Truncate large strings in DarkConsole

Summary:
Ref T8597.  If a page issues a large query (like inserting a blob into file storage), we may try to utf8ize the entire thing. This is slow and pointless.

Instead, truncate tab data after 4096 bytes before sanitizing.

Test Plan: Adjusted limit to 256 bytes, saw long queries get truncated reasonably.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T8597

Differential Revision: https://secure.phabricator.com/D13347

src/applications/console/core/DarkConsoleCore.php

@@ -127,6 +127,13 @@ final class DarkConsoleCore extends Phobject {
       }
       return $data;
     } else {
+      // Truncate huge strings. Since the data doesn't really matter much,
+      // just truncate bytes to avoid PhutilUTF8StringTruncator overhead.
+      $length = strlen($data);
+      $max = 4096;
+      if ($length > $max) {
+        $data = substr($data, 0, $max).'...<'.$length.' bytes>...';
+      }
       return phutil_utf8ize($data);
     }
   }