Cache application visibility in the request cache

Summary: Ref T8575. We check if users can see applications frequently, and caching on the Query isn't especially effective. Use the new Request cache instead.

Test Plan:
  - Saw `/feed/` drop 7% (from ~830ms to ~770ms) on profiles.

Reviewers: btrahan, avivey

Reviewed By: avivey

Subscribers: avivey, epriestley

Maniphest Tasks: T8575

Differential Revision: https://secure.phabricator.com/D13321

src/applications/base/PhabricatorApplication.php

@@ -449,16 +449,27 @@ abstract class PhabricatorApplication
     $class,
     PhabricatorUser $viewer) {
 
-    if (!self::isClassInstalled($class)) {
-      return false;
-    }
+    $cache = PhabricatorCaches::getRequestCache();
+    $viewer_phid = $viewer->getPHID();
+    $key = 'app.'.$class.'.installed.'.$viewer_phid;
 
-    return PhabricatorPolicyFilter::hasCapability(
+    $result = $cache->getKey($key);
+    if ($result === null) {
+      if (!self::isClassInstalled($class)) {
+        $result = false;
+      } else {
+        $result = PhabricatorPolicyFilter::hasCapability(
           $viewer,
           self::getByClass($class),
           PhabricatorPolicyCapability::CAN_VIEW);
       }
 
+      $cache->setKey($key, $result);
+    }
+
+    return $result;
+  }
+
 
 /* -(  PhabricatorPolicyInterface  )----------------------------------------- */
 

src/infrastructure/query/policy/PhabricatorPolicyAwareQuery.php

@@ -35,7 +35,6 @@ abstract class PhabricatorPolicyAwareQuery extends PhabricatorOffsetPagedQuery {
   private $workspace = array();
   private $inFlightPHIDs = array();
   private $policyFilteredPHIDs = array();
-  private $canUseApplication;
 
   /**
    * Should we continue or throw an exception when a query result is filtered
@@ -679,21 +678,13 @@ abstract class PhabricatorPolicyAwareQuery extends PhabricatorOffsetPagedQuery {
    *   execute the query.
    */
   public function canViewerUseQueryApplication() {
-    if ($this->canUseApplication === null) {
     $class = $this->getQueryApplicationClass();
     if (!$class) {
-        $this->canUseApplication = true;
-      } else {
-        $result = id(new PhabricatorApplicationQuery())
-          ->setViewer($this->getViewer())
-          ->withClasses(array($class))
-          ->execute();
-
-        $this->canUseApplication = (bool)$result;
-      }
+      return true;
     }
 
-    return $this->canUseApplication;
+    $viewer = $this->getViewer();
+    return PhabricatorApplication::isClassInstalledForViewer($class, $viewer);
   }
 
 }