[enh] Add Server-Timing header (#1637)

Server Timing specification: https://www.w3.org/TR/server-timing/

In the browser Dev Tools, focus on the main request, there are the responses per engine in the Timing tab.

1 files changed, 21 insertions, 0 deletions

diff --git a/searx/webapp.py b/searx/webapp.py
index 0e1fffe3f..856b013af 100644
--- a/searx/webapp.py
+++ b/searx/webapp.py
@@ -43,6 +43,7 @@ except:
     exit(1)
 from cgi import escape
 from datetime import datetime, timedelta
+from time import time
 from werkzeug.contrib.fixers import ProxyFix
 from flask import (
     Flask, request, render_template, url_for, Response, make_response,
@@ -402,6 +403,8 @@ def render(template_name, override_theme=None, **kwargs):
 
 @app.before_request
 def pre_request():
+    request.start_time = time()
+    request.timings = []
     request.errors = []
 
     preferences = Preferences(themes, list(categories.keys()), engines, plugins)
@@ -437,6 +440,21 @@ def pre_request():
             request.user_plugins.append(plugin)
 
 
+@app.after_request
+def post_request(response):
+    total_time = time() - request.start_time
+    timings_all = ['total;dur=' + str(round(total_time * 1000, 3))]
+    if len(request.timings) > 0:
+        timings = sorted(request.timings, key=lambda v: v['total'])
+        timings_total = ['total_' + str(i) + '_' + v['engine'] +
+                         ';dur=' + str(round(v['total'] * 1000, 3)) for i, v in enumerate(timings)]
+        timings_load = ['load_' + str(i) + '_' + v['engine'] +
+                        ';dur=' + str(round(v['load'] * 1000, 3)) for i, v in enumerate(timings)]
+        timings_all = timings_all + timings_total + timings_load
+    response.headers.add('Server-Timing', ', '.join(timings_all))
+    return response
+
+
 def index_error(output_format, error_message):
     if output_format == 'json':
         return Response(json.dumps({'error': error_message}),
@@ -515,6 +533,9 @@ def index():
     # UI
     advanced_search = request.form.get('advanced_search', None)
 
+    # Server-Timing header
+    request.timings = result_container.get_timings()
+
     # output
     for result in results:
         if output_format == 'html':