Fail quietly when failing to write access log

Summary: See D5874. PhutilDeferredLog's exception on `write()`/`__destruct()` is not especially important and can come at an awkward time. Instead of throwing, just emit an error message to the log.

Test Plan: Faked failed writes and saw an error message in the log instead of many terrible things everywhere.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T3144

Differential Revision: https://secure.phabricator.com/D5875

Author: epriestley

src/infrastructure/PhabricatorAccessLog.php

@@ -22,14 +22,15 @@ public static function getLog() {
       // NOTE: Path may be null. We still create the log, it just won't write
       // anywhere.
 
-      $log = new PhutilDeferredLog($path, $format);
-      $log->setData(
-        array(
-          'D' => date('r'),
-          'h' => php_uname('n'),
-          'p' => getmypid(),
-          'e' => time(),
-        ));
+      $log = id(new PhutilDeferredLog($path, $format))
+        ->setFailQuietly(true)
+        ->setData(
+          array(
+            'D' => date('r'),
+            'h' => php_uname('n'),
+            'p' => getmypid(),
+            'e' => time(),
+          ));
 
       self::$log = $log;
     }

support/PhabricatorStartup.php

@@ -194,16 +194,11 @@ public static function didFatal($message) {
     if ($access_log) {
       // We may end up here before the access log is initialized, e.g. from
       // verifyPHP().
-
-      try {
-        $access_log->setData(
-          array(
-            'c' => 500,
-          ));
-        $access_log->write();
-      } catch (Exception $ex) {
-        $message .= "\n(Moreover, unable to write to access log.)";
-      }
+      $access_log->setData(
+        array(
+          'c' => 500,
+        ));
+      $access_log->write();
     }
 
     header(