Add a setup warning for probable misconfiguration of 'apc.stat'

Summary: Fixes T3501. `apc.stat` should generally be 0 in production and 1 in development. Raise a setup warning if it isn't.

Test Plan:
Hit both setup warnings.

{F49176}

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T3501

Differential Revision: https://secure.phabricator.com/D6376

src/applications/config/check/PhabricatorSetupCheckAPC.php

@@ -31,7 +31,53 @@ final class PhabricatorSetupCheckAPC extends PhabricatorSetupCheck {
         ->setSummary($summary)
         ->setMessage($message)
         ->addPHPConfig('apc.enabled');
+      return;
     }
 
+    $is_dev = PhabricatorEnv::getEnvConfig('phabricator.developer-mode');
+    $is_stat_enabled = ini_get('apc.stat');
+
+    $issue_key = null;
+    if ($is_stat_enabled && !$is_dev) {
+      $issue_key = 'extension.apc.stat-enabled';
+      $short = pht("'apc.stat' Enabled");
+      $long = pht("'apc.stat' Enabled in Production");
+      $summary = pht(
+        "'apc.stat' is currently enabled, but should probably be disabled.");
+      $message = pht(
+        "'apc.stat' is currently enabled in your PHP configuration. For most ".
+        "Phabricator installs, 'apc.stat' should be disabled. This will ".
+        "slightly improve performance (PHP will do fewer disk reads) and make ".
+        "updates safer (PHP won't read in the middle of a 'git pull').\n\n".
+        "(If you are developing for Phabricator, leave 'apc.stat' enabled but ".
+        "enable 'phabricator.developer-mode'.)");
+    } else if (!$is_stat_enabled && $is_dev) {
+      $issue_key = 'extension.apc.stat-disabled';
+      $short = pht("'apc.stat' Disabled");
+      $long = pht("'apc.stat' Disabled in Development");
+      $summary = pht(
+        "'apc.stat' is currently disabled, but should probably be enabled ".
+        "in development mode.");
+      $message = pht(
+        "'apc.stat' is disabled in your PHP configuration, but Phabricator is ".
+        "set to developer mode. Normally, you should enable 'apc.stat' for ".
+        "development installs so you don't need to restart your webserver ".
+        "after making changes to the code.\n\n".
+        "You can enable 'apc.stat', or disable 'phabricator.developer-mode', ".
+        "or safely ignore this warning if you have some reasonining behind ".
+        "your current configuration.");
+    }
+
+    if ($issue_key !== null) {
+      $this
+        ->newIssue($issue_key)
+        ->setShortName($short)
+        ->setName($long)
+        ->setSummary($summary)
+        ->setMessage($message)
+        ->addPHPConfig('apc.stat')
+        ->addPhabricatorConfig('phabricator.developer-mode');
+    }
   }
+
 }