Add show-all feature to the all-flake-occurrences page

appengine/chromium_try_flakes/handlers/all_flake_occurrences.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 from google.appengine.ext import ndb
 from google.appengine.ext.webapp import template
 
 from model.flake import Flake
 
 import datetime
 import logging
 import time
 import webapp2
 
 
 MAX_GROUP_DISTANCE = datetime.timedelta(days=3)
+MAX_OCCURRENCES_DEFAULT = 50
 
 
 def RunsSortFunction(s):  # pragma: no cover
   return s.time_finished
 
 def filterNone(elements):
   return [e for e in elements if e is not None]
 
-def show_all_flakes(flake):  # pragma: no cover
-  occurrence_keys = []
-  for o in flake.occurrences:
-    occurrence_keys.append(o)
-
-  occurrences = filterNone(ndb.get_multi(occurrence_keys))
+def show_all_flakes(flake, show_all):  # pragma: no cover
+  from_index = 0 if show_all else -MAX_OCCURRENCES_DEFAULT
+  occurrences = filterNone(ndb.get_multi(flake.occurrences[from_index:]))
 
   failure_runs_keys = []
   patchsets_keys = []
   flakes = []
   for o in occurrences:
     failure_runs_keys.append(o.failure_run)
     patchsets_keys.append(o.failure_run.parent())
     flakes.append(f for f in o.flakes if f.failure == flake.name)
 
   failure_runs = filterNone(ndb.get_multi(failure_runs_keys))
@@ skipping 29 matching lines @@
   if failure_runs_extended:
     current_group = [failure_runs_extended[0]]
     for f in failure_runs_extended[1:]:
       if current_group[-1].time_finished - f.time_finished < MAX_GROUP_DISTANCE:
         current_group.append(f)
       else:
         grouped_runs.append(current_group)
         current_group = [f]
     grouped_runs.append(current_group)
 
+  show_all_link = (len(flake.occurrences) > MAX_OCCURRENCES_DEFAULT and
+                   not show_all)
   values = {
     'flake': flake,
     'grouped_runs': grouped_runs,
+    'show_all_link': show_all_link,
     'time_now': datetime.datetime.utcnow(),
   }
 
   return template.render('templates/all_flake_occurrences.html', values)
 
 class AllFlakeOccurrences(webapp2.RequestHandler):  # pragma: no cover
   def get(self):
     key = self.request.get('key')
     flake = ndb.Key(urlsafe=key).get()
+    show_all = self.request.get('show_all', 0)
 
     if not flake:
       self.response.set_status(404, 'Flake with id %s does not exist' % key)
       return
 
-    self.response.write(show_all_flakes(flake))
+    self.response.write(show_all_flakes(flake, show_all))