[Culprit-Finder] Add generator cache decorator.

appengine/findit/util_scripts/crash_queries/delta_test/delta_test.py

 # Copyright 2016 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.
 
 import json
 import os
 import pickle
 import subprocess
 
 from crash_queries import crash_iterator
@@ skipping 182 matching lines @@
     git_hash2 (str): A git hash of findit repository.
     start_date (str): Run delta test on testcases after (including)
       the start_date, format should be '%Y-%m-%d'.
     end_date (str): Run delta test on testcases before (not including)
       the end_date, format should be '%Y-%m-%d'.
     client_id (CrashClient): Possible values are 'fracas', 'cracas',
       'cluterfuzz'.
     app_id (str): Appengine app id to query.
     batch_size (int): Size of a batch that can be queried at one time.
     property_values (dict): Property values to query.
-       batch_size (int): The size of crashes that can be queried at one time.
+    batch_size (int): The size of crashes that can be queried at one time.
     verbose (bool): If True, print all the findit results.
   Return:
     (deltas, crash_count).
     deltas (dict): Mappings id to delta for each culprit value.
     crash_count (int): Total count of all the crashes.
   """
   head_branch_name = subprocess.check_output(
       ['git', 'rev-parse', '--abbrev-ref', 'HEAD']).replace('\n', '')
   try:
     deltas = {}
     crash_count = 0
     # Iterate batches of crash informations.
     for index, crashes in enumerate(
-        crash_iterator.IterateCrashes(client_id, app_id,
-                                      fields=CRASH_FIELDS,
-                                      property_values=property_values,
-                                      start_date=start_date,
-                                      end_date=end_date,
-                                      batch_size=batch_size,
-                                      batch_run=True)):
-
+        crash_iterator.CachedCrashIterator(client_id, app_id,
+                                           fields=CRASH_FIELDS,
+                                           property_values=property_values,
+                                           start_date=start_date,
+                                           end_date=end_date,
+                                           batch_size=batch_size,
+                                           batch_run=True)):
       results = []
       for git_hash in [git_hash1, git_hash2]:
         result_path = os.path.join(
             PREDATOR_RESULTS_DIRECTORY, delta_util.GenerateFileName(
                 client_id, property_values, start_date, end_date,
                 batch_size, index, git_hash))
         # Get the culprit results of this batch of crashes.
         results.append(GetResults(crashes, client_id, app_id,
                                   git_hash, result_path,
                                   verbose=verbose))
 
       crash_count += len(crashes)
       # Compute delta between 2 versions of culprit results for this batch.
       batch_deltas = GetDeltasFromTwoSetsOfResults(*results)
       # Print the deltas of the current batch.
       print '========= Delta of this batch ========='
       delta_util.PrintDelta(batch_deltas, len(crashes), app_id)
       deltas.update(batch_deltas)
 
     return deltas, crash_count
   finally:
     with open(os.devnull, 'w') as null_handle:
       subprocess.check_call(['git', 'checkout', head_branch_name],
                             stdout=null_handle,
                             stderr=null_handle)