumbs($crumbs)
       ->setNavigation($nav)
       ->addClass('application-search-view')
       ->appendChild($body);
   }
 
   private function processEditRequest() {
     $parent = $this->getDelegatingController();
     $request = $this->getRequest();
     $user = $request->getUser();
     $engine = $this->getSearchEngine();
 
     $nav = $this->getNavigation();
     if (!$nav) {
       $nav = $this->buildNavigation();
     }
 
     $named_queries = $engine->loadAllNamedQueries();
 
     $list_id = celerity_generate_unique_node_id();
 
     $list = new PHUIObjectItemListView();
     $list->setUser($user);
     $list->setID($list_id);
 
     Javelin::initBehavior(
       'search-reorder-queries',
       array(
         'listID' => $list_id,
         'orderURI' => '/search/order/'.get_class($engine).'/',
       ));
 
     foreach ($named_queries as $named_query) {
       $class = get_class($engine);
       $key = $named_query->getQueryKey();
 
       $item = id(new PHUIObjectItemView())
         ->setHeader($named_query->getQueryName())
         ->setHref($engine->getQueryResultsPageURI($key));
 
       if ($named_query->getIsBuiltin() && $named_query->getIsDisabled()) {
         $icon = 'fa-plus';
       } else {
         $icon = 'fa-times';
       }
 
       $item->addAction(
         id(new PHUIListItemView())
           ->setIcon($icon)
           ->setHref('/search/delete/'.$key.'/'.$class.'/')
           ->setWorkflow(true));
 
       if ($named_query->getIsBuiltin()) {
         if ($named_query->getIsDisabled()) {
           $item->addIcon('fa-times lightgreytext', pht('Disabled'));
           $item->setDisabled(true);
         } else {
           $item->addIcon('fa-lock lightgreytext', pht('Builtin'));
         }
       } else {
         $item->addAction(
           id(new PHUIListItemView())
             ->setIcon('fa-pencil')
             ->setHref('/search/edit/'.$key.'/'));
       }
 
       $item->setGrippable(true);
       $item->addSigil('named-query');
       $item->setMetadata(
         array(
           'queryKey' => $named_query->getQueryKey(),
         ));
 
       $list->addItem($item);
     }
 
     $list->setNoDataString(pht('No saved queries.'));
 
     $crumbs = $parent
       ->buildApplicationCrumbs()
       ->addTextCrumb(pht('Saved Queries'), $engine->getQueryManagementURI())
       ->setBorder(true);
 
     $nav->selectFilter('query/edit');
 
     $header = id(new PHUIHeaderView())
       ->setHeader(pht('Saved Queries'))
       ->setProfileHeader(true);
 
     $box = id(new PHUIObjectBoxView())
       ->setHeader($header)
       ->setObjectList($list)
       ->addClass('application-search-results');
 
     $nav->addClass('application-search-view');
     require_celerity_resource('application-search-view-css');
 
     return $this->newPage()
       ->setApplicationMenu($this->buildApplicationMenu())
       ->setTitle(pht('Saved Queries'))
       ->setCrumbs($crumbs)
       ->setNavigation($nav)
       ->appendChild($box);
   }
 
   public function buildApplicationMenu() {
     $menu = $this->getDelegatingController()
       ->buildApplicationMenu();
 
     if ($menu instanceof PHUIApplicationMenuView) {
       $menu->setSearchEngine($this->getSearchEngine());
     }
 
     return $menu;
   }
 
   private function buildNavigation() {
     $viewer = $this->getViewer();
     $engine = $this->getSearchEngine();
 
     $nav = id(new AphrontSideNavFilterView())
       ->setUser($viewer)
       ->setBaseURI(new PhutilURI($this->getApplicationURI()));
 
     $engine->addNavigationItems($nav->getMenu());
 
     return $nav;
   }
 
   private function renderNewUserView(
     PhabricatorApplicationSearchEngine $engine,
     $force_nux) {
 
     // Don't render NUX if the user has clicked away from the default page.
     if (strlen($this->getQueryKey())) {
       return null;
     }
 
     // Don't put NUX in panels because it would be weird.
     if ($engine->isPanelContext()) {
       return null;
     }
 
     // Try to render the view itself first, since this should be very cheap
     // (just returning some text).
     $nux_view = $engine->renderNewUserView();
 
     if (!$nux_view) {
       return null;
     }
 
     $query = $engine->newQuery();
     if (!$query) {
       return null;
     }
 
     // Try to load any object at all. If we can, the application has seen some
     // use so we just render the normal view.
     if (!$force_nux) {
       $object = $query
         ->setViewer(PhabricatorUser::getOmnipotentUser())
         ->setLimit(1)
         ->execute();
       if ($object) {
         return null;
       }
     }
 
     return $nux_view;
   }
 
   private function newUseResultsDropdown(
     PhabricatorSavedQuery $query,
     array $dropdown_items) {
 
     $viewer = $this->getViewer();
 
     $action_list = id(new PhabricatorActionListView())
       ->setViewer($viewer);
     foreach ($dropdown_items as $dropdown_item) {
       $action_list->addAction($dropdown_item);
     }
 
     return id(new PHUIButtonView())
       ->setTag('a')
       ->setHref('#')
       ->setText(pht('Use Results...'))
       ->setIcon('fa-road')
       ->setDropdownMenu($action_list);
   }
 
+  private function newOverheatedView(array $results) {
+    if ($results) {
+      $message = pht(
+        'Most objects matching your query are not visible to you, so '.
+        'filtering results is taking a long time. Only some results are '.
+        'shown. Refine your query to find results more quickly.');
+    } else {
+      $message = pht(
+        'Most objects matching your query are not visible to you, so '.
+        'filtering results is taking a long time. Refine your query to '.
+        'find results more quickly.');
+    }
+
+    return id(new PHUIInfoView())
+      ->setSeverity(PHUIInfoView::SEVERITY_WARNING)
+      ->setFlush(true)
+      ->setTitle(pht('Query Overheated'))
+      ->setErrors(
+        array(
+          $message,
+        ));
+  }
+
 }
diff --git a/src/infrastructure/query/policy/PhabricatorPolicyAwareQuery.php b/src/infrastructure/query/policy/PhabricatorPolicyAwareQuery.php
index 42d8001ee2..7aa0f28dfe 100644
--- a/src/infrastructure/query/policy/PhabricatorPolicyAwareQuery.php
+++ b/src/infrastructure/query/policy/PhabricatorPolicyAwareQuery.php
@@ -1,726 +1,751 @@
 <?php
 
 /**
  * A @{class:PhabricatorQuery} which filters results according to visibility
  * policies for the querying user. Broadly, this class allows you to implement
  * a query that returns only objects the user is allowed to see.
  *
  *   $results = id(new ExampleQuery())
  *     ->setViewer($user)
  *     ->withConstraint($example)
  *     ->execute();
  *
  * Normally, you should extend @{class:PhabricatorCursorPagedPolicyAwareQuery},
  * not this class. @{class:PhabricatorCursorPagedPolicyAwareQuery} provides a
  * more practical interface for building usable queries against most object
  * types.
  *
  * NOTE: Although this class extends @{class:PhabricatorOffsetPagedQuery},
  * offset paging with policy filtering is not efficient. All results must be
  * loaded into the application and filtered here: skipping `N` rows via offset
  * is an `O(N)` operation with a large constant. Prefer cursor-based paging
  * with @{class:PhabricatorCursorPagedPolicyAwareQuery}, which can filter far
  * more efficiently in MySQL.
  *
  * @task config     Query Configuration
  * @task exec       Executing Queries
  * @task policyimpl Policy Query Implementation
  */
 abstract class PhabricatorPolicyAwareQuery extends PhabricatorOffsetPagedQuery {
 
   private $viewer;
   private $parentQuery;
   private $rawResultLimit;
   private $capabilities;
   private $workspace = array();
   private $inFlightPHIDs = array();
   private $policyFilteredPHIDs = array();
 
   /**
    * Should we continue or throw an exception when a query result is filtered
    * by policy rules?
    *
    * Values are `true` (raise exceptions), `false` (do not raise exceptions)
    * and `null` (inherit from parent query, with no exceptions by default).
    */
   private $raisePolicyExceptions;
+  private $isOverheated;
 
 
 /* -(  Query Configuration  )------------------------------------------------ */
 
 
   /**
    * Set the viewer who is executing the query. Results will be filtered
    * according to the viewer's capabilities. You must set a viewer to execute
    * a policy query.
    *
    * @param PhabricatorUser The viewing user.
    * @return this
    * @task config
    */
   final public function setViewer(PhabricatorUser $viewer) {
     $this->viewer = $viewer;
     return $this;
   }
 
 
   /**
    * Get the query's viewer.
    *
    * @return PhabricatorUser The viewing user.
    * @task config
    */
   final public function getViewer() {
     return $this->viewer;
   }
 
 
   /**
    * Set the parent query of this query. This is useful for nested queries so
    * that configuration like whether or not to raise policy exceptions is
    * seamlessly passed along to child queries.
    *
    * @return this
    * @task config
    */
   final public function setParentQuery(PhabricatorPolicyAwareQuery $query) {
     $this->parentQuery = $query;
     return $this;
   }
 
 
   /**
    * Get the parent query. See @{method:setParentQuery} for discussion.
    *
    * @return PhabricatorPolicyAwareQuery The parent query.
    * @task config
    */
   final public function getParentQuery() {
     return $this->parentQuery;
   }
 
 
   /**
    * Hook to configure whether this query should raise policy exceptions.
    *
    * @return this
    * @task config
    */
   final public function setRaisePolicyExceptions($bool) {
     $this->raisePolicyExceptions = $bool;
     return $this;
   }
 
 
   /**
    * @return bool
    * @task config
    */
   final public function shouldRaisePolicyExceptions() {
     return (bool)$this->raisePolicyExceptions;
   }
 
 
   /**
    * @task config
    */
   final public function requireCapabilities(array $capabilities) {
     $this->capabilities = $capabilities;
     return $this;
   }
 
 
 /* -(  Query Execution  )---------------------------------------------------- */
 
 
   /**
    * Execute the query, expecting a single result. This method simplifies
    * loading objects for detail pages or edit views.
    *
    *   // Load one result by ID.
    *   $obj = id(new ExampleQuery())
    *     ->setViewer($user)
    *     ->withIDs(array($id))
    *     ->executeOne();
    *   if (!$obj) {
    *     return new Aphront404Response();
    *   }
    *
    * If zero results match the query, this method returns `null`.
    * If one result matches the query, this method returns that result.
    *
    * If two or more results match the query, this method throws an exception.
    * You should use this method only when the query constraints guarantee at
    * most one match (e.g., selecting a specific ID or PHID).
    *
    * If one result matches the query but it is caught by the policy filter (for
    * example, the user is trying to view or edit an object which exists but
    * which they do not have permission to see) a policy exception is thrown.
    *
    * @return mixed Single result, or null.
    * @task exec
    */
   final public function executeOne() {
 
     $this->setRaisePolicyExceptions(true);
     try {
       $results = $this->execute();
     } catch (Exception $ex) {
       $this->setRaisePolicyExceptions(false);
       throw $ex;
     }
 
     if (count($results) > 1) {
       throw new Exception(pht('Expected a single result!'));
     }
 
     if (!$results) {
       return null;
     }
 
     return head($results);
   }
 
 
   /**
    * Execute the query, loading all visible results.
    *
    * @return list<PhabricatorPolicyInterface> Result objects.
    * @task exec
    */
   final public function execute() {
     if (!$this->viewer) {
       throw new PhutilInvalidStateException('setViewer');
     }
 
     $parent_query = $this->getParentQuery();
     if ($parent_query && ($this->raisePolicyExceptions === null)) {
       $this->setRaisePolicyExceptions(
         $parent_query->shouldRaisePolicyExceptions());
     }
 
     $results = array();
 
     $filter = $this->getPolicyFilter();
 
     $offset = (int)$this->getOffset();
     $limit  = (int)$this->getLimit();
     $count  = 0;
 
     if ($limit) {
       $need = $offset + $limit;
     } else {
       $need = 0;
     }
 
     $this->willExecute();
 
+    // If we examine and filter significantly more objects than the query
+    // limit, we stop early. This prevents us from looping through a huge
+    // number of records when the viewer can see few or none of them. See
+    // T11773 for some discussion.
+    $this->isOverheated = false;
+    $overheat_limit = $limit * 10;
+    $total_seen = 0;
+
     do {
       if ($need) {
         $this->rawResultLimit = min($need - $count, 1024);
       } else {
         $this->rawResultLimit = 0;
       }
 
       if ($this->canViewerUseQueryApplication()) {
         try {
           $page = $this->loadPage();
         } catch (PhabricatorEmptyQueryException $ex) {
           $page = array();
         }
       } else {
         $page = array();
       }
 
+      $total_seen += count($page);
+
       if ($page) {
         $maybe_visible = $this->willFilterPage($page);
         if ($maybe_visible) {
           $maybe_visible = $this->applyWillFilterPageExtensions($maybe_visible);
         }
       } else {
         $maybe_visible = array();
       }
 
       if ($this->shouldDisablePolicyFiltering()) {
         $visible = $maybe_visible;
       } else {
         $visible = $filter->apply($maybe_visible);
 
         $policy_filtered = array();
         foreach ($maybe_visible as $key => $object) {
           if (empty($visible[$key])) {
             $phid = $object->getPHID();
             if ($phid) {
               $policy_filtered[$phid] = $phid;
             }
           }
         }
         $this->addPolicyFilteredPHIDs($policy_filtered);
       }
 
       if ($visible) {
         $visible = $this->didFilterPage($visible);
       }
 
       $removed = array();
       foreach ($maybe_visible as $key => $object) {
         if (empty($visible[$key])) {
           $removed[$key] = $object;
         }
       }
 
       $this->didFilterResults($removed);
 
       foreach ($visible as $key => $result) {
         ++$count;
 
         // If we have an offset, we just ignore that many results and start
         // storing them only once we've hit the offset. This reduces memory
         // requirements for large offsets, compared to storing them all and
         // slicing them away later.
         if ($count > $offset) {
           $results[$key] = $result;
         }
 
         if ($need && ($count >= $need)) {
           // If we have all the rows we need, break out of the paging query.
           break 2;
         }
       }
 
       if (!$this->rawResultLimit) {
         // If we don't have a load count, we loaded all the results. We do
         // not need to load another page.
         break;
       }
 
       if (count($page) < $this->rawResultLimit) {
         // If we have a load count but the unfiltered results contained fewer
         // objects, we know this was the last page of objects; we do not need
         // to load another page because we can deduce it would be empty.
         break;
       }
 
       $this->nextPage($page);
+
+      if ($overheat_limit && ($total_seen >= $overheat_limit)) {
+        $this->isOverheated = true;
+        break;
+      }
     } while (true);
 
     $results = $this->didLoadResults($results);
 
     return $results;
   }
 
   private function getPolicyFilter() {
     $filter = new PhabricatorPolicyFilter();
     $filter->setViewer($this->viewer);
     $capabilities = $this->getRequiredCapabilities();
     $filter->requireCapabilities($capabilities);
     $filter->raisePolicyExceptions($this->shouldRaisePolicyExceptions());
 
     return $filter;
   }
 
   protected function getRequiredCapabilities() {
     if ($this->capabilities) {
       return $this->capabilities;
     }
 
     return array(
       PhabricatorPolicyCapability::CAN_VIEW,
     );
   }
 
   protected function applyPolicyFilter(array $objects, array $capabilities) {
     if ($this->shouldDisablePolicyFiltering()) {
       return $objects;
     }
     $filter = $this->getPolicyFilter();
     $filter->requireCapabilities($capabilities);
     return $filter->apply($objects);
   }
 
   protected function didRejectResult(PhabricatorPolicyInterface $object) {
     // Some objects (like commits) may be rejected because related objects
     // (like repositories) can not be loaded. In some cases, we may need these
     // related objects to determine the object policy, so it's expected that
     // we may occasionally be unable to determine the policy.
 
     try {
       $policy = $object->getPolicy(PhabricatorPolicyCapability::CAN_VIEW);
     } catch (Exception $ex) {
       $policy = null;
     }
 
     // Mark this object as filtered so handles can render "Restricted" instead
     // of "Unknown".
     $phid = $object->getPHID();
     $this->addPolicyFilteredPHIDs(array($phid => $phid));
 
     $this->getPolicyFilter()->rejectObject(
       $object,
       $policy,
       PhabricatorPolicyCapability::CAN_VIEW);
   }
 
   public function addPolicyFilteredPHIDs(array $phids) {
     $this->policyFilteredPHIDs += $phids;
     if ($this->getParentQuery()) {
       $this->getParentQuery()->addPolicyFilteredPHIDs($phids);
     }
     return $this;
   }
 
+
+  public function getIsOverheated() {
+    if ($this->isOverheated === null) {
+      throw new PhutilInvalidStateException('execute');
+    }
+    return $this->isOverheated;
+  }
+
+
   /**
    * Return a map of all object PHIDs which were loaded in the query but
    * filtered out by policy constraints. This allows a caller to distinguish
    * between objects which do not exist (or, at least, were filtered at the
    * content level) and objects which exist but aren't visible.
    *
    * @return map<phid, phid> Map of object PHIDs which were filtered
    *   by policies.
    * @task exec
    */
   public function getPolicyFilteredPHIDs() {
     return $this->policyFilteredPHIDs;
   }
 
 
 /* -(  Query Workspace  )---------------------------------------------------- */
 
 
   /**
    * Put a map of objects into the query workspace. Many queries perform
    * subqueries, which can eventually end up loading the same objects more than
    * once (often to perform policy checks).
    *
    * For example, loading a user may load the user's profile image, which might
    * load the user object again in order to verify that the viewer has
    * permission to see the file.
    *
    * The "query workspace" allows queries to load objects from elsewhere in a
    * query block instead of refetching them.
    *
    * When using the query workspace, it's important to obey two rules:
    *
    * **Never put objects into the workspace which the viewer may not be able
    * to see**. You need to apply all policy filtering //before// putting
    * objects in the workspace. Otherwise, subqueries may read the objects and
    * use them to permit access to content the user shouldn't be able to view.
    *
    * **Fully enrich objects pulled from the workspace.** After pulling objects
    * from the workspace, you still need to load and attach any additional
    * content the query requests. Otherwise, a query might return objects
    * without requested content.
    *
    * Generally, you do not need to update the workspace yourself: it is
    * automatically populated as a side effect of objects surviving policy
    * filtering.
    *
    * @param map<phid, PhabricatorPolicyInterface> Objects to add to the query
    *   workspace.
    * @return this
    * @task workspace
    */
   public function putObjectsInWorkspace(array $objects) {
     $parent = $this->getParentQuery();
     if ($parent) {
       $parent->putObjectsInWorkspace($objects);
       return $this;
     }
 
     assert_instances_of($objects, 'PhabricatorPolicyInterface');
 
     $viewer_fragment = $this->getViewer()->getCacheFragment();
 
     // The workspace is scoped per viewer to prevent accidental contamination.
     if (empty($this->workspace[$viewer_fragment])) {
       $this->workspace[$viewer_fragment] = array();
     }
 
     $this->workspace[$viewer_fragment] += $objects;
 
     return $this;
   }
 
 
   /**
    * Retrieve objects from the query workspace. For more discussion about the
    * workspace mechanism, see @{method:putObjectsInWorkspace}. This method
    * searches both the current query's workspace and the workspaces of parent
    * queries.
    *
    * @param list<phid> List of PHIDs to retrieve.
    * @return this
    * @task workspace
    */
   public function getObjectsFromWorkspace(array $phids) {
     $parent = $this->getParentQuery();
     if ($parent) {
       return $parent->getObjectsFromWorkspace($phids);
     }
 
     $viewer_fragment = $this->getViewer()->getCacheFragment();
 
     $results = array();
     foreach ($phids as $key => $phid) {
       if (isset($this->workspace[$viewer_fragment][$phid])) {
         $results[$phid] = $this->workspace[$viewer_fragment][$phid];
         unset($phids[$key]);
       }
     }
 
     return $results;
   }
 
 
   /**
    * Mark PHIDs as in flight.
    *
    * PHIDs which are "in flight" are actively being queried for. Using this
    * list can prevent infinite query loops by aborting queries which cycle.
    *
    * @param list<phid> List of PHIDs which are now in flight.
    * @return this
    */
   public function putPHIDsInFlight(array $phids) {
     foreach ($phids as $phid) {
       $this->inFlightPHIDs[$phid] = $phid;
     }
     return $this;
   }
 
 
   /**
    * Get PHIDs which are currently in flight.
    *
    * PHIDs which are "in flight" are actively being queried for.
    *
    * @return map<phid, phid> PHIDs currently in flight.
    */
   public function getPHIDsInFlight() {
     $results = $this->inFlightPHIDs;
     if ($this->getParentQuery()) {
       $results += $this->getParentQuery()->getPHIDsInFlight();
     }
     return $results;
   }
 
 
 /* -(  Policy Query Implementation  )---------------------------------------- */
 
 
   /**
    * Get the number of results @{method:loadPage} should load. If the value is
    * 0, @{method:loadPage} should load all available results.
    *
    * @return int The number of results to load, or 0 for all results.
    * @task policyimpl
    */
   final protected function getRawResultLimit() {
     return $this->rawResultLimit;
   }
 
 
   /**
    * Hook invoked before query execution. Generally, implementations should
    * reset any internal cursors.
    *
    * @return void
    * @task policyimpl
    */
   protected function willExecute() {
     return;
   }
 
 
   /**
    * Load a raw page of results. Generally, implementations should load objects
    * from the database. They should attempt to return the number of results
    * hinted by @{method:getRawResultLimit}.
    *
    * @return list<PhabricatorPolicyInterface> List of filterable policy objects.
    * @task policyimpl
    */
   abstract protected function loadPage();
 
 
   /**
    * Update internal state so that the next call to @{method:loadPage} will
    * return new results. Generally, you should adjust a cursor position based
    * on the provided result page.
    *
    * @param list<PhabricatorPolicyInterface> The current page of results.
    * @return void
    * @task policyimpl
    */
   abstract protected function nextPage(array $page);
 
 
   /**
    * Hook for applying a page filter prior to the privacy filter. This allows
    * you to drop some items from the result set without creating problems with
    * pagination or cursor updates. You can also load and attach data which is
    * required to perform policy filtering.
    *
    * Generally, you should load non-policy data and perform non-policy filtering
    * later, in @{method:didFilterPage}. Strictly fewer objects will make it that
    * far (so the program will load less data) and subqueries from that context
    * can use the query workspace to further reduce query load.
    *
    * This method will only be called if data is available. Implementations
    * do not need to handle the case of no results specially.
    *
    * @param   list<wild>  Results from `loadPage()`.
    * @return  list<PhabricatorPolicyInterface> Objects for policy filtering.
    * @task policyimpl
    */
   protected function willFilterPage(array $page) {
     return $page;
   }
 
   /**
    * Hook for performing additional non-policy loading or filtering after an
    * object has satisfied all policy checks. Generally, this means loading and
    * attaching related data.
    *
    * Subqueries executed during this phase can use the query workspace, which
    * may improve performance or make circular policies resolvable. Data which
    * is not necessary for policy filtering should generally be loaded here.
    *
    * This callback can still filter objects (for example, if attachable data
    * is discovered to not exist), but should not do so for policy reasons.
    *
    * This method will only be called if data is available. Implementations do
    * not need to handle the case of no results specially.
    *
    * @param list<wild> Results from @{method:willFilterPage()}.
    * @return list<PhabricatorPolicyInterface> Objects after additional
    *   non-policy processing.
    */
   protected function didFilterPage(array $page) {
     return $page;
   }
 
 
   /**
    * Hook for removing filtered results from alternate result sets. This
    * hook will be called with any objects which were returned by the query but
    * filtered for policy reasons. The query should remove them from any cached
    * or partial result sets.
    *
    * @param list<wild>  List of objects that should not be returned by alternate
    *                    result mechanisms.
    * @return void
    * @task policyimpl
    */
   protected function didFilterResults(array $results) {
     return;
   }
 
 
   /**
    * Hook for applying final adjustments before results are returned. This is
    * used by @{class:PhabricatorCursorPagedPolicyAwareQuery} to reverse results
    * that are queried during reverse paging.
    *
    * @param   list<PhabricatorPolicyInterface> Query results.
    * @return  list<PhabricatorPolicyInterface> Final results.
    * @task policyimpl
    */
   protected function didLoadResults(array $results) {
     return $results;
   }
 
 
   /**
    * Allows a subclass to disable policy filtering. This method is dangerous.
    * It should be used only if the query loads data which has already been
    * filtered (for example, because it wraps some other query which uses
    * normal policy filtering).
    *
    * @return bool True to disable all policy filtering.
    * @task policyimpl
    */
   protected function shouldDisablePolicyFiltering() {
     return false;
   }
 
 
   /**
    * If this query belongs to an application, return the application class name
    * here. This will prevent the query from returning results if the viewer can
    * not access the application.
    *
    * If this query does not belong to an application, return `null`.
    *
    * @return string|null Application class name.
    */
   abstract public function getQueryApplicationClass();
 
 
   /**
    * Determine if the viewer has permission to use this query's application.
    * For queries which aren't part of an application, this method always returns
    * true.
    *
    * @return bool True if the viewer has application-level permission to
    *   execute the query.
    */
   public function canViewerUseQueryApplication() {
     $class = $this->getQueryApplicationClass();
     if (!$class) {
       return true;
     }
 
     $viewer = $this->getViewer();
     return PhabricatorApplication::isClassInstalledForViewer($class, $viewer);
   }
 
   private function applyWillFilterPageExtensions(array $page) {
     $bridges = array();
     foreach ($page as $key => $object) {
       if ($object instanceof DoorkeeperBridgedObjectInterface) {
         $bridges[$key] = $object;
       }
     }
 
     if ($bridges) {
       $external_phids = array();
       foreach ($bridges as $bridge) {
         $external_phid = $bridge->getBridgedObjectPHID();
         if ($external_phid) {
           $external_phids[$key] = $external_phid;
         }
       }
 
       if ($external_phids) {
         $external_objects = id(new DoorkeeperExternalObjectQuery())
           ->setViewer($this->getViewer())
           ->withPHIDs($external_phids)
           ->execute();
         $external_objects = mpull($external_objects, null, 'getPHID');
       } else {
         $external_objects = array();
       }
 
       foreach ($bridges as $key => $bridge) {
         $external_phid = idx($external_phids, $key);
         if (!$external_phid) {
           $bridge->attachBridgedObject(null);
           continue;
         }
 
         $external_object = idx($external_objects, $external_phid);
         if (!$external_object) {
           $this->didRejectResult($bridge);
           unset($page[$key]);
           continue;
         }
 
         $bridge->attachBridgedObject($external_object);
       }
     }
 
     return $page;
   }
 
 }