Issue mozfr#593: add http headers with perf metrics

- New header: Transvision-perf
- Does not depend on DEBUG of PERF_CHECK to be checked because we don't impact the server logs with http headers and it allows getting perf metrics on production easily

app/classes/Transvision/Utils.php

@@ -340,26 +340,50 @@ public static function getOrSet($arr, $value, $fallback)
     }
 
     /**
-     * Utility function to log the memory used by a script
-     * and the time needed to generate the page
+     * Utility function to return the memory used by a script
+     * and the time needed to compute the data.
+     *
+     * @return array [Memory peak in bytes, Memory peak in MB, Computation time]
+     */
+    public static function getScriptPerformances()
+    {
+        $memory_peak_B    = memory_get_peak_usage(true);
+        $memory_peak_MB   = round(($memory_peak_B / (1024 * 1024)), 2);
+        $computation_time = round((microtime(true) - $_SERVER['REQUEST_TIME_FLOAT']), 4);
+
+        return [$memory_peak_B, $memory_peak_MB, $computation_time];
+    }
+
+    /**
+     * Utility function to log to stderr the memory used by a script
+     * and the time needed to generate the page.
+     * This is used only when the constants DEBUG and PERF_CHECK are set to True
+     * because we don't want to fill our logs with debug data on production.
      *
      * @return void
      */
     public static function logScriptPerformances()
     {
+        list($memory_peak_B, $memory_peak_MB, $computation_time) = self::getScriptPerformances();
+
         if (DEBUG && PERF_CHECK) {
-            $memory = 'Memory peak: '
-                      . memory_get_peak_usage(true)
-                      . ' ('
-                      . round((memory_get_peak_usage(true) / (1024 * 1024)), 2)
-                      . 'MB)';
-            $render_time = 'Elapsed time (s): '
-                           . round((microtime(true) - $_SERVER['REQUEST_TIME_FLOAT']), 4);
-            error_log($memory);
-            error_log($render_time);
+            error_log("Memory peak: {$memory_peak_B} ({$memory_peak_MB}MB)");
+            error_log("Elapsed time (s): {$computation_time}");
         }
     }
 
+    /**
+     * Utility function to log the memory used by a script
+     * and the time needed to generate the page as an HTTP header.
+     *
+     * @return void
+     */
+    public static function addPerformancesHTTPHeader()
+    {
+        list($memory_peak_B, $memory_peak_MB, $computation_time) = self::getScriptPerformances();
+        header("Transvision-perf: Memory: {$memory_peak_B} ({$memory_peak_MB}MB); Time: {$computation_time}s");
+    }
+
     /**
      * Generate a red to green color from a numeric value
      *

app/controllers/api.php

@@ -8,6 +8,8 @@
 if (! $request->isValidRequest()) {
     $json = $request->invalidAPICall();
     include VIEWS . 'json.php';
+
+    return;
 }
 
 switch ($request->getService()) {

app/inc/dispatcher.php

@@ -115,15 +115,27 @@
     $content = ob_get_contents();
     ob_end_clean();
 
+    ob_start();
     // display the page
     require_once VIEWS . 'templates/base.php';
+    $content = ob_get_contents();
+    ob_end_clean();
 } else {
+    ob_start();
     if (isset($view)) {
         include VIEWS . $view . '.php';
     } else {
         include CONTROLLERS . $controller . '.php';
     }
+    $content = ob_get_contents();
+    ob_end_clean();
 }
-
+ob_start();
+// Log script performance in the HTTP headers sent to the browser
+Utils::addPerformancesHTTPHeader();
+$perf_header = ob_get_contents();
 // Log script performance in PHP integrated developement server console
 Utils::logScriptPerformances();
+ob_end_clean();
+print $perf_header . $content;
+die;

app/views/json.php

@@ -10,7 +10,7 @@
 
 // We die here because we never want to send anything more after the JSON file
 $json_data = new Json;
-die($json_data->outputContent(
+print $json_data->outputContent(
     $json,
     isset($_GET['callback']) ? $_GET['callback'] : false
-));
+);

app/views/templates/base.php

@@ -1,8 +1,6 @@
 <?php
 namespace Transvision;
 
-ob_start();
-
 $check['repo']  = isset($check['repo']) ? $check['repo'] : 'aurora';
 $source_locale  = isset($source_locale) ? $source_locale : 'en-US';
 $locale         = isset($locale) ? $locale : 'fr';
@@ -64,7 +62,6 @@
 } else {
     $last_update = "<p>Data last updated: not available.</p>\n";
 }
-
 ?>
 <!doctype html>
 
@@ -153,11 +150,3 @@
 ?>
 </body>
 </html>
-
-<?php
-
-$content = ob_get_contents();
-
-ob_end_clean();
-
-print $content;

tests/units/Transvision/Utils.php

@@ -482,4 +482,16 @@ public function testRedirectToAPI($a, $b)
             ->string($obj->redirectToAPI())
                 ->isEqualTo($b);
     }
+
+    public function testGetScriptPerformances()
+    {
+        $obj  = new _Utils();
+        $data = $obj->getScriptPerformances();
+        $this
+            ->array($data)
+                ->size->isEqualTo(3)
+            ->integer($data[0])
+            ->float($data[1])
+            ->float($data[2]);
+    }
 }