Allow `*.search` Conduit API methods to have data bulk-loaded by extensions

Summary:
Ref T11404. Currently, SearchEngineAttachments can bulk-load data but SearchEngineExtensions can not.

This leads to poor performance of custom fields. See T11404 for discussion.

This changes the API to support a bulk load + format pattern like the one Attachments use. The next change will use it to bulk-load custom field data.

Test Plan:

- Ran `differential.query`, `differential.revision.search` as a sanity check.
- No behavioral changes are expected
- See next revision.

Reviewers: yelirekim, chad

Reviewed By: chad

Maniphest Tasks: T11404

Differential Revision: https://secure.phabricator.com/D16350

src/applications/conduit/query/ConduitResultSearchEngineExtension.php

···
     return $object->getFieldSpecificationsForConduit();
   }
 
-  public function getFieldValuesForConduit($object) {
+  public function getFieldValuesForConduit($object, $data) {
     return $object->getFieldValuesForConduit();
   }
 

src/applications/policy/engineextension/PhabricatorPolicySearchEngineExtension.php

···
     );
   }
 
-  public function getFieldValuesForConduit($object) {
+  public function getFieldValuesForConduit($object, $data) {
     $capabilities = $object->getCapabilities();
 
     $map = array();

src/applications/search/engine/PhabricatorApplicationSearchEngine.php

···
     if ($objects) {
       $field_extensions = $this->getConduitFieldExtensions();
 
+      $extension_data = array();
+      foreach ($field_extensions as $key => $extension) {
+        $extension_data[$key] = $extension->loadExtensionConduitData($objects);
+      }
+
       $attachment_data = array();
       foreach ($attachments as $key => $attachment) {
         $attachment_data[$key] = $attachment->loadAttachmentData(
···
       foreach ($objects as $object) {
         $field_map = $this->getObjectWireFieldsForConduit(
           $object,
-          $field_extensions);
+          $field_extensions,
+          $extension_data);
 
         $attachment_map = array();
         foreach ($attachments as $key => $attachment) {
···
 
   protected function getObjectWireFieldsForConduit(
     $object,
-    array $field_extensions) {
+    array $field_extensions,
+    array $extension_data) {
 
     $fields = array();
-    foreach ($field_extensions as $extension) {
-      $fields += $extension->getFieldValuesForConduit($object);
+    foreach ($field_extensions as $key => $extension) {
+      $data = idx($extension_data, $key, array());
+      $fields += $extension->getFieldValuesForConduit($object, $data);
     }
 
     return $fields;

src/applications/search/engineextension/PhabricatorLiskSearchEngineExtension.php

···
     );
   }
 
-  public function getFieldValuesForConduit($object) {
+  public function getFieldValuesForConduit($object, $data) {
     return array(
       'dateCreated' => (int)$object->getDateCreated(),
       'dateModified' => (int)$object->getDateModified(),

src/applications/search/engineextension/PhabricatorSearchEngineExtension.php

···
     return array();
   }
 
-  public function getFieldValuesForConduit($object) {
+  public function loadExtensionConduitData(array $objects) {
+    return null;
+  }
+
+  public function getFieldValuesForConduit($object, $data) {
     return array();
   }
 

src/applications/spaces/engineextension/PhabricatorSpacesSearchEngineExtension.php

···
     );
   }
 
-  public function getFieldValuesForConduit($object) {
+  public function getFieldValuesForConduit($object, $data) {
     return array(
       'spacePHID' => $object->getSpacePHID(),
     );

src/infrastructure/customfield/engineextension/PhabricatorCustomFieldSearchEngineExtension.php

···
     return $map;
   }
 
-  public function getFieldValuesForConduit($object) {
+  public function getFieldValuesForConduit($object, $data) {
     // TODO: This is currently very inefficient. We should bulk-load these
     // field values instead.