Move XHProf sampling code out of index.php

Summary:
  - Separate the ideas of "requested" (explicit user request) vs "started" (user request or sampling).
  - Move this code out of index.php into the XHProf stuff (general effort to make index.php smaller).

Test Plan:
Verified that profiling still works, and profiling extends to ajax requests.

Set sampling rate to 2, saw 50% samples.

Looked at database, saw sampling data populating properly.

Reviewers: vrana, nh

Reviewed By: vrana

CC: aran

Differential Revision: https://secure.phabricator.com/D4891

src/aphront/console/plugin/DarkConsoleXHProfPlugin.php

@@ -97,8 +97,7 @@ final class DarkConsoleXHProfPlugin extends DarkConsolePlugin {
 
 
   public function willShutdown() {
-    if (DarkConsoleXHProfPluginAPI::isProfilerRequested() &&
+    if (DarkConsoleXHProfPluginAPI::isProfilerStarted()) {
-        (DarkConsoleXHProfPluginAPI::isProfilerRequested() !== 'all')) {
       $this->xhprofID = DarkConsoleXHProfPluginAPI::stopProfiler();
     }
   }

src/aphront/console/plugin/xhprof/DarkConsoleXHProfPluginAPI.php

@@ -27,20 +27,32 @@ final class DarkConsoleXHProfPluginAPI {
       return $header;
     }
 
-    static $profilerRequested = null;
+    return false;
+  }
 
-    if (!isset($profilerRequested)) {
+  public static function shouldStartProfiler() {
+    if (self::isProfilerRequested()) {
+      return true;
+    }
+
+    static $sample_request = null;
+
+    if ($sample_request === null) {
       if (PhabricatorEnv::getEnvConfig('debug.profile-rate')) {
         $rate = PhabricatorEnv::getEnvConfig('debug.profile-rate');
         if (mt_rand(1, $rate) == 1) {
-          $profilerRequested = true;
+          $sample_request = true;
         } else {
-          $profilerRequested = false;
+          $sample_request = false;
         }
       }
     }
 
-    return $profilerRequested;
+    return $sample_request;
+  }
+
+  public static function isProfilerStarted() {
+    return self::$profilerStarted;
   }
 
   public static function includeXHProfLib() {
@@ -56,8 +68,40 @@ final class DarkConsoleXHProfPluginAPI {
   }
 
 
+  public static function saveProfilerSample(
+    AphrontRequest $request,
+    $access_log) {
+
+    if (!self::isProfilerStarted()) {
+      return;
+    }
+
+    $profile = DarkConsoleXHProfPluginAPI::stopProfiler();
+    $profile_sample = id(new PhabricatorXHProfSample())
+      ->setFilePHID($profile);
+
+    if (self::isProfilerRequested()) {
+      $sample_rate = 0;
+    } else {
+      $sample_rate = PhabricatorEnv::getEnvConfig('debug.profile-rate');
+    }
+
+    $profile_sample->setSampleRate($sample_rate);
+
+    if ($access_log) {
+      $profile_sample
+        ->setUsTotal($access_log->getData('T'))
+        ->setHostname($access_log->getData('h'))
+        ->setRequestPath($access_log->getData('U'))
+        ->setController($access_log->getData('C'))
+        ->setUserPHID($request->getUser()->getPHID());
+    }
+
+    $profile_sample->save();
+  }
+
   public static function hookProfiler() {
-    if (!self::isProfilerRequested()) {
+    if (!self::shouldStartProfiler()) {
       return;
     }
 
@@ -79,49 +123,49 @@ final class DarkConsoleXHProfPluginAPI {
   }
 
   public static function stopProfiler() {
-    if (self::$profilerStarted) {
+    if (!self::isProfilerStarted()) {
-      $data = xhprof_disable();
-      $data = serialize($data);
-      $file_class = 'PhabricatorFile';
-
-      // Since these happen on GET we can't do guarded writes. These also
-      // sometimes happen after we've disposed of the write guard; in this
-      // case we need to disable the whole mechanism.
-
-      $use_scope = AphrontWriteGuard::isGuardActive();
-      if ($use_scope) {
-        $unguarded = AphrontWriteGuard::beginScopedUnguardedWrites();
-      } else {
-        AphrontWriteGuard::allowDangerousUnguardedWrites(true);
-      }
-
-      $caught = null;
-      try {
-        $file = call_user_func(
-          array($file_class, 'newFromFileData'),
-          $data,
-          array(
-            'mime-type' => 'application/xhprof',
-            'name'      => 'profile.xhprof',
-          ));
-      } catch (Exception $ex) {
-        $caught = $ex;
-      }
-
-      if ($use_scope) {
-        unset($unguarded);
-      } else {
-        AphrontWriteGuard::allowDangerousUnguardedWrites(false);
-      }
-
-      if ($caught) {
-        throw $caught;
-      } else {
-        return $file->getPHID();
-      }
-    } else {
       return null;
     }
+
+    $data = xhprof_disable();
+    $data = serialize($data);
+    $file_class = 'PhabricatorFile';
+
+    // Since these happen on GET we can't do guarded writes. These also
+    // sometimes happen after we've disposed of the write guard; in this
+    // case we need to disable the whole mechanism.
+
+    $use_scope = AphrontWriteGuard::isGuardActive();
+    if ($use_scope) {
+      $unguarded = AphrontWriteGuard::beginScopedUnguardedWrites();
+    } else {
+      AphrontWriteGuard::allowDangerousUnguardedWrites(true);
+    }
+
+    $caught = null;
+    try {
+      $file = call_user_func(
+        array($file_class, 'newFromFileData'),
+        $data,
+        array(
+          'mime-type' => 'application/xhprof',
+          'name'      => 'profile.xhprof',
+        ));
+    } catch (Exception $ex) {
+      $caught = $ex;
+    }
+
+    if ($use_scope) {
+      unset($unguarded);
+    } else {
+      AphrontWriteGuard::allowDangerousUnguardedWrites(false);
+    }
+
+    if ($caught) {
+      throw $caught;
+    } else {
+      return $file->getPHID();
+    }
   }
 
 }

src/view/page/PhabricatorStandardPageView.php

@@ -163,7 +163,7 @@ final class PhabricatorStandardPageView extends PhabricatorBarePageView {
       require_celerity_resource('aphront-dark-console-css');
 
       $headers = array();
-      if (DarkConsoleXHProfPluginAPI::isProfilerRequested()) {
+      if (DarkConsoleXHProfPluginAPI::isProfilerStarted()) {
         $headers[DarkConsoleXHProfPluginAPI::getProfilerHeader()] = 'page';
       }
 

webroot/index.php

@@ -132,25 +132,7 @@ try {
     $access_log->write();
   }
 
-  if (DarkConsoleXHProfPluginAPI::isProfilerRequested()) {
+  DarkConsoleXHProfPluginAPI::saveProfilerSample($request, $access_log);
-    $profile = DarkConsoleXHProfPluginAPI::stopProfiler();
-    $profile_sample = id(new PhabricatorXHProfSample())
-      ->setFilePHID($profile);
-    if (empty($_REQUEST['__profile__'])) {
-      $sample_rate = PhabricatorEnv::getEnvConfig('debug.profile-rate');
-    } else {
-      $sample_rate = 0;
-    }
-    $profile_sample->setSampleRate($sample_rate);
-    if ($access_log) {
-      $profile_sample->setUsTotal($access_log->getData('T'))
-        ->setHostname($access_log->getData('h'))
-        ->setRequestPath($access_log->getData('U'))
-        ->setController($access_log->getData('C'))
-        ->setUserPHID($request->getUser()->getPHID());
-    }
-    $profile_sample->save();
-  }
 
 } catch (Exception $ex) {
   PhabricatorStartup::didFatal("[Exception] ".$ex->getMessage());